SPECTRUM: China Stumbles on Path to Solar Thermal Supremacy

In the final days of 2018 a 100-megawatt solar thermal generating station capable of running around-the-clock, 365-days-a-year connected to the Northwest China regional power grid. It was a race against time to commission the plant in temperatures as low as -20 celsius—and one that plant designer and builder Beijing Shouhang Resources Saving Co could not afford to lose.

“We must finish on time. Otherwise we may face a heavy financial problem,” says Chen Han, Shouhang’s director for international markets.

Shouhang was racing to beat the Chinese government’s December 31, 2018 deadline to secure a guaranteed price for the plant’s power. The deadline was part of an aggressive demonstration program launched in September 2016 to slash the cost of solar thermal power and catapult Chinese firms to the head of the global pack—much as China did with solar photovoltaics.

Alas, a little more than two years later, China has stumbled on the path to solar thermal supremacy. While Shouhang’s and two more of the program’s 20 approved projects met the deadline, four others were cancelled last year and the remaining 13 projects are in limbo.

Solar thermal plants are a potentially crucial power source for global grids as they add more wind and PV solar. Unlike their weather-dependent cousins, solar thermal plants can efficiently store heat and then raise steam for their turbine-generators at will. They can thus dispatch power when it is needed most, reducing grid reliance on conventional gas, diesel and coal-fired generators.

However, the technology is comparatively costly and thus growing slowly relative to PV and wind. The technology took a public relations hit back in 2014 when birds killed by intense solar flux at the largest U.S. plant sullied solar thermal’s eco-friendly image. China’s program has been viewed as an opportunity to put solar thermal technology back on track, but the delays and cancellations mean it will fall far short.

The government anticipated adding 5.3 gigawatts by 2022—more than has been installed to date worldwide since the technology’s debut in the 1980s. Adding six more facilities that have a shot at starting this year would bring China’s total to just 550 MW, according to the Beijing-based Du Fengli, the Alliance’s secretary general. Two years from approval to completion was too short since most projects targeted high-altitude desert regions in China’s Northwest, a region with fantastic solar resources that also experiences long, punishing winters that limit outdoor construction to as few as  months.

Du adds that many players were trying to jump into solar thermal energy without prior experience building an entire plant, let alone one of commercial scale. The three projects that met the deadline are the exceptions that prove that rule.

SUPCON Solar and nuclear power giant China General Nuclear Power eachcompleted 50-MW plants in Qinghai province late last year, and both had operated pilot plants there since as early as 2009. Their plants use different approaches: CGN’s ‘trough’ plant employs mirrors to concentrate sunlight on glass tubes, while SUPCON’s ‘power tower’ uses heliostat mirrors to focus solar energy on a central receiver.

Shouhang, meanwhile, erected its own ¥3-billion power tower plant on the southwestern edge of the Gobi Desert in Dunhuang, in Gansu province, adjacent to a 10-MW plant that it began building in 2014.

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Heliostats at Shouhang’s 100-MW solar thermal power plant in Dunhuang. Credit: Shouhang

In a bulletin announcing the 100-MW plant’s startup Shouhang likens it to, “a silver sunflower blooming on the Gobi.” A field of 11,935 heliostats—each up to 115.5-square-meters across—illuminate a 260-meter-high tower where the energy heats a mix of molten nitrate salts. Tanks hold enough hot salt to operate the plant’s steam turbine for 11 hours, enabling continuous power output with or without sunlight. 

Shouhang’s core business is heat transfer devices, so it was able to develop and manufacture the bulk of the plant’s solar equipment in-house, according to Chen. The firm also learned a lot from operating the pilot plant. “We have very complete experience,” he says.

Chen says the new plant is completing tests mandated by grid operator State Grid Corp. of China before it can enter regular operation. He says that so far no one has observed dead birds around the tower. That’s as expected, he says, since the site is not frequented by many birds and is not along a migratory bird flyway.

Shouhang helped build CGN’s plant and is under contract to build others. It has also taken over another 100-MW power tower project in Gansu whose developer backed out last year. But Chen says those opportunities are on hold because the power price for further plants has not been set. Such uncertainty makes it difficult to secure financing for future projects.

Du at the Alliance says the rates will be less than the ¥1.15 ($0.17) per kilowatt-hour secured by the first three projects. She says officials have indicated they will be ¥1.14 for plants completed this year and ¥1.10 for those starting up in 2020 and 2021, but the government has yet to put those prices in writing.

Much hangs in the balance as China’s solar thermal developers struggle to sustain the anticipated build-out. Recent modeling from Beijing-based Tsinghua University suggests that solar thermal power plants can slash the cost of managing variable wind and solar power. For example, they found that replacing 5-20 percent of Gansu’s planned wind and solar PV generation with solar thermal plants would provide flexibility worth 24-30 cents per kilowatt-hour to China’s State Grid—a benefit well above the tariff that Shouhang raced to secure.

At the same time, some top solar researchers are warning that Chinese developers promising big cost cuts could pose a risk to the sector. Exhibit A, they say, is a record low 7.3 cent/kwh bid for power from a big plant in Dubai to be engineered and built by power equipment giant Shanghai Electric. “Something is nonstandard in that bid,” cautions Johan Lilliestam, a professor of renewable energy policy at the Swiss government laboratory ETH Zürich in a recent publication from the Paris-based International Energy Agency.

Robert Pitz-Paal, who chairs an IEA solar thermal research program, stated in the same report that “unseasoned Chinese firms” will hurt the technology’s global standing if they can not deliver: “If they fail, this may become the coffin nail for the technology as the confidence of clients in CSP and its potential for cost reduction may be damaged strongly by Chinese suppliers.”

This post was created for Energywise, IEEE Spectrum’s blog about the future of energy, climate, and the smart grid

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.

According to Vic Shao, CEO for the Santa Clara, California-based energy storage startup Green Charge Networks, tightly integrating storage with photovoltaics in some key states—including Hawaii and California—runs afoul of the “net metering” rules by which PV owners earn lucrative retail rates for the surplus power they feed to the grid. Adding storage can disqualify solar systems for net metering, in which utilities can pay their owners wholesale power rates that are several times lower than retail. “That is obviously a pretty big problem for anybody considering solar. That could kill a lot of projects,” says Shao. Continue reading “Storing Solar Energy: A great idea caught on contested ground”

Solar Power and Grid Stability: Scenarios and solutions

hawaii.gridx299Renewable energy is often intermittent, and that variability presents a variety of challenges to power grids. The nature and magnitude of the challenges depends on the time frame — from fractions of a second to seasonal or even multiyear variations — as well as the nature of the grid itself. The latter is evident in two of my articles from last week looking at how seconds-to-minutes fluctuations in solar power complicate grid controllers’ efforts to maintain alternating current at the 60 hertz frequency and the roughly 110 volt power levels required by North American devices.

Fluctuating AC frequency stars in my Technology Review dispatch from the paradise of Kauai, where the island utility is riding an electrical roller coaster as it pushes solar towards 80 percent of peak power flows Continue reading “Solar Power and Grid Stability: Scenarios and solutions”

Minnesota Finds Net Metering Undervalues Rooftop Solar

Utilities should be paying more for their customers’ surplus solar power generation according to a solar pricing scheme approved by Minnesota’s Public Utility Commission last month and expected to be finalized in early April. Minnesota’s move marks the first state-level application of the ‘value of solar’ approach, which sets a price by accounting for rooftop solar power’s net benefits, pioneered by the municipal utility in Austin, TX.

Minnesota is one of 43 U.S. states that requires utilities to pay retail rates for surplus solar power that their customers put on the grid. Utilities across the U.S. are fighting such net metering rules, arguing that they fail to compensate the utility for services that their grid provides to the distributed generator. So last year pro-solar activists and politicians in Minnesota called the utilities’ bluff, passing legislation tasking the state’s Department of Commerce with calculating the true value of rooftop solar power. Continue reading “Minnesota Finds Net Metering Undervalues Rooftop Solar”

Life’s a ‘Paternoster’ (and then you fly)

Solon SE’s new paternoster lift. Credit Kevin Matthews / ArchitectureWeek.

“Don’t leave the planet to the stupid.” The corporate tag line from German solar module manufacturer Solon SE screams: ‘We reject complacency’ (not to mention gentility). It’s a slap-in-the-face warning to expect the unexpected, so I was looking for something completely different when I visited Solon’s one-year old Berlin headquarters on an architectural tour of Germany last week. I was not to be disappointed. What I found is probably the first cyclic elevator system installed anywhere in decades.

No pressing a button and waiting for a lift with this modern incarnation of a late-19th-C elevator design! In a cyclic elevator a string of passenger cars run by in a continuous loop. One simply steps into one of the open cars scrolling up or down through its adjacent elevator shafts and takes off. To your weary Canadian correspondent, presently immobilized in Berlin by an angry planet, the hassle-free transport offered by Solon’s cyclic lift was a source of almost drunken pleasure.

Unfortunately, it may also be quite stupid (so to speak). Continue reading “Life’s a ‘Paternoster’ (and then you fly)”

Deciphering Big Oil’s Retreat from Renewables

road_tanker_refuelling_credit-bpA New York Times article this week concludes that major oil and gas companies are, as the headline roared, “Loath to Follow Obama’s Green Lead.” Such stories bashing Big Oil’s slim investment in renewable energy tend to fall short by failing to consider how renewables intersect with an oil major’s core business, and this one is no exception.

As the Times ably demonstrates, big oil is freezing or cutting investment in renewable energy and doing so from a relatively small base. It notes that Shell, which has frozen spending on wind, solar and hydrogen energy, has invested just $1.7 billion on alternative energy projects since 2004 compared to $87 billion to keep its oil and gas flowing.

That should come as little surprise since Big Oil’s insubstantial and fickle commitment to renewable energy goes back decades. Following the 1973 oil shock, for example, U.S. oil majors of the time such as Mobil and Chevron embraced photovoltaics, only to dump the projects when oil prices crashed and OPEC’s power waned a decade later. British Petroleum’s promise to go “Beyond Petroleum” already looked weak five years ago when it ditched production of next-generation cadmium-telluride thin-film photovoltaics — the technology that Tempe, AZ-based First Solar has since ridden to the top of the world PV market.

Continue reading “Deciphering Big Oil’s Retreat from Renewables”

Toyota’s Underwhelming Solar Prius

2010-prius-credit-toyotaThe solar roof that Toyota is offering as an option on its next-gen Prius hybrid sedean is even less efficaceous than expected, according to specialty publication EVWorld. The solar panels, reports EVWorld, will add not a nanowatt of charge to drive the Prius.

Technology Review looked at the potential impact of a solar roof on the Prius last summer when rumors of Toyota’s plans first emerged. The clear conclusion of the experts: Keep solar panels on rooftops, where they can be tilted towards the sun for maximum efficiency and multiplied to provide the kilowatts of power it takes to drive a car. A solar rooftop would be just a “marketing gimmick” said Andrew Frank, a plug-in hybrid pioneer at the University of California, Davis, and chief technology officer for UC-Davis hybrid-vehicle spinoff Efficient Drivetrains.

Toyota, it turns out, won’t even bother plugging its solar rooftop panel into the 2010 Prius’ nickel-metal hydride battery.

Continue reading “Toyota’s Underwhelming Solar Prius”