Sunday, April 15, 2007

Solar World: Storage is key

The world needs better energy storage techniques if small-scale photovoltaic solar systems are going to make a big impact on carbon emissions, according to a study slated for publication in the Energy Economics journal later this year.

"Electricity supply has to be equal to the demand all day; otherwise there are blackouts. Solar is intermittent -- even a cloud blowing by can push solar sources off the grid quickly," Erin Baker, the study's author, told United Press International in a telephone interview.

Using current technologies, solar can only account for a maximum of 20 percent of the electricity on the national grid, Baker said.

"In order to push solar beyond the 20 percent limit, the electricity (produced at peak sunlight hours) has to feed into batteries that can later feed into the grid," she said.

Baker is an assistant professor of industrial engineering and operations research at the University of Massachusetts, Amherst.

"The report by Baker and colleagues explores the viability of sun-fueled technologies through a combination of evaluations by experts and economic modeling, allowing the researchers to look at solar power's role in the electricity sector in 15-year chunks through 2095," according to a university statement announcing the research project's findings.

"Even if there are research breakthroughs that made the costs of photovoltaics comparable to or less than that of fossil fuels -- roughly 3 cents per kilowatt hour by 2050 -- there would still be a limited impact on emissions unless the advances are combined with improvements in low-cost storage," the statement said.

"The development of complementary technologies, in particular low-cost storage of electricity, is critical. Current technologies do not have good, cheap storage options, and putting all the power into the grid may make it unstable."

At the moment, feeding extra solar energy back onto the grid, and getting paid for it, is just the help homeowners and businesses need to make the big up-front investment involved in installing photovoltaic panels. These payments, generally called feed-in tariffs, are combined with federal and, in many states, state tax breaks to form an incentive package offsetting solar's high costs.

The study focused more on solar's effect on carbon emissions than its effect on people's energy bills.

"When technological breakthroughs are combined with improvements in storage, using solar technology could lower emissions by 20 percent at no additional cost to the economy -- taking a serious bite out of the (world's) carbon problem," the statement said.

The next phase of research, which is just beginning now, is to look at specific battery technologies with an eye on finding the next generation of electricity storage, Baker told UPI.

"I'll be able to comment on specific technologies when you call back in a year," she said jokingly.

She stressed that the study looked at the impact made by relatively small-scale homes and commercial solar photovoltaic users. "We did not focus on (solar thermal) concentrator technology," which can more easily and cheaply be adapted to power-plant scale, Baker said.

Energy Economics is a journal with a mostly academic audience, but the information from the study should eventually disseminate to think tanks and others who can influence policy decisions, Baker said.

"The study is preliminary, but ... the analytic method, which is commonly applied in industry, can be applied at the public policy level," the university statement said.

She said she hopes policymakers and the U.S. Department of Energy can eventually "use the data for (research and development) portfolio analysis," to help them decide which technology projects to support.

"There is definitely potential out there," Baker said of solar energy. "It's well worth making the R&D investment ... (in a) whole portfolio that includes solar, batteries, and even other technologies like wind."

Source: UPI


Gerry Wolff said...

Some of the variability of PV and sources such as wind power can be ironed out by the use of a large-scale grid of highly-efficient 'HVDC' transmission lines. This allows solar electricity to be moved between time zones and, more generally, from areas of surplus to areas of shortage.

Utility-scale 'concentrating solar power' can store solar heat in melted salts so that electricity generation may continue at night or on cloudy days.

Further information about concentrating solar power (CSP) may be found at:



Diva One, and Diva Two said...

Great blog. This storage issue is a critical issue for a place like Alaska where we have limited light in the winter. With large coal deposits near the railbelt it will be difficult to keep coal-fired power off the table locally.

While several regional power companies want to fund a wind farm, our local coop isn't interested in anything but coal and gas produced electricity. With the wind resources we have, if the technology could survive the beating and storage was available, it seems crazy NOT to look into wind power here.

Are 'plug and play' solar units available for the general public to use? I'd like to encourage our coop to 'rent' them out like the phone company used to lease us our phones. Customers would become part of the generating system. Couple that with inexpensive power shut off units for electrical appliances and information about conservation and we can make a much smaller carbon foot print.

Brooke Heppinstall
Palmer, Alaska

ronwagn said...

Storage needs to be done by converting the electricity, on site, to hydrogen as surplus occurs. The hydrogen will then use fuel cells to produce electricity on demand. The wind farms can also sell hydrogen to motorists and other users.

Batteries are not needed, so there is no replacement expense.