Photovoltaic cells and carbon emissions

After a long time we finally have a study on the carbon life cycle cost of modern photovoltaic cells: Fthenakis, Kim, Alsema. Emissions from Photovoltaic Life Cycles. ASAP Environmental Science and Technology, 10.1021.

The bottom line is that PV cells are 11% of the carbon cost of natural gas electricty generation, the cleanest of the fossil fuels. The estimate is that PV cells are 90-100 times better than coal-fired electricity generation (the predominant form of generation in Australia).

The study also assumes that PV cells replace generators in-situ. That is, the results don't include the savings in the reduced size of the electricty grid from having PV cells at the point of power usage (eg, on a house roof). About 30% of electircity is lost in transmission through the grid.

None of this would be surprising except for the FUD from the flat earth brigade that PV cells had a massive carbon footprint from their manufacturing process that was so large it dominated later power generation. The paper shows that this assertion is incorrect.

All in all, it looks like a home PV system has about 1000 times less carbon footprint than South Australian grid electricity.

This isn't to say that all is sweetness and light with PV solar. Most systems still use the grid, and that's a major source of inefficiency and possibly unnecessary investment. The PV gains need to be discounted by a share of the cost of the grid power. At the time time, off-grid is problematic as there is no good metropolitan home electricity storage system that doesn't have a large environmental impact from the chemicals used.

What we need is some of the promising storage systems (such as hot salt) to scale down to domestic application. That's difficult whilst they use exotic technology such as high-temperature pumps.