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einmaldrin_alleshin t1_jacjjlu wrote

Reply to comment by ScienceIsSexy420 in ELI5: What's hard about copying photosynthesis or just using plants for power by No_Dust_5360

Plants are significantly less efficient than solar panels, particularly because they are limited by the amount of CO2 that they can get. 400 PPM is a lot when it comes to climate change, but when you're trying to synthesize carbohydrates, that's a problem.

On top of that, photosynthesis only works in a narrow temperature range, it requires a lot of water that just gets evaporated, and it requires minerals and nitrogen, which have to be produced expending a lot of energy.

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ScienceIsSexy420 t1_jack5ac wrote

Plants are more efficient in terms of energy generated per photon absorbed. As you mentioned, CO2 concentration is absolutely limiting factor for plants, but this could be fairly easily addressed when adapting the technology for a PV cell.

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einmaldrin_alleshin t1_jacq42c wrote

> Plants are more efficient in terms of energy generated per photon absorbed.

That is an incredibly misleading, since chlorophyl does not absorb all photons. It doesn't absorb any infrared, and is mostly transparent between 500 and 600 nm. So by that measurement, you're not counting about half of all sunlight that hits a plant. Silicon based solar may be less efficient per photon, but it absorbs everything from 800nm up to UV.

> but this could be fairly easily addressed when adapting the technology for a PV cell.

You mean DSSC cells? I suppose it's "easy" to demonstrate the effect in a lab under controlled conditions, but in real world applications, where they need to work for decades exposed to the environment, it stops being easy and becomes very, very hard. There's a reason you can't buy them.

They are also not projected to be more efficient than regular solar panels under sunlight, there's just hope that they might become cheaper.

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