A 2 MW battery at the AES Huntington Beach power plant. (Photo: Lauren Sommer)

Energy storage is something we’ve come to take for granted in everyday life. Our cell phones, iPods, cars and computers all depend on batteries. But storing large amounts of energy for the electric grid is another matter entirely. It’s a technical challenge that has yet to be met–but will need to be for the coming age of renewable energy.

California’s grid is designed to deliver electricity on a real-time basis. Every four seconds, the grid operators at the California Independent System Operator (ISO) have to ensure that the energy supply meets the demand in the state, something that’s known as “balancing” the grid (you can see today’s electricity forecast on the ISO site). As a result, they coordinate the one piece of the system that they have control over: the power plants.

Traditional “baseload” generators like gas and nuclear plants produce a steady stream of electrons. But California is adding increasing amounts of solar and wind power to the grid each year. Since the output of a solar or wind farm depends on the sun or wind, the power they produce is intermittent (here’s a time-of-day profile of renewable energy on the grid today). That causes problems for the grid operators on a number of levels. Wind farms produce most of their power at night, but that’s when demand for power is lowest. Energy from solar farms using photovoltaics can drop off substantially when the sun disappears behind clouds. And large solar-thermal arrays ramp up extremely fast when first hit by the sun in the morning.

Energy storage is one of the ways that utilities and grid operators can address this intermittency. By having some extra electricity on hand, they can smooth out the bumps caused by these renewables. Here’s a review of some tried and new technologies for grid storage:

Batteries

There are a number of different kinds of batteries that can be used in grid-scale installations. I visited a two-megawatt battery in Huntington Beach that uses lithium-ion cells, much like a hybrid car or newer power tools. Southern California Edison is working on an 8 MW battery project near the Tehachapi wind farms. But lithium-ion technology has plenty of competitors, many of which have been awarded federal stimulus funding. The primary barrier for batteries is the cost.

A Beacon Power flywheel.

Flywheels

This technology uses rotational energy to store power. Flywheels have an internal rotor that uses electricity to spin at high speeds. When energy is needed, the rotor slows down and generates electricity through a motor. This is used for what’s known as “frequency regulation” on the grid. Since they can charge and discharge power on a second-to-second basis, flywheels smooth out the short-term fluctuations on the grid. Beacon Power has installed flywheels in Tehachapi, California as part of a demonstration project there.

Compressed Air

Using energy produced at non-peak times (at night), compressed air storage projects pump air into large underground caverns. When demand for energy is high, it’s released to run power turbines. PG&E is now planning a 300 MW compressed air facility in Kern County.

Of course, for all these technologies, cost is a major issue, not to mention the siting and planning considerations. To see how they stack up, check out these technology comparison charts from the Energy Storage Association.

Pumped Hydro

In the energy storage world, this is as old-school as it gets. Hydro-power uses water and gravity to generate electricity. Storage is added by pumping that water back uphill to the reservoir, so it can generate power again. Of course, it takes electricity to run the pumps, so the uphill run generally happens at night, when there is cheaper or excess power on the grid. California’s largest pumped hydro facility is PG&E’s Helms Pumped Storage Project outside of Fresno, which has a 1.2-gigawatt capacity (more about that in this Powerpoint presentation). PG&E is reportedly considering two gigawatts of new pumped storage at two other sites in California.

For more, listen to my radio story online and check out the rest of our stories in our ongoing series: 33 x 20: California’s Clean Power Countdown.

While the Secretaries of Energy and Interior were offering confident assurances to a Senate panel about the future of renewables, a consortium of environmental groups was suing them over a plan for major new transmission lines for the western electrical grid.

The groups, represented by lawyers at Oakland-based EarthJustice, produced their own maps to show that the proposed routes appear to miss many areas with the most potential for solar, wind and geothermal resources. Instead, environmentalists say the West-wide Energy Transmission Corridors approved under the Bush administration would seem to line up just about perfectly with major existing and proposed coal-fired power plants (note that the maps themselves are PDF downloads).

According to EarthJustice:

“The Bush corridors plan ignores the Renewable Portfolio Standards (RPS) adopted by nine of the eleven western states to increase use of the region’s vast wind, solar, and other forms of renewable energy. The approximately 6,000 miles and 3.2 million acres of federal land in eleven western states designated as energy corridors puts imperiled wildlife at risk and slices or brushes against the borders of iconic public lands. Among these are Utah’s Grand Staircase-Escalante National Monument, Arches National Park, and New Mexico’s Sevilleta National Wildlife Refuge.”

I asked Katie Renshaw, a Washington-based lawyer for EarthJustice, if Energy and Interior wouldn’t have updated their plans since the Bush-era maps were approved. “As far as we’ve seen, they haven’t,” said Renshaw.  “An analysis was never really completed.”

The lawsuit comes just days after energy entrepreneur T. Boone Pickens revealed that he’s having to reconsider his plans for a major network of wind turbines through Texas. The reason: no transmission lines.

In California and elsewhere, proposed transmission lines have run afoul of environmental interests, as Rob Schmitz reported in his New Gridlock series for Climate Watch.

Update: Scott Streater has more on the controversy over siting renewables in a New York Times Greenwire post.

Copper meets ice in the Ice Bear rooftop cooler. Photo: Kristine Wong

Latest technology designed to improve grid performance, decrease peak energy demand
By Kristine Wong
When the hot weather hits town, everyone wants to cool off. Some down a cold drink, others take a dip in the pool. But most just turn on a switch–for the air conditioning or the fan. But when everybody jumps for the switch at the same time, the electrical grid is pushed to the max, which can lead to blackouts, as well as use of peak energy generators. Peak generators are used just a few times during the year but use more fossil fuels than other power plants.

Now, with the realization that climate change is upon us, along with advances in technology, there are new ways to stay cool while conserving energy and cutting carbon emissions at the same time. Several products showcased this week at the Edison Electric Institute conference  in San Francisco seem to have the potential to do just that.

Take SmartMeter, for instance. The program from PG&E will monitor and control home energy use by satellite, and adjust energy consumption accordingly by supply and demand via a few palm-sized monitors. Right now, it’s still in demonstration mode. But PG&E will offer voluntary enrollment in 2010, and aims to outfit all households by 2012, according to Peter Chan, a PG&E supervisor in Demand Response Operations (“demand response” is industry-speak for systems that can adjust electrical use at the consumer end). Redistributing energy as needed avoids the need to bring peak generators online. Customers lower their energy bills and can also override the system if, say, that load of laundry really needs to go into the dryer now.

The Ice Bear aims to reduce the energy needed to cool low-rise buildings (under 3 stories), using rooftop energy storage that works in conjunction with the building’s air conditioning system. Developed by Windsor, CO-based Ice Energy, a rectangular unit about the size of a sub-compact car sits on the roof and stores energy at night. It releases the energy during peak daytime periods.

The company claims that using off-peak stored power during peak hours reduces carbon emissions by 40%. And the key technology is–well, ice. Major components include a block of ice threaded with a network of copper coils designed to keep the ice from melting, a condenser that makes the ice, and a controller that achieves the building’s thermostat level most efficiently in conjunction with the building’s air conditioning system. The unit uses R410, a refrigerant which the company says is more efficient than more commonly used refrigerants such as R-22. The system comes with a price tag topping $8000 but utilities are apparently bullish on Ice Bear and have bought thousands of units–13,000-15,000 units can conserve up to 50 megawatts, according to company spokeswoman Therese Wells.

The conference also featured previews of potential “game-changing” technologies. PG&E panelist and Director of Emerging Clean Technologies Hal La Flash told the audience about a solar “nantenna,” a flexible panel that may replace solar panels in the future. And Mike Howard, Senior Vice President of Research & Development at the Electric Power Research Institute, spoke of being 5-to-10 years away from the debut of LED lighting that has the potential to be even more energy efficient than compact fluorescent bulbs.

It’s being promoted as a kind of switchplate referendum. Begun in Sydney, Australia, in 2007, it’s a simple concept, which may be part of its appeal: Wherever you are, at 8:30 local time tomorrow (Saturday) evening, turn off the lights for one hour.

Last year organizers estimated that 50 million people complied. California icons like the Golden Gate Bridge went dark. This year, about two dozen California cities and counties have signed up to participate, as well as the State of California.

They’re not telling you to turn off your computer or iPhone, however. Electrons we save at the light switch might be made up for on the Internet, which will likely be abuzz with a worldwide conversation documenting the event on blogs and social networks like Twitter (tag your updates with #earthour and #location). Photo sites will be bombarded with picture uploads.

Personally, I’ll be in the high desert of New Mexico, beyond the sight of any town or even neighbors, so the event won’t make for much of a snaphot.

It might also be a bit anticlimactic for the folks who run California’s power grid. I asked Gregg Fishman at the California ISO (Independent System Operator) if they’d be able to see a dip in the load at 8:30 p.m. tomorrow. He’s not counting on it: “It will probably have some impact but it’s really hard to measure,” he told me.

This time of year, the state is usually pulling about 27-28,000 megawatts at that hour on a Saturday evening. In fact, if you look at the ISO’s grid status graph, you can see a little spike around 8 p.m., as people normally start turning lights on. But Fishman says that even though “most of the load is lighting” at that hour, it may be hard, even for grid technicians, to measure the actual effect of Earth Hour.

But of course, that’s kind of beside the point. The event isn’t designed to achieve palpable energy savings for one hour. It’s supposed to be a visual show of support for policies designed to reduce energy consumption and the global carbon footprint. Recent surveys have shown that economic woes have pushed concerns about global warming and the environment to their predictable recessionary lows, at least in this country. Tomorrow night we’ll find out how the rest of the world feels about it.

That’s the term that Interior Secretary Ken Salazar is using to describe the transmission web that will facilitate the nation’s transformation to clean energy. Some random notes from his (and others’) appearance today before the Senate Energy & Natural Resources Committee:

Salazar:

- 6,000 miles initially identified on BLM lands for new transmission lines on the “Electron Superhighway,” 1,000 on US Forest Service lands.

- Access to land for transmission will be the “Achilles heel” of the plans for a new  clean-power grid.

- Oil & gas need to be part of a “comprehensive energy plan,” along with renewables. The US now imports 70% of its oil.

- Seven major onshore leases already approved, auctioning off another 34 million acres along the Gulf Coast this week.

Ron Wyden (D-OR):

- Let’s use the “backlog of deadly fuels” on the floor of federal forests to generate bio-fuels and reduce fire danger at the same time (Energy Act of 2000 apparently excluded forest slash from its definition of “biomass.”)

- Hydrokinetic (wave & tidal) power should be higher on the priority list for energy development.

John McCain (R-AZ):

- The Obama administration “has effectively killed nuclear power in the foreseeable future, for this country” (by its actions regarding Yucca Mountain and reprocessing of fuel).

Phil Moeller, FERC (Federal Energy Regulatory Commission):

- Wave & tidal power could potentially fill 10% of the nation’s energy portfolio.

Joanna Prukop, NM Secretary of Energy, Minerals & Natural Resources:

- Wind energy is now price-competitive with natural gas (about 5 cents/KW-Hour currently) and could thrive without federal subsidy. Solar, not so much.

Dan Arvizu, Director, Nat’l Renewable Energy Lab:

- Used the term “smart grid” one hour and 38 minutes into the hearing, the first and only time it was mentioned.

You can view the entire webcast at the DOI archive.

By the way,  Salazar will hold a public hearing on energy policy in San Francisco on April 16th. It’ll start at 9 a.m. at UCSF’s Mission Bay Conference Center.