You can certainly make Fresnel lenses that focus light, but without some sort of active control, it’s not physically possible to focus light from an unknown direction onto the same spot. That would be a thermodynamic law violation by focusing blackbody radiation. So what’s the advantage of this metamaterial stuff over Fresnel lenses? (Those work well enough, but of course aren’t quite economically practical.)
Also, that metamaterial company you mentioned, their website shows regular solar panels with this metamaterial coating on them, not a system that focuses light onto smaller PV panels.
I’m of course aware of the split-spectrum solar proposals using diffraction gratings, but that’s another thing that died off with the fall in PV prices.
Coal gasification typically has exergy efficiency <50%. You can get ~60% exergy efficiency, but biomass would certainly be worse than coal. Some plastics might be similar, I guess, but for wood you’d be looking at maybe 1.6x the losses, so something like 36% exergy efficiency from biomass to syngas. Then with 60% conversion to electricity you have ~22% efficiency, worse than boilers & steam turbines and with higher capital costs.
Yes, some simulations of wood gasification have given better numbers, but I don’t trust them. Coal gasification is much better understood, it’s used on a large scale in China, we know how it performs in practice, and we know biomass gasification is worse.
Combined cycle gas turbines can do 60% efficiency, and fuel cells are more expensive than those, so you probably wouldn’t use fuel cells.
You can certainly make Fresnel lenses that focus light, but without some sort of active control, it’s not physically possible to focus light from an unknown direction onto the same spot. That would be a thermodynamic law violation by focusing blackbody radiation. So what’s the advantage of this metamaterial stuff over Fresnel lenses? (Those work well enough, but of course aren’t quite economically practical.)
Also, that metamaterial company you mentioned, their website shows regular solar panels with this metamaterial coating on them, not a system that focuses light onto smaller PV panels.
I’m of course aware of the split-spectrum solar proposals using diffraction gratings, but that’s another thing that died off with the fall in PV prices.
Coal gasification typically has exergy efficiency <50%. You can get ~60% exergy efficiency, but biomass would certainly be worse than coal. Some plastics might be similar, I guess, but for wood you’d be looking at maybe 1.6x the losses, so something like 36% exergy efficiency from biomass to syngas. Then with 60% conversion to electricity you have ~22% efficiency, worse than boilers & steam turbines and with higher capital costs.
Yes, some simulations of wood gasification have given better numbers, but I don’t trust them. Coal gasification is much better understood, it’s used on a large scale in China, we know how it performs in practice, and we know biomass gasification is worse.
Combined cycle gas turbines can do 60% efficiency, and fuel cells are more expensive than those, so you probably wouldn’t use fuel cells.