24 Hour Solar Thermal Plants

 

The Chilean government recently gave the go-ahead on a massive solar thermal plant that is expected to produce electricity 24 hours a day, seven days a week—a considerable feat for a plant that depends solely on solar energy. The plant, proposed for a site in Chile’s Tamarugal province, would consist of three 150 megawatt solar thermal towers, which become heated as mirrors placed around each tower reflect sunlight onto it.

That heat is transferred to molten salt, which circulates through the plant during the day and is stored in tanks at night. The salt, a mixture of sodium nitrate and potassium nitrate that’s kept at a balmy 1,050 degrees Fahrenheit (566 degrees Celsius), is used as a “heat transfer fluid.” As energy is needed, the salt can be dispatched to a heat exchanger, where it will lend its heat to water to create a super-heated steam. That steam is used to move a traditional steam turbine to create electricity.

The molten salt generates high quality super-heated steam to drive a standard steam turbine at maximum efficiency and generate reliable non-intermittent electricity during peak demand hours.

SolarReserve, the US-based company that proposed this project, has also proposed two others—a 260 MW, 24-hour plant near the city of Copiapó in the Atacama Region of Chile, as well as a 390 MW, 24-hour plant in the Antofagasta Region. Mary Grikas, a SolarReserve spokesperson, told Ars via e-mail that Copiapó is shovel-ready, and now Tamarugal is, too, with the Chilean government’s recent approval, which assessed the site for environmental impact. The plant in Antofagasta is still waiting on permitting approval.

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100 Percent Green California

California’s Senate leader wants the Golden State to shift to 100 percent renewable electricity by 2045, pushing it to lead the country in grabbing that green power goal.

Environmentalists are cheering California Senate President Pro Tempore Kevin de León’s (D) plan to double, and accelerate, the state’s current renewables mandate of 50 percent by 2050. Oscar-winning actor Leonardo DiCaprio even tweeted his thanks to de León among his 17 million followers.

The nation’s most populous state switching to fully renewable electricity sounds idealistic. But several experts said it can be done — with a lot depending on definitions, technological advancements and acceptable price tags.

“2045 is a long way away,” said Severin Borenstein, economics professor at the University of California, Berkeley’s Haas School of Business. “A lot could happen between now and 2045.”

Energy storage through batteries “could get a lot cheaper. That could make the goal much more attainable and much more cost-effective,” he added. Wind and solar energy already are close in price to natural gas, he said. “If you could actually store the power cost-effectively, then you could make it work much more effectively.”

Others warned major expenses would ensue. Large-scale solar and wind projects often go in deserts or other open areas, requiring added infrastructure to move the power to cities, said Evan Birenbaum, who led the environmental strategies program at Los Angeles-area utility Southern California Edison Co. before leaving in 2014. He now heads Chai Energy, which focuses on reducing household energy consumption.

“You would need to build new transmission lines to support the incoming [renewable] power,” Birenbaum said. “Old power lines might not be able to support it.”

Utility substations also likely would need upgrades, he said, adding, “You’re talking about many billions of dollars that have to be invested in that new renewable energy future. It’s the ratepayer who will have to pay for that.”

Borenstein said that calculating how much it will cost nearly 30 years from now is “nearly impossible to answer. … Imagine going back 30 years,” when the internet-connected cellphones used now didn’t exist.

“It’s very hard to predict technology 30 years in advance,” he added.

FFT: Although goals and estimates for 100% renewable energy may not be accurate to the year, the challenge gives us perspective as we progress towards the goal. Who knows, maybe we’ll even beat it.

( Visit the full article at the Scientific America )

https://www.scientificamerican.com/article/can-california-go-100-percent-green/