In all the talk about possible solar energy systems (photovoltaic, thermal, wind, etc.) has any process actually delivered better efficiency than good old photosynthesis (as practiced by green plants)?
It seems to me that our scientists ought to be looking at usinga synthetic version of this process, whereby plants convery oxygen, water, and coarbon dioxide into sugars and starches. Is anyone looking at this?
Plants convert about 9% of sunlight. But it looks like half of that 9% is used to keep the leaf alive so really only 5% is available. But there are so many numbers in that article that it seems it could be anywhere from 5% to 10%
Photovoltaic is in the range of 10 to 20%.
Photosynthetic efficiency isn’t very impressive actually. If you compare the total inputs (solar energy on an area over time) and total outputs (chemical energy stored in biomass), most plants are actually only about 1% efficient. Crop plants do a bit better, and sugar cane is one of the most efficient at around 8%. And that’s raw biomass – if you’re converting it into a useful fuel like ethanol or diesel, you lose even more energy, and even with the best crops you’re lucky to get 0.5% efficiency. ETA: There are technologies being developed that convert more of the plant into useful energy. Cellulose is a huge fraction of most plants, but currently only starches and oils are readily converted into fuels. Enzymes that break down cellulose would produce useful fuel from nearly all of the plant biomass. Still even the most optimistic technologies might only have 3-4% efficiency.
In comparison, ordinary solar cells are around 15% efficient at converting sunlight directly into usable electricity.
Still, there are some research labs that are trying to take the photosynthetic components and engineer them into devices. These devices might not be very efficient, but they eventually might be cheaper to produce or at least have some niche application.
Efficiency might not be that important a goal. The sunlight is happening anyway, and almost all of it doesn’t do anything “useful” in the sense that we define efficiency in power generation. Price per watt is probably the only metric that we should consider, unless other things turn out to be problems.