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MIT Researchers Turn Used Car Batteries into Solar Cells

Scientists at MIT have concocted what could become the ultimate in green energy: a solar panel made out of hazardous waste. 

In research paper reported in the journal Energy and Environmental Science, researchers describe a method for making perovskite solar cells using the lead from recycled car batteries. The technique can be done in a low-temperature, benign process that’s simpler than today's methods, they say. And after 18 months of testing, the researchers found that their experimental solar cells matched the efficiency of many commercial silicon cells, MIT said yesterday.

Perovskite is a class of materials that has caught the interest of solar photovoltaic researchers because they have made rapid progress in improving the efficiency of solar cells made from materials in the past three years. Compounds in this group promise to be very cheap and relatively simple to manufacture. One company, called Oxford Photovoltaics, is seeking to make commercial solar perovskite cells that can be applied as coatings on windows and other outdoor building surfaces.

One downside is that the material contains a small amount of lead. Extracting lead from ore is a high-temperature, polluting process that creates lead vapor and dust that’s difficult to contain, the MIT researchers note. And if companies begin to produce perovskite solar cells at large volumes, the materials they would be mining and processing could become a serious health or environmental hazard, they say.

(Two labs recently reported perovskite cells using tin instead of lead, but these are much less efficient.)

The other looming problem with lead is that technologies such as lithium ion batteries are advancing to the point that they could soon displace lead acid batteries in cars and trucks. The result, the researchers fear, is a glut of unwanted batteries containing a huge amount of lead waste.

About 90 percent of lead acid batteries in the United States are recycled, but problems remain. In 2011, the New York Times reported that an increasing number of old car batteries are being exported to Mexico from the United States for recycling, but that the work is done with crude methods that expose people to lead poisoning.

The MIT scientists say they have a better idea. In their paper, they spell out a multi-step process they say will give the lead from all those batteries a second life. They've demonstrated the ability to synthesize perovskite solar material using the electrodes straight out of a used lead-acid battery. Lead from the anode is mixed with nitric acid and the lead oxide (made from the lead dioxide cathode) is mixed in acetic acid. Then each compound is mixed with potassium iodide.

The solutions are then purified and deposited on a thin flexible film, which acts as the substrate for the solar cell. (You can watch a step-by-step video demonstration below.) Because it’s a relatively simple process, the researchers are optimistic that it can work at large scale cheaply. And because each of the perovskite cells are just half a micrometer thick, the researchers estimate that a single car battery could produce enough solar panels to provide electric power for 30 households.

MIT professor Angela Belcher and the paper’s lead author, Po-Yen Chen, say they don’t intend to start a company to commercialize their technology. Instead, they wanted to show people who are developing and manufacturing perovskite solar cells that the lead from old batteries performs just as well as mined lead. 

“This paper is about the excitement in the field of these [perovskite] materials and thinking about the environmental implications of extracting lead,” Belcher says. “The beauty is that this new process is pretty interchangeable with the current production method.”

Mexico Opens Its Grid to Competition

As part of a wider reform of its energy market, Mexico is privatizing its energy regulator and will begin allowing private companies to sell energy to, and add capacity to, its electricity grid. The country's president, Enrique Peña Nieto, enacted the laws (English summaries) on Monday, August 11th (Spanish pdf). Petroleum and electricity have been state monopolies in law since the 1917 constitution and in practice since the late 1930s, when Mexico succeeded in expropriating foreign energy firms' holdings.

The change in direction is in part a response to very poor productivity: Mexican industrial customers pay around 72 percent more than American counterparts for electricity, according to a Deloitte report (pdf).  PriceWaterhouseCoopers estimates that the Mexican grid has 18 percent transmission losses, over double the OECD average of seven percent (pdf).

The US-Mexico border sees only a small amount of electricity trading today, but this reform could be an opportunity for American firms with generation and transmission construction experience. Private companies already generate around one third of Mexico's electricity, but they must sell it to the Federal Electricity Commission (CFE), the national regulator and distributor of electricity. Under the new laws, they will be able to bid for access to the grid and compete for clients. In the long run, that should lead to lower prices.

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An Energy-Storing Wind Turbine Would Provide Power 24/7

Electricity is the perfect form of power in all respects but one. It can be produced and used in many different ways, and it can be transmitted easily, efficiently, and economically, even over long distances. However, it can be stored directly only at extremely high cost. With some clever engineering, however, we should be able to integrate energy storage with all the important modes of generation, particularly wind-generated power.

Right now, to store electricity affordably at grid-scale levels, you need to first convert it into some non-electrical form: kinetic energy (the basis for flywheels), gravitational potential (which underlies all pumped-hydro storage), chemical energy (the mechanism behind batteries), the potential energy of elastically strained material or compressed gas (as in compressed air energy storage), or pure heat. In each case, however, you lose a significant percentage of energy in converting it for storage and then recovering it later on.

What if instead you were to completely integrate the energy storage with the generation? Then you wouldn’t have to pay for the extra power-conversion equipment to put the electricity into storage and recover it, and you wouldn’t suffer the losses associated with this two-way conversion. One of the most attractive ideas, I believe, is to integrate storage with wind-generated power. I’ll come back to that in a minute.

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Tesla, Panasonic Team Up for "Giga" Battery Factory

Tesla Motors this week announced they’d inked a deal with battery-maker Panasonic for a proposed battery “gigafactory.” The electric car automaker also provided some substance to the rumors that the factory will be sited in Reno, Nev.

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Filling Up a Fuel-Cell Car With Hydrogen Gets One Step Closer

From construction materials to livestock to aeronautical engineering to ice cream, the U.S. National Institute of Standards and Technology (NIST) keeps an annual tally of the weights and measures needed for industries throughout the nation’s economy. NIST’s Handbook 44 is like a Whole Earth Catalog for the durable and consumable goods sold in the United States, including gasoline—and now hydrogen.

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Green Mountain Power Goes Green, Saves Green

At a time when some forecasts for the future of electrical utilities see gloom—volatile fossil fuel prices hiking rates and killing profits while customers wean themselves from the grid in favor of renewables, distributed storage, and smart micro grids—it’s no surprise that some of the 3300 electric utilities in the United States have dug in their heels. Florida’s top electrical utilities, for instance, have reportedly strongly resisted the rise of solar power in the sun-drenched state.

Yet a few utilities are actively bucking the industry trend of rising rates and resistance to clean energy. In 2014 alone, for instance, Vermont’s top electric provider, Green Mountain Power (GMP), has announced a 2.46-percent rate cut while also receiving the advocacy group Vote Solar’s 2014 Solar Champion award—the only utility to be so honored.

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GE Claims Fuel Cell Breakthrough, Starts Pilot Production

General Electric has developed a way to convert natural gas using a combination of fuel cell and an engine, an approach it hopes will finally result in broad adoption of stationary fuel cells.

The industrial giant's research arm on Tuesday disclosed details on its solid-oxide fuel cell research efforts and said it has started a pilot line at a factory in upstate New York to manufacture the generators. As first reported here last year, GE has achieved relatively high efficiency by coupling two generators and hopes to bring down costs by using cheaper materials.

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Survey: Climate Experts Favor Retiring Coal, Keeping Nuclear

If you were the scientific advisor to a $200-billion venture capital fund that aims to limit global warming over the next 20 years, what investment would you recommend as having the single biggest impact? A survey of climate experts found that a majority listed the retirement of coal power—or the sequestering of their emissions—as the top priority for investment.

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Wind Farm Fires Far More Common Than Reported, Study Finds

Fires in wind turbines are happening ten times more often than they are reported, according to new research from Imperial College London, the University of Edinburgh and SP Technical Research Institute of Sweden.

The incidence of fire is still far less than in fossil fuel-based energy industries, such as oil and gas, which suffer thousands of fire accidents per year. The wind industry reports about 11 fires per year, but the researchers found there are more likely about 117 wind turbine fires annually across more than 200,000 turbines. For the wind industry, the fires are the second leading cause of accidents after blade failure.

Inside of the turbine’s nacelle, hydraulic oil and plastics share the same tight space as machinery and electrical wires. When there is overheating or faulty wiring it can catch fire. The nacelles are perched behind the turbines so high winds often fuel the flames.

Because the turbines are so tall and are often in remote areas, they are usually destroyed before the fire can be suppressed. In 90 percent of the cases, the fire leads to substantial downtime or a total loss of the wind turbine.

“Worryingly our report shows that fire may be a bigger problem than what is currently reported,” Guillermo Rein, from the department of mechanical engineering at Imperial College London, said in a statement. “Our research outlines a number of strategies that can be adopted by the industry to make these turbines safer and more fire resistant in the future."

The researchers looked at data from the past 30 years and found that fire accounted for 10 to 30 percent of the reported turbine accidents, with reports increasing. The leading cause of the fires was lightening strikes. That was followed by electrical malfunction, mechanical failure, and errors with maintenance.

One industry group, RenewableUK, welcomed the report overall but questioned the data sources used by the researchers. “Wind turbines are designed to international standards to meet mandatory health and safety standards including fire safety risks. State of the art monitoring systems ensure that the vast majority of turbine fires can be dealt with quickly and effectively,” Chris Streatfeild, director of health and safety for RenewableUK, said in a statement. “This is supported by an HSE-commissioned report in 2013, which concluded that the safety risks associated with wind turbines are well below all other comparable societal risks.”

Some of the strategies the researchers suggest to prevent ignition include passive fire protections, such as lightning protection systems and switching to non-combustible oils and insulating materials. Smoke alarms and fire suppression systems could also help minimize the extant of fire damage.

The researchers also plan to evaluate the frequency and impact of fire on solar panels in the future.


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