For the past decade, California has been a leader in the clean-energy revolution. Groundbreaking state laws require our major utilities to purchase 33 percent of their power from renewable sources by 2020. And some green-energy experts expect that mandate to rise to 50 percent or more in the following decade. To date, the rapid growth of solar and wind power has fueled the move to renewables. But for California to fulfill its green-energy future, it must solve an important problem: how to deliver electricity to consumers when the sun isn't shining and the wind isn't blowing.
We rely on what's essentially a 19th-century technology — the electrical grid — to deliver power to our homes. The grid encompasses power plants, high-voltage transmission lines, local circuits, and just about everything they touch: whatever it takes to generate and distribute power. Throughout the 20th century, the concept evolved and improved, and grids of various sizes began delivering power more reliably to ever more places in the United States and around the world.
But in the 21st century, a major shortcoming of our existing grid looms large: Electricity dissipates instantly on it. This use-it-or-lose-it system is a problem for wind energy, since wind blows strongest at night, when demand for electricity is low, and for solar energy, which can't provide power once the sun goes down, or when a cloud passes overhead. That means considerable energy from wind and the sun is lost if it isn't used at the moment it's available.
On top of that, the intermittent, sometimes unpredictable energy output of solar panels and wind turbines can spell trouble for our outdated grid, like large-scale blackouts and brownouts or surges on local circuits that can fry electronics.
In short, the system needs an upgrade. It needs a buffer to help balance supply and demand, without which the grid can suffer catastrophic failure. It needs a sponge to soak up excess power and deliver it at peak times. It needs a regulator to smooth out the steep peaks and valleys that result from solar and wind ramping on and off with the weather. And it needs to do all this while meeting the country's most stringent greenhouse gas-reduction targets in a state that is forecasted to continue growing in population, and therefore energy demand, for decades to come.
Continue reading here.