The Drawbacks of a Renewable Grid

Matt Wald

The following is a guest post from Matt Wald, senior director of policy analysis and strategic planning at NEI. Follow Matt on Twitter at @MattLWald.

California researchers have sketched out an American energy system that they say can be powered almost entirely by wind, water and sunlight, by 2050. It’s an interesting thought experiment, with some valid insights, but it’s a little like hopping from New York to California on one foot. Even if you could do it, would you really want to?

The paper, summarized here, is not just a recipe for just powering the electric system, but for converting everything that uses oil or natural gas to run on electricity instead – including ships, cars and even airplanes. The airplanes would fly on hydrogen derived from water molecules split with electricity.

Electrification is almost always a good idea, because it improves efficiency, cuts pollution, and can cut geopolitical risk. We are in the early stages (at least, we hope it’s the early stages) of an effort to convert part of the transportation sector to electricity. President Obama once predicted a million electric cars by 2015.

A few years ago, when oil was $140 a barrel, advocates of multi-billion dollar offshore wind farm complex also suggested that their source could be used to displace heating oil used to keep New England homes warm in winter.

But a reality check is in order. The clock is ticking towards 2050 and those things haven’t happened. The wind farm idea mostly went away when the prices of oil and natural gas oil crashed, and the wholesale price of electricity went with it. Electric cars didn’t go away but we have only about 300,000 of them, counting plug-in hybrids. Those are still advancing, although they have lost some of their consumer appeal with the lower price of gasoline.

And we’re all for de-carbonizing the electric system, because the grid can be transformed safely much faster than Boeing or the Federal Aviation Administration can transform the airline system to anything approaching carbon-free.

The whole system can change, say the authors, from Stanford and Berkeley; what’s needed, they say, is political will. It’s worth pointing out that much more modest steps, like building wind machines off Cape Cod, or building a network of long-distance direct current transmission lines, have faced very stiff political opposition.

One problem the authors make clear is the difference between energy and power – or kilowatt-hours and kilowatts. Getting enough renewable energy is the easy part; getting it when you need it is something else. That makes their analysis more sophisticated than those by other fans of solar and wind. But to solve the problem, they describe storing some of the energy by methods that are not now in commercial use, like heating up soil.

In fact, the storage issues are quite formidable partly because the resource varies by season. For those of us who don’t live on the equator, if we install enough solar cells to meet winter demand, we’ll have a wasteful surplus in summer.

The Massachusetts Institute of Technology recently published a detailed analysis called The Future of Solar Energy, which makes a related point. Solar is so time-limited that if the system has too much of it, solar production will push the market price of electricity way down at noontime (see image below). Wind already cannibalizes other carbon-free generating capacity in some places at night, because it produces most when demand is lowest.

Penetration grows, net peak load gradually decreases, narrows, and shifts.

Storing mid-day energy to cook my evening meal, or night-time energy to heat my morning coffee, is by no means impossible. But with the batteries now available, the ratio of the price of the storage container to the price of the contents is wildly unfavorable, like storing tap water in a solid gold cup. A kilowatt-hour retails for around 11 cents, and at a windy midnight may be far less on the wholesale grid, but the battery needed to store that kilowatt-hour it is in the range of $400. Season-to-season storage – the electric equivalent of a wood pile behind the house – is not a near-term prospect.

Experts with a broader view of energy, like the Electric Power Research Institute, a non-profit utility consortium, generally call for a more balanced mix of generation, as in this study, which has been intermittently updated.

The authors don’t make clear what they don’t like about nuclear power, but we can intuit that they don’t like nuclear fuel accumulating at reactors around the country, with no clear plan for burial. Neither do we. But we suspect that we’ll see the political will to move forward with a federal program to dispose of nuclear waste before we see a consensus to radically convert our electricity and energy systems.