Posts Tagged ‘Wind Energy’

Renewable energy’s mismatch with the grid

September 4, 2017

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.

(more…)