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800,000 Microinverters Remotely Retrofitted on Oahu—in One Day

Utilities are asking more of the rooftop solar systems that increasingly are popping up throughout their distribition grids. As we profile in this month’s Spectrum, leading utilities are deputizing solar system’s inverters to function as junior grid regulators to help stabilize the grid. Hawaiian Electric Company and inverter manufacturer Enphase Energy just showed how swiftly such upgrades can happen.

In a single day Enphase and HECO remotely reprogrammed some 800,000 microinverters attached to individual photovoltaic panels on Oahu, accounting for roughly 60 percent of the island’s distributed solar capacity according to Ameet Konkar, Enphase Energy’s senior director for strategic initiatives. Those systems deliver up to 140 megawatts, nearly as much power as the state’s largest conventional power plant, says Konkar.

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Making Solar "Wallpaper" Cheaper, More Efficient

I’m sure that there are tons of reasons why solar panels aren’t absolutely everywhere. Expense, aesthetics, and so forth. But really, we should have them wherever light is, shouldn’t we? No reason not to harvest all of that energy, right? VTT Technical Research Centre of Finland has developed a beautiful, flexible, and entirely recyclable type of organic solar panel that can be mass-produced by printing it on film so that it can be as ubiquitous as wallpaper, and look like it, too.

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Japan Seeks to Rein In a Solar Juggernaut

Clashing energy interests on the Japanese island of Kyushu have prompted Japan's government to clamp down on solar power development nationwide. While the government calls it a necessary revision to assure grid stability amidst rapidly rising levels of intermittent solar energy, critics see a pro-nuclear agenda at work—one that could stunt Japan's renewable energy potential.

Solar development in Japan has exploded since the Fukushima nuclear disaster of 2011. Thanks to an attractive feed-in tariff (FIT) program that guarantees premium rates for renewable power generation pushed through in the disaster’s aftermath, developers have since installed over 10 gigawatts of solar capacity. The solar surge marks a return to glory for the country that once dominated the global PV industry.

But Japan’s solar revival has occured under a cloud. The pro-nuclear Liberal Democratic Party regained power in late 2012, intent on restarting idled nuclear reactors that once generated nearly one-third of Japan’s electricity. The nuclear cloud produced its first lightning bolts on Kyushu in September, and has now spread nationwide.

The conflict between the solar revival and hopes for a nuclear revival burst into the open on Kyushu just a few weeks after island utility Kyushu Electric Power had been given a green light to restart a pair of 890-megawatt reactors (the first restarts approved by Japan's nuclear regulators). On 28 September, Kyushu Electric announced that it had frozen the interconnection of large solar developments.

Kyushu Electric argued that rising solar power capacity threatened the stability of its grid. Since the FIT’s introduction, solar capacity on Kyushu had grown more than 40-fold to 3.4 gigawatts, and Japan’s Ministry of Economy, Trade, and Industry (METI) had qualified a further 8.4 gigawatts of solar projects for FIT pricing. If all of the latter were built, argued the utility, solar generation on Kyushu could at times exceed the island’s 8-GW minimum daytime power demand.

At least four more utilities followed Kyushu Electric’s lead and froze solar interconnections on their grids, arguing that the solar surge threatened their ability to balance supply and demand.

METI came to the utilities’ defense last month, affirming their argument that solar threatened grid stability and proposing new rules for solar and wind power installations aimed at combatting that supposed threat.

The proposals, to be formally adopted early this year, provide a slate of conditions under which utilities are empowered to refuse new interconnections. These include limits to how much renewable energy seven of Japan's 10 vertically-integrated utilities must accept under the FIT.

For Kyushu, it means the island's utility has METI's blessing to limit total solar installations to 8.17 GW. That means Kyushu Electric can refuse interconnections for 5 GW of pending solar projects already certified by METI and further gigawatts awaiting FIT certification.

The new rules also expand all utilities’ power to temporarily turn off PV systems without compensating solar developers.

Many analysts viewed the new rules as a game-changer for solar development in Japan. "It appears likely that a sizeable part of the 69.4 GW of projects that have gained approval under the country’s FIT will not be built," wrote PV Magazine in late December.

Gordon Johnson of Axiom Capital Research told stock market news outlet Benzinga that the utilities’ expanded curtailment powers would deal the solar market a “drubbing” this year. Previously utilities could curtail output from solar arrays on as many as 30 days per year. The new rules allow curtailment for up to 360 hours per year—a reformulation that would allow a utility to clip most of the output from a solar farm for over three months, according to Johnson. As a result, he said, solar project financiers would have difficulty determining the return on investment to be expected from solar projects.

Some developers say the market impacts will take a while to filter down. A source from Hamburg-based Conergy told solar industry business magazine PV Tech last week that the firm remains confident that previously-approved projects will keep the company busy for the next two years. However, the Conergy executive acknowledged that METI’s new provisions could complicate those projects.

Renewable energy advocates argue that METI has overreacted. METI’s revised rules go well beyond what is required to maintain grid stability according to the Tokyo-based Japan Renewable Energy Foundation, founded in 2011 by Japanese telecoms maverick Masayoshi Son (whose Softbank Corp. is itself a solar power investor). In an e-mail to IEEE Spectrum, JREF director Mika Ohbayashi called METI's calculation of renewable energy limits “very conservative (and not realistic).”

Ohbayashi says that METI’s calculations begin by setting aside transmission capacity and power demand for Japan's idled reactors. She says METI’s limits also fail to take account of each utility’s ability to export excess power generation to neighboring utilities.

Japan’s grid does have one notorious power-transfer limitation: the frequency divide that obstructs the free-flow of AC power between eastern and western Japan. However, Ohbayashi says, transmission lines amongst the utilities on either side of that divide offer considerable and vastly underused exchange capacity that can facilitate the integration of renewable energy.

Ohbayashi cites the example of Hokkaido, whose utility had 520 MW of solar power on its system as of last month. Under METI’s proposal, the utility can now limit additional solar installations to 650 MW. The total would equal just 40 percent of Hokkaido's minimum demand and, according to Ohbayashi, ignores the island's ability to export 600 megawatts of power via its cable interconnection with the main island of Honshu. In 2013, that cable carried 16,940 MWh of power from Hokkaido—equivalent to a little more than one day at full-power operation—leaving plenty of spare capacity to carry surplus renewable energy.

Eric Johnston, who frequently covers energy for the English-language daily The Japan Times, sees METI's revisions as evidence that solar, wind, and other renewables face a “bumpy road” in Japan, where they must confront more than just the technical and financial challenges renewable developers confront globally. In Japan, writes Johnston, renewable energy also confronts “political and bureaucratic hostility that makes overcoming the other issues all the more difficult.”

China Dominates the World of Wind, but the U.S. Wind Energy Market Rebounds

In 2014, the wind energy market in the United States grew sixfold, but it was still dwarfed by the world leader in wind: China.

China’s 2014 wind installations were up nearly 40 percent over 2013’s, according to new data from Bloomberg New Energy Finance (BNEF). China installed 20.7 gigawatts last year, nearly half of the world’s total and more than four times the 4.7 gigawatts installed in the United States.

The strong figures for wind reflect a solid year for clean energy investment worldwide. Global clean technology investment was $310 billion in 2014, according to BNEF—up 16 percent from the previous year, but still a little lower than its peak of $317.5 billion in 2011.

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AutoCharge is Microsoft Research's Take on Wireless Charging with Light

Remember a few years ago when the mere fact that we had ways of charging gadgets wirelessly was futuristic and awesome? Remember slightly after that when everyone realized that all of the wireless charging solutions involved compromises that made them not that that much better than plugging your stuff into a wall? Like, having to put your phone in one specific place to charge it, or (and this is especially dumb) having to plug some kind of dongle into your phone to take advantage of a plug-free wireless charging pad?

If you still have to think about charging a phone (or anything else), and you still have to plan around charging it, the fact that the actual charging itself is technically wireless becomes little more than a novelty. Really, what we want is mindless, effortless charging, and Microsoft Research has an idea of how that might happen.

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This Paper "Slinky" Could Power Internet of Things

Origami that harvests energy from the same effect behind most static electricity could eventually be used to power electronics in a cheap, lightweight, environmentally friendly way.

Static electricity usually results from a phenomenon called triboelectricity. When two different materials repeatedly come into contact and then separate, the surface of one material can steal electrons from the surface of the other. This is why rubbing your feet on a carpet or a running comb through your hair can build up static electricity.

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Brimstone and Nanotech May Boost Batteries

Batteries that pair lithium with sulfur may now be a major step closer to propelling electric vehicles three times farther than the lithium-ion batteries used to do so today, researchers say.

For electric vehicles to have a 500-km range, their batteries would need to store nearly double the energy they do now. One possible solution are lithium-sulfur batteries, which store more electrons kilo for kilo than lithium-ion batteries. Moreover, sulfur is extremely abundant, relatively light, and cheap, making it potentially very attractive for use in novel batteries.

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Can Methane Act as a Storage Medium for Renewable Energy?

Researchers from the Karlsruhe Institute of Technology (KIT) in German have demonstrated a novel method of converting the outputs of biogas facilities into methane. The new type of methanation plant can fit inside a standard shipping container, and could be combined with renewable energy production as a means of storing the excess and intermittent supply that is inherent to wind and solar power.

“As conventional methanation processes reach their limits at this point, we have developed a new reactor concept,” said Siegfried Bajohr, the leader of the new project, in a press release. The concept takes the products of biomass gasification—hydrogen, carbon dioxide, and carbon monoxide—and uses a nickel catalyst to produce methane and water. The catalysis is done in a “honeycomb catalyst carrier,” already used as catalytic converters in cars, which are “characterized by a high thermal conductivity and mechanical robustness.”

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Particles Make Paths to Get More Out of Batteries

A major fraction of the energy in all batteries lies untapped. Now, scientists have found a new way to pull some of it out—materials that change into pathways for electricity within the battery over time. The scientists report their results this week in the journal Science.

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Perovskite Solar Cell Bests Bugbears, Reaches Record Efficiency

Perovskite solar cells are one of the hottest prospects in clean energy research, offering good power outputs from low-cost materials that are relatively simple to process into working devices. But their rapid progress has not been without some stumbling blocks. 

Firstly, the cells’ power conversion efficiency often varies depending on how it is measured, suggesting an underlying instability in the cells’ light-gathering perovskite materials. That’s bad news for photovoltaic panels that need to work for a decade or more. Secondly, researchers were struggling to extend the range of the light wavelengths that the cells could harvest, a key strategy for improving their efficiency beyond the 20 percent or so achieved by typical silicon or thin-film solar cells. Some of the field’s leading lights have spent much of last year grappling with these issues.

Now a team researchers in South Korea has developed a perovskite blend that addresses both these challenges, and delivers what they say is the highest-efficiency perovskite cell to date.

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