Technology Review has an article reviewing the prospects of diesel hybrid vehicles. PSA Peugeot CitroŽn has demonstrated a record efficiency diesel hybrid but the diesel and the hybrid both add to the total cost.
What's holding back commercialization is cost. A diesel-powered car in Europe already costs $1,750-2,400 more than an equivalent gasoline model, and PSA estimates that making a diesel hybrid could double that premium. Hence, PSA says controlling costs will be a challenge, but it is starting to engineer cost-shaving solutions.
Note that even in Europe with much higher gasoline prices the diesel hybrid is still seen as too expensive to justify the fuel savings.
But diesel hybrids would be more efficient than gasoline hybrids.
What's clear is that diesel hybrid technology has significant potential. According to a 2003 study by MIT's Laboratory for Energy and the Environment, a study that remains one of the most comprehensive projections for propulsion technologies, diesel hybrids should outperform nearly all other propulsion technologies through 2020 -- including fuel-cell cars that run on hydrogen derived onboard from gasoline. Fuel cells using pure hydrogen offered a marginal benefit in efficiency, but only when combined with hybrid technology, and at a significantly higher price.
But the hydrogen fuel cells only make sense if or when materials are found to store hydrogen at room temperature. If active air conditioning is needed to keep the hydrogen cold then cars will use energy even when stationary.
In theory fuel cells burning liquid hydrocarbons might surpass diesel engines in efficiency and would not suffer the hydrogen storage problem.
What will mature more rapidly? Battery technologies or fuel cell technologies? If battery technologies mature more rapidly then the world could move toward all electric vehicles. If fuel cells mature more rapidly then battery improvements could still get used in combination with fuel cells to power fuel cell hybrids. Batteries allow regenerative braking to capture energy that would otherwise be lost. Unless a fuel cell design can enable a non-battery dependent method of capturing the braking energy the role of battery-based hybrids seems set to grow even if fuel cells start competing with the internal combustion engine.
Technology Review has another article reporting on an advance at the University of North Carolina at Chapel Hill that may greatly reduce the cost of fuel cells.
Joseph DeSimone, the UNC-Chapel Hill chemistry and chemical engineering professor who heads the lab where the work was done, thinks they can increase the membrane's surface area 20 to 40 times by using different patterns, increasing the power density proportionately.
Such improvements in power density mean that a much smaller fuel cell could provide adequate power for a vehicle. The material is also easier to work with, which should reduce manufacturing costs.
They mention that these fuel cells might work well with methanol. I'm guessing the fuel cell cost problem is going to get solved before the hydrogen storage problem. So initial vehicle fuel cells are probably going to burn liquid hydrocarbons.
|Share |||Randall Parker, 2006 April 06 09:56 PM Energy Policy|