By Lisa Meadows

The state of California has set big goals for switching over to green energy within the next decade. The difference with these energy sources is that they depend on the weather.

Water (hydro energy), wind (wind turbines), and sun (solar energy) are the key components to generating renewable energy. In California, lawmakers have set high standards for how green we want to be in the next 10 to 20 years. The goal is to have switched over 33 percent of the state to renewable energy sources by 2020 and half of the state by 2030.

Since all three are affected by the weather, that means high stakes weather forecasting for the California Independent Systems Operator. This government group manages the state’s power grid. Steven Greenlee of Cal ISO says, “We have to make sure that the grid is ready to deliver all of those megawatts that the utilities need to meet these goals.”

Figuring out the forecast for these energy sources falls on the shoulders of Meteorologist Amber Motley. She’s in charge of short-term forecasting at Cal ISO.

“We forecast temperature and turn that into an energy use forecast, and then determine the generation that means to be online for it,” she says. If Amber is off by two degrees, that could impact the power grids’ reliability and cost. She says a one-degree error when temperatures are in the 90s can mean a difference of 500 megawatts of generation.

Cloud cover is important too. Cloud cover means the use of solar energy is out. As it turns out, clouds are one of the hardest weather elements to predict. Our forecast models are pretty good at predicting the weather, but one of the things they struggle the most with is predicting cloud cover.

Cal ISO says we are already well on our way to reaching the state’s green energy goal. They say during fall and spring, when the load is not as high, we hit 33 percent renewable resources at times. Getting renewable energy won’t be a problem for sunny California; the trick is going to be transferring it. Since a lot of these renewable resources like solar farms are out in areas that aren’t very populated, the challenge from an engineering standpoint being able to deliver the power over a longer distance consistently and reliably. They say they are well on their way to reaching the renewable energy goal set by the state. And the forecast confidence in reaching that goal is high.

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