A natural gas power plant in Long Beach that uses "once-through" cooling.
We hear a lot about how green our energy is in California. Instead of using coal, the state runs on natural gas and increasingly, renewable power.
But there’s a hidden cost to our energy supply: water use. In fact, every time you turn on a light, it’s like turning on your faucet. It’s been calculated that it takes 1.5 gallons of water to run a 100-watt light bulb for 10 hours.
The way water and power work together is a lot like a tea kettle. Steam drives the power industry.
How Power Needs Water
You can see it at the Gateway Generating Station, a natural gas power plant in the northeast Bay Area. The plant looks complicated but making power is pretty simple. Step number one: burn natural gas. That produces a lot of heat.
“You’ve got 1,700-degree exhaust energy, or waste heat,” says Steve Royall of PG&E, who is giving me a tour through the maze of pipes and compartments. The heat hits pipes that are filled with water and the water is boiled off to create steam. That’s step number two: make steam to turn a steam turbine, which is attached to a generator. It’s the water that’s making the power.
Source: National Renewable Energy Laboratory. Illustration by Andy Warner.
A big solar developer makes a major move toward storing electricity
Solar-thermal plants use mirrors or "heliostats" to focus sunlight on a tower receptor that produces steam to generate electricity.
A major barrier for solar power has always been that it doesn’t work at night (Duh). A few years ago, developers of big “utility-scale” solar projects were able to shrug this off to some degree. But Oakland-based BrightSource Energy has reversed field and decided to add to several projects the ability to store electricity for distribution after dark.
BrightSource managers say times have changed. Where utilities once wanted all the renewable capacity they could get, to meet state requirements, the priority has since shifted to having those renewable electrons available when they’re needed.
“The challenges of integrating photovoltaics and wind into the grid have driven a much deeper appreciation for those that can be highly reliable,” BrightSource CEO John Woolard told me in a phone interview. Continue reading →
Construction of one of three planned solar thermal towers at the Ivanpah Solar Electric Generating System, Ivanpah Dry Lake, CA
Construction of the Ivanpah site is reportedly on-schedule for completion in 2013
The National Clean Energy Summit 4.0 opens in Las Vegas on Tuesday, bringing policy makers and industry leaders from around the country together to “chart the course for the future of energy in America.” It’s also attracting lots of media, which is why on Monday Oakland-based BrightSource Energy opened the gates to the construction site of its 3,500 acre Ivanpah Solar Complex, which lies just over the California border, 45 minutes southwest of the Las Vegas Strip.
About 15 reporters donned hard hats and safety goggles in 100-plus temperatures to tour the active construction site in the Mojave Desert, along with officials from BrightSource, San Francisco-based construction company Bechtel Corp., and NRG Energy, which, along with Google, is the project’s main investor. Continue reading →
UPDATE: Since this post was first published, the BLM has also given the nod to another major solar energy installation, the approximately 400-megawatt Ivanpah project, being developed in San Bernardino County by Oakland-based BrightSource Energy.
The Tessera project will use "SunCatchers" to concentrate solar power. (Image: Tessera Solar)
Tessera Energy’s 700-megawatt Ocotillo project, located in the Imperial Valley, about 100 miles east of San Diego, and a smaller photovoltaic (PV) project by San Ramon-based Chevron Corp., are both cleared to go forward.
The two projects set a precedent not just for California. On a call with reporters this morning, Department of Interior Secretary Ken Salazar called it a “historic day,” saying the two projects “bear the distinction of being the first large-scale solar energy projects ever approved for construction on our nation’s public lands.” Continue reading →