TEN FAQS ABOUT SOLAR THERMAL POWER

Solar thermal power is sometimes called concentrating solar power or CSP.  These labels refer to technologies that use the energy of the sun to produce steam, directly or indirectly.  The steam is then piped to a convention power generation system to make electricity.  The difference between a solar thermal plant and a conventional fossil-fueled power plant is that conventional plants create steam by burning fuels that release carbon into the atmosphere.

Solar thermal power plants, often also called Concentrating Solar Power (CSP) plants, use sunlight to produce steam, which is then used to generate electricity.  By contrast, photovoltaic (also known as PV) systems use special panels to collect sunlight and convert it directly to electricity.  “Thermal” refers to the fact that it is the heat of the sunlight that is used, and “concentrating” refers to the fact that solar thermal systems concentrate the sunlight, in much the same way that a magnifying glass does, to harness its heat.
Solar thermal plants are large utility-scale projects that generate enough power to serve tens of thousands of homes.  Their power is usually sold to public utilities, which then sell it to their customers.  Photovoltaic systems are usually much smaller and are usually installed on residences, schools, or office buildings.

In theory, a solar thermal plant can be built anywhere that the sun shines, however cost considerations dictate that they be built in areas of high solar radiation – a measure of how much power can be generated in a single square meter of surface area in a typical year.  The best solar radiation is found in high desert areas, such as the Mojave Desert in Southern California, where the sun shines reliably 330 to 350 days a year.  Another major consideration is that solar plants need to be built in the vicinity of power transmission lines serving markets large enough to use all of the power generated by the plant.

The answer depends on two factors:  a) the solar insularity (see FAQ 3) of the plant location, and b) the specific technology being used.  In general, a typical 100 MW solar thermal plant will occupy 600 to 800 acres.  Installing solar power plants on an area covering only 1% of the Mojave Desert would provide enough solar power to serve 75% of the homes in California.

Carbon emissions are reduced by 600 pounds for each MW hour of solar power that displaces an equal amount of fossil-fuel power.  Installing solar power plants on an area covering 1% of the Mojave Desert would reduce annual carbon emissions by over 20 million tons.

The peak demand period for electricity is the hottest part of the day, when air conditioners are running in offices and homes.  This is the same time of day when solar power is produced.  In addition, because sunshine is reliable and consistent in the desert areas where solar power plants are typically built solar power is also consistent and reliable. Conversely, another common form of renewable power production, wind power, normally has its peak production period during the nighttime hours, and is much less predictable and reliable.

Unlike the photovoltaic systems typically installed on rooftops, CSP plants produce their electricity by first producing steam then using that steam to generate electricity.  Thus, CSP plants can be fitted with gas-fired boilers to produce steam when the sun is not shining, enabling the plants to produce electricity at any time.  This provides valuable back-up generation capacity to utility companies for use when wind power is not available, or demand is unusually high. Another method is to install thermal storage to store heat during the daylight hours and release that heat during the night to make electricity.  At this time, such storage systems are not economical, but it is anticipated that the cost will come down and make the use of solar power viable around-the-clock.

The cost of fuel represents about 60% of the cost of producing electricity from fossil-fueled plants.  CSP plants require no fuel, thus the cost of the power they produce is not affected by the vagaries and risks associated with fossil fuel prices. Other than very slight increases in maintenance and operating expenses due to inflation, the cost of power produced by a CSP plant will not change over its economic life.

Solar thermal power is probably cheaper than power from fossil fuels when all cost externalities are considered.  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. In order to better control this matter, legislative and regulatory bodies are moving to require the sequestration of carbon to keep it out of the atmosphere, or apply a corrective pricing mechanism, such as a carbon tax, to fossil-fueled power plants.  Either measure will lead to the cost of solar thermal power becoming cheaper to the consumer than fossil fuel based energy.

Even without pricing cost externalities, the cost of solar thermal power is going down.  As more plants are built and technologies improve, this price should continuously drop over the next ten years with the result that the price of solar power seems likely to be in the same range as power from fossil fueled plants, even without carbon emissions costs considered.

The combination of environmental concerns and persistently higher prices for commodity fuels has caused a number of states to adopt Renewable Portfolio Standards (RPS) that require their utilities to purchase as much as 33% of their power from renewable energy sources such as wind, hydro and solar by specified dates.  These and other regulatory mandates including federal mandates and tax incentives provide an environment conducive to the development of alternative energy solutions and make the building of solar power plants cost effective.

A favorable governmental and regulatory climate makes the delivery of renewable energies possible.  And, these requirements, such as the RPS in place for California that requires utilities to purchase 20% of its power from renewable sources by 2011 and 33% by 2017, help to encourage utilities to make the development of alternative energy sources possible.

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TEN FAQS ABOUT BRIGHTSOURCE ENERGY

BrightSource Energy, Inc. designs and builds large scale solar power plants that can deliver low-cost solar energy in the form of steam and or electricity to industrial and utility customers worldwide at prices competitive with fossil fuels.  BrightSource Energy enables industrial and utility customers to lessen their dependency on fossil fuels by providing a cost effective clean source of power during periods of peak usage.

BrightSource Energy was founded as Luz II in 2004 by Arnold Goldman.  Mr. Goldman has been in the solar energy field for over twenty years and was the founder and CEO of Luz International Ltd., which built nine large solar power plants in the 1980s   In 2004 Mr. Goldman reassembled a number of members of the original Luz International executive and technical team and founded Luz II to develop a new solar energy technology to take advantage of renewed interest in the use of renewable energy to produce electricity and regulatory / legislative support of such projects.

In 2006, the name of the company was changed from Luz II, Inc. to BrightSource Energy, Inc.  The Luz II name was retained by BrightSource’s wholly owned subsidiary in Israel, which is responsible for engineering and development, and the supply of solar fields for BrightSource plants.

BrightSource Energy is a privately held company. Its principal investors include: VantagePoint Venture Partners, Morgan Stanley, Draper Fisher Jurvetson, J.P. Morgan, And Chevron Technology Ventures.

Luz International was the solar technology company that successfully designed, built, financed, and operated nine solar energy plants in Southern California between 1984 and 1991. Luz International remains to this day, as the only company in the world to have built large-scale commercial solar thermal projects – the 350 MW SEGS projects in the Mojave Desert – which are still in operation today.

SEGS is the acronym for Solar Electricity Generating Stations, which was the name given to the type of power plants built by Luz International in the Mojave Desert in Southern California between 1984 and 1991.  Fifteen of the key members of the Luz International engineering and commercial team that built those SEGS are now key members of the BrightSource team.

Unlike solar photovoltaic technologies, which convert sunlight directly to electricity through silicon or other solid-state materials, BrightSource Energy’s solar thermal technology converts sunlight to heat, in the form of steam or hot air that is then used to drive a turbine to produce electricity.  The technology used by BrightSource is called Dynamic Power Tower, or DPT.

DPT™ stands for Dynamic Power Tower and is a BrightSource design based on the solar power tower concept proven by the DOE Solar I and Solar II projects in the 1980s.  The innovations that BrightSource has brought to the power tower design make it far less expensive to build and more efficient in its production of electricity. 

A DPT solar field, known as a Solar Power Cluster (SPC), consists of an array of thousands of relatively small flat glass mirrors placed in the desert and an associated power tower and receiver (solar boiler) which converts the light received into useful heat.  These mirrors reflect sunlight onto the collection surface of the solar boiler approximately 300 feet in the air on top of a tower.  The concentrated sunlight focused on the collection surface is used to directly heat steam, which then drives a turbine/generator to produce electricity.

A properly located and constructed solar power plant is a more desirable source of power generation for utilities than other types of renewable energy, such as wind plants, because solar plants produce the greatest amount of power at the time when the demand on the utility is greatest – sunny afternoons.  A BrightSource DPT plant has a further advantage in that it can be fitted with auxiliary boilers, which will enable them to reliably supply electricity to the grid during both solar and non-solar hours, and during any extended period of solar disruption. 

Both photovoltaic systems and solar thermal systems have a role to play.  Photovoltaic installations are well suited for individual installations in residences and small commercial or industrial facilities where they complement and supplement energy supplied by public utilities.  By contrast, solar thermal installations are designed to provide large quantities of power for direct sale to public utilities to reduce the need for electricity produced by fossil fuel power plants.

Solar thermal power, using BrightSource’s DPT solar technology can be produced for about half the cost of electricity produced by photovoltaic systems, making solar thermal the lowest-cost form of solar power yet available.  The economy of scale and lack of costly specialized materials will allow BrightSource plants to achieve the lowest cost of solar electricity in the world. 

BrightSource’s DPT technology has several significant advantages over other solar thermal technologies:  a) unlike most solar thermal technologies, DPT plants produce steam directly from solar energy, b) the steam has a much higher temperature (550° C vs 380° C), which results in more efficient operation, c) the mirrors that reflect the sunlight move in two dimensions to follow the sun during the day and during the seasons (other technologies only move in one dimension), d) the glass used in the mirrors is less expensive because it is flat, not curved, and e) DPT solar fields can be installed on uneven or sloping ground.

The solar fields for the SEGS plants built by Luz International utilize long rows of curved glass mirrors to heat synthetic oil, which is piped to a heat exchanger to produce steam at about 375° C.  This steam is used to drive a steam turbine to produce electricity.  By contrast, the DPT 550 technology uses thousands of small flat glass mirrors (known as heliostats) to focus sunlight on a solar boiler located on top of a tower.  The sunlight heats steam directly to a temperature of about 550° C and the steam is used to drive a steam turbine to produce electricity.

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