Solving Intermittency


The IEEE has taken on the problem of energy intermittency, one of the most frequently cited criticisms of solar and wind power. Intermittency simply means that the sun doesn't always shine and the wind doesn't always blow. So you could hardly base your entire energy grid on those kinds of sources. (Our piece on improvements in solar energy from last week was met with exactly this objection from several commenters.) Of course, wind and solar don't have to become our primary sources of energy in order for intermittency to be an issue. It would be a problem any time people are relying on power and can't get it.


One interesting potential  solution would be the establishment of transnational power grids -- grids encompassing enough of the earth's surface to compensate for the fact that the wind isn't always blowing (nor is the sun always shining) everywhere at once. Such schemes are highly ambitious, and will require the development of ultrahigh-voltage DC power transmission. Direct Current is the answer -- Tesla could have told us that. The Alternating Current (AC) power used in today's grids would simply dissipate over the great distances involved.

The other likely vehicle for fighting intermittency is massive energy storage. This can come in any of several forms:
Surplus energy from the concentrators could be stored either chemically or thermally. Chemical systems might be based on the reversible dissociation of ammonia or on dissociated metal hydrides. Thermal ones might store the heat directly in concrete or in molten salt.
Compressed air and water are two more possible storage media for massive amounts of energy. We already know how to store energy using air and water, although certainly not at the scale that would be required for backing up the grid.

It's exciting to see something like this IEEE report. Energy intermittency is a solvable problem. Igf one of these ideas isn't the solution, something else will prove to be.






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