MIT's Technology Review reports on an experimental thermal rectifier made from nanotubes that preferentially allows heat to flow more easily in one direction.
Scientists have been precisely controlling electric current for decades, building diodes and transistors that shuttle electrons around and make computers and cell phones work. But similarly controlling the flow of heat in solids stayed in the realm of theoretical physics--until now.
Alex Zettl and his colleagues at the University of California, Berkeley (UC Berkeley), have shown that it is possible to make a thermal rectifier, a device that directs the flow of heat, with nanotubes. If made practical, the rectifier, which the researchers described in last week's Science, could be used to manage the overheating of microelectronic devices and to help create energy-efficient buildings, and it could even lead to new ways of computing with heat.
The difference in the ease of heat flow they produced was not enormous. But it was a good start. Think of it as a material that has a higher insulation rating in one direction than another.
Imagine two sides of a wall. Sometimes the outside is hotter. Sometimes the inside is hotter. It is not hard to imagine scenarios where you would want heat to flow out when it is too hot but to never flow in. Or perhaps you'd want to control the direction of heat flow depending on the season. The ability to easily flip around a section of thermal rectifier wall material would come in very handy.
The use of thorium to power nuclear reactors holds out the prospect of a huge reduction in nuclear wastes, a nuclear fuel cycle that is much more proliferation resistant, lower costs, and a fuel that is many times more plentiful than uranium. Australian science writer Tim Dean examines the prospects for thorium reactors in a recent article and finds two avenues of technological advance that might make thorium powered nuclear reactors feasible. The more immediately promising approach uses a mixture of thorium with other radioactive materials.
The main stumbling block until now has been how to provide thorium fuel with enough neutrons to keep the reaction going, and do so in an efficient and economical way.
In recent years two new technologies have been developed to do just this.
One company that has already begun developing thorium-fuelled nuclear power is the aptly named Thorium Power, based just outside Washington DC. The way Thorium Power gets around the sub-criticality of thorium is to create mixed fuels using a combination of enriched uranium, plutonium and thorium.
At the centre of the fuel rod is the 'seed' for the reaction, which contains plutonium.
Wrapped around the core is the 'blanket', which is made from a mixture of uranium and thorium. The seed then provides the necessary neutrons to the blanket to kick-start the thorium fuel cycle. Meanwhile, the plutonium and uranium are also undergoing fission.
The primary benefit of Thorium Power's system is that it can be used in existing nuclear plants with slight modification, such as Russian VVER-1000 reactors. Seth Grae, president and chief executive of Thorium Power, and his team are actively working with the Russians to develop a commercial product by the end of this decade. They already have thorium fuel running in the IR-8 research reactor at the Kurchatov Institute in Moscow.
The potential to use existing reactors to burn thorium lowers the barrier to use of thorium. Success in existing reactors could catalyze the construction of new reactors designed to use thorium from their start.
He also goes over Carlo Rubbia's proposal to use a particle accelerator to shoot a stream of protons into a thorium reactor.
AN ALTERNATIVE DESIGN does away with the requirements for uranium or plutonium altogether, and relies on thorium as its primary fuel source. This design, which was originally dubbed an Energy Amplifier but has more recently been named an Accelerator Driven System (ADS), was proposed by Italian Nobel physics laureate Carlos Rubbia, a former director of one of the world's leading nuclear physics labs, CERN, the European Organisation for Nuclear Research.
An ADS reactor is sub-critical, which means it needs help to get the thorium to react. To do this, a particle accelerator fires protons at a lead target. When struck by high-energy protons the lead, called a spallation target, releases neutrons that collide with nuclei in the thorium fuel, which begins the fuel cycle that ends in the fission of U-233.
Governments should accelerate research into new nuclear reactor designs that promise to lower wastes and reduce costs.
Operating commercial buildings consumes a sixth of all the energy used in the Western world. Getting rid of air conditioning could cut that consumption by as much as a third -- but people don't like to work in sweltering heat.
So MIT researchers are making computer-based tools to help architects design commercial buildings that cool occupants with natural breezes.
Buildings can be designed to encourage airflow and maintain temperatures that minimize or eliminate the need for conventional air-conditioning systems. "That approach improves air quality, ensures good ventilation and saves both energy and money," said Professor Leon R. Glicksman, director of MIT's Building Technology Program. Indeed, studies have shown that people generally feel more comfortable in a naturally ventilated building than in an air-conditioned one.
The researchers studied a buildig in Luton Britain which cools using natural ventilation and built a computer model to simulate how the building's air circulates. They were able to find ways to improve the design of natural ventilization designs and think they can cut air conditioning costs in half.
"We found what we initially thought were some strange results when we did the full-scale-building tests," said Glicksman. "But using the computer model, we now understand the physics of it, first of all confirming that it's a real effect and second, why it occurred." Such effects can be corrected by building in automatic control systems that, for example, turn on the vent fans when needed to ensure the continuous flow of fresh air.
Based on these findings, the MIT team is formulating a simple, user-friendly computer tool that will help architects design for natural ventilation. They plan to incorporate the tool into their "Design Advisor," a web site (designadvisor.mit.edu) that lets architects and planners see how building orientation, window technology, and other design choices will affect energy use and occupant comfort.
Natural ventilation does, of course, have its limits. For example, during hot summers in Hong Kong or even Boston, conventional air conditioning would still be needed. But just using natural ventilation during spring and fall in Boston, for example, could save at least half the energy now used for year-round air conditioning, the researchers estimate.
Most popular discussions about energy costs tend to revolve around cars and other vehicles. But boosting efficiency of new building designs seems to me an easier goal to achieve and does not require so many basic breakthroughs in science and technology.
Here's an unusual approach for generating electricty in a car: Imagine burning fuel to generate an extremely bright light so that the light can strike photodiodes to generate electricity for the various subsystems in cars that need electricity.
MIT researchers are trying to unleash the promise of an old idea by converting light into electricity more efficiently than ever before.
The research is applying new materials, new technologies and new ideas to radically improve an old concept -- thermophotovoltaic (TPV) conversion of light into electricity. Rather than using the engine to turn a generator or alternator in a car, for example, the new TPV system would burn a little fuel to create super-bright light. Efficient photo diodes (which are similar to solar cells) would then harvest the energy and send the electricity off to run the various lighting, electrical and electronic systems in the car.
Such a light-based system would not replace the car's engine. Instead it would supply enough electricity to run subsystems, consuming far less fuel than is needed to keep a heavy, multi-cylinder engine running, even at low speed. Also, the TPV system would have no moving parts; no cams, no bearings, no spinning shafts, so no energy would be spent just to keep an engine turning over, even at idle.
"What's new here is the opportunity for a much more effective energy system to be created using new semiconductor materials and the science of photonics," said Professor John Kassakian, director of the Laboratory for Electromagnetic and Electronic Systems (LEES), where the work was conducted. The idea is to create intense light, let it shine on new types of photo diodes to make electricity, and bounce any excess light back to the light source to help keep it glowing-hot. In theory, Kassakian said, efficiency could be as high as 40 percent or 50 percent.
Of course the "In theory" part means they haven't yet achieved such a high level of efficiency. But I'm surprised that burning fuels could be made to emit such a high percentage of their energy as photons to even make possible such a high efficiency for electric generation. If such a high level of efficiency could be achieved then it would have a lot of other practical uses. How about burning fuel to generate electricity for houses or commercial buildings? Or why not use the electricity to power the car rather than use an internal combustion engine?
An article in Technology Review reports the Altair Nanotechnologies lithium ion battery has the fast charging and discharging needed for all electric vehicles.
Advances in lithium-ion battery technology over the last few years have experts and enthusiasts alike wondering if the new batteries may soon make high-performance electric vehicles widely available. Now one company, Altair Nanotechnologies of Reno, NV, has announced plans to start testing its new batteries in prototype electric vehicles, with road tests scheduled to begin by year-end.
The batteries can be recharged in 6 to 8 minutes.
Also, Gotcher says an electric vehicle using their batteries could charge in about the time it takes to fill a tank of gas and buy a cup of coffee and snack -- six to eight minutes.
...
Gotcher says the new battery materials can be produced for about the same cost as conventional lithium-ion materials, but will have two to three times the lifespan of today's batteries.
Lithium is lightweight. Lithium-based batteries could make electric cars feasible.
Nanoparticles that provide much more surface area allow the batteries to charge and discharge much more rapidly.
The added surface area of nanoscale particles on electrode materials helps the ions escape, freeing more of them to travel and provide bursts of power or quick recharging.
Some electrochemists think lightweight high energy density batteries are within the realm of the physically possible. Development of long lasting, quick charging, cost competitive, and lightweight batteries could make electric cars commonplace. Such a development would greatly reduce our dependence on oil and allow any energy source that can produce electricity (e.g. nuclear, coal, wind, solar) to replace oil for most transportation needs.
Will coal ever become a clean source of energy?
A new chemical process for removing unwanted minerals from coal could lead to reductions in carbon dioxide emissions from coal-fired power stations.
There is already a way of burning coal in a cleaner, more efficient fashion that would reduce carbon dioxide emissions: this is where the coal is turned into a gas and used to drive a turbine. However, problems with cleaning the coal before it is burnt have made generating electricity in this way very expensive. This new chemical process could make it more commercially viable.
Under development by a University of Nottingham team with EPSRC funding, the new approach involves using chemicals to dissolve unwanted minerals in the coal and then regenerating the chemicals again for re-use. This avoids the expense of using fresh chemicals each time, as well as the need to dispose of them, which can have an environmental impact. By removing unwanted minerals before the coal enters the power plant the new process helps protect the turbines from corrosive particles.
The aim is to cut unwanted minerals in coal from around 10% to below 0.05%, making the coal 'ultra clean'. Removing these minerals before using the coal to generate power prevents the formation of harmful particles during electricity production. To do this, the team is using specific chemicals to react with the minerals to form soluble products which can be separated from the coal by filtration. This process is known as 'leaching'. Hydrofluoric acid is the main chemical being tested. The chemicals not only dissolve the minerals but are also easy to regenerate from the reaction products, so they are constantly recycled. It is this aspect that has largely been overlooked in past research, but is virtually essential if chemical coal-cleaning is to be environmentally and commercially viable.
With half of US electricity (and probably most mercury emissions) coming from coal and a strong possibility that percentage will even increase I'm for anything that'll make coal cleaner. But in my view for decades the regulatory pressure on the coal burners hasn't been tough enough.
One of the reasons I favor nuclear power is precisely because coal plants pollute so much.
As for the argument that terrorists will some day explode a nuclear bomb next to a nuclear plant: First off, I think Islamic terrorists really won't be able to resist the temptation to nuke New York City and DC first. Second, the terrorists already have nuclear power plants to nuke. Third, imagine (and this isn't going to happen until after nukes have gone off) all the existing nuclear power plants were dismantled precisely to deny the terrorists nukes as targets. Well, there goes NYC or DC then.
One solution to the nuke plant as terrorist nuke bomb target would be to build nuclear power plants underground. But, again, we'll still lose millions of people if terrorists can get nukes to a Western country.
My guess is if terrorists ever set off a nuke the Western response will be so severe and far reaching that this will happen only once. I'm far more afraid of terrorists releasing genetically engineered pathogens than I am of terrorist nukes.
If you place a high probability on huge costs from global warming then go back and read my post "Planned Coal Plants Reverse 5 Times CO2 Impact Of Kyoto Protocol". So even if burning cleaned up coal reduces CO2 by as much as 20% for a given amount of generated electricity the growth in total coal demand is going to be so great that CO2 emissons from coal will still rise. The only way to stop the CO2 emissions would involve expensive CO2 sequestering technology. Anyone for 2 or more cents per kwh of electricity just for CO2 emissions elimination? I'm not expecting that to happen in the US or China for the next 10 years. Beyond that point I'm still not expecting it in China. Ditto India.
You have three current choices for satisfying most future demand growth in electric energy: Nuclear, coal, or higher prices. Accelerated energy research across a broad array of technologies could produce more choices in the future.
Has GM been pursuing hydrogen as a Machiavellian intrigue to delay a shift to a better technology? I've never believed that. But some people have made this argument in the comments sections of previous posts. Well, suppose that hydrogen vehicles turn out to work and General Motors puts them into production (see below). Paranoid conspiracists then could always argue that the success was an accident and that the plotters thought that scientists wouldn't so quickly come up with workable solutions. Conspiracy theorising can pretty much explain away any evidence and make it fit a conspiracy theory. Chemists have achieved sufficient density of hydrogen in a storage material for transportation needs but their method still requires a very low temperature.
Chemists at UCLA and the University of Michigan report an advance toward the goal of cars that run on hydrogen rather than gasoline. While the U.S. Department of Energy estimates that practical hydrogen fuel will require concentrations of at least 6.5 percent, the chemists have achieved concentrations of 7.5 percent — nearly three times as much as has been reported previously — but at a very low temperature (77 degrees Kelvin).
The research, scheduled to be published in late March in the Journal of the American Chemical Society, could lead to a hydrogen fuel that powers not only cars, but laptop computers, cellular phones, digital cameras and other electronic devices as well.
"We have a class of materials in which we can change the components nearly at will," said Omar Yaghi, UCLA professor of chemistry, who conducted the research with colleagues at the University of Michigan. "There is no other class of materials where one can do that. The exciting discovery we are reporting is that, using a new material, we have identified a clear path for how to get above seven percent of the material's weight in hydrogen."
The materials, which Yaghi invented in the early 1990s, are called metal-organic frameworks (MOFs), pronounced "moffs," which are like scaffolds made of linked rods — a structure that maximizes the surface area. MOFs, which have been described as crystal sponges, have pores, openings on the nanoscale in which Yaghi and his colleagues can store gases that are usually difficult to store and transport. MOFs can be made highly porous to increase their storage capacity; one gram of a MOF has the surface area of a football field! Yaghi's laboratory has made more than 500 MOFs, with a variety of properties and structures.
Yaghi sounds optimistic about solving the temperature problem using his metal-organic frameworks (MOFs) approach. He also does not see cost as an obstacle.
"We have achieved 7.5 percent hydrogen; we want to achieve this percent at ambient temperatures," said Yaghi, a member of the California NanoSystems Institute. "We can store significantly more hydrogen with the MOF material than without the MOF."
MOFs can be made from low-cost ingredients, such as zinc oxide — a common ingredient in sunscreen — and terephthalate, which is found in plastic soda bottles.
"MOFs will have many applications. Molecules can go in and out of them unobstructed. We can make polymers inside the pores with well-defined and predictable properties. There is no limit to what structures we can get, and thus no limit to the applications."
In the push to develop hydrogen fuel cells to power cars, cell phones and other devices, one of the biggest challenges has been finding ways to store large amounts of hydrogen at the right temperatures and pressures. Yaghi and his colleagues have now demonstrated the ability to store large amounts of hydrogen at the right pressure; in addition, Yaghi has ideas about how to modify the rod-like components to store hydrogen at ambient temperatures (0–45°C).
"A decade ago, people thought methane would be impossible to store; that problem has been largely solved by our MOF materials. Hydrogen is a little more challenging than methane, but I am optimistic."
In a separate story "Seicmic" points me to an announcement by General Motors that they expect to start selling hydrogen cars in 4 to 9 years. (same article here)
General Motors Corp has made major steps in developing a commercially viable hydrogen-powered vehicle and expects to get the emission-free cars into dealerships in the next four to nine years, a spokesman told Agence France-Presse.
GM also expects it will be able to 'equal or better gas engines in terms of cost, durability and performance' once it is able to ramp up volume to at least 500,000 vehicles a year, spokesman Scott Fosgard said.
Hydrogen storage containers, like batteries, are just a way to store energy. The cheapest way to make hydrogen currently is from fossil fuels. But a workable way to store hydrogen at room temperature would, like better batteries, make it a lot easier to end the dependence of cars on oil. Advances in solar, wind, and nuclear power will eventually lower their costs far enough to make them cheaper sources of energy for producing hydrogen. Also, a cost effective hydrogen storage technology, just like cheaper batteries, would allow solar wind to supply a larger fraction of all used energy because the ability to store energy helps any energy source that is not continuously available.
We still also need a big acceleration of research and development on both photovoltaics and nuclear reactor designs. We need cheaper non-fossil fuels energy sources. The storage problems are not going to be what prevents the transition away from fossil fuels. Higher costs of alternatives remain the biggest obstacle to phasing out fossil fuels.
Can an easy way to tap fusion energy be developed? A new study on a way to create fusion with waves has found neutrons were generated by this approach.
Troy, N.Y. — A team of researchers from Rensselaer Polytechnic Institute, Purdue University, and the Russian Academy of Sciences has used sound waves to induce nuclear fusion without the need for an external neutron source, according to a paper in the Jan. 27 issue of Physical Review Letters. The results address one of the most prominent questions raised after publication of the team’s earlier results in 2004, suggesting that “sonofusion” may be a viable approach to producing neutrons for a variety of applications.
By bombarding a special mixture of acetone and benzene with oscillating sound waves, the researchers caused bubbles in the mixture to expand and then violently collapse. This technique, which has been dubbed “sonofusion,” produces a shock wave that has the potential to fuse nuclei together, according to the team.
But other scientists were skeptical of the results from that earlier round of sonofusion experiments.
In response to earlier criticisms this group of scientists has tried a sonofusion approach that did not use a external source of neutrons.
The telltale sign that fusion has occurred is the production of neutrons. Earlier experiments were criticized because the researchers used an external neutron source to produce the bubbles, and some have suggested that the neutrons detected as evidence of fusion might have been left over from this external source.
“To address the concern about the use of an external neutron source, we found a different way to run the experiment,” says Richard T. Lahey Jr., the Edward E. Hood Professor of Engineering at Rensselaer and coauthor of the paper. “The main difference here is that we are not using an external neutron source to kick the whole thing off.”
In the new setup, the researchers dissolved natural uranium in the solution, which produces bubbles through radioactive decay. “This completely obviates the need to use an external neutron source, resolving any lingering confusion associated with the possible influence of external neutrons,” says Robert Block, professor emeritus of nuclear engineering at Rensselaer and also an author of the paper.
The experiment was specifically designed to address a fundamental research question, not to make a device that would be capable of producing energy, Block says. At this stage the new device uses much more energy than it releases, but it could prove to be an inexpensive and portable source of neutrons for sensing and imaging applications.
To verify the presence of fusion, the researchers used three independent neutron detectors and one gamma ray detector. All four detectors produced the same results: a statistically significant increase in the amount of nuclear emissions due to sonofusion when compared to background levels.
A way to produce energy from fusion would put a pretty permanent end to our energy woes. But using more conventional approaches to creating the conditions under which fusion happens looks like it will take decades before fusion reactors are a reality. Can a less conventional approach provide a cost effective solution much sooner? If it did the implications would be staggering. Energy is the only resource whose limits matter for what humanity can accomplish. There is no single mineral whose short supply would stop or reverse economic growth. With enough energy we can mold many types of matter into states that would allow those types of matter to substitute for whatever is in short supply.
Buildings could be pre-cooled in the mornings.
Engineers have developed a method for "precooling" small office buildings and reducing energy consumption during times of peak demand, promising not only to save money but also to help prevent power failures during hot summer days.
The method has been shown to reduce the cooling-related demand for electricity in small office buildings by 30 percent during hours of peak power consumption in California's sweltering summer climate. Small office buildings represent the majority of commercial structures, so reducing the electricity demand for air conditioning in those buildings could help California prevent power-capacity problems like those that plagued the state in 2000 and 2001, said James Braun, a Purdue University professor of mechanical engineering.
The results focus on California because the research was funded by the California Energy Commission, but the same demand-saving approach could be tailored to buildings in any state.
"California officials are especially concerned about capacity problems in the summertime," said Braun, whose research is based at Purdue's Ray W. Herrick Laboratories.
A building's physical mass could get cooled down in the morning and therefore help keep the building cooler later in the day.
Findings will be detailed in three papers to be presented on Monday (Jan. 23) during the Winter Meeting of the American Society of Heating, Refrigerating and Air-Conditioning Engineers in Chicago. Two of the papers were written by Braun and doctoral student Kyoung-Ho Lee. The other paper was written by researchers at the Lawrence Berkeley National Laboratory, a U.S. Department of Energy laboratory managed by the University of California.
The method works by running air conditioning at cooler-than-normal settings in the morning and then raising the thermostat to warmer-than-normal settings in the afternoon, when energy consumption escalates during hot summer months. Because the building's mass has been cooled down, it does not require as much energy for air conditioning during the hottest time of day, when electricity is most expensive and in highest demand.
Better ways could be found to do this where humans are less affected by temperature changes. A building could get constructed (or upgraded) to contain a large mass (made out of lead perhaps?) that gets cooled at night more than the air does. The air conditioner could cool it down way below normal room temperature (say close to freezing or even below). Granted the method reported here requires only an upgrade to the thermostat electronics. But it has drawbacks and limits on what it can achieve. Demand could get shifted for more hours or even days if a high density mass was cooled in the summer. Also using solar or wind energy such a mass could get heated in the winter whenever the wind blew or the sun shined.
Basically they shift demand from the afternoon to the morning.
Precooling structures so that it takes less power to cool buildings during times of peak demand is not a new concept. But researchers have developed a "control algorithm," or software that determines the best strategy for changing thermostat settings in a given building in order to save the most money. Research has shown that using a thermal mass control strategy improperly can actually result in higher energy costs. Factors such as a building's construction, the design of its air-conditioning system, number of windows, whether the floors are carpeted, and other information must be carefully considered to determine how to best use the method.
"The idea is to set the thermostat at 70 degrees Fahrenheit for the morning hours, and then you start adjusting that temperature upwards with a maximum temperature of around 78 during the afternoon hours, " Braun said. "When the thermostat settings are adjusted in an optimal fashion, the result is a 25 percent to 30 percent reduction in peak electrical demand for air conditioning.
But currently there is little incentive for most businesses to shift a portion of their electricity demand from afternoon to morning. What is needed are utility rate structure changes to implement dynamic pricing so that current price comes closer to the marginal price. That'd make electricity much more expensive during peak times but cheaper during low usage times.
"If you couple this reduction in demand with a utility rate structure that charges more during critical peak periods, utility costs will drop. Without such a change in peak rates, though, the actual impact on operating costs is relatively small, with about $50 in annual savings per 1,000 square feet of building space.
"A good incentive for reducing peak demand would be to impose a higher peak demand charge for the critical peak-pricing periods, and if customers reduce their consumption during these times, they are rewarded with lower energy costs for the rest of the time."
Some of the technology developments needed to allow demand shifting are pretty low tech. It is easy to develop a computer program that will vary the thermostat setting as a function of the time or day and not much harder to develop software and a communications system to broadcast marginal prices so that companies could adjust their demand as a function of current electric prices. The bigger obstacle is at the policy level, not the technological level.
If public utilities were to more widely implement dynamic pricing of electricity then businesses would pretty quickly implement lower tech methods of adjusting demand. At the same time, incentives would then come into existence to develop better technologies for shifting demand. For example, the value of better battery technologies would increase and therefore dynamic pricing would accelerate the development of better battery technologies.
An acceleration of battery technology development in response to dynamic electric pricing would eventually accelerate the shift toward hybrid and pure electric cars. Increased demand for electric power storage technologies would increase investment to develop such technologies.
The deployment of technologies and business practices that allow rapid demand adjustment in response to dynamic pricing would be bullish for both solar and wind electric power. Businesses would treat rises in electric prices that happen when the sun isn't shining or the wind isn't blowing as reason to shift business activity (or accumulation of energy in batteries or cool or heat in previously mentioned building masses) toward the times when the sun does shine and the wind does blow. To put it another way: if demand can be made more dynamic by market forces then the inconstancy of solar and wind power would pose less of a problem for their wider spread adoption. Greater market forces in electric power distribution would accelerate energy technology development and deployment.
Ewing, NJ | 4 January 2006 -- Global Photonic Energy Corporation (GPEC), developer of organic photovoltaic (OPVtm) technology for ultra-low cost high power solar cells, announced that the company's research partners at Princeton University and the University of Southern California (USC) have achieved a new record in an organic solar cell that is responsive to light in the near infrared (NIR) range of the solar spectrum. NIR radiation is invisible to the human eye.
Many so-called "night vision" devices operate by sensing infrared light which is emitted by warm objects and makes up a substantial portion of all energy reaching the earth from the sun. Under only NIR radiation, the Princeton solar cell would appear to be generating power in the dark -- as the human eye is only sensitive to visible light.
This latest achievement is the highest level of conversion performance yet achieved for an organic solar cell in the IR portion of the solar spectrum. The Company's researchers detail this latest achievement in the December 2 issue of Applied Physics Letters.
The Global thirst for energy is continually expanding. Renewable energy sources have experienced rapid growth in recent years as costs have improved. Global solar cell production has grown over 20% annually for the last 20 years, reaching sales of $6 billion in 2004. This strong growth has resulted in a world-wide shortage of semiconductor silicon driving 2005 solar cell prices higher. Cost is a critical factor in the continued expansion of the solar cell industry. Currently, solar-generated power is four to six times more expensive to consumers than coal-generated power.
Silicon crystals are too expensive as a starting material for making photovoltaics cells. The development of organic photovoltaic materials holds the potential for much cheaper photovoltaics. These Princeton and USC researchers (see below) are not only pursuing organically based photovoltaics but they are also pursuing the development of much higher efficiency photovoltaics. The odds are developing a way to double or triple the conversion efficiency of organic photovoltaics will not increase costs per square meter of materials anywhere near as much. So cost per unit of energy produced will drop.
Recent efforts have focused on the use of "organic" materials. Organic semiconductors contain the ubiquitous element carbon and are capable of achieving ultra-low cost solar power generation that is competitive with traditional fossil fuel sources. Organic materials have the potential to achieve ultra-low cost production costs and high power output. The materials are ultra-thin and flexible and can be applied to large, curved or spherical surfaces. Because the layers are so thin, transparent solar cells can be applied to windows creating power-generating glass that retains its basic functionality.
GPEC sponsors research by Professor Stephen R. Forrest at Princeton and Professor Mark E. Thompson at USC. Professor Forrest's research team has focused on organic "small-molecule" devices that are assembled literally a molecule at a time in highly efficient nanostructures. These devices have layers and/or structural elements that can be extremely small -- at only 0.5 billionth of a meter thick and can be applied to low-cost, flexible plastic surfaces.
These scientists want to boost absorption of photons near the infrared frequency range because that is where much of the energy in sunlight is found.
One challenge for organic solar cells has been the efficient capture and conversion of sunlight. Sunlight consists of photons (particles of light) that are delivered across a spectrum that includes invisible ultraviolet (UV) light, the visible spectrum of colors -- violet, indigo, blue, green, yellow, orange and red -- and the invisible infrared or IR spectrum. The amount of incoming photons across the UV, visible and IR spectrums is about 4%, 51% and 45%, respectively. The photons absorbed by a solar cell directly impacts the power output. To achieve high power output, solar devices must take advantage of as much of the solar spectrum as possible. Typical organic solar cells absorb only a fraction of the visible portion of the solar spectrum. In fact, the best organic solar cells absorb and convert only about 1/3 of the total available light utilizing primarily the visible portion of the spectrum.
"This latest device demonstrates that significant power can be harvested from the IR and near-IR portion of the solar spectrum.", said Dr. Stephen R. Forrest. "In fact, this novel approach has the potential to double the power output of organic solar devices with power harvested from the near-IR and IR portion of the solar spectrum. With this approach we are well on our way to power levels exceeding 100 watts per meter", Forrest concluded.
Imagine organic photovoltaics coating windows especially in hot climates. Instead of letting in the infrared frequencies the photovoltaics convert those photons to useful electricity. So instead of heating a building and thereby increasing the demand for air conditioning the photovoltaic coating could keep out heat and turn it into electricity that would power air conditioners.
In the longer run imagine nanomaterials-based photovoltaic coatings that could adjust how much electricity they let into a room or into a car depending on whether a human was in the room or car. When a human was present the material could become transparent to allow ing lighting or provide the ability to look outside. House and car windows could be turned dark or transparent by dynamically changing nanostructures. When no one was in a car or house room the windows could become dark and that would mean the nanocoatings were absorbing the light that hit them and turning them into electric to charge batteries (which of course will be made from some nanomaterials as well). So on a hot summer day your car's seats wouldn't get as hot. Also, the inside trim wouldn't degrade as rapidly due to sun damage.
GPEC is funded by electric power industry venture capitalists Kuhns Brothers.
LOS ALAMOS, N.M., January 4, 2006 -- Los Alamos National Laboratory scientists have discovered that a phenomenon called carrier multiplication, in which semiconductor nanocrystals respond to photons by producing multiple electrons, is applicable to a broader array of materials that previously thought. The discovery increases the potential for the use of nanoscrystals as solar cell materials to produce higher electrical outputs than current solar cells.
In papers published recently in the journals Nature Physics and Applied Physics Letters, the scientists demonstrate that carrier multiplication is not unique to lead selenide nanocrystals, but also occurs with very high efficiency in nanocrystals of other compositions, such as cadmium selenide. In addition, these new results shed light on the mechanism for carrier multiplication, which likely occurs via the instantaneous photoexcitation of multiple electrons. Such a process has never been observed in macroscopic materials and it explicitly relies on the unique physics of the nanoscale size regime.
According to Richard Schaller, a Los Alamos scientist on the team, "Our research of carrier multiplication in previous years was really focused on analyzing the response of lead selenide nanocrystals to very short laser pulses. We discovered that the absorption of a single photon could produce two or even three excited electrons. We knew, somewhat instinctively, that carrier multiplication was probably not confined to lead selenide, but we needed to pursue the question."
Lead project scientist Victor Klimov explains, "Carrier multiplication actually relies upon very strong interactions between electrons squeezed within the tiny volume of a nanoscale semiconductor particle. That is why it is the particle size, not its composition that mostly determines the efficiency of the effect. In nanosize crystals, strong electron-electron interactions make a high-energy electron unstable. This electron only exists in its so-called 'virtual state' for an instant before rapidly transforming into a more stable state comprising two or more electrons."
Sooner or later some scientists are going to discover high efficiency photovoltaic materials that can be made very cheaply. This sort of research should get more funding. The benefits will be enormous when they come. Why not get the benefits sooner?
Also see my previous post on the work of Schaller and Klimov from May 2005: "Quantum Dots May Boost Photovoltaic Efficiency To 65%".
The days of Edison's light bulb are numbered.
Take an LED that produces intense, blue light. Coat it with a thin layer of special microscopic beads called quantum dots. And you have what could become the successor to the venerable light bulb.
The resulting hybrid LED gives off a warm white light with a slightly yellow cast, similar to that of the incandescent lamp.
Until now quantum dots have been known primarily for their ability to produce a dozen different distinct colors of light simply by varying the size of the individual nanocrystals: a capability particularly suited to fluorescent labeling in biomedical applications. But chemists at Vanderbilt University discovered a way to make quantum dots spontaneously produce broad-spectrum white light. The report of their discovery, which happened by accident, appears in the communication "White-light Emission from Magic-Sized Cadmium Selenide Nanocrystals" published online October 18 by the Journal of the American Chemical Society.
In the last few years, LEDs (short for light emitting diodes) have begun replacing incandescent and fluorescent lights in a number of niche applications. Although these solid-state lights have been used for decades in consumer electronics, recent technological advances have allowed them to spread into areas like architectural lighting, traffic lights, flashlights and reading lights. Although they are considerably more expensive than ordinary lights, they are capable of producing about twice as much light per watt as incandescent bulbs; they last up to 50,000 hours or 50 times as long as a 60-watt bulb; and, they are very tough and hard to break. Because they are made in a fashion similar to computer chips, the cost of LEDs has been dropping steadily. The Department of Energy has estimated that LED lighting could reduce U.S. energy consumption for lighting by 29 percent by 2025, saving the nation's households about $125 million in the process.
Doesn't that amount of savings seem small? Does the United States really spend such a small amount of money on incandescent light electricity?
LEDs are more efficient because they do not emit in the infrared.
Of course, quantum dots, like white LEDs, have the advantage of not giving off large amounts of invisible infrared radiation unlike the light bulb. This invisible radiation produces large amounts of heat and largely accounts for the light bulb's low energy efficiency.
The breakthrough came accidentally and was the result of making quantum dots smaller than they are usually made.
Bowers works in the laboratory of Associate Professor of Chemistry Sandra Rosenthal. The accidental discovery was the result of the request of one of his coworkers, post-doctoral student and electron microscopist James McBride, who is interested in the way in which quantum dots grow. He thought that the structure of small-sized dots might provide him with new insights into the growth process, so he asked Bowers to make him a batch of small-sized quantum dots that he could study.
"I made him a batch and he came back to me and asked if I could make them any smaller," says Bowers. So he made a second batch of even smaller nanocrystals. But once again, McBride asked him for something smaller. So Bowers made a batch of the smallest quantum dots he knew how to make. It turns out that these were crystals of cadmium and selenium that contain either 33 or 34 pairs of atoms, which happens to be a "magic size" that the crystals form preferentially. As a result, the magic-sized quantum dots were relatively easy to make even though they are less than half the size of normal quantum dots.
After Bowers cleaned up the batch, he pumped a solution containing the nanocrystals into a small glass cell and illuminated it with a laser. "I was surprised when a white glow covered the table," Bowers says. "I expected the quantum dots to emit blue light, but instead they gave off a beautiful white glow."
"The exciting thing about this is that it is a nano-nanoscience phenomenon," Rosenthal comments. In the larger nanocrystals, which produce light in narrow spectral bands, the light originates in the center of the crystal. But, as the size of the crystal shrinks down to the magic size, the light emission region appears to move to the surface of the crystal and broadens out into a full spectrum.
As all matter of materials get made at smaller sizes more interesting, unexpected, and useful behaviors of materials will be found.
Yet another promising photovoltaics fabrication method:
Imagine a future in which the rooftops of residential homes and commercial buildings can be laminated with inexpensive, ultra-thin films of nano-sized semiconductors that will efficiently convert sunlight into electrical power and provide virtually all of our electricity needs. This future is a step closer to being realized, thanks to a scientific milestone achieved at the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab).
Researchers with Berkeley Lab and the University of California, Berkeley, have developed the first ultra-thin solar cells comprised entirely of inorganic nanocrystals and spin-cast from solution. These dual nanocrystal solar cells are as cheap and easy to make as solar cells made from organic polymers and offer the added advantage of being stable in air because they contain no organic materials.
Their point about stability is important. Think about how plastic and rubber (made from hydrocarbons) degrade under exposure to sunlght. The longer photovoltaics last the better the economics become. Also, rather than bolting the photovoltaics onto structure surfaces in separate apparatuses if the photovoltaics could get built right into structure surfaces even larger cost reductions become possible.
"Our colloidal inorganic nanocrystals share all of the primary advantages of organics -- scalable and controlled synthesis, an ability to be processed in solution, and a decreased sensitivity to substitutional doping - while retaining the broadband absorption and superior transport properties of traditional photovoltaic semiconductors," said Ilan Gur, a researcher in Berkeley Lab's Materials Sciences Division and fourth-year graduate student in UC Berkeley's Department of Materials Science and Engineering.
Gur is the principal author of a paper appearing in the October 21 issue of the journal Science that announces this new development. He is a doctoral candidate in the research group of Paul Alivisatos, director of Berkeley Lab's Materials Sciences Division, and the Chancellor's Professor of Chemistry and Materials Science at UC Berkeley. Alivisatos is a leading authority on nanocrystals and a co-author of the Science paper. Other co-authors are Berkeley Lab's Neil A. Fromer and UC Berkeley's Michael Geier.
While the initial conversion efficiency is still low the process lends itself to scaling up at low cost should they find ways to boost conversion efficiency.
In this paper, the researchers describe a technique whereby rod-shaped nanometer-sized crystals of two semiconductors, cadmium-selenide (CdSe) and cadmium-telluride (CdTe), were synthesized separately and then dissolved in solution and spin-cast onto a conductive glass substrate. The resulting films, which were about 1,000 times thinner than a human hair, displayed efficiencies for converting sunlight to electricity of about 3 percent. This is comparable to the conversion efficiencies of the best organic solar cells, but still substantially lower than conventional silicon solar cell thin films.
"We obviously still have a long way to go in terms of energy conversion efficiency," said Gur, "but our dual nanocrystal solar cells are ultra-thin and solution-processed, which means they retain the cost-reduction potential that has made organic cells so attractive vis-a-vis their conventional semiconductor counterparts."
Silicon crystals that are used in manufacturing current silicon photovoltaic cells represent a large fraction of total photovoltaics costs. Approaches that avoid the need to make lots of relatively thick crystals are probably essential for driving down the cost of photovoltaics far enough to make photovoltaic installations ubiquitous. So any new photovoltaic fabrication method that avoids the use of silicon crystals warrants notice.
Another advantage of this approach is low weight. Thin film solar cells with high durability and low weight could potentially get coated onto electric and hybrid car surfaces to recharge batteries.
Compare this report to my previous post UCLA Team Cuts Photovoltaics Cost With Plastics. Note the 15 to 20 year life expectancy for the UCLA approach. The Lawrence Berkeley material would probably last longer. But which group can boost conversion efficiency the most and the soonest?
Purdue University researchers have discovered a way to operate uranium pellets in nuclear reactors at lower temperature which also will allow the pellets to last longer before needing replacement.
WEST LAFAYETTE, Ind. – Purdue University nuclear engineers have developed an advanced nuclear fuel that could save millions of dollars annually by lasting longer and burning more efficiently than conventional fuels, and researchers also have created a mathematical model to further develop the technology.
New findings regarding the research will be detailed in a peer-reviewed paper to be presented on Oct. 6 during the 11th International Topical Meeting on Nuclear Reactor Thermal Hydraulics in Avignon, France. The paper was written by Shripad Revankar, an associate professor of nuclear engineering; graduate student Ryan Latta; and Alvin A. Solomon, a professor of nuclear engineering.
The research is funded by the U.S. Department of Energy and focuses on developing nuclear fuels that are better at conducting heat than conventional fuels. Current nuclear fuel is made of a material called uranium dioxide with a small percentage of a uranium isotope, called uranium-235, which is essential to induce the nuclear fission reactions inside current reactors.
Better heat conduction allows cooler internal operating temperature and hence less cracking and longer life. This could reduce the interval between refuelings, allowing reactors to have more up-time and also reduce fuel consumption.
"Although today's oxide fuels are very stable and safe, a major problem is that they do not conduct heat well, limiting the power and causing fuel pellets to crack and degrade prematurely, necessitating replacement before the fuel has been entirely used," Solomon said.
Purdue researchers, led by Solomon, have developed a process to mix the uranium oxide with a material called beryllium oxide. Pellets of uranium oxide are processed to be interlaced with beryllium oxide, or BeO, which conducts heat far more readily than the uranium dioxide.
This "skeleton" of beryllium oxide enables the nuclear fuel to conduct heat at least 50 percent better than conventional fuels.
"The beryllium oxide is like a heat pipe that sucks the heat out and helps to more efficiently cool the fuel pellet," Solomon said.
A mathematical model developed by Revankar and Latta has been shown to accurately predict the performance of the experimental fuel and will be used in future work to further develop the fuel, Revankar said.
Pellets of nuclear fuel are contained within the fuel rods of nuclear fission reactors. The pellets are surrounded by a metal tube, or "cladding," which prevents the escape of radioactive material.
Longer lasting fuel also translates into less waste generated.
Because uranium oxide does not conduct heat well, during a reactor's operation there is a large temperature difference between the center of the pellets and their surface, causing the center of the fuel pellets to become very hot. The heat must be constantly removed by a reactor cooling system because overheating could cause the fuel rods to melt, which could lead to a catastrophic nuclear accident and release of radiation – the proverbial "meltdown."
"If you add this high-conductivity phase beryllium oxide, the thermal conductivity is increased by about 50 percent, so the difference in temperature from the center to the surface of these pellets turns out to be remarkably lower," Solomon said.
Revankar said the experimental fuel promises to be safer than conventional fuels, while lasting longer and potentially saving millions of dollars annually.
"We can actually enhance the performance of the fuel, especially during an accident, because this fuel heats up less than current fuel, which decreases the possibility of a catastrophic accident due to melting," Revankar said. "The experimental fuel also would not have to be replaced as often as the current fuel pellets.
"Currently, the nuclear fuel has to be replaced every three years or so because of the temperature-related degradation of the fuel, as well as consumption of the U-235. If the fuel can be left longer, there is more power produced and less waste generated. If you can operate at a lower temperature, you can use the fuel pellets for a longer time, burning up more of the fuel, which is very important from an economic point of view. Lower temperatures also means safer, more flexible reactor operation."
Solomon said a 50 percent increase in thermal conductivity represents a significant increase in performance for the 103 commercial nuclear reactors currently operating in the United States.
A small group of academic researchers figured out how to reduce uranium consumption, increase reactor performance, and reduce waste generation and all in one fell swoop. Pretty impressive. Nuclear reactor technology continues to advance just as other energy technologies advance.
Even if oil production peaks in the next 10 years I do not see the economies of developed countries being slowed down for long. Too many good minds would react to necessity and demonstrate once again that it really is the mother of invention.
A UCLA team may have found a path to make photovoltaics cost competitive.
In research published today in Nature Materials magazine, UCLA engineering professor Yang Yang, postdoctoral researcher Gang Li and graduate student Vishal Shrotriya showcase their work on an innovative new plastic (or polymer) solar cell they hope eventually can be produced at a mere 10 percent to 20 percent of the current cost of traditional cells, making the technology more widely available.
"Solar energy is a clean alternative energy source. It's clear, given the current energy crisis, that we need to embrace new sources of renewable energy that are good for our planet. I believe very strongly in using technology to provide affordable options that all consumers can put into practice," Yang said.
The use of purified silicon currently prevents photovoltaics from reaching cost competitiveness. Another approach being pursued is the development of plants for making less purified silicon. But the plastics approach bypasses the problem altogether.
The price for quality traditional solar modules typically is around three to four times more expensive than fossil fuel. While prices have dropped since the early 1980s, the solar module itself still represents nearly half of the total installed cost of a traditional solar energy system.
Currently, nearly 90 percent of solar cells in the world are made from a refined, highly purified form of silicon -- the same material used in manufacturing integrated circuits and computer chips. High demand from the computer industry has sharply reduced the availability of quality silicon, resulting in prohibitively high costs that rule out solar energy as an option for the average consumer.
Made of a single layer of plastic sandwiched between two conductive electrodes, UCLA's solar cell is easy to mass-produce and costs much less to make -- roughly one-third of the cost of traditional silicon solar technology. The polymers used in its construction are commercially available in such large quantities that Yang hopes cost-conscious consumers worldwide will quickly adopt the technology.
Independent tests on the UCLA solar cell already have received high marks. The nation's only authoritative certification organization for solar technology, the National Renewable Energy Laboratory (NREL), located in Golden, Colo., has helped the UCLA team ensure the accuracy of their efficiency numbers. The efficiency of the cell is the percentage of energy the solar cell gathers from the total amount of energy, or sunshine, that actually hits it.
The conversion efficiency they have achieved is not yet high enough. But they think they can achieve a 3 or 4 times increase in conversion efficiency to make it competitive.
According to Yang, the 4.4 percent efficiency achieved by UCLA is the highest number yet published for plastic solar cells.
"As in any research, achieving precise efficiency benchmarks is a critical step," Yang said. "Particularly in this kind of research, where reported efficiency numbers can vary so widely, we're grateful to the NREL for assisting us in confirming the accuracy of our work."
Given the strides the team already has made with the technology, Yang calculates he will be able to double the efficiency percentage in a very short period of time. The target for polymer solar cell performance is ultimately about 15 percent to 20 percent efficiency, with a 15–20 year lifespan. Large-sized silicon modules with the same lifespan typically have a 14 percent to 18 percent efficiency rating.
Plastic decays in sunlight. So I'm not surprised by the projected 15 to 20 year lifespan. Other approaches as replacements for silicon could potentially last longer.
This development is not yet ready for market.
The plastic solar cell is still a few years away from being available to consumers, but the UCLA team is working diligently to get it to market.
"We hope that ultimately solar energy can be extensively used in the commercial sector as well as the private sector. Imagine solar cells installed in cars to absorb solar energy to replace the traditional use of diesel and gas. People will vie to park their cars on the top level of parking garages so their cars can be charged under sunlight. Using the same principle, cell phones can also be charged by solar energy," Yang said. "There are such a wide variety of applications."
Photovoltaics will become cost competitive some day. But it is very hard to guess when. The fact that talented groups of researchers (including some start-ups with funding from major venture capitalists) are working on approaches that avoid the high cost of silicon crystals makes me optimistic that a breakthrough will come within 10 years. We also still face the battery problem for how to store it for night use and also for transportation.
Lehigh University researchers have found a cheaper way to reduce mercury emissions from coal plants.
Researchers at Lehigh University's Energy Research Center (ERC) have developed and successfully tested a cost-effective technique for reducing mercury emissions from coal-fired power plants.
In full-scale tests at three power plants, says lead investigator Carlos E. Romero, the Lehigh system reduced flue-gas emissions of mercury by as much as 70 percent or more with modest impact on plant performance and fuel cost.
The reductions were achieved, says Romero, by modifying the physical conditions of power-plant boilers, including flue gas temperature, the size of the coal particles that are burned, the size and unburned carbon level of the fly ash, and the fly ash residence time. These modifications promote the in-flight capture of mercury, Romero said.
Aside: One hears Orwellian talk of "clean coal" as if it is a reality today. But if coal was already so clean there'd be no need for research in how to reduce coal power plant emissions.
Coal-fired power plants are considered to be the biggest sources of mercury emissions. Only now 35 years after the Clean Air Act did the US EPA finally get around to restricting mercury emissions from coal plants.
Coal-fired power plants are the largest single-known source of mercury emissions in the U.S. Estimates of total mercury emissions from coal-fired plants range from 40 to 52 tons.
The U.S. Environmental Protection Agency last March issued its first-ever regulations restricting the emission of mercury from coal-fired power plants. The order mandates reductions of 23 percent by 2010 and 69 percent by 2018. Four states - Massachusetts, New Jersey, Connecticut and Wisconsin - issued their own restrictions before the March 15 action by the EPA.
My take on the Bush Administration mercury reduction regulations is that they came after too many years and do not reduce mercury rapidly enough. Similarly, I fault the Clinton Administration for not already imposing more restrictive standards 10 years ago. Neurotoxins are bad. We should do a lot more about neurotoxins than about the possible threat of global warming. But global warming is a far more fashionable worry.
The trick is to make the mercury become oxidized.
The changes in boiler operating conditions, said Romero, prevent mercury from being emitted at the stack and promote its oxidation in the flue gas and adsorption into the fly ash instead. Oxidized mercury is easily captured by scrubbers, filters and other boiler pollution-control equipment.
Note that computer simulations played a role in identifying operating conditions likely to reduce mercury emissions. This is part of a much larger long running trend where simulations speed up the rate of scientific and technological advance. What I'd like to know: Just how much faster will science and technology be able to advance 20 or 30 years from now due to the ability to rapidly run simulated experiments? Will the rate of advance speed up by orders of magnitue due to simulations alone?
The ERC team used computer software to model boiler operating conditions and alterations and then collaborated with Western Kentucky University on the field tests. Analysis of stack emissions showed that the new technology achieved a 50- to 75-percent reduction of total mercury in the flue gas with minimal to modest impact on unit thermal performance and fuel cost. This was achieved at units burning bituminous coals.
Only about one-third of mercury is captured by coal-burning power plant boilers that are not equipped with special mercury-control devices, Romero said.
Romero estimated that the new ERC technology could save a 250-megawatt power unit as much as $2 million a year in mercury-control costs. The savings could be achieved, he said, by applying the ERC method solely or in combination with a more expensive technology called activated carbon injection, which would be used by coal-fired power plants to reduce mercury emissions. The resulting hybrid method, says Romero, would greatly reduce the approximately 250 pounds per hour of activated carbon that a 250-MW boiler needs to inject to curb mercury emissions.
Reductions of emissions of sulfur and nitrogen oxides causes, as a side effect, a big reduction in mercury emissions as well. So a more rapid tightening of sulfur and nitrogen oxide emissions would also lead to reduced mercury emissions.
Humans have doubled or tripled the amount of mercury in the atmosphere.
Best estimates to date suggest that human activities have about doubled or tripled the amount of mercury in the atmosphere, and the atmospheric burden is increasing by about 1.5 percent per year. Global anthropogenic emissions of mercury are estimated to range between 2000 and 6000 metric tons per year. Electric utilities, municipal waste combustors, commercial and industrial boilers, and medical waste incinerators account for approximately 80 percent of the total amount. Coal-fired utility boilers are the largest point source of unregulated mercury emissions in the United States.
I'd really like to know how much of the mercury in fish is there due to human pollution. Have humans doubled or tripled the amount of mercury in fish? I've yet to come across any reports on research that attempts to quantify the impact of human mercury sources on fish.
Chlorine plants are another major source of mercury.
In 2000, for instance, these chlorine plants reported 79 tons of mercury consumed, according to federal and industry data cited in the report. Fourteen of those tons were emitted or released into the environment; the rest - 65 tons - was officially classified as "unaccounted for" by the US Environmental Protection Agency (EPA).
That's an amount that shocks environmentalists because, by contrast, the nation's 497 mercury-emitting power plants sent 49 tons of the toxin into the air that year, Oceana reports.
A relatively small number of all the chlorine plants still use mercury in the United States and a larger number in Europe use mercury. Why not shut down the old plants or force those plants to shift to mercury-free manufacturing methods?
Indeed, most of the 43 chlor-alkalai manufacturing plants in the US today use advanced mercury-free manufacturing processes that are relatively clean. But nine US factories - and 53 older ones in Europe - still use older "mercury-cell" technology that requires huge quantities of mercury to do the same job, Oceana reports.
One can debate about the effects of green house gases for decades and people have. But mercury is bad for the brain. Why let chlorine or power plants emit much mercury at all?
The development of an economically viable way to extract oil from oil shale would put a ceiling on oil prices and would extend the oil era by decades. It would also increase the odds of significant global warming. Well, in light of all that a variety of media outlets are reporting that Shell Oil thinks it can produce oil from oil shale at $30 per barrel using an in situ process where the shale is cooked without first mining it onto the surface.
They don't need subsidies; the process should be commercially feasible with world oil prices at $30 a barrel. The energy balance is favorable; under a conservative life-cycle analysis, it should yield 3.5 units of energy for every 1 unit used in production. The process recovers about 10 times as much oil as mining the rock and crushing and cooking it at the surface, and it's a more desirable grade. Reclamation is easier because the only thing that comes to the surface is the oil you want.
And we've hardly gotten to the really ingenious part yet. While the rock is cooking, at about 650 or 750 degrees Fahrenheit, how do you keep the hydrocarbons from contaminating ground water? Why, you build an ice wall around the whole thing. As O'Connor said, it's counterintuitive.
Shell has received approval from Rio Blanco County, state and federal officials to conduct a $50 million, two- to four-year study of a groundwater freezing process, said Jill Davis.
“We’re still looking to decide if we’ll move on to commercial production by the end of the decade,” she said. “It’s been promising, so we want to take it to the next level with an environmental test of our ‘freeze wall’ process.”
Refrigerants, such as ammonia dioxide, are circulated through underground pipes to freeze the groundwater and earth to keep groundwater out of an oil-shale formation.
“We’ve tested the process in a circular pattern and this will be a football field-shaped rectangle in an area more like where commercial production could happen,” she said.
Some estimates for the amount of oil in shale range as high as 1 trillion to 1.8 trillion barrels. Assume that 1 trillion barrels could be extracted. The United States currently uses about 20.5 million barrels per day which is about a quarter of current world oil demand. World oil demand is projected to rise to 119 million barrels per day by 2025 or about a 50% increase. Suppose we take that 119 million barrel figure and round it off to 120 million barrels. Also let us assume that oil shale could yield 1 trillion barrels of oil. That oil shale would satisfy total world oil demand by this equation: 1,000,000 million barrels/(365 days per year times 120 million barrels per day) which equals only 22 years at the projected year 2025 consumption rate. Even oil shale can delay the end of the oil era by a couple of decades. Still, we could use those decades to develop technologies to lower the cost of nuclear and photovoltaic solar power.
Since the future prospects for oil shale remain uncertain, the RAND report recommends that the federal government refrain from major investments in oil shale development until the private sector is prepared to commit its technical, management and financial resources. However, the report recommends a few low-cost efforts that can begin in the near future to move oil shale development forward.
The report by the RAND Environment, Energy and Economic Development program says that between 500 billion and 1.1 trillion barrels of oil are technically recoverable from high-grade oil shale deposits located in the Green River geological formation, covering parts of Colorado, Utah and Wyoming.
The mid-point of the RAND estimate – 800 billion barrels – is three times the size of Saudi Arabia's oil reserves. This is enough oil to meet 25 percent of America's current oil demand for the next 400 years.
The benefits of a competitive oil shale industry are substantial. For an output of 3 million barrels per day, the study estimates direct economic benefits of about $20 billion per year. Federal, state and local governments would receive about half of this amount in the form of lease payments, royalties and taxes.
Production at 3 million barrels per day also could likely cause oil prices to fall by 3 to 5 percent, saving American oil consumers roughly $15 billion to $20 billion annually, according to the report. A multimillion-barrel per day oil shale industry could also create several hundred thousand jobs in the United States.
The in situ process may avoid many of the environmental problems that arise from oil shale mining.
Another technical development that has been taking place involves heating the oil shale while it is still in the ground – a process called in-situ conversion. Mining is not required. Instead, electric heating elements are placed in bore holes, slowly heating the shale oil deposit. The released liquids are gathered in wells specifically designed for that purpose.
In contrast to surface mining, in-situ conversion does not permanently modify land surface topography and may be significantly less damaging to the environment. Small field tests conducted by Shell Oil involving an in-situ approach appear promising. While larger scale tests are needed, Shell anticipates that this method may be competitive with crude oil priced below $30 per barrel. RAND has not developed an independent estimate of the price level needed to make in-situ conversion competitive.
On the environmental side, adverse land and ecological impacts will accompany oil shale development no matter which approach is used. Oil shale production will also result in airborne and greenhouse gas emissions that could severely limit oil production levels.
Colorado has the largest oil shale deposits and some deposits have more oil per ton of rock.
Steve Wiig, geologist for the Rock Springs BLM office, said Wyoming oil shale, on average, would produce 15 to 30 gallons of oil per ton of oil shale rock. He said the Colorado and Utah deposits could produce 30 to 40 gallons, with some sites capable of producing 60 gallons of oil per ton of oil shale.
For example, one of the star witnesses of Gibbons' hearings was Jack Savage, president of Utah-based Oil-Tech Inc. He said the company is ready to start cooking oil out of shale with a retort it has built near Vernal, Utah.
"We have been working on this for 15 years," Savage said. "Now we're ready to go."
Savage, once president of companies that manufactured golf bags and other sporting goods, said he can turn shale into oil for $10 to $22 a barrel, depending on market conditions. Savage pushed for an accelerated federal leasing program, but he's already leased 38,000 acres of state land in Utah and says he's working on a research-and-development bid to continue work on his project.
The biggest problem with mining oil shale comes as a result of heating oil shale rock. The rock expands in size and then can't just get put back where it was excavated.
How close are we to cost effective photovoltaic cells?
Golden, Colo. — Solar concentrators using highly efficient photovoltaic solar cells will reduce the cost of electricity from sunlight to competitive levels soon, attendees were told at a recent international conference on the subject. Herb Hayden of Arizona Public Service (APS) and Robert McConnell and Martha Symko-Davies of the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) organized the conference held May 1-5 in Scottsdale, Ariz.
"Concentrating solar electric power is on the cusp of delivering on its promise of low-cost, reliable, solar-generated electricity at a cost that is competitive with mainstream electric generation systems," said Vahan Garboushian, president of Amonix, Inc. of Torrance, Calif. "With the advent of multijunction solar cells, PV concentrator power generation at $3 per watt is imminent in the coming few years," he added.
We have seen steady progress in photovoltaic concentrator technology. We are working with advanced multijunction PV cells that are approaching 38% efficiency, and even higher is possible over time. Our goal is to install PV concentrator systems at $3 per watt, which can happen soon at production rates of 10 megawatts per year. Once that happens, higher volumes are readily achieved," Hayden, Solar Program Coordinator at APS, said.
Growth in the photovoltaic (PV) concentrator business was reflected in the conference attendance, three times that of the 2003 version. This rapid growth was attributed to recent PV concentrator installations and sales forecasts along with excitement created by new solar cell efficiencies approaching 40%. At the conference, NREL announced a new record efficiency of 37.9 percent at 10 suns, a measure of concentrated sunlight. Soon thereafter Boeing-Spectrolab, under contract to NREL and the Department of Energy, surpassed the NREL record with 39.0 percent at 236 suns announced at the European photovoltaic conference in Barcelona, Spain. The efficiency of a solar cell is the percentage of the sun's energy the device converts to electricity.
Photovoltaic (PV) concentrator units are much different than the flat photovoltaic modules sold around the world; almost 1,200 megawatts of flat PV modules were sold last year. PV concentrators come in larger module sizes, typically 20 kilowatts to 35 kilowatts each, they track the sun during the day and they are more suitable for large utility installations.
Those 1,2000 megawatts of flat PV modules sold last year are equivalent to 1 nuclear power plant running only part of the day. So maybe they equal a third or a quarter of a nuclear power plant. However, see the following article where one person is quoted estimating 14,000 megawatts of PV sold in the last year in the world.
Note the concentrator installations are more complex because they have mechanical components to keep the photovoltaics pointed at the sun. This is probably not practical for home roof photovoltaics due to materials, installation, and maintenance costs. Then will large commercial photovoltaics electric power generator facilities become cost effective before residential solar power?
Update: The San Francisco Chronicle has an article about growing venture capital funding of photovoltaics start-ups. Venture capital start-ups are pursuing flexible and cheap plastic photovoltaics.
Nanosys and Nanosolar in Palo Alto -- along with Konarka in Lowell, Mass. -- say their research will result in thin rolls of highly efficient light-collecting plastics spread across rooftops or built into building materials.
These rolls, the companies say, will be able to provide energy for prices as low as the electricity currently provided by utilities, which averages $1 per watt.
Note that the $3 per watt hope from the first article is 3 times the $1 watt figure to compete against utilities.
The Sand Hill Road venture capitalists are interested in photovoltaic materials that require far less capital equipment to produce.
"Silicon is very capital-intensive. You don't need a clean room for plastic power where capital costs are one-tenth of silicon," said Raj Atluru, managing director at the venture capitalist firm of Draper Fisher Jurvetson in Menlo Park, a major investor in Konarka.
Cheap solar power is inevitable. But when?
The Christian Science Monitor has an article on the rising interest in third generation plus and fouth generation nuclear power plants. Nuclear power could meet projected future demand for electricity.
In the US alone, utilities will need to build 281 gigawatts of new generating capacity by 2025 as demand rises and older coal- and oil-fired plants are closed, the DOE estimates.
Would you rather have 281 1 gigawatt coal-fired electric generator plants or 281 1 gigawatt nuclear powered electric generator plants? In the future wind and solar may add to those choices. But for large scale expansion of base generation capacity the two realistic choices today are nuclear and coal. If you oppose one you have to be willing to support the other.
Nuclear designs most likely in the next wave of nuclear reactor construction will be simplified versions of existing light water reactors refined to have fewer possible points of failure and more passive handling of problems.
The latest designs likely to hit the grid come from US manufacturers Westinghouse and General Electric, as well as foreign companies such as Areva in France.
These designs make extensive use of natural processes, such as convection and gravity, in their emergency cooling systems instead of the mammoth pumps and series of valves found in older reactors, which are prone to failure or operator error, says Per Peterson, who chairs the nuclear engineering department at the University of California at Berkeley. Only a small number of battery-operated valves need to open for the emergency cooling systems to kick in. The combination not only reduces the amount of internal plumbing at the plant, he says, it also reduces the need for diesel generators that keep the cooling system operating in case the plant is shut down for maintenance or an emergency.
Overall, "the new, simplified designs eliminate an enormous amount of equipment inside the reactor building," he says. That reduction leads to plants that are much cheaper to build and maintain, he adds. These designs first emerged about four years ago as "third-generation" designs. They have evolved into what many are calling third-generation-plus designs.
The article also reviews a multinational effort of the United States, Britain, Japan, and several other countries to develop fourth generation nuclear reactor designs with the goal of choosing a couple of new designs by 2012. I think they ought to accelerate their work and develop next generation designs more rapidly.
The Christian Science Monitor also has an article about "capture ready" coal plants build to be more easily upgraded to capture and sequester carbon dioxide emissions.
Even environmentalists are wary. Some see the capture-ready idea as another excuse for power companies to drag their heels on a far more advanced clean-coal technology called integrated gasification combined cycle or IGCC.
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A big question is cost. Although making a plant capture ready represents only a small fraction of a power plant's construction budget, the equipment to capture CO2 would almost certainly run into serious money, experts say. Even if a reasonable technology were found, installing it in a capture-ready coal plant would raise construction costs some 50 percent (75 percent for plants not capture ready), Gibbins estimates. And running such a plant would raise the cost of producing electricity at least 40 percent due to heat loss involved in the carbon-capture process, he adds.
What is the cost of IGCC versus capture ready plants that are upgraded to do CO2 capture? I'm guessing IGCC would be cheaper. Also, I'm guessing that IGCC will be less polluting for other categories of pollutants such as sulfur oxides and mercury. Anyone know for sure?
Also, how does IGCC electric compare to nuclear electric in cost?
See my previous post "Cost Estimates For New Nuclear Power Plants".
Photovoltaic solar cell efficiency might be boosted to 65% by use of quantum dots.
Golden, Colo. — Researchers at the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) have shown that nanotechnology may greatly increase the amount of electricity produced by solar cells.
In a paper published in a May issue of the American Chemical Society's Nano Letters journal, an NREL team found that tiny "nanocrystals," also known as "quantum dots," produce as many as three electrons from one high energy photon of sunlight. When today's photovoltaic solar cells absorb a photon of sunlight, the energy gets converted to at most one electron, and the rest is lost as heat.
The research demonstrates the potential for solar, or photovoltaic, cells that reduce wasteful heat and maximize the amount of the sun's energy that is converted to electricity—a key step toward making solar energy more cost-competitive with conventional power sources.
The NREL research team, led by Arthur Nozik, included Randy Ellingson, Matt Beard, Justin Johnson, Pingrong Yu, and Olga Micic, and worked in collaboration with theorists Alexander Efros and Andrew Shabaev of the Naval Research Laboratory (NRL) in Washington, D.C.
The findings are further confirmation of pioneering work by Nozik, who in 2000 predicted that quantum dots could increase the efficiency of solar cells, through a process now termed "multiple exciton generation," or "MEG". Last year, Richard Schaller and Victor Klimov of Los Alamos National Laboratory in New Mexico were the first to demonstrate the electron multiplication phenomenon predicted by Nozik, using quantum dots made from lead selenide.
They say the existing solar cells go as high as 33% efficiency of conversion. But production solar cells installed on roofs are typically much lower efficiency than that. So if this new approach could be manufactured cheaply it would be at least 3 times higher in efficiency than existing manufactured solar cells.
"We have shown that solar cells based on quantum dots theoretically could convert more than 65 percent of the sun's energy into electricity, approximately doubling the efficiency of solar cells," Nozik said. The best cells today convert about 33 percent of the sun's energy into electricity.
The NREL and NRL researchers' paper also describes a new theoretical foundation for the multiple exciton generation process that is based on certain unique aspects of quantum theory.
The recent work demonstrates MEG in quantum dots of a second semiconductor material, lead sulfide.
The NREL/NRL work not only shows higher overall efficiency for multiple exciton generation,
it also establishes that the process occurs with lower photon energies, meaning it could make use of an even greater portion of the sun's light spectrum.
I am just guessing but this approach might be cheap to manufacture. Lead and sulfur are cheap. Selenium is also used (see below). Is selenium expensive?
Note above the reference to work by Richard Schaller and Victor Klimov that provided experimental evidence that led to this work. See my post from April 26, 2004 "Nanocrystal Photovoltaics May Achieve 60% Conversion Efficiency" for more on Schaller and Klimov's work.
We report ultra-efficient multiple exciton generation (MEG) for single photon absorption in colloidal PbSe and PbS quantum dots (QDs). We employ transient absorption spectroscopy and present measurement data acquired for both intraband as well as interband probe energies. Quantum yields of 300% indicate the creation, on average, of three excitons per absorbed photon for PbSe QDs at photon energies that are four times the QD energy gap.
Thanks to Dave Gobel for the tip.
Use of hydrogen to transport and store enerfgy is still a distant prospect.
WEST LAFAYETTE, Ind. – Researchers conclude in an article to be published in June that it could take "several decades" to overcome daunting technical challenges standing in the way of the mass production and use of hydrogen fuel cell cars.
The article notes that "success is not certain" in efforts to develop inexpensive, hydrogen-powered fuel cells and to create the vast storage and transportation infrastructure needed for the vehicles, stressing that hydrogen's "wide-scale use is laden with potential technical, economic and societal impasses." In case fuel cells never do become practical for cars, the researchers conclude, it would be wise for the nation to "maintain a robust portfolio of energy research and development" in other areas.
"In my mind, developing practical hydrogen fuel cells for cars is definitely doable, but we must solve very daunting technical challenges," said Rakesh Agrawal, Purdue University's Winthrop E. Stone Distinguished Professor of Chemical Engineering.
The article will appear as the cover story in the June issue of the AIChE Journal, a publication of the American Institute of Chemical Engineers. The article was written by Agrawal, Martin Offutt, from the National Research Council, and Michael P. Ramage, a retired executive from ExxonMobile Corp.
Fuel cells cost too much to build and have short operating lifetimes.
"Today's fuel cells generate power at a cost of greater than $2,000 per kilowatt, compared with $35 per kilowatt for the internal combustion engine, so they are more than 10 times more expensive than conventional automotive technology," Agrawal said. "At the same time, fuel cells have an operating lifetime for cars of less than 1,000 hours of driving time, compared with at least 5,000 hours of driving time for an internal combustion engine.
"That means fuel cells wear out at least five times faster than internal combustion engines. If I buy a new car, I expect it to last, say, 10 years, which equates to about 3,000 hours of driving time. If my fuel cell only lasts 1,000 hours, you can see that's not very practical."
Cheaper and longer lasting catalysts are needed. Plus, in order to use fuel cells to burn hydrogen the hydrogen transportation and storage problems need to be solved.
To bring down the cost of fuel cells, less expensive catalysts and membrane materials are needed, Agrawal said.
Developing an infrastructure of hydrogen storage and transportation represents other significant challenges.
"A fuel-cell car built with today's technology would cost about $250,000, but you would have no place to fill up the tank," Agrawal said.
Hydrogen is a light gas, which makes it more expensive to transport and store. Because its molecular weight is only 2 – compared with heavier gases, such as methane, which has a molecular weight of 16 – less hydrogen is contained in the same space as heavier gases, making its transport more expensive.
Agrawal sees hydrogen vehicles starting to show up on the road in the year 2020.
"I believe we can probably solve the technological problems related to making hydrogen fuel cells practical as a replacement for the internal combustion engine, but it won't be easy and it likely won't happen very soon," Agrawal said. "An optimistic prediction would be that a significant number hydrogen fuel cell cars will be entering the marketplace around 2020, and by 2050 everybody will be driving them."
But that is an optimistic prediction. A lot of problems must be solved to even start hydrogen deployment in 2020. In the meantime the market for gas-electric hybrid vehicles is going to become quite large. Many of those hybrids will be pluggable and some people will be charging them from their home outlets. Photovoltaics might drop to the point that a portion of that car battery recharging will be done using electric generated right at home.
Suppose nuclear power experiences a resurgence. Hydrogen could be generated at nuclear plants. But if superconductor technology continues to improve and battery technology does as well then superconducting power lines which suffer no resistance might deliver nuclear power to electric vehicle batteries more conveniently at home at a lower cost than a hugely expensive infrastructure for delivering hydrogen to fuel stations.
In my view hydrogen's eventual role as primary vehicle fuel is by no means assured. Future solutions to hydrogen's technological problems will not compete with today's other energy technologies. Hydrogen's supporting technologies will compete with tomorrow's batteries, superconductors, and other energy technologies. Those competing technologies will be delivering benefits decades before hydrogen begins to do so and therefore industry, academic, and government labs will continue to refine those other technologies. By the time hydrogen is ready the competiton might be too firmly entrenched and cheap to be dislodged.
Fuel cells have a future independent of hydrogen. If the cost and durability problems with fuel cells could be solved for burning hydrocarbon liquid fuels then fuel cels could be adopted much more rapidly as a more efficient way to burn fossil fuels. Liquid fuel burning fuel cells could even work in hybrid vehicles with batteries providing increased efficiency through regenerative braking.
DENVER, CO (April 28, 2005): Luca Technologies LLC today announced that its researchers have confirmed the presence of a resident, methane-generating community of microorganisms ("microbial consortium") in substrate samples taken from the 110,000 acre Monument Butte oilfield located in North Eastern Utah. This site represents the latest in a series of active "GeobioreactorsTM" that Luca Technologies has identified since its first demonstration of this phenomenon in the Powder River Basin coalfields of Wyoming. Geobioreactors are sites where microbial conversion of underground hydrocarbon deposits (oil, oil shales, and coal) to methane is ongoing. Such Geobioreactors may offer the potential of turning currently finite energy reserves into methane "farms