Tag: solar

These Batteries Rock

Wind and solar energy generation is criticized for not being always-on, so people have been looking to batteries to steady the flow of energy. Over at Cambridge, there are some people who think that a new type of battery made out of gravel could help with the full adoption of sustainable energy.

Isentopic claims its gravel-based battery would be able to store equivalent amounts of energy but use less space and be cheaper to set up. Its system consists of two silos filled with a pulverised rock such as gravel. Electricity would be used to heat and pressurise argon gas that is then fed into one of the silos. By the time the gas leaves the chamber, it has cooled to ambient temperature but the gravel itself is heated to 500C.

After leaving the silo, the argon is then fed into the second silo, where it expands back to normal atmospheric pressure. This process acts like a giant refrigerator, causing the gas (and rock) temperature inside the second chamber to drop to -160C. The electrical energy generated originally by the wind turbines originally is stored as a temperature difference between the two rock-filled silos. To release the energy, the cycle is reversed, and as the energy passes from cold to hot it powers a generator that makes electricity.

Isentropic claims a round-trip energy efficiency of up to 80% and, because gravel is cheap, the cost of a system per kilowatt-hour of storage would be between $10 and $55.

Keep reading at The Guardian.

Origami Solar Cells from MIT

Those ever smart people at MIT are using origami to model solar cells to make them more efficient. The greater the surface area the more sunlight can be absorbed and used, check out these crazy creations:

Jeffrey Grossman, the Carl Richard Soderberg Associate Professor of Power Engineering at MIT’s Department of Materials Science and Engineering (DMSE), was inspired by the way trees spread their leaves to capture sunlight and wondered how efficient a three-dimensional shape covered in solar cells could be, and what its optimal shape would look like. He worked with a second-year DMSE graduate student, Marco Bernardi, to create a computer program that mimics biological evolution, starting with basic shapes and letting them evolve, changing slightly each time and selecting those that perform best to start the next generation. He found that such systems could produce relatively constant power throughout the day without the need for tracking, and produce significantly more power overall for a given area — for example two and a half times as much as a flat array when the height equals the length and width. He is continuing to work on finding the best shapes and teaming up with Professors Vladimir Bulović and David Perreault (EECS) to build a prototype system. The team believes that solar panels based on this concept could be shipped flat and then unfolded at the site to their complex shapes.

From MIT.

Powering Tomorrow With Ancient Plant Technology

Photosynthesis is how plants convert energy from the ball of fire in the sky into useful plant-growing energy. The USA’s Department of Energy is actually looking into how photosynthesis can be used to power our homes and even turn homes into miniature power stations using the power of nature.

According to Nocera, his new system can work at ambient temperatures and pressures, without corrosion in a simple glass of water, even polluted water. “If you need pure water for energy storage, they’ll drink it,” Nocera said. “Use puddle water instead.” In fact, Nocera has been running his prototype on untreated water from the Charles River in Boston. And it’s cheap, not $12,000 per kilowatt like commercial electrolyzers that do the same thing. “That’s not going to help the energy situation for the U.S. or poor people of the world.”

Using the electricity generated by a photovoltaic array five meters by six meters, Nocera claims he can split enough water in less than four hours “to store enough energy for the average American home” for a day, a little more than 30 kilowatt-hours. “We need to stop making big energy systems one a time to service lots of people. We need to do it the old American way of making one small one and then manufacturing that system to give it to the masses.”

Read more at Scientific American

Distributed Solar Power Lights the Future

Large solar power installations require a lot of space and a lot of approvals. As a reaction to this, smaller solar power installations have been approved and placed close to transmission centres. This is a more reliable and sustainable energy network than what existed before.

Over the past few weeks, some 1,300 megawatts’ worth of distributed solar deals and initiatives have been announced or approved. At peak output, that is the equivalent of a big nuclear power plant.

Two weeks ago in California, regulators authorized the utility Southern California Edison’s program to install 500 megawatts of solar on commercial rooftops. A few days later, they recommended that Pacific Gas and Electric, the dominant utility in Northern California, be given the green light for its own 500-megawatt initiative that aims to install ground-mounted photovoltaic arrays near electrical substations and urban areas.

The Sacramento Municipal Utility District said in January that it took only a week to sell out its 100-megawatt solar program, which offers developers the opportunity to build photovoltaic projects of up to five megawatts.

And last week, the New York Power Authority announced a program to install 100 megawatts of solar arrays around the state.

“All of this is a great indication that solar prices are continuing to get a lot cheaper and that results in scale,” said Adam Browning, executive director of Vote Solar, a San Francisco nonprofit that promotes renewable energy.

Keep on reading about distributed solar power.

Renewable Energy in China is Booming

When most people think of China and energy coal generally comes to mind, indeed China is the world’s biggest user of coal for energy. That may not change anytime soon but what the Chinese government is doing now is expanding their renewable power and becoming the world’s largest exporter of renewable technology. We can all benefit from increased use of renewable energy even if it just offsets new coal power plants from being built.

China has also leapfrogged the West in the last two years to emerge as the world’s largest manufacturer of solar panels. And the country is pushing equally hard to build nuclear reactors and the most efficient types of coal power plants.

These efforts to dominate renewable energy technologies raise the prospect that the West may someday trade its dependence on oil from the Mideast for a reliance on solar panels, wind turbines and other gear manufactured in China.
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China’s top leaders are intensely focused on energy policy: on Wednesday, the government announced the creation of a National Energy Commission composed of cabinet ministers as a “superministry” led by Prime Minister Wen Jiabao himself.

Regulators have set mandates for power generation companies to use more renewable energy. Generous subsidies for consumers to install their own solar panels or solar water heaters have produced flurries of activity on rooftops across China.