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Storing Solar Energy: A great idea caught on contested ground

Adding energy storage to sites with rooftop solar power generation offers a range of potential benefits. A battery can help smooth out solar’s inherently variable supply of power to the local grid, and even keep buildings powered during blackouts. Consequently, power-conversion innovators are developing a host of new products designed to reduce the cost and improve the efficiency of integrated solar-storage systems. 

Some analysts project a boom in the co-location of solar and energy storage. GTM Research, for example, foresees that co-located PV and storage will grow from $42 million in 2014 to more than $1 billion by 2018. However, the market is moving slower than it might thanks to a little-discussed regulatory roadblock in the United States.

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Costa Rica Runs on Renewables For 75 Days

Costa Rica has been coasting on nothing but renewable power since the start of 2015, according to news from the Costa Rican Electricity Institute (ICE).

The study found that during January, February, and at least the first half of March, the nation’s grid has been running on mostly hydropower, with geothermal, wind, biomass, and solar rounding out the power generation mix. Costa Rica has not had to use any of its oil reserves for electricity.

Heavy rainfall has allowed four hydropower plants to run at maximum capacity. The ICE estimates that the country will continue to see mostly renewable production in the second quarter, with power prices dropping further; a price reduction of up to 15 percent is expected for consumers.

On average, hydropower comprises about 75 percent of Costa Rica’s electricity generation, and geothermal, at about 12 percent, is the country’s second-leading source of power according to the International Energy Agency.  

Costa Rica has an ambitious goal of becoming the first carbon-neutral nation by 2021, although some have questioned how much political support there is for the goal within that timeframe.

The country, which has successfully reforested a large portion of its land, has been voted the “greenest and happiest” country on Earth by the New Economics Foundation. Reforestation has been a priority, but so have large-scale renewable energy projects.

There are plans to open the government-controlled electricity market, according to the UN. There are also incentives for renewable power plants over 7 megawatts. Additionally, government is offering incentives for biofuels.

In 2013, Costa Rican government announced three geothermal projects valued at nearly US $1 billion, with major funding coming form the Japanese International Cooperation Agency. Costa Rica has also been increasing its wind capacity, doubling it to about 150 megawatts at the end of 2013, from 74 megawatts in 2008. In 2014, an additional 49 megawatts of wind power came online.

Costa Rica is not alone in pushing the envelope and achieving impressive gains in clean energy. Last year, Germany met nearly three-quarters of its peak power needs with renewable energy—primarily wind and solar. Another country that already gets nearly all of its electricity from hydro, Norway, is also diversifying its renewables portfolio by investing in wind.

Other countries such as Australia and the United States are adding renewables at an impressive rate, but it still may not be enough to unseat fossil fuels as the primary source of electricity there in coming decades.


Perovskites for "Tandem" Solar Cells

By developing a way to coat silicon photovoltaics with crystals known as perovskites, researchers are creating tandem solar cells that may be substantially better at converting light to electricity than conventional solar cells while also being manufactured at low cost.

Although photovoltaics based on crystalline silicon currently account for 90 percent of the global photovoltaic market, the power conversion efficiency of silicon photovoltaics has been at a creep, advancing from 25 percent to 25.6 percent in the past 15 years. In order to produce solar cells with higher efficiencies while making the most of the existing manufacturing capacity for silicon photovoltaics, the industry has explored devices that combine silicon with other materials. But these so-called tandem solar cells, despite offering better efficiencies, have have yet to capture more than a fraction of a percent of the global photovoltaic market. Why? Because they are typically made using expensive processes.

Scientists at MIT and Stanford, hoping to achieve high efficiency without high costs, looked into creating tandem solar cells using perovskites, which have recently become the darlings of the photovoltaic world. The efficiencies of solar cells made from perovskites have shot up from under 4 percent to more than 20 percent in the last five years or so, quickly catching up to silicon. Moreover, perovskites are inexpensive and easily produced in labs. The MIT-Stanford group detailed its findings in today’s online edition of the journal Applied Physics Letters.

In the new tandem solar cells, a layer of methylammonium-lead(II)-iodide perovskite is stacked on top of crystalline silicon. The device also incorporates layers of other materials on top of and between the perovskite and silicon to assist with the flow of electric charge. The perovskite absorbs higher-energy visible photons, while the silicon absorbs lower-energy infrared photons. According to the researchers, dividing the spectrum of sunlight between specialized absorbing layers is more efficient than letting a single layer attempt to convert the entire spectrum by itself.

The team says it developed a 1-square-centimeter tandem solar cell with a 13.7 percent conversion efficiency. The scientists suggest that if they could improve each component of the tandem solar cell to match the highest-quality devices available today, they could achieve an efficiency of roughly 29 percent; ultimately, they predict, perovskite-silicon tandems could surpass 35 percent efficiency.

The Eiffel Tower at sunset

New Commercial Buildings in France Must Get Green Roofs or Solar Panels

For the most part, Europe has been steadily advancing towards a smarter, more efficient power grid, heavily based on renewable energy as opposed to coal or nuclear power plants. There’s enough reliance on solar power, in fact, that solar eclipses have the potential to cause gigawatt-scale power fluctuations. France, however, is still primarily dependent on nuclear power, which provided over 80 percent of its power in 2012. In an effort to rebalance its energy mix, the French parliament has approved a law mandating that all new commercial buildings feature roofs that are at least partially covered in either solar panels or plants.

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Better Battery Anodes Made From Packing Peanuts

Packing peanuts are excellent at protecting fragile objects but terrible for the environment. Recycling them is not cost-effective, so most end up in landfills, where they could sit around for a hundred years or more.

But the pesky little pieces of foam could be turned into anodes for lithium-ion batteries, Purdue University researchers say. The chemical engineers have found a simple, inexpensive way to convert packing peanuts into carbon nanoparticles and microsheets that perform better than the graphite anodes used in today’s batteries.

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European Grid Operators 1, Solar Eclipse 0

Weather forecasts calling for bright sun today across Europe drove up tensions in advance of the partial solar eclipse that blocked the sun’s rays and plunged much of the continent into a brief period of darkness this morning. Grid operators were bracing for record swings in solar power generation because of the celestial phenomenon. Some power distributors in Germany had warned of fluctuations in frequency, notifying customers and suggesting that they shut down sensitive equipment.

In the end, while clear weather made for some excellent eclipse viewing, the electrical story ultimately felt more like Monty Python’s radio coverage of the 1972 eclipse. As if audio coverage of a quintessentially visual event isn’t absurd enough, the Pythons closed their fictitious report in the ultimate anticlimax, as a sudden rainstorm swept in to spoil the solar spectacle. Europe’s interconnected power grid brought about an equally anticlimactic ending today by delivering rock-solid stability throughout the 2.5-hour eclipse.

In fact, according to Enrico Maria Carlini, Head of Electric System Engineering for National Dispatching at Rome-based transmission system operator Terna, the grid was more stable than normal. Carlini had joked last week about doing a rain dance to dampen solar output during before and after the eclipse. Today he took satisfaction from the fact that the frequency of Europe’s power barely budged from its 50 hertz standard.

If transmission system operators had been struggling to keep power capacity and demand in balance during the eclipse, the frequency would have diverged strongly from 50 hertz. But according to Carlini, it strayed only ±25 millihertz all morning, which he says is about the half of normal variability in Europe’s grid frequency. 

The grid rolled over the solar swings partly because they were smaller than the worst case scenarios for which operators had been preparing for many months. In all, Europe lost and regained about 17 gigawatts of solar power generation this morning, according to the European Network for Transmission System Operators for Electricity (ENTSO-E) in Brussels. That is a lot of power—just shy of the total solar capacity installed across the United States as of the start of 2015—but just half of the swing that ENTSO-E had warned of in its February eclipse analysis

TSOs thus confronted the possibility of solar swings with overwhelming force. German TSOs had double the normal personnel on hand in their control rooms. They also had enough gas- and coal-fired power capacity on standby to double the effectiveness of their standard contingency plans for keeping the grid balanced, says Bruno Burger, an expert in renewable energy integration at the Fraunhofer Institute for Solar Energy Systems in Freiburg. “The TSOs really massively prepared,” says Burger.

Today’s solar swings still represented the biggest power gyrations that Germany’s TSOs have ever confronted, according to Burger. Germany’s solar generation was at nearly 13 GW when the lunar shading began. At the peak of the eclipse, at around 10:30 CET, it had crashed to just 5.4 GW. Then, by noon, it had rushed back up to about 20 GW. That post-eclipse surge would have soaked up about 50 percent more than the maximum negative power reserve capacity that Germany’s TSOs had in place in 2013 and 2014. “This was a big challenge for the TSOs,” says Burger.

Still, they could have handled plenty more, claims an analysis (in German) by Burger’s group, which estimates that Germany’s power installations can provide up to 25.6 GW of regulating capacity per hour. Bloomberg reported today that TSOs called up only about 30 percent of the balancing power that plant owners tendered.

Terna, whose Italian power plants are less conventional than the ones its German TSO counterparts can call upon, took an additional measure to balance this morning’s eclipse-driven solar swings: For the first time ever, it exercised its authority to order the nation’s largest, most advanced solar power plants to regulate themselves. 

“Those plants were ordered to limit their output to about 30 percent of total capacity from 7 am to 2 pm CET,” says Carlini. That action, he says, reduced the solar power deflation during the eclipse by about 500 megawatts and trimmed the post-eclipse rebound by 2 GW. Under Italian law, solar plant owners will absorb the lost revenue because this was an “emergency procedure,” says Carlini, who doesn’t expect that authority to be wielded again before the next eclipse in 2027..

Burger says Germany’s TSOs could have also shut down solar capacity, but chose not to because German law requires TSOs to compensate the solar plants. An analysis by Berlin-based research group Energy Brainpool estimated that would be more expensive than ramping fossil-fired power plants up and down. As reported by PV Magazine yesterday, shutting down solar generation could nearly triple the cost of handling the eclipse to €9.95 million (US$10.7 million).

Solar generation data from Germany's TSOs and their solar forecast for Friday March 20 accessed yesterday via energy information portal ...img


Tough Questions for ITER's New Director General, Bernard Bigot

When ITER, the International Thermonuclear Experimental Reactor project, was launched in 1985, the plans called for a huge reactor that would demonstrate that the fusion of hydrogen atoms into helium atoms would be a source of unlimited energy. Its founding nations (Russia, the United States, Japan, and the EU (China and Korea subsequently joined the project in 2003, and India in 2005)) also hoped it would reduce drastically the problem of nuclear waste that plagues fission reactor projects.

The design approved in 1988 featured a tokamak in which huge superconducting magnets would trap an extremely hot plasma made of hydrogen atoms inside a toroidal steel vessel. Because of the vessel’s size, scientists would be able to induce a fusion reaction that would yield up to 10 times as much energy as is injected in order to heat the plasma.

But that early promise quickly hit the cold reality that large-scale projects frequently encounter large-scale problems. The ITER project never enjoyed an easy life, especially when the United States withdrew its support in 1998, hopped in again in 2005, then drastically reduced its outlays for the project in 2008.

An external report in 2013 blamed a series of missed deadlines and cost overruns on the ITER organization’s weak management of a decentralized organization. The total estimated cost for the project is now at €15 billion (about $16.5 billion), which is almost double the cost of CERN's Large Hadron Collider. Despite that level of government largesse, recent plans to achieve “first plasma” by 2020, and the first demonstration of energy production by 2027, are now being revised. A new schedule should be finalized by the end of the year.

So, what happens if the sponsors of the reactor, located in Cadarache in Southern France, decide to pull the plug? Contracts totaling €6.5 billion (about $7 billion)— €3.5 billion of which are for completing construction on the site—would be in limbo. The 500 contractors who now work on the building site would be out of work. So might the 600 staffers employed directly by ITER organization with its €275 million annual budget. According to ITER, 72 percent of these employees are engineers and scientists. 

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New Trick Promises Perovskite Solar Films For Windows and Walls

A new low-temperature method for making perovskite solar cells paves the way for high-efficiency, colorful, see-through photovoltaic films that could be laminated on windows or plastered on walls.

Perovskite solar cells have become darlings of the photovoltaic world in the past five years. Their efficiencies in that time have soared from a meager 4% to over 20%, quickly catching up to silicon’s 25%.

Another appeal of these solar cells is that the light-absorbing perovskite layers are easy and much cheaper to make than silicon wafers. Mix some precursor chemical solutions, coat it on a substrate and then heat it to evaporate the solvent, and you have yourself a film of perovskite crystals.

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Solar Power Generation Could Exceed California's Demand Up to 5 Times

Solar energy could exceed California's current energy demand three to five times using equipment built on and around the state's existing infrastructure, claim researchers at the Carnegie Institution for Science at in Stanford, Calif. They detailed their findings online March 16 in the journal Nature Climate Change.

With a total area of more than 400,000 square kilometers, California has more land than 189 countries, including Germany. A little more than 8 percent of this land has already been developed by humans. The Stanford scientists explored how much opportunity this developed land presented for power generation via photovoltaic solar power and concentrating solar power. Photovoltaics convert light directly into electricity, whereas concentrating solar power typically uses concentrated sunlight to heat fluid that drives a steam turbine to generate electricity.

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Porous Crystal Supersuckers Capture Carbon

Porous crystals could scrub carbon dioxide from industrial fumes for half the energy often needed now, scientists say. These novel materials could also help clean the air in submarines and on the International Space Station.

All in all, these new materials could slash the amount of energy now consumed in carbon capture by half or more, researchers at the University of California, Berkeley say. They detailed their findings in the March 12 issue of the journal Nature.

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