Renewable energy’s mismatch with the grid

Falling cost of photovoltaic cells. Chart via QIC.

The existing U.S. electrical grid can’t handle too much solar and wind energy.   They’re too variable.   They can’t be counted on when they’re needed most.

Until this changes, electric utilities will continue to rely on their aging fossil fuel and nuclear power plants as certain sources of power.

The problem, as Gretchen Bakke describes it in The Grid: the Fraying Wires Between Americans and Our Energy Future, is in the unique nature of electricity as a commodity.   It is the only commodity that has to be used as soon as it is produced.

The historic economic problem of electric power utilities is that they have to be able to supply as much electric power as their customers need at any point in time, but that most of the time this capacity goes unused.   This is especially acute in the USA, Bakke wrote, because we Americans insist on being able to use as much electricity as we want, any time we want it.

The Public Utility Regulatory Power Act – PURPA – requires electric utilities to buy renewable energy at a price equal to their cost of making non-renewable energy.    Now wind and solar electricity are reaching the point in which they’re competitive with fossil fuels and nuclear energy.

Bakke reported that 7 percent of U.S. electricity is generated from renewables.   The percentage is bound to increase.   Denmark reportedly gets 40 percent of its energy just from wind.

The problem is that wind and solar power are not always available when and where they’re needed.  The windiest and sunniest parts of the North American continent are not necessarily where the population is concentrated.   And the windiest and sunniest times of day are not necessarily when energy is most needed.

So some utilities are faced with the problem of insufficient solar and wind energy during some hours of the day, and so much solar and wind energy at other times that managers have to scramble to prevent the grid from being fried.

Solar power, by definition, is only available during the daytime.   But electric power use peaks in the early afternoon.   Fossil fuel and nuclear energy, on the other hand, can be turned on at any time of the day.   Until this mismatch is eliminated, electric utilities can’t stop using non-renewable coal, oil, natural gas or uranium.

Energy supply and demand on a typical day.  Chart via QIC

As the chart above indicates, the answer lies in better means of energy storage.   Right now the only one in widespread use is pumped-storage hydroelectric power.   Electric utilities pump water uphill into reservoirs or behind dams; the power is needed, water flows downhill to power generators.

One ideal solution would be widespread adoption of electric cars.   The car would be plugged in to a power source when it is not in use.  During times of peak demand, electric utilities could draw down power from all those automobile batteries without having to ramp up coal or nuclear plants.

All that is required is to sell the American public on buying electric cars, and having a battery charging system in every garage and on every parking lot.

Bakke said the U.S. military is the only institution that has made this work.   She said all “non-tactical” military vehicles on U.S. soil are electric.   This works because the military controls both the vehicles and the sources of power.

Maybe this idea could be applied to electrical appliances.   Make them chargeable, like cell phones.   Then during the day, your refrigerator, dishwasher and other appliances could build up a charge, then draw down during the day.   That would solve your peak energy demand.   I admit I have no idea what would be required to make this technologically and economically feasible.

The other possibility is what Bakke calls “demand optimization.”   That means giving up the idea that we can have all the electricity we want any time of day we want it.

Bakke envisions something called the “smart grid” or the “Internet of things.”   The idea is that appliances would be semi-autonomous, and programmed to start up when electricity is cheapest and most abundant.

You would put your clothes in the washer-dryer and an algorithm in the machine would determine when the clothes were washed.  You would program your vacuum cleaner to run a certain number of times a week, and its programming would decide when—probably late at night.

Industries and businesses would be paid to stop drawing from the grid when demand is high or supply is low.  Suppliers of electricity would be paid to go off-line when there’s danger of a power surge.   All this would be agreed to in advance, and controlled by microprocessors—what Bakke calls a “wise gird”.

Her book closes on a note of techno-utopianism not supported by the facts she cites.   Hope is not a plan.

Then again, she is a professor of anthropology, and her job as an anthropologist is to collect and understand the stories that members of a given culture tell each other.   It’s not her job to come up with a better story than the Federal Energy Regulatory Commission’s or the North American Electric Reliability Council.

A Footnote on Reliability

Gretchen Bakke’s vision of the future of the electrical grid is that more institutions and municipalities will develop their own sources of electricity, both for emergencies and to sell on the grid.

As time goes on, centralized electric power generation would be partly or wholly replaced by “microgrids”.   This would increase the reliability of the system.

Electricity would be transported shorter distances, creating fewer points of possible failure.    Because there would be more sources of power, the failure of any single power sources or transmission line would have less impact.   Because the generating plants would be run by institutions that depend on the power supply, the operators would have a personal stake in making the system more reliable.

I don’t think solves the problem of incentives—the fact, which Bakke pointed out, that maintaining the grid is a cost but not a source of profit.

She said, rightly, that the electric grid is a public good, like the highway system.   We the public long ago learned that privately owned toll roads are no substitute for public roads.   Maybe we need to replace the privately owned electrical transmission system with a publicly owned system.

We the public would have equal access to the grid.  Buyers and sellers would be free to make their own deals, without some other profit-seeking entity acting as gatekeeper.


Aging and Unstable, the Nation’s Electrical Grid Is ‘The Weakest Link’, interviews with Gretchen Bakke on National Public Radio.


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3 Responses to “Renewable energy’s mismatch with the grid”

  1. peteybee Says:

    Good stuff.

    As you point out, the concept of “capacity utilization” is central to the economics of electric generation – it determines how quickly the initial cost of a plant can be paid off.

    The capacity utilization of everything other than wind and solar is expected to decrease. (varying with local climate, time of day, and season.)

    For most of the US, this devastates the economics of baseload generation technologies with high up-front cost. That means nuclear. It’s happening now – the US is basically pulling the plug on future deployment of nuclear power. I think the second-to-last planned nuke project in SC was just cancelled after a ton of money sunk into it, and the last one in GA is now uncertain, Westinghouse is bankrupt, loan guarantees to nuke projects kicked off in the 2000’s threaten to take down Toshiba as well.

    At the same time we want to retire coal due to CO2 / climate change and other pollutants.

    That will ultimately leave the top technologies for electric generation ultimately as a combination of wind, solar, and natural gas. (Again depending on local climate, time of day, and season.)

    And until battery storage tech catches up to the wind/solar generation, we will, out of necessity, have to maintain and probably even subsidize a fossil fuel technology with capacity adding up to everything that wind and solar deliver on an “average” day, paying for its initial cost, even if that capacity is rarely used.


  2. oiltranslator Says:

    I realize some applications of nuclear energy interfered terribly with Altrurian plans for Nationalsocialist and similar dictatorships, and their resentment is only too natural. But so what? What is wrong with building nuclear reactors? Canadian CANDU reactors are profitably exporting electricity to These States, and both of the successful party platforms this past election were pro-energy and pro-grid. The kleptocracy party that copied its planks from CPUSA and the Green socialists got the drubbing it deserved.


  3. greenl4l Says:

    Reblogged this on Green Living 4 Live.


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