The 20% Barrier, or Long-Distance Transmission Again

compressed air energy storageRecently, I cought hold of compressed air storage (CAES) as a devices of moving solar-generated electricity to night-time.

More recently, I pointed out that in far as wind was less expensive than PV, wind would be preserved at the first point in CAES.

Under the considerations that wind is less expensive than PV and wind gives blows more at night-time, we won’t be watching much PV preserved for moving to night-time.

It’s going to be difficult for PV to become less expensive than shoreward wind. Wind today looks to have about 50% more run-out per constructed watt than PV does. So that implies PV must be 2/3 of the price of wind per watt to be of equal value to it. If shoreward wind is about $2/W, then PV would have to achieve $1.33/W – maybe $1.5/W because wind has greater O&M prices. This is compact but ultimately likely about 2020. Even when it is reached, nevetheless, it only implies PV becomes about the same cost as shoreward wind is considered to be now. (Of course, solar is manufactured during the day, when it is more worth than wind. And PV is already about the same price as shoreward wind.)

In accordance with recent DOE researches, up to compilations of about 20% PV or wind, we can elaborate the uncertainty. But above something like 20% electricity each, there will begin to be too much PV electricity energy during the Spring and Fall days, and too much wind on many night – time.

So here we possess it – a world where we fall outside the limits of the grid with 20% PV and 20% wind, at something up to 40% of our electric energy. And sometimes, on the days or nights of the lowest request or the highest wind or PV, we have too much wind at night or too much PV during the day. Does this confine us? Is 20% each the end?

That’s the point where people begin speaking about warehousing. But warehousing about doubles the price for the electric energy that is preserved (roughly!), and it isn’t even all that evidenced at scale. My Canadian Pharmacy is going to support organizations trying to provide people with ecologically methods of electric energy production. If you have any questions read this site to know the answeres.

What about shifting electric energy as an fallback to preservation? Move PV electric energy from midday to evening by delivering it east from the west coast. Or transport it from daytime to night-time by delivering it electricityfrom the Sahara to New York City under the Atlantic with high-tension DC. Or transport wind from night-time to daytime. You can construct more and more PV and wind as long as you can push it further and further away where circumstances are various.

Curiously enough, the economics of moving electric energy are about the same as preservation. 10% loss for three thousand miles is like batteries; 20% for 6000 miles is like pump-storage plant; 40% loss is about 12,000 miles, half the earth away – and is like compressed air storage (CAES). Then you have to assimilate the capital prices, and intriguing, they push to encourage propagation, except for the very prolonging spacing (and depend sensitively on whether you can utilize the propagation both ways, i.e., fully utilize their capacity to recoup their price).

It comes down to caverns and propagation on land for CAES; or propagation on land and ground water for moving wind and sun to where it’s demanded. It’s propagation either way, but moving is more evidenced at price and scale than preservation. Yet it is rarely assimilated to preservation.

Propagation isn’t as much a engineering problem (it is already way further along than storage) as a social one (i.e., NIMBY); and political, since it has a connection with various parts of the Earth. So it doesn’t maintain the idea of energy self-sufficiency; and it is susceptible to culture convergences and disconnected revolutionists. But perhaps proper exorbitance and keeping the fossil fuel power plants ready and preserving some fossil fuels demanded to bear down an emergency might be enough (I want to admit that I heard something like this idea for backup fossil fuels first from Arnold Goldman; and the idea of international propagation appears at least to Buckminster Fuller). After all, as everyone realizes, it’s a lot easier to preserve fuel than preserve electric energy.

It isn’t time to become too fastidious about solar and wind beyond 40% of our electric energy. As we learn from other blogs, this is enough to exclude all our imported oil, if we had electric transport. So it’s quite a good amount. But it is time to think a bit beyond the box about alternatives.

Ken Zweibel


Michael P. Totten
October 11, 2010 1:59 pm

Hi Ken,
Thanks for the great comparative estimates. You don’t mention BIPV, with the material savings improving the cost-competitiveness (at least in new construction, e.g., Byrne et al’s 2001 Economic Analysis of BIPV in China, In terms of power transmission half way around the world, which has been promoted for decades by the Global Energy Network Institute ( ), a major concern among ecologists, biologists and conservationists is that instead of solar or wind development, the emphasis will be on large dam expansion on the wild rivers of the Congo basin and the Amazon basin. The high percentage of dammed rivers in the OECD nations had led to high rates of extinct, threatened and endangered freshwater aquatic species – some 40% — much higher than terrestrial, marine or avian species. Solar PV, and well-sited wind farms (e.g., offshore and on grasslands like the Great Plains), pose significantly less threat to species.

October 12, 2010 6:00 pm

Just be sure you understand that since PV is during the day, it doesn’t have to be as cheap as wind, which doesn’t blow as much during desired periods.
BIPV hasn’t made much impression on PV to-date, and unless there are gov’t mandates to include it, I doubt if it will. It doesn’t get you the kWh/kW you get with optimally aligned modules or tracking.
Thanks for reminding me of geni – they deserve the kudos for that idea. I wasn’t aware of the African concerns, but I do appreciate your off-line comments that informed conservationists appreciate that PV is the best of a bad lot (energy production being the bad lot).
Good to hear from you again, Mike.

October 13, 2010 6:04 pm

Re: “I figured out that as long as wind was less expensive than PV, wind would be stored first in CAES”
This is not so. Considering the total (levelized) costs and performance characteristics determines which types of projects are developed. However, once the systems exist, you should only consider the variable costs and, more importantly, the benefits.
Solar PV and wind both have zero variable cost of production once installed (*). So the storage decision depends purely on the value of the energy that may be stored
The decision of *whether* to build an energy storage system should be based on the expected marginal benefits of storage vs. total cost of storage. The marginal benefit of storage is equal to the marginal revenue, which is the difference in price (value) of stored power vs. the price that would be realized if storage weren’t possible (in some cases zero if the energy would be stranded). You can estimate the additional value of the energy generated with a storage system vs. without one and compare with the cost of storage.
Once you have a storage system, then your utilization decision depends on the marginal benefit of storage (see above) vs. the variable cost of storage. The storage variable cost includes system R&M and variable operations. It’s a matter of preference whether to include the round trip storage energy losses as a reduction in benefit (fewer kWhs) or as a variable cost, but the calculation is the same.
Thus, the prioritization of storage for these two zero variable costs generation technologies should not include their amortized CapEx costs, but instead should focus on the near term market conditions that determine the value of the kWh stored vs. sold instantaneously.
* Actually wind does have some variable costs, but it’s usually impractical to shut them down to reduce wear and tear and the variable costs are in any case very low compared to conventional generation variable costs.

October 19, 2010 4:07 am

I believe the difference is you are looking it at from a system wide view in traditional utility terms. My assessment is in terms of dedicated storage (or transmission, for that matter).

October 19, 2010 12:46 pm

I think my approach is the most sound in those situations as well. As admin, you’ve got my underlying email, so do feel free to pop me an email to discuss further, especially if you’ve got a specific situation in mind. It would be fun to get into the details (without needing to know the actual location or any identifying information) with you. I’m a former engineer and now do quite a bit of financial analysis, so I enjoy working with technical folks on financial questions.

October 20, 2010 7:04 pm

Ken: you don’t need fossil fuels at all.
Just use PV electricity to synthesize methane from air and water. You can use this methane as long-term storage and to offset the PV plant variability by coupling it with a CCGT.
Check this out:
Also, coupling PV with an utility-scale NaS battery will give you baseload-type dispatchability at only a few cents/kWh cost.