Energy of the future - solar thermal power!

	27 May 2008
	my profile my cabinet my tracker my labels my bookmarks my notes Google, Goldman Sachs and oil firm Chevron believe that earth's future energy needs lie in the sun, and are willing to invest millions in that belief By Sourya Biswas What does the largest search engine in the virtual world and the largest investment bank in the real world have in common, besides each being worth billion of dollars - in real money that is? Well, for one, Google and Goldman Sachs both believe that earth's future energy needs lie in the sun, and are willing to invest millions in that belief. And for good measure, they are joined by one of the biggest oil companies, Chevron, as well. All these big names have poured in big money in companies that specialise in solar thermal technology. This technology is a lot simpler technically than the more popular solar photovoltaic cells that convert sunlight directly to electricity. Here, sunlight is focused with mirrors to heat oil in glass pipes to about 370 degrees Celsius, which is used to turn water to steam. The steam spins an electric turbine to generate electricity by electromagnetic induction. Solar thermal collectors are characterised by the US Energy Information Agency as low, medium, or high temperature collectors. Low temperature collectors are flat plates generally used to heat swimming pools. Medium-temperature collectors are also usually flat plates but are used for creating hot water for residential and commercial use. High temperature collectors concentrate sunlight using mirrors or lenses and are generally used for electric power production. However, we are concerned here only with the high temperature collectors, which some opine, can satisfy as much as 50 per cent of America's energy needs by 2020. Moreover, they feel that the cost of the technology, presently higher than coal, oil and gas, may soon fall below those of conventional energy sources. Considering the rapid rise that oil has seen in recent weeks, such beliefs are not entirely unjustified. One of the biggest believers in this technology, and one of the earliest to put money in, is Indian-born venture capitalist Vinod Khosla. He has been one of the co-founders of Sun Microsystems and became a general partner of the venture capital firm Kleiner, Perkins, Caufield & Byers in 1986, after which he formed his own firm Khosla Ventures in 2004. Using his association with these firms he has invested heavily in renewable and new energy sources like ethanol and solar energy. In September 2007, Khosla led a $40-million investment in solar power producer Ausra Inc. with Kleiner, Perkins, Caufield & Byers. Ausra's proprietary technology significantly reduces the cost of a solar thermal power plant and so is capable of significantly reducing global carbon emissions normally associated with electricity generation. In December 2007 it announced it was building the first US manufacturing plant for solar thermal power systems, in Las Vegas. The 130,000-square-foot, highly automated manufacturing and distribution centre will produce the reflectors, towers, absorber tubes, and other key components of the company's solar thermal power plants Ausra's plants will produce electricity at 10 cents a kilowatt-hour starting in 2010, and the price will fall to 8 cents a few years later as it adopts systems with fewer parts that will be less costly when widely deployed, the company says. ''We are going to beat coal,'' says Bob Fishman, Ausra's CEO. A solar thermal unit that begins operation in 2010 will produce power at 14.2 cents a kilowatt hour, almost three times the 4.8 cents for a plant using pulverized coal, the US Energy Information Administration estimates. Both Chevron and Google have invested in solar energy startup BrightSource Energy Inc. Other investors in this company include JP Morgan and Morgan Stanley. In March 2008, BrightSource entered into a series of power purchase agreements with PG&E for up to 900MW of electricity. BrightSource is currently developing a number of solar power plants in the Mojave Desert of Southern California, with construction of the first plant planned to start in 2009. Goldman Sachs is seeking land to lease as demand out-paces wind turbines and geothermal, the other competitors to solar energy for top position in the renewable energy stakes. Others have filed more than 50 applications with the US Bureau of Land Management to lease government-owned desert property for solar power systems. Another big name in solar thermal power is Florida Power & Light Company, the principal subsidiary of FPL Group, Inc. commonly referred to by its initials, FPL. Although a conventional electricity producer and distributor in over 20 American states, it too has invested heavily in solar thermal technology and is the main owner of the SEGS solar power plants, the largest array in the world. Solar Energy Generating Systems (SEGS) is the name given to nine solar power plants in California's Mojave Desert, where sunlight is among the best available in the United States. SEGS III, VII are located at Kramer Junction, with SEGS VIII, IX at Harper Lake and SEGS I, II at Daggett respectively. The installation uses parabolic trough solar thermal technology along with natural gas to generate electricity. The plants have a 354 MW installed capacity, making it the largest installation of solar plants of any kind in the world. By comparison, the largest photovoltaic plant, which is in Spain, produces 20 MW, although a 40 MW PV installation (Waldpolenz Solar Park) is under construction in Germany and a 154 MW PV Solar power station in Victoria, Australia, is planned. The SEGS power plants were commissioned between 1984 and 1991. The facilities have a total of over 1,000,000 mirrors and cover more than 1,600 acres (6.4 square-km). SEGS VIII (80 MW) and SEGS IX (80 MW) are the largest solar power plants individually and collectively in the world. The parabolic reflectors have an efficiency of more than 90 per cent, compared with 80 per cent for a typical bathroom mirror. That means a reflector reflects 90 per cent of the sunlight that falls on it while absorbing the rest. FPL uses 15,000-litre trucks to spray water weekly to clean the surfaces, seven feet off the ground. ''There's always been a solar resource here,'' says Harvey Stephens, a production manager and one of 100 workers at the plant. ''It's just that it hasn't been cost-effective enough.'' However, all that may soon change. Costs for solar thermal may fall as low as 3.5 cents a kilowatt-hour by 2020, according to a report commissioned by the US Energy Department. Meanwhile, coal expenses may rise. Moreover, there are other costs to producing electricity using coal, pollution for instance. The US Congress is considering limits on carbon dioxide and other greenhouse gas emissions. The purchase of pollution permits may be required under a measure the US Senate will begin debating next month. However, solar thermal power suffers from one very obvious drawback - its complete dependence on sunlight. If the skies are cloudy, no electricity can be produced. Solar thermal companies are trying to develop backup heat storage using pressurized boiling water or molten salt that can be warmed to more than 1,000 degrees. Solar power ''fits with our peak demand very well as long as the sun is cooperating, ''says Michael Yackira, CEO of Sierra Pacific Resources, the company that owns utilities serving Las Vegas and other Nevada cities. ''When it's cloudy, when it's raining, when it's dark, it doesn't produce power.'' However, even with this drawback, the future of solar thermal power is ''bright'', pun intended. And many more investments can be expected in this ''sunshine'' sector, pun intended again.

Some interesting facts about solar thermal power news

27 May 2008
solar thermal power plants are a lot like conventional power plants - with one major difference Solar thermal power plants, often also called concentrating solar power (CSP) plants, produce electricity in much the same way as conventional power stations. The difference is that they obtain their energy input through concentrated solar radiation, rather than fossil fuels, and then convert it to high-temperature steam or gas to drive a turbine or motor engine. This difference means that no pollutants are emitted in producing the electricity. A solar thermal power plant built on about 1 per cent of the surface of the Sahara Desert would be sufficient to satisfy the entire world's electricity demand. Solar energy arrives on the earth at a maximum power density of about 1 kilowatt per square meter. However, solar "productivity" is limited by certain geographical factors, including cloud cover and atmospheric humidity. In sunny, arid locations, one square kilometer of land can generate as much as 100 gigawatt hours (GWh) of electricity per year using solar thermal technology, enough power for 50,000 households. Solar thermal power plants reduce air pollution: The solar energy falling on an area the size of a basketball court is equivalent to 650 barrels of oil a year In other words, each square meter of CSP concentrator surface is enough to reduce annual consumption of 200 to 300 kilograms (kg) of carbon dioxide. In addition, the "energy payback" time of CSP systems, taking into account the energy expended in their manufacture, is about five months, which compares well with their useful life of approximately 30 to 40 years. Most of the CSP solar field materials can be recycled. Solar thermal power is reliable and available when needed most - during peak demand hours In most developed countries, the peak demand period - during the hottest part of the day, when air conditioners are running in the office and home - coincides with the period of time when the solar thermal power plant is at peak production. In addition, solar thermal power, as predictable and reliable as the sun shining in the desert, is a renewable alternative to natural gas "peakers", as opposed to other forms of renewable energy, which are either baseload or intermittent. Solar thermal power plants can be built (relatively) quickly Solar power plants can generally be built in their entirety within a few years and can follow demand more closely than most conventional power projects. This is primarily because solar plants are built almost entirely with modular, commodity materials and thus have short development and construction times. In contrast, many types of conventional power projects, especially coal and nuclear plants, require long lead times, and this causes significant disparities between the demand and the supply. Solar thermal power plants are big - but relative to other types of power plants - they're space efficient CSP plants seem to use a lot of land, but when looking at electricity output versus total size, they use less land than hydroelectric dams (including the size of the lake behind the dam) or coal plants (including the amount of land required for mining and excavation of the coal). While all power plants require land and have an environmental impact, the best locations for solar power plants are on land, such as deserts, for which there might be few other uses. Solar thermal power can be used with energy storage systems or combined with other energy sources to provide all day power CSP plants can be designed for solar-only or for hybrid operation, as in California where gas-fired boilers provide steam to back-up solar-generated steam. Thermal energy storage systems, including molten salt, can extend the operational time of solar thermal power plants, sometimes with six to 12 hours of storage. In addition, solar thermal power can complement other renewable energy sources, such as wind, which are available during off-peak hours. Solar thermal power plants create permanent jobs and are good for the local economy There are two main reasons why solar thermal power plants offer an economic advantage: (1) they are labor intensive, so they generally create more jobs per dollar invested than conventional electricity generation technologies, and (2) they use primarily indigenous resources, such that most of the energy dollars can be kept at home. Most importantly, there is no need to import the energy source (i.e., sunshine) and spend local funds outside of the region. Solar thermal plants produce electricity whose current and future costs are known with certainty Electricity produced from solar thermal power plants is a fixed-cost generation resource, generally sold through long term (20 or 30 year) power purchase agreements in which the cost to the consumer is known in advance. Additionally, a diversified portfolio of energy sources, including solar thermal, decreases consumers' exposure to market fluctuations, including the volatile cost of natural gas (which solar thermal typically replaces in the portfolio). The reduced demand for natural gas itself will lead to lower prices. Solar thermal power can be cheaper than power from fossil fuels when all cost externalities are considered (and even when they're not) While many of the costs of fossil fuels are well known, others (pollution related health problems, environmental degradation, the impact on national security from relying on foreign energy sources) are indirect and difficult to calculate. These are traditionally external to the pricing system, and are thus often referred to as externalities. According to the Stern Review, published in October 2006 by the British government's treasury, global warming is the result of colossal market failure, i.e., failure to price fossil fuel's externalities correctly. A corrective pricing mechanism, such as a carbon tax, could lead to renewable energy, such as solar thermal energy, becoming cheaper to the consumer than fossil fuel based energy. (See: Energy of the future - solar thermal power!)

Solar Energy Commission proposed

Aarti Dhar

NEW DELHI: The Centre proposes to set up a Solar Energy Commission, with equal participation from the private sector.

It is to tap the solar energy potential for meeting the future energy needs of the country.

The initial investment for the project will be around $ 10 billion.

Autonomous body

The Commission, on the lines of the Atomic Energy Commission, will be an autonomous body under the Department of Science and Technology.

It will be responsible for the deployment of commercial and near-commercial solar technologies.

It will establish a solar research facility at an existing establishment to coordinate research and development activities being carried out in the public and private sectors.

Solar collectors

It is estimated that just about 2 per cent of India's land mass under solar collectors, at current efficiency levels, could meet the country's entire energy requirements even 25 years from now.

Together with indirect solar energy, this potential source of clean energy holds the promise of energy independence for India.

India is endowed with a rich solar resource exceeding 1600 kWh/m2 per annum.

The Commission will be responsible for realising integrated private sector manufacturing capacity for solar material, cells and modules, networking of Indian research efforts with international initiatives with a view to promoting collaborative research and acquiring and adapting technology, besides establishing a regulatory framework and providing funding available under the global climate mechanisms.

Coverage target

Over the next 7-10 years, the Commission will aim to deliver at least 80 per cent coverage for all low temperature (less than 150 degrees Celsius) and at least 60 per cent coverage for medium temperature (150 to 250 degrees Celsius) applications of solar energy in all urban areas, industries and commercial establishments.

Rural solar thermal applications will also be pursued under private-public partnership, wherever feasible. Commensurate local manufacturing capacity to meet this level of deployment, with necessary technology tie-up, will also be established.

Solar energy conversion systems fall into three categories according to their primary energy production: solar electricity, solar thermal systems and solar fuels. The untapped energy potential of each of these three generic approaches is well beyond current usage levels.

The challenges

The main challenges before the government are to reduce the cost/watt of electricity to compete with fossil and nuclear electricity, identifying cost-effective methods to convert sunlight into storable, dispatchable thermal energy that bridges the diurnal cycle and to produce chemical fuels directly from sunlight that could be used as cheap solar fuel.

© Copyright 2000 - 2008 The Hindu

Big players line up for solar projects in Haryana

Financial Express
Preeti Parashar
Posted online: Saturday , May 10, 2008 at 0105 hrs

Chandigarh, May 9 With the tariff for generation of power through solar energy being fixed at an attractive rate of Rs 15.96 per unit by the Haryana Electricity Regulatory Commission (HERC), the state is confident of attracting top corporate houses to set up solar power projects.

Being the fourth state after Rajasthan, Punjab and West Bengal to announce tariffs for power generation through solar energy, Haryana is hopeful to lead the race with maximum tariffs so far. A few leading groups like Reliance Industries Ltd, Albina Power (Indiabulls company), ACME Telepower, Epuron Renewable Energy Power, Emco, RS India Wind Energy and Admire Energy Solutions (Moser Baer company) etc have already evinced interest in producing power from solar energy in Haryana.

Sumita Misra, director of Haryana Renewable Energy Development Agency (HAREDA) told FE, "We invited expressions of interest and have received 20 proposals from Independent Power Producers (IPP) with a capacity of producing 127 mw from solar energy.

Processing is on and the projects will soon be allocated to the companies. HERC has fixed an attractive tariff rate of Rs 15.96 per unit for projects to be commenced upto December 31, 2009 and Rs 15.16 per unit for projects commencing between December 31, 2009 and March 31, 2010.

The centre, under its scheme to promote electricity generation through solar energy, is providing generation based incentives at Rs 12 per unit for solar photovoltaic power and Rs 10 per unit for solar thermal technology for number of units sold to the state power utilities."

The solar insolation level of Haryana is in the range of 5.5 kwh to 6.5 kwh per sq mt of area and there is a huge potential for using solar energy for various thermal and electrical energy applications in the state. Haryana is likely to earn about Rs 20-25 crore per mw of electricity generated from these projects.

The maximum installed capacity of solar power generation in the country is about 200 kw at present and to promote this green technology, the new and renewable energy ministry has set a target of generating 50 mw from solar energy for the entire country with 25 mw of power to be generated by 2010-11 and a state not producing more than 10 mw through solar power projects. A major challenge for the IPPs seems to be the escalating land prices in Haryana.

DOE Marks $60 M for Solar Thermal Funding

Written by Hank Green

Thursday, 08 May 2008

The most near-term, cost-effective solar solution is undoubtedly solar thermal. While photovoltaics, which convert light directly into electricity, can have a significantly smaller footprint and higher efficiency...solar thermal has generally proven that it can create electricity at a lower cost. With that in mind, the U.S. Department of Energy has decided to spend $60 M over the next five years developing low-cost concentrating solar thermal technology (like the parabolic trough pictured from Schott Solar.) They plan on making between 10 and 20 awards to industry and universities working on increasing the efficiency and decreasing the costs of solar thermal power. They will also be funding projects related to "advanced thermal storage." At first this might seem slightly unrelated. In fact, what they're looking for is a way to store the heat captured during the day so that they can continue to generate electricity throughout the night. This is another possible advantage to solar thermal technology. If the heat can be stored in some medium, say molten salt for example, then that medium could, in effect, make the solar plant a giant battery. Photovoltaic plants, on the other hand, would require some other form of backup energy to keep the juice flowing at night.

On the Rise: Solar Thermal Power and the Fight Against Global Warming

05/08/2008

Download the full report.

News Release

Executive Summary

Global warming is real, is happening now, and is largely caused by human activities. To prevent the worst impacts of global warming, the United States must take action to reduce global warming pollution quickly and dramatically. Electricity generation accounts for more than a third of America's emissions of global warming pollution. Preventing catastrophic global warming, therefore, will require the United States to shift away from highly polluting sources of power, such as coal-fired power plants, and toward clean, renewable energy.

Concentrating solar power (CSP) technologies—which use the sun's heat to generate electricity—can make a large contribution toward reducing global warming pollution in the United States, and do so quickly and at a reasonable cost. CSP can also reduce other environmental impacts of electric power production, while sparking economic development and creating jobs.

The United States has limited time to transition away from dirty energy sources and toward clean, renewable energy.

• The latest climate science tells us that the United States and the world must reduce emissions of global warming pollutants quickly and dramatically to prevent the most catastrophic impacts of global warming.

• Should global average temperatures to increase by more than 2° Celsius, scientists warn that dangerous impacts from global warming will become inevitable, including flooding of coastal cities, the loss of large numbers of plant and animal species, and increases in extreme weather, wildfire and drought.

• To have a reasonable chance of preventing a 2° C increase in global average temperatures, the world must keep the concentration of global warming pollution in the atmosphere below 450 parts per million.1

• The United States must, at minimum, reduce its greenhouse gas emissions by 15-20 percent from 2000 levels by 2020, and by 80 percent by 2050 to prevent catastrophic impacts from global warming. Other nations must act aggressively as well.

• America's electric power plants produce more carbon dioxide (the leading global warming pollutant) than the entire economy of any nation in the world other than China.

• Even if America uses energy efficiency improvements to prevent future growth in electricity consumption, the nation will still need to expand its renewable generating  capacity dramatically. Reducing carbon dioxide emissions from power plants to 20 percent below 2000 levels by 2020, for example, would require the U.S. to generate 15 to 24 percent of its electricity from new renewable sources—or between 158 GW and 257 GW of new renewable energy by 2020. The need for clean energy will further accelerate in future decades as the United States seeks to meet increasingly stringent targets for emission reductions.

Concentrating solar power is ready to reduce global warming pollution, and can begin doing so right away.

• America has immense potential to generate power from the sun. The National Renewable Energy Laboratory has identified the potential for nearly 7,000 gigawatts (GW) of solar thermal power generation on lands in the southwestern United States—more than six times current U.S. electric generating capacity. Other sunny areas of the United States, such as the mountain West, the Great Plains and Florida, can also generate power from solar thermal energy.

• Solar thermal power plants covering a 100-mile-square area of the Southwest— equivalent to 9 percent the size of Nevada—could generate enough electricity to power the entire nation.

• Building just 80 GW of CSP capacity—a target that is achievable by 2030 with sufficient public policy support—would produce enough electricity to power approximately 25 million homes and reduce carbon dioxide emissions from U.S. electric power plants by 6.6 percent compared to year 2000 levels. Solar thermal power can make even greater contributions in the years to come—precisely the time when the nation must achieve deep cuts in global warming pollution.

• CSP plants are increasingly cost-competitive with other power generation technologies that do not produce carbon dioxide. The cost of energy from solar thermal power plants is estimated to be approximately 14 to 16 cents/kWh—competitive in cost with theoretical coal-fired power plants that capture and store their carbon dioxide emissions and with new nuclear power plants.

• CSP development has accelerated dramatically since the beginning of 2007. More than 2,800 MW of solar thermal projects are in some phase of development nationwide and could be completed by 2012. CSP benefits the environment and America's economy.

• CSP power is clean. Its only necessary emission, water vapor, is harmless. By developing CSP, America can avoid the need for coal-fired power plants—which emit health-threatening mercury, particulate matter, and smog-forming pollutants and consume large quantities of water—and nuclear power plants, which consume large amounts of water and produce radioactive waste.

• CSP can play a leading role in the electric power system. Unlike intermittent forms of renewable energy, CSP plants with thermal energy storage can deliver power when it is needed to serve demand. CSP plants can be designed to provide either peak or baseload power, enabling them to address a variety of needs within the electric grid.

• Solar thermal plants create permanent jobs for local economies. Construction of 80 GW of CSP power has the potential to generate between 75,000 and 140,000 permanent, green jobs for Americans.

• CSP and other forms of renewable energy reduce demand for natural gas, thereby reducing prices. Installing 4 GW of CSP in California could save Californians between $60 million and $240 million per year in the cost of natural gas.

• America's vast potential for CSP could one day produce renewable electricity to be used in vehicles—thereby reducing the nation's dependence on oil. Strong public policies can increase the use of CSP in the United States. Priority actions include:

• Enacting a national Renewable Electricity Standard (RES) that requires 25 percent of all U.S. electricity to come from renewable resources—and a certain percentage from solar power technologies—by 2025. States should also enact RES policies or expand their existing RES targets.

• Expanding and extending the Renewable Electricity Investment Tax Credit can give CSP project developers the financial certainty they need to move forward.

• Enacting caps on global warming pollution at both the national and state levels, which will encourage the development of clean, low-carbon energy sources like concentrating solar power and encourage the retirement of America's dirtiest electric power plants. Money raised by auctioning allowances under a cap-and-trade system should help support renewable energy development and reduce the cost of the program to consumers.

• Creating feed-in tariffs for renewable energy sources, which provide financial rewards to generators who feed renewable energy into the power grid. Widely used in Europe, feed-in tariffs aim to move renewable energy to non-subsidized cost competition with conventional energy, creating fair markets between new and traditional electricity sources.

• Providing access to transmission for CSP, in particular through western regional policy agreements and initiatives, can ensure that solar power can be delivered to power consumers. New transmission lines should be built to renewable resource areas before they are built to traditional power generators and be sited and designed to minimize environmental impacts. The federal government should also fund existing research and development on a high-voltage direct current transmission backbone.

• Creating an annual $3 billion fund for research, development, and deployment of renewable energy for 2009, which can ensure that CSP and other renewable energy technologies are available to meet America's energy and climate challenges. The fund should be renewed for the next 10 years, committing $30 billion over the next decade. These dollars should come from shifting funds away from coal, oil, gas and nuclear power subsidies.

[Previous] [Next]

U.S. DOE putting up $60M for solar thermal

By David Ehrlich

Published May 1, 2008 - 3:30am

body:

The U.S. Department of Energy announced that it plans to invest up to $60 million in solar thermal technology over five years.

The department said the cash would support the development of low-cost concentrating solar power technology for fiscal 2008 through fiscal 2012.

"Harnessing the natural and abundant power of the sun and more cost-effectively converting it into energy is an important component of our comprehensive strategy to commercialize and deploy advanced clean, alternative technologies that will allow us to become less reliant on foreign oil," said Clarence Albright, under secretary of energy.

The DOE said the funding would be made available for projects from industry and academia that develop advanced thermal storage concepts and heat transfer fluids to further increase the efficiency of concentrating solar power plants.

"The administration's investment in solar technology will not only bolster innovation, but will help meet the president's goal of making solar power cost-competitive with conventional sources of electricity over the next seven years," said Albright.

The department said it plans to make 10 to 25 awards through the competitive solicitation.

With a minimum 20 percent cost share by the private sector for research and development phases and a minimum 50 percent private cost share for final demonstration phases, the DOE said the total research investment under the solicitation is expected to exceed $75 million.

Bright Source’s Power Tower

Solar thermal power is considered an important step towards developing large scale sources of clean electricity, but within this sector there are some very distinct applications of the technology.  Bright Source Energy, with offices in Oakland, California, and Tel Aviv, Israel, is building next generation "power tower" solar thermal power plants.

The power tower. (Photo: Bright Source Energy)

The stated advantages of power tower technology seem to make a lot of sense.  The solar field of mirrors require no plumbing going to each mirror, containing a thermal transfer fluid, because the two-axis tracking mirrors point to a central boiler.  This saves considerable expense to install and maintain plumbing throughout the solar field. 

Also, because each mirror sits atop a single independently placed post, the ground underneath the solar field can be left relatively irregular and uneven.  With parabolic trough technology, for example, the ground beneath the troughs must be almost perfectly smoothed, meaning far more site preparation is required.

Less obvious but also significant are the costs saved by utilizing super heated steam coming from one central boiler atop a tower, because this design allows the water to be air cooled instead of water cooled.  In order for solar thermal power to require minimal input of water, the water needs to be continuously recirculated - it heats up in the boiler, drives the turbine, then must be cooled and condensed before returning to the boiler for heating.  If this isn't done, in a closed loop the back pressure of the steam after passing through the turbine would largely counteract the pressure of the incoming steam, ruining the efficiency of the device. 

Because a power tower concentrates the entire energy of the solar field into one boiler, the steam is superheated to 550 degrees centigrade.  In the parabolic trough designs, where the heat transfer fluid flows into dozens of distributed heat exchanging tubes above the focal point of dozens (or hundreds) of separate mirrors, the energy of the solar field is less concentrated, achieving a significantly lower top temperature of 300-350 degrees centigrade.

Because the differential between the super hot 550 C steam is so much greater than the ambient air temperature, even in the desert, air cooling is viable with a power tower design, but is not viable with trough designs.  Air cooling systems are less expensive than water cooling systems, and they use less water.  Bright Source estimates their process loses about 1/2 an acre foot for every megawatt-year of electricity they generate, compared to about 20x that amount for designs that require water cooling - even though all of these designs recirculate.

Not only is Bright Source Energy using what could emerge as the most cost effective solar thermal design, but they are well on their way to implementing their technology.  Their pilot plant in Israel, with a 60 meter tower and 1,600 mirrors, is in testing currently and will go active in mid-June.  The plant will generate 5.0 megawatts of thermal energy, which with a boiler efficiency of 74% and a turbine efficiency of 45% will output 1.5 megawatts of electricity.  That is just the beginning.

The solar field and power tower. (Photo: Bright Source Energy)

With a management team that includes several of the executives who built the original solar thermal plants at Kramer Junction in California in the early 1990's - still operating profitably with an output of over 350 megawatts - Bright Source Energy is likely to be the first company to build new large scale solar thermal plants in California for 20 years.  Their application, filed with the California Energy Commission in Sept. 2007, was the first one filed since 1989, and proposes a 400 megawatt solar complex to be built in Ivanpah, California, in the Mojave desert near the Nevada border.

The power tower - looking across a reflecting mirror. (Photo: Bright Source Energy)

Solar without the Panels

Utilities are using the sun's heat to boil water for steam turbines.

By Peter Fairley

Investors and utilities intent on building solar power plants are increasingly turning to solar thermal power, a comparatively low-tech alternative to photovoltaic panels that convert sunlight directly into electricity. This month, in the latest in a string of recent deals, Spanish solar-plant developer Abengoa Solar and Phoenix-based utility Arizona Public Service announced a 280-megawatt solar thermal project in Arizona. By contrast, the world's largest installations of photovoltaics generate only 20 megawatts of power.

In a solar thermal plant, mirrors concentrate sunlight onto some type of fluid that is used, in turn, to boil water for a steam turbine. Over the past year, developers of solar thermal technology such as Abengoa, Ausra, and Solel Solar Systems have picked up tens of millions of dollars in financing and power contracts from major utilities such as Pacific Gas and Electric and Florida Power and Light. By 2013, projects in development in just the United States and Spain promise to add just under 6,000 megawatts of solar thermal power generation to the barely 100 megawatts installed worldwide last year, says Cambridge, MA, consultancy Emerging Energy Research.

The appeal of solar thermal power is twofold. It is relatively low cost at a large scale: an economic analysis released last month by Severin Borenstein, director of the University of California's Energy Institute, notes that solar thermal power will become cost competitive with other forms of power generation decades before photovoltaics will, even if greenhouse-gas emissions are not taxed aggressively.

Solar thermal developers also say that their power is more valuable than that provided by wind, currently the fastest-growing form of renewable energy. According to the U.S. Department of Energy, wind power costs about 8 cents per kilowatt, while solar thermal power costs 13 to 17 cents. But power from wind farms fluctuates with every gust and lull; solar thermal plants, on the other hand, capture solar energy as heat, which is much easier to store than electricity. Utilities can dispatch this stored solar energy when they need it--whether or not the sun happens to be shining. "That's going to be worth a lot of money," says Terry Murphy, president and chief executive officer of SolarReserve, a Santa Monica, CA, developer of solar thermal technology. "People are coming to realize that power shifting and 'dispatchability' are key to the utility's requirements to try to balance their system."

In fact, the capacity to store energy is critical to the economics of the solar thermal plant. Without storage, a solar thermal plant would need a turbine large enough to handle peak steam production, when the sun is brightest, but which would otherwise be underutilized. Stored heat means that a plant can use a smaller, cheaper steam turbine that can be kept running steadily for more hours of the day. While adding storage would substantially increase the cost of the energy produced by a photovoltaic array or wind farm, it actually reduces the cost per kilowatt of the energy produced by solar thermal plants.

The amount of storage included in a plant--expressed as the number of hours that it can keep the turbine running full tilt--will vary according to capital costs and the needs of a given utility. "There is an optimal point that could be three hours of storage or six hours of storage, where the cents per kilowatt- hour is the lowest," says Fred Morse, senior advisor for U.S. operations with Abengoa Solar. Morse says that the company's 280-megawatt plant in Arizona, set to begin operation by 2011, will have six hours of storage, while other recent projects promise seven to eight.

Morse says that while the design of solar thermal power stations is rapidly diversifying, most will use essentially the same system for storing energy: tanks full of a molten salt that remains liquid at temperatures exceeding 565 °C. "It's basically two tanks with a lot of heat exchangers, pipes, and pumps," says Morse. For a sense of scale, consider that the 50-megawatt plants that Germany's Solar Millennium is building in Spain near Granada will employ 28,500 tons of molten salt in twin tanks standing 14 meters high and 38.5 meters in diameter.

While molten salt is the most popular storage option, developers are experimenting widely to find the best means of collecting heat in the first place, and integrating collection and storage. Abengoa's plant in Arizona (see below image) will use a "trough" design in which arrays of parabolic mirrors concentrate sunlight onto a glass tube carrying a commercial heat-transfer oil such as therminol. Some of the heated oil heats the molten salt in storage while the rest directly generates steam. Abengoa Solar's vice president for technology development, Hank Price, says that the plant's trough energy-collection design is the one most commonly used today, thanks largely to improvements in the glass tubes. Ceramic-metal absorption coatings have increased the amount of heat captured by the tubes to the point that plants using them produce 30 percent more power than the first-generation solar thermal demonstration projects of the early 1990s.

Economies of scale: Spanish solar-power-plant developer Abengoa Solar plans to build and begin operating this 280-megawatt solar thermal power plant in Gila Bend, AZ, by 2011. The plant's rows of mirrors, thermal storage tanks, and power-generating turbines will cover nearly three square miles. Phoenix-based utility Arizona Public Service will buy the power--enough to supply 70,000 Arizona homes.
Credit: Abengoa Solar

SolarReserve, in contrast, is developing systems that directly heat molten salt. Its designs call for so-called power towers in which arrays of mirrors focus sunlight onto elevated towers. The company, launched in January, is a joint venture between energy investment bank U.S. Renewables Group and aerospace firm Hamilton Sundstrand, whose subsidiary Rocketdyne built molten-salt heat receivers for a 10-megawatt power-tower demo plant that operated in the early 1990s.

SolarReserve's Murphy says that the power-tower system should be cheaper to build than trough-collection systems, since it doesn't require miles of glass tubing. More important, he says, it should produce higher-quality steam. That's because it will directly heat its molten salt to about 565 °C, about 165 degrees hotter than the oils in a trough plant.

That increased thermodynamic efficiency will be key, says Murphy, when water shortages force thermal power plants in hot, dry deserts to abandon water-based cooling of their used steam. (Steam that's passed through the turbine must be cooled and condensed so that it can be reused.) Alternative cooling techniques are more energy intensive, cutting into a plant's overall efficiency. The hotter a plant runs, says Murphy, the lower the losses from alternative cooling schemes. "We're going to experience 3 to 4 percent loss," he says, "and [the trough plants] are going to be losing 7 to 8 percent."

Abengoa's Price agrees that power towers do, in theory, have thermodynamic advantages, which is why Abengoa has built its own 10-megawatt demo in Spain and is building a second at 20 megawatts. But Price questions whether investors will support the direct jump to 100-to-200-megawatt power-tower plants that SolarReserve envisions. "There's a lot of technical risk in doing that," he says. "We need to scale up in a way that's financeable."

Is Desert Solar Power the Solution to Europe's Energy Crisis?

By Jens Lubbadeh

A tiny fraction of the sun's energy that shines upon the deserts of North Africa and the Middle East could meet all of Europe's electricity demands. The technology to harness the energy already exists. So why is hardly anyone investing in it?

The oil of the 21st century is not buried deep within the earth. Instead, it falls on its surface -- as sunshine.

"The sun is the hidden asset of North Africa and the Middle East," says Gerhard Knies, a spokesman for the Trans-Mediterranean Renewable Energy Cooperation (TREC), a network of scientists and politicians from various countries who have taken it upon themselves to solve Europe's energy problem.

Their vision, which they call Desertec, is to turn desert sun into electricity, thereby harnessing inexhaustible, clean and affordable energy.

"We don't have an energy problem," says Hans Müller-Steinhagen, of the German Aerospace Center (DLR). "We have an energy conversion and distribution problem."

Müller-Steinhagen has been commissioned by Germany's Environment Ministry to check the feasibility of Desertec in several studies. His conclusion is that Desertec is a real possibility.

In his studies, he has scrutinized the energy situation in Europe, North Africa and the Middle East from the point of view of the post-oil era. Out of all the alternative energy sources, one stands head and shoulders above the rest: "No energy source even comes close to achieving the same massive energy density as sunshine," Müller-Steinhagen says.

And no other energy source is available over such a large area. Every year, 630,000 terawatt hours in the form of solar energy falls unused on the deserts of the so-called MENA states of the Middle East and North Africa.

In contrast, Europe consumes just 4,000 terawatt hours of energy a year -- a mere 0.6 percent of the unused solar energy falling in the desert.

Powering Europe from the Desert

Europe needs a lot of electricity, but gets little sun. The MENA countries, on the other hand, get a lot of sun, but consume little electricity. So, the solution is simple: The south produces electricity for the north. But how would the enormous energy transfer work? And how do you turn desert sun into electricity?

It's actually relatively easy. Desertec is low-tech -- no expensive nuclear fusion reactors, no CO2-emitting coal power plants, no ultra-thin solar cells. The principle behind it is familiar to every child who has ever burnt a hole in a sheet of paper with a magnifying glass. Curved mirrors known as "parabolic trough collectors" collect sunlight. The energy is used to heat water, generating steam which then drives turbines and generates electricity. That, in a nutshell, is how a solar thermal power plant works.

Energy can be harnessed even at night: Excess heat produced during the day can be stored for several hours in tanks of molten salt. This way the turbines can produce electricity even when the sun is not shining.

Should the Sahara, therefore, be completely covered with mirrors? No, says Müller-Steinhagen, producing a picture by way of an answer. It shows a huge desert in which are drawn three red squares. One square, roughly the size of Austria, is labelled "world." "If this area was covered in parabolic trough power plants, enough energy would be produced to satisfy world demand," he says.

A second square, just a fourth of the size of the first one, is labelled "EU 25," in a reference to the 25 member states the European Union had before Bulgaria and Romania joined in 2007. This area could produce enough solar energy to free Europe from dependence on oil, gas and coal. The third area is labelled "D," for Germany. It is merely a small dot.

A Win-Win Situation

Under the plan, the sun-rich states of North Africa and the Middle East would build mirror power plants in the desert and generate electricity. As a side benefit, they could use residual heat to power seawater desalination plants, which would provide drinking water in large quantities for the arid countries. At the same time they would obtain a valuable export product: environmentally friendly electricity.

"The MENA countries are in a three-way win situation," says Müller-Steinhagen. But Europe also wins: it frees itself from its dependence (more...) on Russian gas, rising oil prices, radioactive waste and CO2-spewing coal power plants.

For countries such as Libya, Morocco, Algeria, Sudan and especially Middle Eastern states, the solar power business could be the start of a truly sunny future. It could create jobs and build up a sustainable energy industry, which would bring money into these countries and enable investment in infrastructure.

In fact, Desertec is no futuristic vision -- the technology already exists and is tried and tested. Since the mid 1980s, solar thermal power plants have been operating trouble-free in the US states of California and Nevada. More plants are currently being built in southern Spain. And building work has started on solar thermal power plants in Algeria, Morocco and the United Arab Emirates.

Müller-Steinhagen has calculated what the energy switch would cost: To generate 15 percent of Europe's electricity demand, around €400 billion ($623 billion) would be needed by 2050 to pay for the construction of solar thermal power plants. The power plants would cost €350 billion, while €50 billion would have to be spent on an electricity grid network to transport electricity from North Africa to Europe.

This would require a network of high-voltage direct current transmission lines -- also a technology which exists and is tried and tested. It is the only way to transport electricity for thousands of kilometers with relatively little energy loss.

But if it is all so simple, then why do countries with enough solar radiation build expensive and dangerous nuclear power plants, instead of investing in this simple technology? Are there not deserts in the US? Why are Americans not freeing themselves from their oil dependence through solar power? And why has no one really started to exploit the technology?

"After the solar thermal power plants were built in California and Nevada, people lost interest in solar thermal power because fossil fuels became unbeatably cheap," says Müller-Steinhagen. Solar power was neglected even though the US was in the advantageous position, compared to the MENA region, of being a single political entity rather than a conglomerate of countries with differing interests. The US could achieve energy self-sufficiency through solar thermal power plants in the sunny south-west. But it was only recently that scientists writing in the respected magazine Scientific American unveiled a "Solar Grand Plan" for the US.

Cheap oil has stood in the way of a solar thermal breakthrough. Although sunshine abounds in Saudi Arabia, the United Arab Emirates, Kuwait and other countries, so does oil. However these rich countries could also afford to build solar thermal power plants. "In Saudi Arabia or the United Arab Emirates, electricity costs half a cent per kilowatt hour," Müller-Steinhagen says. "This makes it hard to convince people of the benefits of solar thermal power."

Lack of Awareness

"There is a lack of awareness in MENA countries about what this technology can do," says Samer Zureikat, founder of the Frankfurt-based renewable energy company MENA Cleantech. "If you talk to people there about solar power, they think of small solar panels that power street lamps. They don't think of enormous power plants that can supply enough electricity for a whole country."

For Zureikat, the switch to solar thermal energy is an inescapable necessity: "Europe needs energy. North Africa and the Middle East need water -- and fast."

Müller-Steinhagen agrees with him. In a different study, he investigated the region's future need for water and the possibility of desalinating sea water with solar thermal-produced energy. The study's conclusion was that water shortages in the MENA region would triple by 2050.

The interest in solar thermal power is slowly growing. Masdar, an Abu Dhabi-based firm which invests in alternative energy, is a partner in a project constructing three solar thermal power plants in Spain. It also wants to build them in its own country.

Admittedly, solar thermal-produced power is still not competitive. However, conventionally generated energy is getting more and more expensive -- and solar thermal power gets cheaper with the construction of every new power plant. By 2020 at the latest, Müller-Steinhagen predicts, solar-thermal electricity will be the same price as fossil fuel-generated energy. On top of that, solar thermal has greater price stability as the sun yields unlimited and free energy, which does not require elaborate and costly raw material extraction.

Solar Sarko

Müller-Steinhagen wants people to take another look at the technology -- and quickly. Now is the right time, he says: Europe's old power plants are coming to the end of their operational lives and new ones have to be built. These investments will decide the future of our power, given that the operational lives of power plants extend into decades.

And politicians are starting to take an interest in the idea. The German government is supporting it. On the European level, German members of the European Parliament such as the Green Party's Rebecca Harms and Matthias Groote from the center-left Social Democratic Party are throwing their weight behind Desertec.

Even French President Nicolas Sarkozy has also suddenly discovered solar energy, despite his recent sales of nuclear power plants to North African states. "We are being inundated with enquiries from France," says Müller-Steinhagen. Sarkozy wants to promote solar energy within his controversial Union for the Mediterranean (more...), a proposal for a loose alliance of countries bordering the Mediterranean Sea and other EU states.

SPD politician Groote is hoping for "new initiatives when France takes over the EU presidency in the second half of the year." However, his Green Party colleague Harms warns against too much optimism: "There is still only a minority in the European Parliament promoting solar thermal power. We are still a long way from a unified energy policy."

Too many questions remain unanswered. Who will pay for the electricity network? Who would own it? Could the various stakeholders agree on a collective guaranteed price for solar thermal electricity fed into the grid?

The latter issue is especially important for investors and industry. Wolfgang Knothe, a board member of MAN Ferrostaal, an industrial services provider, says: "We need political security to get going."

A lack of money is not the problem. "Renewable energy is in," says Nikolai Ulrich of HSH Nordbank. "It is relatively easy at the moment to get investment for renewable energy projects."

Desertec is still only a vision. But visions are needed, says Knothe: "Without Kennedy's dream, there wouldn't have been a moon landing."

Then, the will to make the vision reality existed, although the technology did not. With Desertec, it is exactly the reverse: The technology is available -- but the will is missing.

 

SkyFuel secures $17m to commercialise solar trough

Solar thermal specialist announces plans to ramp up production of solar collector

BusinessGreen Staff, BusinessGreen, 30 Apr 2008

US-based solar thermal technology developer SkyFuel has this week announced that it has secured $17m in funding as it seeks to commercialise its parabolic trough solar collector.

The funding comes from cleantech investment firm Leaf Clean Energy, which said the backing would allow the firm to begin commercial deployment of its SkyTrough solar collector and continue research and development work on a new Linear Fresnel system, designed to better track sunlight throughout the day.

SkyFuel claims its parabolic troughs have been developed using a patented mirrored film, which is highly reflective and resilient and significantly cheaper than the expensive glass mirrors typically used in solar thermal systems.

Solar thermal systems work by concentrating the sun's energy to generate temperatures high enough to create steam, which in turn is used to drive turbines. The systems are regarded as currently the most cost effective form of solar energy, however, the sector has been hampered by the relatively high cost of manufacturing and maintaining the mirrors required to capture the sun's energy.

Dr. Arnold Leitner, founder and CEO of SkyFuel, said that the new mirrored film had the potential to "disrupt" the solar thermal power market and significantly reduce set up costs for solar thermal projects. "The SkyTrough significantly advances parabolic trough design using advanced materials to greatly reduce cost, while continuing to deliver the proven performance and simplicity of the only currently commercially viable solar thermal power technology," he added.

The company it is currently working with a number of independent power producers to develop utility-scale solar thermal power plants in the US and abroad.