Sorry, but I just can’t buy this:
PG&E is pledging to buy the power at an agreed-upon rate, comparable to the rate specified in other agreements for renewable-energy purchases, company spokesman Jonathan Marshall said. Neither PG&E nor Solaren would say what that rate was, due to the proprietary nature of the agreement. However, Marshall emphasized that PG&E would make no up-front investment in Solaren’s venture.
“We’ve been very careful not to bear risk in this,” Marshall told msnbc.com.
Solaren’s chief executive officer, Gary Spirnak, said the project would be the first real-world application of space solar power, a technology that has been talked about for decades but never turned into reality.
“While a system of this scale and exact configuration has not been built, the underlying technology is very mature and is based on communications satellite technology,” he said in a Q&A posted by PG&E. A study drawn up for the Pentagon came to a similar conclusion in 2007. However, that study also said the cost of satellite-beamed power would likely be significantly higher than market rates, at least at first.
In contrast, Spirnak said Solaren’s system would be “competitive both in terms of performance and cost with other sources of baseload power generation.”
I just can’t see how. Unless there are going to be many satellites, the system has to be in GEO to provide baseload power to any given region on earth. They talk about putting up a 200 MW system with “four or five” “heavy lift” launches (where this is apparently defined as 25 tons).
Suppose the conversion efficiency of the cells is a generous 30%, the DC-MW conversion is 90%, the transmission efficiency is 90% and the MW-AC conversion efficiency is 90% (generous numbers all, I think). That gives an overall efficiency of 22% from sunlight to the grid. The solar constant in space is 1.4kW/m
That doesn’t include the mass of the conversion electronics, basic satellite housekeeping systems (attitude control, etc.) and the transmitting antenna, which has to be huge to get that much power that distance at a safe power density.
So even ignoring the other issues (e.g. regulatory, safety studies, etc.) that Clark mentions, I think this is completely bogus until I see their numbers. And probably even then.