Concentrating solar power with storage is coming soon—but how soon?
“The tower’s foundation has 900,000 pounds of steel reinforcing rods and 4,800 cubic yards of concrete and the tower has 800,000 pounds of rebar and 4,300 cubic yards of concrete,” said Crescent Dunes Site Manager Brian Painter.
A total of 70 million pounds of molten salts at 550 degrees Fahrenheit, he explained, will flow over a daytime run from the cold tank to the top of the tower where it will achieve a temperature of 1050 degrees F and either flow through the heat exchanger to turn the holding tank’s water into steam to generate electricity or flow into the hot tank which will hold enough in storage to dispatch up to ten hours of electricity at the project’s nameplate 110-megawatt capacity and be stored until needed.
Construction started at Crescent Dunes in September 2012. Scheduled to begin generating electricity by the end of this year, it is the only one of SolarReserve’s four planned CSP tower projects in construction in the U.S.
“We now have almost $100 million in equity in the Crescent Dunes project,” said CEO Kevin Smith, in addition to the $737 million Department of Energy loan guarantee. A 25-year, $0.135-per-kilowatt-hour power purchase agreement (PPA) with Nevada Energy, Smith added, guarantees the equity investors their return and the DOE full repayment with interest on the loan.
SolarReserve’s 150-megawatt Rice tower project in California’s Mojave Desert is fully permitted, has transmission access, and, in January, finalized its renegotiated PPA (at an undisclosed rate) with PG&E. However, SolarReserve’s 200-megawatt Saguache tower project in Colorado and 100-megawatt Crossroads tower in Arizona are fully permitted but without power contracts.
“PPAs are harder to get these days,” Smith acknowledged. “Many utilities have met their state mandated renewables quotas and are increasingly interested in the more familiar natural gas option at current bargain basement prices.”
Though Smith believes the U.S. PPA market will come back, many doubt that solar power towers can deliver electricity profitably at competitive prices. They point to the Crescent Dunes contracted rate with NV Energy, significantly above fossil fuel prices, as proof.
“It’s a little unfair to expect the first project to produce power at the same price as a combined cycle gas turbine plant when you’ve built 100,000 gas plants around the world,” Smith said. “The Tonopah project is the first. It is like something handmade. When they built the first PV panel by hand, did it cost the same as the hundred-millionth panel? We expect to see prices go down.”
Rice, Saguache, and Crossroads all require further financial backing, which, Smith admitted, is now also difficult to find. “[There is] no DOE loan guarantee program, no 1603 Treasury grant financing for the investment tax credit — just the tax credit market.”
The loan guarantee program, Smith said, “was really a win-win and has been very successful, 97 percent or 98 percent successful. The very low interest rate helps get U.S. technology and projects off the ground and creates jobs. The U.S. government uses it for many sectors of the economy.” But, he observed, “it is not likely to be available again in the near term.”
Meanwhile, Smith said, “we are taking this U.S. technology to the world. We are working on joint ventures in Saudi Arabia, in Morocco, in South Africa, in Chile, in China and in other markets.”
SolarReserve’s capability to provide solar energy that can be used to generate electricity long after the sun goes down is the differentiator, Smith believes. “CSP is going to require storage to be competitive.” Abengoa and BrightSource Energy, SolarReserve’s two major U.S. competitors, Smith noted, have stepped up the development of their storage capabilities.
Financing will be easier, Smith said, when Crescent Dunes is on-line and proving SolarReserve’s concept at utility scale.
That is scheduled to happen by December 31 of this year, but, Painter acknowledged while driving back to Tonopah in the mid-February snowstorm, the company still has “a lot to do.”
In a pair of recent papers, Yale engineers report a novel and cost-effective way to improve the efficiency of crystalline silicon solar cells through the application of thin, smooth carbon nanotube films. These films could be used to produce hybrid carbon/silicon solar cells with far greater power-conversion efficiency than reported in this system to date.
“Our approach bridges the cost-effectiveness and excellent electrical and optical properties of novel nanomaterials with well-established, high efficiency silicon solar cell technologies,” said André D. Taylor, assistant professor of chemical and environmental engineering at Yale and a principal investigator of the research. The researchers reported their work in two papers published in December, one in the journal Energy and Environmental Science and one in Nano Letters. Mark A. Reed, a professor of electrical engineering and applied physics at Yale, is also a principal investigator. Silicon, an abundant element, is an ideal material for solar cells because its optical properties make it an intrinsically efficient energy converter.
But the high cost of processing single-crystalline silicon at necessarily high temperatures has hindered widespread commercialization. Organic solar cells—an existing alternative to high-cost crystalline silicon solar cells—allow for simpler, room-temperature processing and lower costs, researchers said, but they have low power-conversion efficiency. Instead of using only organic substitutes, the Yale team applied thin, smooth carbon nanotube films with superior conductance and optical properties to the surface of single crystalline silicon to create a hybrid solar cell architecture. To do it, they developed a method called superacid sliding. As reported in the papers, the approach allows them to take advantage of the desirable photovoltaic properties of single-crystalline silicon through a simpler, low-temperature, lower-cost process. It allows for both high light absorption and high electrical conductivity. “This is striking, as it suggests that the superior photovoltaic properties of single-crystalline silicon can be realized by a simple, low-temperature process,” said Xiaokai Li, a doctoral student in Taylor’s lab and a lead author on both papers.
“The secret lies in the arrangement and assembly of these carbon nanotube thin films,” In previous work, Yale scientist successfully developed a carbon nanotube composite thin film that could be used in fuel cells and lithium ion batteries. The recent research suggests how to extend the film’s application to solar cells by optimizing its smoothness and durability. “Optimizing this interface could also serve as a platform for many next-generation solar cell devices, including carbon nanotube/polymer, carbon/polymer, and all carbon solar cells,” said Yeonwoong (Eric) Jung, a postdoctoral researcher in Reed’s lab and also a lead author of the papers.
Read more at: http://phys.org/news/2013-02-carbon-prospects-solar-energy-devices.html#jCp
LONDON — Argentina, which along with Venezuela has the least renewable energy in Latin America, is set to expand solar capacity as much as 35-fold as the government plans its first incentives for individual projects.
International developers are planning plants in Argentina’s western regions, which get about twice the solar radiation of the largest solar market, Germany. In the past year, they’ve applied to build 11 projects of about 20 megawatts each, said Marcelo Alvarez, head of solar for trade group Camara Argentina de Energia Renovable, or CADER.
The work would help President Cristina Fernandez de Kirchner‘s administration meet an ambition to get 8 percent of Argentina’s power from renewables by 2016, up from 2 percent now. The nation that defaulted on debts in 2001 and seized energy company YPF SA last year is struggling to lure overseas capital and is relying on domestic measures to pay for solar.
Argentina plans to build 3,000 megawatts in clean-energy capacity, of which about 10 percent may come from solar, according to CADER. About 625 megawatts, mainly small hydropower projects, are in operation. Solar accounts for only 6.2 megawatts of that capacity.
“Financing is a huge challenge in Argentina, as there are very limited financing lines available,” said Eduardo Tabbush, an analyst at Bloomberg New Energy Finance in London. “Small and medium-sized projects need to rely on the local bond market and local trusts.”
Regulation passed in 2011 allows developers to negotiate premium tariffs directly with the government and grid operator Cammesa, without relying on clean-energy tenders arranged by Enarsa. Officials are working on long-term contracts for power from the plants, negotiated on a case-by-case basis, gaining the interest of companies from Spain to China, Nordio said.
The country has organized only one tender so far, granting long-term contracts for 895 megawatts in 2010. That included 20 megawatts awarded to Genneia SA for Argentina’s first large solar parks, enough to power about 30,000 homes. Enarsa is backing five companies to start work on projects before the government signs off on tariffs that will support the industry.
The policy changes have attracted companies such as China’s Sky Solar Holdings Co., which has teamed up with Enarsa to build a 20-megawatt solar complex in San Juan province for about $70 million. Spain’s Solaria Energia & Medio Ambiente SA and local developer Aldar SA also have similar agreements.
Four of the 11 solar-project proposals being assessed have already been approved, have funds and are waiting for a tariff to be granted before starting, according to CADER’s Alvarez. These include the Sky Solar and Solaria ventures, as well as a U.S.-sponsored project in Catamarca and another in Mendoza by a local developer. Most will be split into 5-megawatt solar parks receiving tariffs of $200 to $400 a megawatt-hour, he said.
Following the state tender, Genneia built a $26 million, 5-megawatt solar park that opened last April and was Latin America’s largest until bigger projects were completed in Peru. Argentina’s other large solar plant, a $10 million, 1.2-megawatt project, was completed by Spain’s Comsa SA a year earlier for the San Juan government.
Neighboring Brazil leads Latin America in installed renewables capacity, according to a report by the Inter-American Development Bank and New Energy Finance. Venezuela has the least at 0.1 percent of total electricity generation.
Latin America and the Caribbean have more than 6,000 megawatts of solar sites under development, according to a Maxim Group LLC report. That includes about 2,800 megawatts in Chile and 1,400 megawatts in Brazil.
The region operates only a handful of utility-scale solar parks, those of 1 megawatt or more. Boosted by three parks of more than 20 megawatts each in Peru, such projects across the region can now generate about 105 megawatts and will produce more than 800 megawatts in a year’s time, according to BNEF.
Solar energy in Argentina can also substitute diesel-fueled capacity in remote areas off the grid. A World Bank-backed program has already installed 4 megawatts of small plants, and about 1,500 megawatts of diesel capacity could be swapped for solar, according to Enarsa’s Nordio.
Developers in the country are mainly dependent on above-market tariffs because photovoltaic energy is far from competing with grid-connected power, which benefits from some of the lowest prices in the region as it’s subsidized by the state.
The funding constraints and high cost of debt, in part a legacy of Argentina’s 2001 bond default, are unlikely to ease anytime soon, the IADB report showed, citing last year’s nationalization of YPF as evidence of the investment risk.
With few overseas investors, regional development banks offer one of the scant other options to fund projects, according to Santiago Lagos, head of local solar developer Genneia.
“The most challenging aspect is country risk,” Lagos said by phone. “Private banks, either local or foreign, are not interested in funding renewable-energy projects here so we are talking to multilaterals such as the Corp. Andina de Fomento.”
Genneia financed its first solar park with an $18.8 million loan from state-owned Banco de Inversion & Comercio Exterior SA and is now seeking funds for its other projects, all of which qualify for a $550-a-megawatt-hour tariff.
Even with financing constraints, Argentine solar is luring European developers suffering from reduced subsidies at home, as well as solar-panel makers willing to provide more attractive terms amid a global supply glut. The country will continue to promote the industry as it pursues its emission-reduction commitments, expands power capacity and seeks to curb reliance on diesel imports for off-grid generators, CADER’s Alvarez said.
“Two or three years ago, solar developers had no interest in Argentina,” he said. “Now we get calls from interested parties every day.”
Houma’s two mixed-income apartment communities for the elderly were retrofitted with the photovoltaic solar panels in late 2011 as part a national property developer and managers’ renewable energy initiative.
The panels generate about 147 kilowatts of power per hour in direct sunlight, covering the cost of 50 to 60 percent of the buildings’ hall lights, elevators, air-conditioning systems and other power-operated amenities, said Tim Talley, HRI Properties facilities manager.
The installation is part of a project at six residential facilities in Shreveport, New Orleans and Houma that are run by HRI Properties. The $10 million project, paid for by HRI, is expected to produce about 1.4 million kilowatt hours of solar energy per year from all its properties.
HRI representatives said it is the largest solar installation in the state.
The property owners pay a fixed rent equal to roughly 75 percent of the electricity savings, Talley said.
Melissa Ardoin, property manager of the apartments, said she isn’t sure of the exact savings, but she and the other 115 Bonne Terre residents are enjoying it.
“It’s working real well,” Ardoin said. “It’s keeping the cost down for the housing meters, and the residents are enjoying the covered parking.”
It’s saving at least a couple hundred dollars a month for residents’ power bills, she said.
Talley said the company would like to expand its solar program to other states. It decided to launch the project in Louisiana because of the Department of Natural Resources’ EmPower Louisiana program, which received $71.7 million in federal stimulus dollars in 2009. The state also offers an income tax credit for residential building owners who install wind- or solar-energy systems.
The solar panels sit atop more than 100 carports in Bonne Terre’s parking lots and were installed in less than two months.