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By Robert Rapier on Aug 8, 2009 with no responses

Running the Electric Grid with eSolar

As I often do on a Saturday morning, I was up early reading through energy headlines. I happened across this story on eSolar:

Bill Gross’s Solar Breakthrough

“We are producing the lowest cost solar electrons in the history of the world,” Bill Gross is telling me. “Nobody’s ever done it. Nobody’s close.”

“We have a cost-effective, no-subsidy solar power solution and it’s for sale, anywhere around the world,” he says.

The article was intriguing, and inevitably led me back to eSolar’s website to get a better idea of whether the claims appear to have merit. There, I watched the slide show on the technology, and caught this bit: A single unit generates 46 MW of clean electricity on a footprint of 160 acres.

While this doesn’t help me figure out whether they can deliver on the hype, it does enable me to update a couple of essays that I have written before:

A Solar Thought Experiment

Replacing Gasoline with Solar Power

In the first, I made an attempt to calculate the area that would be required to equal the entire installed electric capacity of the U.S. – using only solar power. (Yes, I understand that this number falls to zero at night). The numbers quoted above from eSolar – combined with the latest data on installed electrical generating capacity – enabled me to update that calculation.

Per the EIA, total installed electrical generating capacity in the U.S. is approximately 1 million megawatts. If we scale up eSolar’s claim of a required footprint of 160 acres to produce 46 MW of electricity, then it would require 5,435 square miles of eSolar technology to equal current U.S. electrical capacity. This is a square of 73.7 miles by 73.7 miles. This is greater than the 2,531 square miles calculated in the previous essay, but that essay only considered the area for solar panels. The present calculation encompasses the footprint of the plant.

Looking back at the gasoline calculation, I came up with 1,300 square miles required in my previous essay to replace the energy gasoline provides. Using the current eSolar numbers changes that number to 2,413 square miles, or a square of 49 miles on each side.

Of course all of the normal caveats apply as spelled out in the previous essays. The key point is not to read these sorts of thought experiments too literally. I tend to do them to get my head around the scale of certain problems. Complaints of “the cost is too great” or “the power is intermittent” – addressed by caveats in the previous essays – completely miss the point of the essay. It is sort of like trying to figure out how much biomass would be required to power the world. If the calculation is 10 times the current annual output of biomass, then that’s not going to work. If it is 1/100th the current annual output of biomass, then that might work (again, pending lots of other things working out).

In this case, I find this eSolar thought experiment encouraging insofar as the required land area isn’t a clear knockout.