Natural gas and nuclear power plants produce consistent streams of energy, the sun and wind are much less predictable. If a major cloud system travels over a Solar field, that causes the Solar power to drop off. However, grid operators have to keep the natural gas plants running in the background. If they’re turned off, some can take up to four to eight hours to start up again and California’s highest demand for electricity also happens right as the sun goes down with people returning home from work. Grid operators need natural gas power plants at the ready to meet that peak and to fill the gap that’s left by Solar power.

By combining Solar, wind, natural gas, as well as hydropower, nuclear and others it is inevitable that on some days, they’re making more electricity than California needs.

By combining power grids through to other states, it could provide financial and practical solutions. The alternative option would be to store the un-used power, “Energy storage is probably the biggest hammer in the toolbox,” says Paul Denholm, analyst at the National Renewable Energy Lab in Colorado. But until prices come down, storage remains costly.

PacifiCorp is one neighboring states power supplier that California is looking to partner up with. A decision that not everyone is in agreement with. “PacifiCorp is by far the largest owner of coal plants in the Western United States,” says Travis Ritchie, an attorney with the Sierra Club. In 2014, more than 60 percent of PacifiCorp’s electricity came from coal power.

“That’s a big problem for California,” he says. “We have put forth a lot of really great policy measures to stop coal for climate reasons, for pollution reasons.”

As well as pollution there is the financial implication levied on to the decision. In order to stick within the state’s climate change law, AB 32, means that electricity from other states has a price tacked on that raises the cost of fossil fuels to account for their carbon emissions.

“Will California actually lose the ability lead on climate issues if it gives up its power to Utah and Wyoming, two states that are actively fighting everything about climate change that California is working to promote?” he says.

Several state legislators have the same concern. In February, they sent a letter to Governor Jerry Brown raising red flags about the merger.

“We have made great strides to make sure that our electricity is as clean as possible,” says California Assembly Speaker Anthony Rendon. “I want to make sure that joining a wider grid doesn’t impact that.”