Fuel Cell Performance

>In the real world peak energy demand, and price, occur at mid-day due
>to air conditioning loads. Solar cells are ideally suited to meeting
>this peak demand, since they produce energy at exactly the right time.
>If peak loads can be handled by solar cells, then there is
>significantly less need for centralized power plants.
>
Maybe, maybe not... (more below)

> A decentralized
>production system is also much more robust to black outs of the kind
>we've seen recently
>
I've heard this (which seems to have become a mantra in the Green/renewable energy community) all over the place, but it actually doesn't make sense when you think about it. Large scale grid failures aren't nice, certainly, but the overall reliability of the electric grid is something like 99.98%, far, far, far higher than the reliability for power of any single centralized or decentralized power plant. The purpose of the large-scale interconnects is in part to improve reliability so that a plant being down for maintenance or other reasons in one area doesn't prevent that area from having electric service. The fact that so many things in NY City relied on continuous electric power (which the residents learned after it was lost) only shows you how, under normal circumstances, the grid is so extremely reliable people can take it for granted.

Solar photovoltaics are particularly subject to low capacity factors of course - they only make power when the sun is up. Calling rooftop solar power a solution to "blackouts" is laughable.

> The
>key to making this work economically are electric meters than charge
>not only by the amount of electricity used, but also by the time it is
>used. This is as practiced by the grid itself for major energy
>transfers. This, not pork for the energy producers, is what we need in
>a national energy bill.
>
This certainly seems a good idea in principle, either way. You're right
that solar PV can help supply peak power - effectively what you are
doing by installing PV systems is providing load leveling (and a net
gain in electric capacity) which is kind of a holy grail of electric
companies - they would love to be able to run their generators
continuously at a constant level, to make maximum use of their capital
investments, and to help with capacity planning. Utilities have to
build generating capacity to meet peak demand. To the extent that
rooftop solar PV can actually reduce peak demand from the grid, that
means a lower capacity requirement for centralized power.

Buuuuuuutttt... solar PV is actually a very expensive way to meet peak
power demand. The competition is gas turbine plants, which have very low
capital costs and are dominated by the fuel costs. These can be built
small and close to where peak demand is located. PV is a high
capital-cost, zero fuel-cost technology; low capital cost (and high fuel
cost if necessary) is a much better economic match for peaking power supply.

Arthur