DOI: 10.1149/2.034208jes
Breaking the barriers for low-cost energy storage / August 1, 2012

A new low-cost, “air-breathing” battery has the capacity to store between eight and 24 hours’ worth of energy. The rechargeable and eco-friendly battery uses the chemical energy generated by the oxidation of iron plates that are exposed to the oxygen in the air—a process similar to rusting. “Iron is cheap and air is free,” says Sri Narayan, professor of chemistry at the University of Southern California (USC). “It’s the future.” Details about the battery were published in the Journal of the Electrochemical Society. Narayan’s patent is pending, and both the federal government and California utilities have expressed interest in the project. Iron-air batteries have been around for decades—they saw a surge in interest during the 1970s energy crisis, but suffered from a crippling problem: a competing chemical reaction of hydrogen generation that takes place inside the battery (known as hydrolysis) sucked away about 50 percent of the battery’s energy, making it too inefficient to be useful.

Narayan and his team managed to reduce the energy loss down to 4 percent—making iron-air batteries that are about 10 times more efficient than their predecessors. The team did it by adding very small amount of bismuth sulfide into the battery. Bismuth (which happens to be part of the active ingredient in Pepto-Bismol and helps give the pink remedy its name) shuts down the wasteful hydrogen generation. Adding lead or mercury might also have worked to improve the battery’s efficiency, but wouldn’t have been as safe, Narayan says. “A very small amount of bismuth sulfide doesn’t compromise on the promise of an eco-friendly battery that we started with,” he adds.

The California Renewable Energy Resources Act, signed into law by Gov. Jerry Brown in April 2011, mandates that the state’s utilities must generate 33 percent of their power from renewable energy sources by the end of 2020. This aggressive push toward renewable energy sources presents utilities with a problem: solar power works great on clear days and wind power is wonderful on windy days, but what can they do when it’s cloudy and calm out? People still need electricity, and won’t wait for the clouds to clear to turn the lights on. Currently, solar and wind power make up a relatively small part of the energy used in California. In 2009, 11.6 percent of electricity in the state was generated by wind, solar, geothermal, biomass and small hydroelectric plants combined. (Large hydroelectric plants accounted for an additional 9.2 percent.) As such, dips in energy generation from solar and wind power plants can be covered by the more predictable coal-burning grid.

As California moves toward more renewable energy, solar- and wind-power plants will need an effective way of storing large amounts of energy for use during clouding and calm days. Traditionally, utilities store power by pumping water uphill into reservoirs, which can then release the water downhill to spin electricity-generating turbines as needed. This method is not always practical or even feasible in drought-ridden California, where water resources are already in high demand and open reservoirs can suffer significant losses due to evaporation, Narayan says. Batteries have typically not been a viable solution for utilities. Regular sealed batteries, like the AAs in your TV remote, are not rechargeable. Lithium-ion batteries used in cell phones and laptops, which are rechargeable, are at least 10 times as expensive as iron-air batteries. Despite his success, Narayan’s work is still ongoing. His team is working to make the battery store more energy with less material.

[Collaborators include additional researchers from USC and Andrew Kindler of NASA’s Jet Propulsion Laboratory at Caltech. Funding for this research came from the Advanced Research Projects Agency for Energy, an arm of the US Department of Energy.]

Sri R. Narayan
email : srnaraya [at] usc [dot] edu

Danielle Fong
email : Dani.Fong [at] gmail [dot] com

An early drawing of the first prototype built by Danielle Fong and LightSail — a device that uses excess electrical power to compress and store large amounts of air in a small space. This compress air can then be used to generate energy when it’s actually needed. According to LightSail, the prototype can reproduce about 70 percent of the energy put in to it.
View the full diagram

World’s Most Wired Steam Punk
by Caleb Garling / 07.02.12

Danielle Fong was 12 years old when her mother decided she should go to college. Danielle’s teachers didn’t agree. Though an aptitude test put her above 99 percent of students who had already graduated from high school, her teachers said the move to college would ruin her education. But her mother sent her anyway. “Why would I conceivably put my child through six more years of that bullshit?” remembers Danielle’s mother, Trudy Fong, who was 15 when she herself went to college. “I didn’t bring my kid into the world to have her tortured — and be treated like dirt for being brilliant.”

Little more than a decade later — after graduating from Canada’s Dalhousie University and then dropping out of the Ph.D. program at the Princeton plasma physics lab when she decided academic research was as broken as grade school — Danielle Fong is the chief scientist and co-founder of a company called LightSail Energy. Based in Berkeley, California, this tiny startup is built on an idea that’s as unorthodox as Fong’s education. LightSail aims to store the world’s excess energy in giant tanks of compressed air. The goal is to plug these tanks into wind and solar farms, so that they can squirrel away energy for times when it’s most needed, much like reservoirs store rain water. The wind and the sun are prime sources of renewable energy, but they generate power unpredictably. LightSail’s compressed air tanks, Fong and company say, will make the power grid that much more efficient — and ultimately make the world a greener place.

In 2010, Danielle Fong and LightSail took their compressed air storage idea to the U.S. Department of Energy’sAdvanced Research Projects Agency, seeking a grant for their work. The agency turned them away, saying she and her team were unfit to manage a company, that the idea wouldn’t work anyway, and that her air compressor would likely explode. But like her mother, Danielle didn’t listen. Backed by $15 million in funding from green-minded venture capital outfit Khosla Partners and with a team of 32 employees, LightSail is pushing ahead with its plan to reinvent the power grid. Fong believes the potential market for compressed air tanks will exceed $1 trillion over the next 20 years. “People get skittish,” says Fong, who is now all of 24. “If you have your own resources and have a real effort, it doesn’t matter what the rest of the world thinks, in its knee-jerk, fight-or-flight response.”

In a way, Fong is going back to the future. Compressed air tanks have been used to store energy as far back as the late 19th century. They were installed in cities across the globe, from Paris to Birmingham, England to Buenos Aires. Germany has been using the technology for the past 30 years, and a power company in Alabama opened a facility in 1991. The idea is a simple one: If you have a power source — whether it’s gas or coal or renewable sources such as wind — you can use the energy to cram air into a tank. When the air compresses, it heats up, as we all know from high school physics — or just from pumping up a bicycle tire. Then, when you need the energy at some point down the road, this stored heat can be turned back into power. It’s a bit like coiling and releasing a spring. The rub is that you lose power with each transfer, and you lose heat when the air is in storage. Because it’s less than efficient, compressed air storage never caught on in a big way. Current systems often lose more than 50 percent of the power originally put into them, since they use the released energy to run a generator — which only loses more power.

Since the 1700s, scientists have struggled to store energy in more efficient ways, working to refine everything from Galvanic fuel cells to modern-day batteries. The question is always the same: How do we build a system that lets us storage energy and then retrieve almost all of it? But Steve Crane — LightSail’s CEO and a geophysics Ph.D. — says Danielle Fong has cracked at least part of the code. “It’s a little arrogant to put it this way,” he says, “but I think that Danielle has succeeded where Edison and others have failed.” The trick? Fong added water. LightSail’s prototype sprays a dense mist into the compressed air tanks, and this absorbs the heat produced during compression. Water can store heat far more efficiently than air, and with this mist, Fong says, the prototype more easily stores and releases power. It heats up the tanks to temperatures that are only about 10 to 20 degrees warmer than the environment, as opposed to several thousand degrees. The tanks are still pressurized to about 3,000 pounds per square inch — and Fong hopes to increase that amount — but since the power is stored at lower-temperatures, it’s easier to insulate the tanks. Some compressed air storage systems sit deep underground, taking advantage of the earth’s natural insulation, but LightSail’s tanks sit above ground, which is less costly. When you want the heat back, you just reverse the process, spraying the warm water out of the compression tank as the air expands, and it drives a piston to reproduce the power. But in both storing the heat and spitting it out, you need just the right amount of water. LightSail has tested nearly 40 nozzle heads — not to mention various tank designs — in an effort to achieve just the right mix. According to Fong, her system doubles the efficiency of compressed air, from about 35 percent to roughly 70 percent.

You might think of Danielle Fong as a real-life incarnation of Steampunk, that science-fiction literary genre that re-imagines Victorian technology in a post-apocalyptic future. The difference is that her prototype isn’t fiction. Fong’s original plan was to put her tanks into cars. She holds up Elon Musk, the founder of electric car pioneer Tesla, as a role model. “He was willing to go all out,” she says. But rather than equip cars with combustable engines or rechargeable batteries, LightSail planned to fill them with compressed air. The hot air would drive the pistons in a new breed of automobile engine. But after a nudge from their backers, Fong and team decided that — whatever Musk has accomplished with Tesla — convincing old-school automakers to put these tanks into their vehicles was an almost insurmountable task. So she chose another almost insurmountable task: Reinvent the power grid.

The world is already moving to renewable energy sources such as wind and solar farms. But these don’t produce a steady stream of power. Some days you have sun, and some days you don’t. Plus, more power is typically consumed at night, when solar farms are no longer generating energy, so you need an efficient way of storing it. Fong envisions a power grid that behaves more like the internet, where resources are evenly distributed across the world and they can be readily accessed whenever they’re needed. Yes, the grid is fundamentally designed to distribute power to places of need, and we have “peaking plants” that only operate when additional power is required. But Fong hopes to provide a level of efficiency the world has never seen, especially in large countries like India and China, where power grids are less developed. “It dramatically makes it easier and more economical to do a network this way,” she says, “rather than in a way where your expensive assets have to be designed for the peak anticipated loads over the next 20 years.”

Is this doable? According to Samir Succar, a researcher at Princeton University’s Environmental Institute, compressed air storage could indeed improve the efficiency of wind and solar farms and other less-than-predictable energy sources. But he points out that wind and solar power still accounts for only a small portion of the power grid, and that compressed air doesn’t make sense for more traditional — and more predictable — sources such as coal and gas. “We just don’t have penetration rates that would require energy storage right now,” he says. What’s more, he says, power companies have little incentive to build energy storage centers — whether they use compressed air or some other technology. According to Succar, the power giants prefer to invest in technologies with a proven history, such as natural gas. What’s more, because compressed air can mean so many different things, it can be difficult for these companies to understand which technologies are the most efficient.

Tom Zarella — CEO of a competing compressed air outfit, SustainX — agrees that no matter how effective the hardware built by LightSail or his own company, the task ahead is immense. While some are pushing for greener forms of energy, the political and economic barriers aren’t exactly coming down. According to both Zarella and Fong, the collapse of solar outfit Solyndra — after it had won a $535 million U.S. loan guarantee — soured investors and turned the political discourse against alternative energy efforts. “The moment of ‘Me Too!’ investing in clean energy — where people believe it is easy — is over,” Fong says. “We realize that.” But she says there are some basic realities that will float LightSail to the top: air is free, and it’s everywhere. Any country can use it without depending on another. She says that some of the company’s initial targets include Third World countries, isolated towns and islands that operate without power grids and depend on diesel generators and other local power sources. Much of the wattage generated by these sources is wasted, she says, and her compressed air tanks can turn things around. But she’s eying the United States as well. The Department of Energy’s National Renewable Energy Laboratory recently released a report saying about 75 percent of the United States is suited to compress air storage because it could accommodate buried tanks. But Fong doesn’t need to bury hers. She can put them anywhere. “We know we can sell as many of these as we can make,” she says, insisting that by 2015, her company will be growing threefold every year. “This has never been achieved in any industrial setting. At all. But there’s no other possible energy storage solution that can do that. And if we don’t do it, pretty solid models about the climate — and the way the economy is going to go and what people will do with coal plants — will fuck the world.” Some may doubt whether all this will happen. And others may doubt whether Danielle Fong has the right plan to deal with it. But she’s used to that.


Second day of blackouts leaves nearly 10 percent of humanity without power
by Philip Bump / 31 Jul 2012

This is not a repeat from yesterday. It is worse. For the second day in a row, power consumption in India vastly exceeded available supply, due in part to high temperatures. The result: grid failure that first struck the northern part of the country — which had the same issue yesterday — then, the eastern. Reuters suggests that the outage affected 670 million people — 9.5 percent of all people on Earth. For nearly four hours, power and transportation systems in the nation’s capital were at a standstill, forcing hospitals and “VIP zones” to rely on generator backups. From the Pittsburgh Post-Gazette:

Hundreds of trains stalled across the country and traffic lights went out, causing widespread traffic jams in New Delhi. Electric crematoria stopped operating, some with bodies half burnt, power officials said. Emergency workers rushed generators to coal mines to rescue miners trapped underground.

At least 46 of the 200 trapped miners have since been rescued.

That coal miners were trapped is not without irony. The root of India’s electricity problem, exposed by surging demand in high temperatures, is that a wobbly infrastructure is combined with too little generation. A business trade group puts the blame for generation issues specifically on “the nonavailability of coal.” As we noted last week, the quality of India’s domestic coal is largely too poor for recent-generation coal plants.

The Times’ Andy Revkin has a good round-up of deeper explanations for the power failures, further explaining the link between India’s power problems and its coal problems. He cites theWall Street Journal, which blames environmental regulations:

More than half of India’s power-generation capacity of 205 gigawatts is coal-based, and Coal India Ltd., the world’s biggest coal producer, is unable to produce enough owing to delays in getting environmental clearances for mining. Meanwhile, government giveaways in the form of free electricity to farmers and a reluctance among politicians to raise power tariffs to sufficiently cover costs have drained cash reserves from the largely state-run electricity-distribution companies, leaving them with mounting debt and hampered ability to purchase power.

But again, it’s not clear that mining more coal would solve the country’s problems. If generation facilities can’t use the coal, there’s not much point in sending more people down to retrieve it.

[For more on the power outage (which is now largely resolved): The BBC has a good gallery of images. The Times of India is running a liveblog.]


A man cleans panels installed at a solar plant at Meerwada village of Guna district in the central Indian state of Madhya Pradesh June 18, 2012. Life in the remote Indian village of Meerwada used to grind to a standstill as darkness descended. Workers downed tools, kids strained to see their school books under the faint glow of aged kerosene lamps and adults struggled to carry out the most basic of household chores. The arrival of solar power last year has changed all that. On a humid evening splashed with rain, fans whirr, children sit cross-legged to swat up on their Hindi and delighted people can actually see what they are eating and drinking. REUTERS-Adnan Abidi

Off-grid power shines in India solar village
by Jo Winterbottom  /  Aug 1, 2012

Life in the remote Indian village of Meerwada used to grind to a standstill as darkness descended. Workers downed tools, kids strained to see their schoolbooks under the faint glow of aged kerosene lamps and adults struggled to carry out the most basic of household chores. The arrival of solar power last year has changed all that. On a humid evening, fans whirr, children sit cross-legged to study their Hindi and mother-of-seven Sunderbai is delighted people can actually see what they are eating and drinking. “When it was dark, we used to drink water with insects in, but now we can see insects, so we filter it and then drink,” said the 30-year-old, whose flame-orange sari and gold nose ring are small defiances in a life close to the poverty line.

Children watch television powered by solar energy at Meerwada village of Guna district in the central Indian state of Madhya Pradesh June 18, 2012. REUTERS-Adnan Abidi

Meerwada, on a dirt track rutted by rains and outside the reach of the national grid, struck lucky when U.S. solar firm SunEdison picked it to test out business models and covered the hefty initial expense of installing hi-tech solar panels in the heart of the village. But rapidly falling costs and improved access to financing for would-be customers could encourage the spread of such systems down the line, while simpler solar schemes are already making profits in areas where the grid either does not extend or provides only patchy power. And Asia’s third-largest economy, where just this week hundreds of millions were left without electricity in one of the world’s worst blackouts, needs all the help it can get in easing the strain on its overburdened power infrastructure. The country’s Ministry of New and Renewable Energy (MNRE) hopes solar systems that bypass the national grid will account for just under one percent of total installed capacity by 2022. Still a mere flicker, but that 4,000-megawatt (MW) goal would be way up from 80 MW now when so-called off-grid solar systems are still out of reach for most of the country’s rural poor.

Large-scale solar facilities that directly feed the grid, such as those at an over 600 MW solar park recently launched with great fanfare in Gujarat, have been gaining traction for some time. But potential growth in off-grid solar power offers a ray of hope to the around 40 percent of India’s 1.2 billion population that the renewable power ministry estimates lack access to energy. People like those in the village just 200 meters away from Meerwada, who rely on a hand pump for water and cook by torchlight as hungry goats creep up on them out of the gloom. Covering initial investment on solar is key as, in a country with around 300 days of sunshine a year, subsequent costs are largely limited to maintenance and repairs. “The high up-front capital cost is one of the adoption barriers (for solar projects),” said Krister Aanesen, associate principal at McKinsey & Company’s renewable energy division. “Although diesel is more expensive on a full-cost basis, you defer cash outlay for the fuel … the cash outlays are different and that’s one of the key challenges.”

Small-scale direct current (DC) systems from Karnataka in the south to Assam in the north-east have already cleared that hurdle, supplying simple lights and mobile phone chargers at 100-200 rupees ($1.80-$3.60) per month per light — prices that typically allow installers to cover their initial costs in time. Private company Mera Gao Power fits roof-top solar panels and then transmission to other houses who pay about 40 rupees to connect, with costs thereafter about 25 rupees per week, said Nikhil Jaisinghani, one of the firm’s founders. That means it should currently take about 12 months to repay panel installation expenses of about $2,500 for 100 houses, though the cost is set to fall. Initial expenses are far more onerous on more comprehensive mini-grids like the one in Meerwada, which includes a room full of batteries that can store enough electricity to provide round-the-clock supply to the village and which has recently started powering water pumps. California-based SunEdison reckons it cost $100,000-$125,000 to build the 14 kilowatt (KW) plant in Meerwada, an expense that would have demanded fees way too high for the 400 or so villagers, whose per capita income is about $250 a year.

The firm expects initial capital costs to come down enough to make alternating current (AC) systems affordable in villages like Meerwada in a few years, with improving technology and fierce competition reducing hardware costs, while enhanced battery storage driven by the auto industry’s push on electric cars is also helping. SunEdison, which sells solar power plants and services worldwide to commercial, government and utility customers, has over 50 MW of interconnected solar electricity in India, with projects ranging from small rooftop installations to part of the Gujarat solar park. “Three years ago, the panel price was $2.60 per watt. Today it is 75 cents a watt. I don’t think it will halve in the next few years but I clearly see 50 cents a watt by 2014/15,” said Ahmad Chatila, president and chief executive of MEMC Electronic, SunEdison’s parent company. In the meantime, the government is offering 30 percent of the project cost and in some cases low-interest loans for solar power systems under its Jawaharlal Nehru National Solar Mission policy launched in 2010. But that still means systems are beyond the reach of many poor, rural customers, so some solar companies are putting up the 20 percent deposits on loans required by banks or acting as guarantors for customers who are outside the conventional banking system.

A man stands inside his illuminated house powered by solar energy at Meerwada village of Guna district in the central Indian state of Madhya Pradesh June 18, 2012. REUTERS-Adnan Abidi

Back in Meerwada, which lies in central India’s Madhya Pradesh, the villagers have added an unexpected ingredient to the cost equation — frugality. Lights even now are turned on only when darkness falls and fans target the youngest children and the elderly, saving on power use. Only the village leader, Sampat Bai, has been able to afford a television but it’s open to all and her bare-walled main room is crowded when the latest epic dramas come on screen and the children have finished their homework. Manorbai, a 30-something mother who is now making more money by working at night to mend and sew on her vintage black-and-gold foot-pedal sewing machine, has a simple message on the future. “Our village has power and other villages should too,” she said.


Wilson Solar Grill Stores the Sun’s Energy for Nighttime Fuel-Free Grilling
by Bridgette Meinhold / 08/14/11

Many of us will be firing up our grills this weekend for some well-deserved barbecue time. After all, barbecuing is one of America’s greatest past times, but it certainly isn’t one of our most environmentally friendly. Whether you prefer charcoal, wood chips or propane, grilling releases emissions and contributes to poor air quality. Up until now, solar powered grilling has required, as you might expect, the sun, which means traditional fuel-fired grills are required after sunset. But new solar technology developed by MIT professor David Wilson could bring a nighttime solar-powered grill to the market very soon; an invention also of great benefit to those in developing nations who rely on wood to cook all their food.

Wilson’s technology harnesses the sun and stores latent heat to allow cooking times for up to an amazing twenty five hours at temperatures above 450 degrees Fahrenheit. The technology uses a Fresnel lens to harness the sun’s energy to melt down a container of Lithium Nitrate. The Lithium Nitrate acts as a battery storing thermal energy for 25 hours at a time. The heat is then released as convection for outdoor cooking.
“There are a lot of solar cookers out there,” says Wilson, “but surprisingly not many using latent-heat storage as an attribute to cook the food.” Wilson developed the idea after spending time in Nigeria, where wood is used for cooking, which causes a number of problems. Not only is cooking with firewood leading torespiratory illnesses, but is also increasing the rate of deforestation and women are being raped while searching for wood.

A group of MIT students are working with the technology to develop a prototype solar grill. Derek Ham, Eric Uva, and Theodora Vardouli are conducting a study through their multi-disciplinary course “iTeams,” short for “Innovation Teams”, to determine the interest in such a concept and then hopefully launch a business to manufacture and distribute these grills. The goal is to develop a business model for distributing solar grills to developing nations as well as a grill for the American market. The American version is expected to be a hybrid propane/solar model that will allow for flame cooking as well as through thermal convection.

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