The Myth of Wind and Solar “Capacity”

Last week, our Department of Energy’s Energy Information Administration released an announcement and a graph that appeared to show wind as the leading new source of electricity.

“Wind, natural gas, and solar made up almost all new electric generation capacity in 2015, accounting for 41%, 30%, and 26% of total additions, respectively, according to preliminary data. The data also show a record amount of distributed solar photovoltaic (PV) capacity was added on rooftops throughout the country in 2015.”



Source: Department of Energy, Energy Information Administration

Such statistics are cited in the US and around the world, particular by anti-fossil/anti-nuclear/anti-hydro green groups to argue that their policies won’t lead to energy poverty but rather a future full of cheap, plentiful, reliable solar and wind energy.

But extravagant claims always use a misleading word that, if you spot, you know something deceptive is going on. That word is capacity–as in wind being the leading new source of “electrical generation capacity.”

When you hear that wind has the most increased capacity, you are supposed to think that it has the most increased ability to provide electricity in the way we need it–affordably and reliably.

But in energy, “capacity” is actually a technical term meaning the maximum momentary ability to produce electricity–not the consistent, long-term ability to produce electricity, which is what matters to human life.

For the kinds of energy I call “reliables”–coal, oil, gas, hydro, nuclear, capacity is roughly equal to ability because their fuel sources are stored, always available, and therefore controllable. A nuclear power plant, for example, might have the ability to run at 90% of “capacity” month after month.

But for the kinds of energy I call “unreliables”–solar and wind, whose fuel sources are intermittent, unpredictable, and most of the time unavailable, the term “capacity” is inherently misleading. A wind farm may operate near maximum capacity at brief, unpredictable moments and produce little to nothing the rest of the time. Those unreliable bursts might add up to 20-30% its supposed capacity. A set of solar panels may operate near capacity in the middle of the summer in the middle of the day when there are no clouds, but most of the time it has far less ability, when clouds (or non-summer seasons) come that ability can disappear, and at night the panels obviously have no electrical generation ability. For the purposes of providing individuals the cheap, plentiful, on-demand electricity they need, this is useless.

The actual ability of wind and solar is essentially zero. Witness the celebrated electric grid of Germany.


13 Chapter 2 2.4 Monthly Intermittency

Sources: European Energy Exchange Transparency Platform; Federal Statistical Office of Germany

Since solar and wind can always dip to zero, it has to purchase enough real capacity from reliables to give everyone the electricity they need. Thus, the solar and wind are unnecessary and indeed problematic since they add unpredictable, destabilizing electricity to the grid. Such wastefulness helps explain why Germans pay 3-4 times for electricity what we do in the US.

Every time you hear some claim about wind and solar capacity remember that since their reliable capacity is zero, more “capacity” means more dead weight and higher prices–until and unless someone can create independent solar or wind power plants with affordable mass storage. The lack of one single such plant in the world illustrates how inefficient and convoluted such an arrangement would be.

Energy professionals: when we discuss energy in public let’s stop using the misleading word capacity, certainly when it comes to unreliables. Or we can start labeling unreliables with their real, meaningful, reliable capacity: 0.