Shiny Rocks May Be Good For Solar Energy

February 19, 2009 in accelerating change, energy generation, solar electricity by nils | 3 comments

Fool's Gold (image by Clearly Ambiguous, CC 2.0 licensed)

Interesting note flying around the blogosphere yesterday (see here, here, and here, amongst many websites featuring the news) about a research project done at Berkeley. It found that, based on material cost and availability, solar photovoltaics made with iron pyrites (aka Fool's Gold) are more likely to solve our energy crisis than PV made with silicon or CIGS thinfilms. This is due to both the cost of the raw materials and their availability - both crystalline silicon and the CIGS precursors are relatively expensive and relatively rare. Iron pyrite and its precursors are among the most common elements on earth, in contrast.

What we've found is that some leading thin films may be difficult to scale as high as global electricity consumption... if our objective is to supply the majority of electricity in this way, we must quickly consider alternative materials that are Earth-abundant, non-toxic and cheap. These are the materials that can get us to our goals more rapidly.

The paper noted that PV cells made with iron pyrite are not as efficient as those made with silicon, but here's where it gets interesting. I did a Google search yesterday to find out just how efficient those iron pyrite solar cells are - and I can't find them. There are a handful of papers about iron pyrite solar cells, but none that indicate it's anywhere near being ready to compete even on the low-efficiency end. (E.g., see here, in a paper from 2000.)

So, that may mean I'm just not any good at searching on Google, and be that as it may. The other side of the coin is that this report lines up with what I've been saying since October - it's not about the efficiency of the cells, it's about the price/performance. We have plenty of surface area on which to put solar cells, even if they aren't very efficient. What we don't have is lots of extra money to pay for them - so low-efficiency cells that have a good price performance ratio - $1-2/kw or $0.10-0.30/kwh - are what we're looking for.

(And of course, we need to be a lot more efficient in our energy usage, and be able to store that good sun power we've generated.)

In any case, I'm now looking forward to hearing about iron pyrite-based solar cells - if you know of any post-2000 research on this topic, definitely let me know!