Wind and Solar Energy: Transforming the Grid with Clean Energy, Reliably, Every Day

Despite years of successful experience, dozens of studies, and increasing utility support for clean energy, urban myth holds that electricity from renewable energy is unreliable.  Yet over 75,000 megawatts (MW) of wind and solar power have been integrated, reliably, into the nation’s electric grid to date.  That’s enough electricity to supply 17.9 million homes.

And, as a new NRDC fact sheet published Friday illustrates, the electric grid can handle much higher levels of zero-carbon wind and solar power, far more than what’s necessary to achieve the relatively modest carbon emission reductions in the U.S. Environmental Protection Agency’s plan to limit pollution from existing power plants. 
...
Wind and solar power have hit the big leagues

There is more renewable energy flowing through the power grid than ever before.  At times wind has supplied more than 60 percent of the total demand on some utility systems, without reliability problems.  And solar power now routinely contributes 10 to 15 percent of midday electricity demand in California, which has more solar panel installations than anywhere in the country.

Accurate forecasts and advanced technologies matter

Due to more precise weather forecasts and sophisticated technologies, grid operators increasingly can predict--and control--wind and solar generation levels.  Accurate predictions of wind speed and solar conditions help grid operators efficiently schedule renewable energy into the system.  Using advanced and often-automatic control systems, grid operators can both increase and decrease the power output into the grid, which helps to stabilize the grid’s electrical frequency and maintain reliability.

Wind and solar need less backup power than coal, gas, and nuclear

Every power plant on the grid needs “backup” power in case something happens to prevent it from generating as much electricity as planned.  PJM, in charge of most of the grid from New Jersey to Illinois, currently holds 3,350 MW of expensive, fast-acting contingency reserves 24/7 to ensure that it can keep the lights on in case a large fossil or nuclear power plant unexpectedly breaks down.  In contrast, MISO – the grid operator for the middle part of the country with the most wind power in the nation – needs almost no additional fast-acting power reserves to back up its 10,000-plus MW of wind power on the system.

Why is so little backup power needed for wind and solar?  In contrast to the large, abrupt, and often unpredictable changes in electricity output from coal and nuclear power plants, wind output changes tend to be gradual and predictable, especially when wind turbines are spread over larger areas.  The fact that a wind farm is a collection of many smaller turbines also helps, since the failure of one has little impact on the farm’s total output.

Read more at Wind and Solar Energy:  Transforming the Grid with Clean Energy, Reliably, Every Day