December 30, 2009
Hot Electrons To Double Solar PV Efficiency?
Researchers at Boston College have found evidence that a theory about how to double photovoltaic sunlight conversion efficiency might really work.
The results are a step toward solar cells that break conventional efficiency limits. Because of the way ordinary solar cells work, they can, in theory, convert at most about 35 percent of the energy in sunlight into electricity, wasting the rest as heat. Making use of hot electrons could result in efficiencies as high as 67 percent, says Matthew Beard, a senior scientist at the National Renewable Energy Laboratory in Golden, CO, who was not involved in the current work. Doubling the efficiency of solar cells could cut the cost of solar power in half.
First Solar, Solyndra, Nanosolar, and other contenders are already developing lots of ways to cut manufacturing costs. If the cost cutting trend continues PV will become cost effective for a larger number of potential buyers even without a big efficiency boost. But a doubing in efficiency would be on top of these manufacturing innovations.
Thank you for this post. In answer to your question about CO2 emitted per MWhr, I've put some numbers together below.
Typical emission per BTU release for coal burned for electricity generation in this country is 0.095 grams. Divide that by 0.33 to account for thermodynamic efficiency of powerplant and transmission line losses. (factor of three is an easy number to remember and probably accurate to within a few %) Divide by 0.000029 kWhr(thermal) per BTU. Voila: 993 grams per kWhr of electricity delivered to your abode. About a metric tom per MW-hr(e), which is another easily remembered number. If it was generated by burning coal.
Conversion factors and average emission from Transportation Energy Data Book, #27
Also see: http://www.eia.doe.gov/cneaf/coal/quarterly/co2_article/co2.html
Here is what it looks like in front of the powerplant:
"A large coal train called a "unit train" may be two kilometers (over a mile) long, containing 100 cars with 100 tons of coal in each one, for a total load of 10,000 tons. A large plant under full load requires at least one coal delivery this size every day. Plants may get as many as three to five trains a day, especially in "peak season", during the winter months when power consumption is high."
And we all inhale...
Meanwhile back at the ranch, the AGW hype gets challenged everyday and quoteth the raven... evermore. Ocean Destruction will soon replace climate change that replaced global warming that replaced greenhouse effect, since CO2 levels are right now in the historic low range in paleo-climate terms its understandable that phase 5 of the alarmist insistence CO2 is a bitch will move through many more reincarnations until the either the questionable physics is proved wrong or the next iceage sends them into oblivion. Did all those fish millions of years ago when CO2 was 5 to 10 times what it is now have a
and btw, why all the govt insistence, ie california, germany, the usual leftist regimes of failure that mandate utilities not only buy this solar crap but that they pay the feed in tariff and then after they meet the quota reset it so they have to buy more, is there a problem with real demand for this garbage? A little fascism is good when its green I suppose.
that's from 2000. The latest for 2008: ftp://ftp.eia.doe.gov/pub/oiaf/1605/cdrom/pdf/ggrpt/057308.pdf
nickg thanks for that, its changed +.6%.