BERLIN (Reuters) - A group of companies from Europe and northern Africa will meet in Munich on Monday to map out concrete steps for a series of large-scale renewable energy projects worth 400 billion euros ($560 billion) over 40 years.
They will launch a venture to explore the feasibility of harvesting solar thermal energy from the deserts of northern Africa and the Middle East to be used within the next decade or so in those regions and Europe.
Invited by German reinsurer Munich Re, executives from blue chip companies such as Siemens, E.ON, RWE and Switzerland's ABB along with firms from southern Europe and northern Africa will be at the inaugural meeting.
About 10 companies are expected to sign a memorandum of understanding setting up the Desertec Industrial Initiative.
Despite uncertainties associated with such vast multinational projects and concerns about political stability in the Mediterranean region, host Munich Re said the companies were eager to move forward with the next concrete steps.
"We believe the time is ripe for projects like this," said Alexander Mohanty, a Munich Re spokesman. "It's a great vision for the future. But we're not dreamers. This is the start of an industry initiative and we're looking for results.
"We're not just setting up a 'working group' to meet from time to time. The focus is on concrete results. The initiative will be doing lobby work, getting a dialogue going. The issue of the power price is important to be able to raise capital."
The European Union and German government are also firmly behind the projects. EU Commission President Jose Manuel Barroso and Chancellor Angela Merkel both expressly praised the idea behind Desertec at a recent Berlin meeting of energy executives.
Growing global efforts to slow climate change by reducing greenhouse gas emissions along with a projected increase in energy demand in the Middle East and northern Africa make the projects all the more attractive, its proponents say.
Analysts are eagerly waiting for details.
"I think it's a serious project, but it will take a very long time until there will be concrete news," said Commerzbank analyst Robert Schramm.
"The time schedule seems a bit overambitious. The technology is certainly there and it makes sense but there are political factors that need to be taken into consideration regarding the Sahara region."
HARNESSING SUN'S POWER
The Desertec Foundation has noted in six hours the world's deserts receive more energy than mankind consumes in a year.
The projects would use concentrated solar power (CSP) -- a technology that uses mirrors to harness the sun's rays to produce steam and drive turbines to produce electricity -- from the Sahara and deliver to markets locally and in Europe.
Using high-voltage direct current transmission lines there is only a minimal power loss of 3 percent per 1,000 kilometers.
Solar thermal is a well-tested technology from operation since the 1980s of an installation in the U.S. Mojave Desert as well as in Spain, but it is a more expensive source of electricity than fossil fuels.
Desertec officials hope the Sahara could be supplying 20 gigawatts of power -- the equivalent of 20 large conventional power plants -- by 2020 and one day deliver 15 percent of Europe's electricity, helping the EU meet CO2 reduction targets.
"After the founding we're planning to invite more companies to join in," said Michael Straub, head of marketing at the Desertec Foundation in Hamburg.
"At first we'll be studying which countries and which areas could be used for the first plants, and we'll also be studying the costs, the financing and other fundamental questions."
Straub said one project is already moving ahead; it would link power produced in Tunisia with users in southern Italy. He said it was possible it could be on line within five years.
Germany's Solar Millennium, which helped develop Spain's Andasol 1 solar thermal project, will also be at the Desertec meeting as is German solar technology company Schott Solar.
(Additional reporting by Christoph Steitz in Frankfurt; editing by Philippa Fletcher)
In 2013 the world will see the real future of solar technology. That's when the world's largest dispatchable power plant, the 290 MW Starwood 1 will start producing power day and night, on cloudy or sunny days.
Starwood 1 will showcase two critical future technologies. The first is power storage. Without storage, you will only have power when the sun is shining. And while that can work to a point, it will never power the whole world. We'll still need something to take care of the base-load, and that something, as of right now, is coal.
Different ideas have been cooked up for storing the power created by solar power plants – batteries, ultracapacitors, hydrogen generation, flywheels – but all of these are far from being affordable enough for large scale power needs. The alternative is to store power as heat before it's converted to thermal energy.
Fortunately, there is a fairly good and relatively inexpensive solution to thermal storage, one which Starwood 1 implements. Starwood 1's concentrating troughs feed heated liquid in large insulated molten salt tanks at 734 degrees Fahrenheit. When needed, these tanks will release steam, driving turbines at night or during cloudy weather.
The second big technology featured in Starwood 1 is concentrated solar power (CSP). CSP has seen commercial deployments since the 1980s, but has failed to dominate the industry. However, expect that to change as the maximum theoretical efficiencies of concentrated power designs are much higher than those of standard photovoltaics. CSP can be used to enhance thermal (as is done here) or to enhance photovoltaic technologies.
When completed Starwood 1 will cover 1900 acres of desert land. Unlike wind turbines there's a low risk of bird strikes, and the construction team is working to minimize the impact on ground-based local wildlife. Flash from the plant (burst of bright light when viewed from certain angles) is a concern, but given the remote location, this shouldn't prove a problem.
Locate approximately 75 miles west of Phoenix, the plant will produce enough power for 73,000 customers. The construction will also create 7700 jobs. The construction won't be cheap – the plant will cost $2.7B USD, but it should pay for itself and then some. If it can live up to its promise, which seems likely, expect more CSP plants and thermal storage installations to pop up across sunny remote areas of the U.S. southwest in the near future.
Publication Date:04-March-2007 09:00 AM US Eastern Timezone Source:Diane Hirth-Tallahassee Democrat.
What's a rectangle of dirt today may turn into an entirely energy self-sustainable house of the future by December.
The Off-Grid Zero Emission Building or OGZEB is being built at Florida State University under the watchful eye of mechanical engineering professor Anjaneyulu Krothapalli, with the help of several other faculty and graduate students.
"We are building a house that's not connected to the grid, completely run by solar during the day, and the house during the night will be running on hydrogen," he said. "That is unique. All the materials in the house are recyclable and green materials."
"In about five years," was Krothapalli's estimation of how soon a house like this could be affordable and produced commercially.
On Tuesday, there was a groundbreaking for OGZEB, which will be built just south of Tennessee Street near the north entrance to FSU's campus.
The house will incorporate a way to make hydrogen using solar energy and an innovative fuel cell that both currently have patent applications pending.
Hydrogen will be used for the big energy consumption in the house, such as heating, cooling and generating hot water.
OGZEB's interior design is FSU-generated too, incorporating sustainable materials like bamboo floors.
FSU scraped together $200,000 for the project, which is receiving support from private partners like Mad Dog Design and Construction. The FSU Sustainable Energy Science and Engineering Center is seeking more financial support for OGZEB.
"We are building the building at cost," said Kristin Dozier of Mad Dog. "We really want the knowledge base to present to our clients."
The cool tool here is creative solar financing. Solar-electric panels are pretty much a commodity, but still high priced. What's new is an innovative way for a homeowner to afford an expensive solar set up. Nine months ago I covered my studio roof with 5 kilowatts of solar panels financed by a solar company. We are generating about 85% of the electricity we use now. Here's how it works.
You sign up with a company that installs high-quality panels on your property for no money down. Zero dollars! On sunny days the panels make electrons which run your meter backwards. The quantity of panels are sized to cover about 80-90% of your current electric bill, so that you should be expected to pay the utility only 10-20% of what you pay now. In addition to the much smaller payment to your electric grid company you will also now pay the solar company a fee based on the number of watts you send into the grid. This is how they make money to cover the costs of installing the panels and their profit. The rates they will charge you per kilowatt will be less than the utility rates, so your total bill for electricity will be less each month. (Not zero, not half, but less.) Because the solar company makes money by how much electricity your panels produce they have a clear incentive to maintain the panels' performance and keep them clean and the inverters going. After 15-18 years, you own the panels and set up free and clear.
You could think of this as a lease-to-own option for solar panels, where the solar company's rents for electricity are cheaper than the utility grid's. Those cheaper rents are made possible in part by government solar subsidizes, which the solar company will claim on your behalf. But this is a business. While you may be generating 90% of your usage, because you are leasing the panels, your total combined bill will not be 90% less. It may only be 10% less per month. But since it costs you nothing or little up front, over 18 years that 10% adds up. In California, one company providing this zero down financing is SolarCity.
While I got a bid from SolarCity, we went with a slightly different deal from SunRun. Rather than zero down, we paid for half of the installation. That investment bought us a better rate for the electricity that we generate. In fact for the next 18 years we pay a fixed rate for electricity. The average California rate is expected to at least double, and we are projected to save $80,000 over 18 years. We could have gone all the way and bought the panels outright and then paid no lease. But we went with SunRun because this path requires either half, or no, down payment, and because SunRun specs out, installs, insures, owns and maintains the solar panels on our roofs. Also, they guarantee a certain level of output performance.
The actual rates that SunRun or SolarCity charge you depends on the particulars of your place -- the solar climate in your town, the pitch and orientation of your roof, potential shade, and local electric rates. Solar engineers use a really cool computerized tool (above) which takes a annualized panoramic to determine your solar potential. From this they can accurately predict your site's solar potential and lay out a design to maximize it by the hour. The image below was taken on the roof of my studio where our panels now lay.
Solar panels these days are low profile (you can't see ours from the street), modular, and require a minimum penetration into the roof. (The picture at the beginning of this review shows the panels being installed on our roof.) Our 28 panels made it through the rainy season with no problems. If there is a problem, the owner -- SunRun -- takes care of it. (There are escrow mechanisms should SunRun go out of business.)
The technical term for this kind of financing is a "solar power purchasing agreement" or a Solar PPA. Solar PPAs were first used for commercial properties -- huge flat roofs converted for collecting electricity. SunRun, SolarCity and a few others have adapted solar PPAs for home residential use. Right now SunRun operates in California, Massachusetts, and Arizona. SolarCity, California and Arizona. SunPower seems to have dealers in many states, though I have not used them. Coverage is being expanded rapidly so it's worth rechecking. Here is a PDF document answering the FAQ on "whether a solar PPA is right for you."
Like a lot of folks, we've wanted solar electricity for a long while but the significant up-front costs of installing it didn't seem to make sense. Zero dollars down makes sense. Half down and a fixed 18-year rate makes sense.
And watching my daily stats on the SunRun website, seeing the meter run backwards, really makes sense.
Perhaps still stinging from criticism on coal receiving the lion's share of clean energy funding in the budget last week, the Australian Government has highlighted a lofty goal - to build four solar farms that generate three times as much power as the world's current largest project based in California. The Rudd Government says it remains committed to ensuring 20 per cent of Australia's electricity comes from renewable sources by 2020.
Under the Government's $1.365 billion Solar Flagships plan, such a project would see the farms generating a combined 1 gigawatt of renewable energy generated electricity; the equivalent of an average sized coal fired power station.
The new solar farms will be built via a tender to be called later this year. The farms may consist of both solar thermal and solar panel (solar photovoltaic) technologies.
The successful companies and technologies chosen will be based on a competitive assessment, with an important criteria of industry development, including capacity to boost domestic manufacturing and future export potential.
Launched in January this year; Bonn, Germany based IRENA works on behalf of the renewables sector to promote the acceleration of renewable energy uptake worldwide. The organisation provides advice and support for countries, assists in the development of regulatory frameworks and the building of capacity. IRENA currently has 80 members.
The Rudd Government sees the membership of IRENA as a strengthening of Australia's role as a global leader in tackling climate change and the knowledge gained from operating the Solar Flagships program will contribute to the worldwide fight against carbon pollution.
Sunny summer days are beautiful, yet in the office a hot day can be altogether stressful. Because productivity can suffer under such conditions, more and more buildings are being fitted with air-conditioning systems. This is where solar air conditioning comes in: The summer sun, which heats up offices, also delivers the energy to cool them. The thermal use of solar energy offers itself: Days that have the greatest need for cooling are also the very same days that offer the maximum possible solar energy gain.
The demand for air conditioning in offices, hotels, laboratories or public buildings such as museums is considerable. This is true not only in southern Europe, but also in Germany and middle Europe. Under adequate conditions, solar and solar-assisted air conditioning systems can be reasonable alternatives to conventional air conditioning systems. Such systems have advantages over those that use problematic coolants (CFCs), not to mention the incidental CO2 emissions that are taking on increasingly critical values.
Sorption-assisted air conditioning: collector system on the rooftop of Chamber of Commerce and Industry in Freiburg, Germany. Photo: Fraunhofer ISE.
The trend towards solar-assisted air conditioning is met by the organizers of the forum "Solar assisted Air-Conditioning of Buildings" at the convention Intersolar 2002: The German Association for Solar Energy (Die Deutsche Gesellschaft für Sonnenenergie (DGS)), the Fraunhofer Institute for Solar Energy Systems (Fraunhofer Institut für Solare Energiesysteme ISE), the Institute for Maintenance and Modernization of Buildings at the Technical University of Berlin (Institut für Erhaltung und Modernisierung von Bauwerken e.V. an der TU Berlin), and the Pforzheimer Solar Promotion Corporation (Pforzheimer Solarpromotion GmbH) are all offering a two-day international forum on the state of technology, the energy and economic aspects of solar cooling as well as the possible fields of application. Next to German companies, organizations from the entire world have registered including firms from Israel, Ghana, Spain, India, the Netherlands, Belgium, and Austria. This Solar-Report will briefly inform you over the possibilities and technology of solar air conditioning and will also cover economic aspects.
Basic structure of a solar air conditioning system
What is Solar Air Conditioning?
Should buildings be cooled with the help of solar energy, then water-assisted air conditioning systems or ventilation systems can be powered with heat that is made available by solar collectors. No long-term intermediate storage is necessary in months of high solar energy gain or in southern lands. The sun can, at least seasonally at our latitudes, provide a substantial part of the energy needed for air conditioning. Combination water-assisted systems and ventilation systems are also possibilities.
How does Solar Air conditioning Work?
The basic principle behind (solar-) thermal driven cooling is the thermo-chemical process of sorption: a liquid or gaseous substance is either attached to a solid, porous material (adsorption) or is taken in by a liquid or solid material (absorption).
The sorbent (i.e. silica gel, a substance with a large inner surface area) is provided with heat (i.e. from a solar heater) and is dehumidified. After this "drying", or desorption, the process can be repeated in the opposite direction. When providing water vapor or steam, it is stored in the porous storage medium (adsorption) and simultaneously heat is released.
Processes are differentiated between closed refrigerant circulation systems (for producing cold water) and open systems according to the way in which the process is carried out: that is, whether or not the refrigerant comes into contact with the atmosphere. The latter is used for dehumidification and evaporative cooling. Both processes can further be classified according to either liquid or solid sorbents. In addition to the available refrigerating capacity, the relationship between drive heat and realized cold energy (coefficient of performance; COP) is also an essential performance figure of such systems (see Table 1 at end of article).
Absorption Refrigeration Machines
In Germany, closed absorption refrigeration machines with liquid sorbent (water-lithium bromide) are most often operated in combination with heat and power generation (cogeneration) (i.e. with block unit heating power plants, district heating), but can also be assisted by vacuum tube solar collectors (operating temperature above 80 °C). With a single-step process the COP is 0.6-0.75, or up to 1.2 for a two-step process. A market overview is available from the Consortium for Economical and Environmentally Friendly Energy Use (Arbeitsgemeinschaft für sparsamen und umweltfreundlichen Energieverbrauch (ASUE)).
Adsorption Refrigeration Machines
Closed processes with solid sorbents work with so-called adsorption refrigeration machines (operating temperatures 60° - 95°; COP = 0.3 - 0.7). Solar energy can easily be used in the form of vacuum tube or flat plate collectors. A pilot system used for a laboratory's climate control at the University Clinic of Freiburg is fitted with tube collectors; the Fraunhofer ISE also took part in its scientific conception. The refrigerating machine is composed of two adsorbers, one an evaporator and the other a condenser. An adsorber chamber takes up the water vapor, which is transformed into the gas phase under low pressure and low temperatures (about 9°C) within the evaporator. Granulated silicate gel, well known as an environmentally friendly drying agent, then accumulates it (adsorbs the water vapor). In the other sorption chamber the water vapor is set free again (the chamber is regenerated or "charged") by the hot water from the solar collector (about 85°C). The pressure increases and at the temperature of the surroundings (30°C) the water vapor can be transformed once again into a fluid within a cooling tower (condensed). Through a butterfly valve the water is led back into the evaporator and the cycle begins from the beginning. Both the condensed water (low temperature) and the sorption heat (high temperature) are discharged.
Main components of the system at the University Clinic of Freiburg: Adsorption refrigeration machine (left) and solar thermal system (right).
The thermal operating power for this adsorption refrigeration machine is produced by vacuum tube collectors with a surface area of 170 m². Additionally, heat storage tanks improve the use of the solar heat. A cold storage tank functions as a buffer during short-term demand fluctuations. During colder times of the year, the solar energy heats the air inflow thereby reducing heating costs.
Sorption-Assisted Air Conditioning
Although the process of sorption-assisted air conditioning has been known for a long time, it has only been used in Europe for about 15 years. In principle, under middle European climate conditions, sorption-assisted air conditioning systems can be operated everywhere an air conditioner is wanted, for example in ventilation control centers. Their economical operation is then possible if cost-effective heat energy is available, i.e. from cogeneration plants, rather than from over loaded district heating systems. New heat sources, offering much promise, are solar thermal systems. Open sorption-assisted air conditioning systems are fresh air systems, that is they dry the outside air through sorption, pre-cool it with a heat reclamation rotor and finally cool it to room temperature through evaporation-humidification. The main principle of sorption-assisted air conditioning is shown in the graphic. The solar energy is used to dehumidify the sorbent.
Basic structure of the process of sorption-assisted air conditioning.
The most important steps of the process are:
1-2 Sorptive dehumidification of outside air with simultaneous rise in temperature through the freed adsorption heat 2-3 Cooling of the air in the heat reclamation rotor in the countercurrent to the exhaust air 3-4 further cooling of air through evaporation-humidification; the air inflow to the building has a lower temperature and less water vapor than the outside air 4-5 Heating of the air and if necessary addition of water vapor 5-6 Lowering of building's exhaust air temperature through evaporative cooling in the humidifier 6-7 Heating of exhaust air in the countercurrent to the air inflow in the heat reclamation rotor 7-8 Further heating of the exhaust air through external heat sources (i.e. solar thermal system) 8-9 Regeneration of the sorption rotor through the desorption of the bound water
At present, systems with rotating sorption wheels (sorption rotors) are mostly in use. The sorption wheel has small air channels that create a very large surface contact area, which has been treated with a material that easily takes up moisture, such as silica gel. The inflow air is dehumidified in one of the two sectors of the rotor and heated through the adsorption process (the exhaust air serves to dry the rotor). Finally, the inflowing air is cooled down in a heat reclamation rotor. The heat transfer here is made possible through the contact between the air and the rotor material. The last step in cooling the inflowing air is with conventional evaporation humidification.
How well do Solar-Assisted Air Conditioning Systems Operate?
Scientists of the Freiburg Fraunhofer Institute for Solar Energy Systems ISE (Freiburger Fraunhofer Instituts für Solare Energiesysteme ISE) tested solar assisted air conditioning systems for a study of the International Energy Agency (IEA) in the context of the TASK 25 "Solar-Assisted Air Conditioning of Buildings". Detailed descriptions and results of the compared systems can be gathered from the study's conclusion [1]. Year simulations of five variants of a solar-assisted system for air conditioning were conducted and compared to a conventional system for different climates (Trapani/Sicily; Freiburg and Coenhagen).
Energy Balance
Without the use of solar energy, thermally powered climate control raised the primary energy use (thermal and electrical) for all of the tested locations. The reason for this is the lower operating numbers of this process in comparison to electrically powered compression refrigeration machines.
Whether absorption or adsorption refrigerating machines are used, a solar-covered share for cooling of 30 % (Freiburg) and almost 50 % (Trapani) is required to affect a primary energy savings. The solar-covered share for cooling is the portion used for cooling during the summer that comes from heat made available by the solar thermal system. With coverage shares of up to 85 %, the primary energy use can be decreased by over 50 % compared to the conventional reference system. The results were ascertained from an example reference office building and can therefore not simply be applied to other cases or buildings.
In Trapani the sorption assisted air conditioning, in combination with a compression refrigeration machine, led to a small primary energy savings with a solar coverage share of 30 %. If the sun delivers 85 % of the heat for the air conditioning, then just about 50 % of the primary energy can be saved. In this case there are two apparent positive aspects: the sorption-assisted air conditioning can effectively be used for air dehumidification and additionally it can achieve relatively good overall efficiency.
Photo: Sorption-assisted air conditioning system in Portugal.
Cost Effectiveness
Although over 20 systems that use thermal solar energy to air condition buildings and that can be technically and economically assessed have been installed in Germany, there are still a number of obstacles to be overcome when it comes to the implementation of solar-assisted air conditioning. In the twelve countries taking part in the TASK 25 of the Solar and Heating Program of the IEA, experience with about 30 systems has been gained and currently 10 systems are being tested as a part of a demonstration program. Such pilot and demonstration programs are still necessary so that cost reductions become possible and so that relevant energy savings can be assured. Standardized programs, matured concepts and the development of components are starting points that can contribute to improved cost effectiveness and wide applicability of solar-assisted air conditioning.
Because solar cooling is based on thermally driven processes instead of the normal electrical cold production, the costs for the used heat plays a central role: a fundamental problem arises from the inherently higher costs of solar heat compared to heat energy produced by fossil fuel systems or waste heat. Experts at the Fraunhofer ISE expect no economical advantages of the solar air conditioning in this respect. Their use becomes interesting if favorable requirements for a high output of solar heat are present and if the system also delivers energy for heating. The cost of electricity could also pose an argument for solar cooling: The thermally powered cooling process requires only a fourth (absorption/adsorption) or half (sorption-assisted air conditioning) of the electrical power required by the conventional reference system.
The ISEs comparative testing showed that during the process the sorption-assisted air conditioning connected to a conventional machine (compression refrigeration machine) represents the most promising system combination, at least for a Mediterranean climate. The sorption-assisted air conditioning produced the lowest costs at all locations, while the adsorption machines were the most expensive solution. The scientists at the Fraunhofer ISE see a chance for sorption-assisted air conditioning in the cooperation between German facilities and companies that have gained experience with the operation of sorption processes for climate control and large solar thermal systems. Using this know-how, especially in Mediterranean regions, a gap could be found in the market.
Process
closed
open
Coolant circulation
closed refrigerant circulation systems
open refrigerant circulation systems (in contact with the atmosphere)
Process baic principle
cold water production
air dehumidification and evaporative cooling
Sorbent type
solid
liquid
solid
liquid
Typical material systems (refrigerant/sorbent)
water- silica gel ammonia- salt*
water-water-lithium bromide, ammonia- water
water-silica gel
water- lithium chloride- cellulose
water- calcium chloride, waterlithium chloride
Marketable technoloy
adsorption refrigeration machine
absorption refrigeration machine
sorption assisted air conditioning
-
Marketable output [kW cooling]
adsorpzion refrigeration machine [50 - 430 kW]
absorption refrigeration machine: 35 kW - 5 MW
20 kW - 350 kW (per module)
-
Coefficient of Performance (COP)
0.3 - 0.7
0.6 - 0.75 (one step)
<1.2 (two step)
0.5 - >1
>1
Typical operating temp.
60 - 95°C
80 - 110°C (one step)
130 - 160°C (two step)
45 - 95°C
45 - 95°C
Solar technology
vacuum tube collector, flat plate collector
vaccum tube collector
flat plate collector, solar air collector
flat plate collector, solar air collector
*still in development
Table 1: Overview of processes for thermally powered cooling and air conditioning
Material and Pictures: Fraunhofer ISE: Solarserver Editor: Rolf Hug. We thank Dr. Hans-Martin Henning and Diplom Engineer Carsten Hindenburg for their friendly support.
Parabolic trough solar collector PTC is often oriented with its axis horizontally in the North-South or East-West direction. However, it may be set in a position where its axis makes an angle Ψ with the south direction. The main objective of the present work is to study the effect of this angle on the collection efficiency. An algorithm for calculating the collection efficiency for any time period has been developed. The results obtained by using this algorithm by using this algorithm show that the maximum daily collection efficiencies ηc,d all over the year are obtained for the N-S orientation at sites having latitude angles Φ ≤ 15°. For latitude angles Φ > 15°, ηc,d are much higher in summer days than in winter ones for N-S orientation. In the case of orienting die collector with an angle 70° lt; Ψ ≤ 90°, ηc,d are higher in winter days than in summer ones This orientation is preferable to obtain almost constant output of PTC through the whole year. The results show also that a trough oriented with an angle of 70° from N-S direction has almost a constant daily collection efficiency all over the year in order of 82% when considering the reflectivity of the collector surface equal to unity. Also, the effect of orientation on yearly collection efficiency ηc,y are minor at latitude angle Φ between 30° and 40° while the effect of orientation becomes important outside this range.
Rising up, like a mirage in the middle of the desert outside Eilat, is a giant yellow tulip in whose heart lies a massive crystal. Surrounding it: a field of mirrors that slowly move back and forth, following the sun.
Hallucinatory though it may sound, this is no mirage. The tulip is actually a solar tower with an aperture that directs sunlight into a solar receiver that drives a high-powered turbine, and the 30 tracking mirrors below are called heliostats.
It's an ambitious project initiated by Israeli company AORA to construct the world's first solar-thermal powered gas turbine station. The plant, with its distinctive 30-meter high tulip-shaped tower, is now nearing completion at Kibbutz Samar in Israel's southern Arava region.
AORA, of Israeli EDIG group, is a developer of applied ultra-high temperature concentrating solar power (CSP) technology. The breakthrough of CSP is that it can power a 100kW gas micro-turbine; other solar technologies currently available can only power much larger steam turbines. AORA says it is the worlds' first company to commercialize the use of a solarized gas turbine engine.
The government recently showed support when Minister of National Infrastructures, Binyamin Ben Eliezer signed AORA's license provide solar electricity to the national grid -- the first such license to be granted by Israel to solar-thermal technology.
Being able to run the equivalent of a jet engine on solar power, means the system is efficient at far smaller power blocks, Yuval Susskind, COO of AORA, explains to ISRAEL21c. This enables smaller scale projects that require less land and shorter towers (30m vs. 70-120m and more), and which are easier to build, finance and operate.
"Israel has all the climate conditions, but we don't have huge available tracts of land. AORA is the first to bring the size of a solar field down to something like a soccer pitch or a baseball diamond," says Susskind.
Business looks bright - abroad The installation at Samar will be the model for many more to come, says Haim Fried, CEO of AORA, and will include the framework for selling power to the national grid over a long-term period.
The company expects to begin power generation any day. Once it begins generating power, Fried says, the Samar unit will provide 100kW electric power to the grid, as well as 170kW thermal power - enough to supply 50 households at an average of 2kW per household. "That's the average use in Israel. The US is a bit more," he explains.
Fried notes that selling power to the local grid close to the customer base is more efficient because there is no need to step up and down voltage, as is done when transmitting power from a central power station. By generating locally, the power is fed in low voltages, via the local distribution grid, for standard domestic use in the home. It also relieves the load on the high voltage distribution grid.
Location is key, he adds because AORA's installations require direct radiation. "The set up cost is the same in the Arava or Tel Aviv but for the same investment I get more direct sunshine at Samar, so I'll get more power out of it."
The company's business plan has two profit centers: in Israel it will sell power to the national grid through partnerships. Outside Israel, the company will set up joint ventures with local partners to build solar power stations and sell clean energy to the grid.
Costs haven't been finalized yet, but Fried says installations will be competitively priced and estimates that AORA will become profitable after selling 20 units.
"We're also probably going to do a joint venture in Spain," he adds. "We want to do more in Israel but there's a problem with the feed-in tariffs, which are too low. In Spain, they pay 29.9 eurocents, which is much more favorable. If Israel doesn't change the rates then we'll have to do more business outside."
Sunny technology The AORA system is hybrid, meaning it can run on solar, as well as almost any alternative fuel, including biogas, biodiesel and natural gas. Being located in an agricultural community such as Samar, Susskind points out, means ready access to unlimited amounts of biogas, courtesy of the kibbutz cowshed. "So it can run on sunshine during the day, biogas at night and be operational 24 hours a day," he says.
The system is also modular and scalable; more base units - each comprising a tulip tower and 30 heliostats on a half-acre of property - can be added as demand grows.
Modularity enables each unit to be located independently with no need for one large, flat, contiguous expanse of land. Strung together, the units can form a utility-scale power plant. Being modular also means greater reliability, the company states, as servicing a single base unit does not require a complete shutdown.
The key components of AORA's Power Conversion Unit (PCU) are the micro-turbine and the solar receiver, whose technology resulted from collaboration with the Weizmann Institute and Rotem Industries.
The patented receiver uses the sun's energy to heat air to a temperature of 1,000 degrees Celsius and direct this energy into the turbine. The turbine then converts this tremendous thermal energy into electric power.
The solar receiver and some other key components are proprietary technologies and will always be manufactured in Israel, says Fried. However, other components, such as the tower and heliostats, are made of simple materials and can be manufactured wherever a base unit is to be set up according to AORA's specifications.
The company unveiled the Samar project in February, at the annual Eilat-Eilot Renewable Energy Conference. "The response was very positive - which is a great compliment because of the high professional level there," says Fried.
"Greentech has to look good" AORA's tulip is painted bright sunny yellow. Susskind says this was because the dusty red of the Arava hills overpowered the gold color. "One reason for selecting Samar was its proximity to the highway. I want every kid to see this tower when they're heading for a family vacation in Eilat," he says.
The company hired architect Haim Dotan to design the tower. "We didn't think we could afford it but we met with him, and told him about our vision: that there would be many towers like this all over the world. He was so excited about the project that he said he would do it in any case. He said it would make the desert bloom - that's why it's in the shape of a flower. He loves the desert and wants it to be beautiful."
AORA also has a vision of setting up a roadside attraction for tourists: an alternative energy education center that will showcase not just the company's own technology, but other cleantech being developed and tested in the region as well. The company has already been in talks with the regional council, which is interested in the project.
After the Samar facility is completed, AORA plans to expand into larger scale power generating plants of 5MW and more. "By late 2009, we plan on setting up our first international installations in strategic markets," says Fried. These include the Mediterranean, southern Europe, Australia, California, Arizona and the US Sun Belt states. At a later stage, the company aims to enter the African market. "We view China - where we already successfully constructed and operated a pilot unit - Africa and other remote regions as the true market for the AORA system," says Fried.
Q: What are the different types of concentrating solar energy technologies? Why are they limited to the southwestern United States? -- Bertha Z., Berea, KY
A:
There are two main types of concentrating solar energy technologies: concentrating photovoltaics (CPV) and concentrating solar thermal (CST). Together they are commonly referred to as concentrating solar power (CSP), although sometimes CSP is used interchangeably with CST.
1. Concentrating photovoltaics (CPV) uses lenses or mirrors to focus or increase the sun's light on a photovoltaic solar cell or panel. This technology includes both a low-concentration approach, which increases the sun's magnification by less than 5 "suns," and high concentration approach, which can increase the magnification by hundreds of suns. High-concentration CPV uses focusing lenses to concentrate the sun's rays on a single, high efficiency solar cell that is very small, on the order of 1-centimeter square.
When you hear about a new world record for PV efficiency that exceeds 40%, it is generally this type of technology they are utilizing. CPV's "better mousetrap" uses less photovoltaic material (tiny, high efficiency cells), concentrates the sun and increases performance, hopefully enough to offset any additional costs.
2. Concentrating solar thermal (CST) technology uses mirrors to focus the sun's light on a heat capturing point, the heat from which can then be either used directly or converted to electricity. The three basic designs of CST are troughs, towers and dish-engine systems.
Troughs are set-up in large horizontal fields that contain long loops of piping (many kilometers for large installations). The pipes collect the 600+ degree (F) heat from light reflected off mirrors that concentrate the sunlight in a line on the pipes. Troughs have the longest proven operating history and the least number of unknowns for CSP technology project development.
Towers use a mirror field that is set-up around the tower. The mirrors focus sunlight on a heat receiver at the top that collects the heat and transfers it to piping inside the tower where is it circulated and used to make electricity. The design minimizes the field of piping to the vertical tower height to a few hundred meters and can reach temperatures in excess of 1000 degrees (F). While currently there are very few commercially operating tower installations, based on announcements, this technology may grow rapidly.
Dish-engine systems look like satellite dishes and focus light on a Sterling engine mounted on an arm in front of the mirrors. Each dish-engine is an autonomous generator—unlike the other CSP technologies that use a central power plant design—and utilizes a temperature and pressure difference to produce kinetic movement inside the engine, which is then converted to electricity.
An interesting development for troughs (and possibly towers in the future) is the interest on the part of utilities in "hybrid-solar power plants," which include the pairing or retrofitting of natural gas or coal power plants with the thermal input or boost from CSP.
The one thing that is common among the different kinds of concentrating solar power technologies is that unlike traditional photovoltaic panels, they need "direct normal" solar radiation, i.e. sunlight that can cast a shadow. A certain percentage of solar radiation is made up of diffuse or scattered light, caused by clouds, humidity or particulates. Solar resource measurements are reported as either "direct" normal radiation (no diffuse light) or total radiation (diffuse + direct).
The southwest has the highest percentage of "direct normal" radiation of nearly anywhere in the world, making this one of the best regions for development of CSP. However, there is one CSP trough project in Florida—a hybrid CSP plant that will augment a natural gas plant—and a number of trough and tower projects in Spain. CSP will work in both areas, but performance will be commensurately reduced based on the direct normal radiation profiles.
The CSP industry is growing fast in Spain and the United States, and SEPA is tracking over 5,000 MW of new project announcements that are slated for development over the next five years. Not all of them will be built—permitting, financing, technology and other factors need to fall into place first—but the industry is poised for rapid growth regardless of any individual project's outcome.
International energy integrator EnergyMixx AG says that its wholly owned subsidiary, HelioDynamics, has successfully completed commissioning of its latest solar project.
The project, which incorporates HelioDynamic's linear Fresnel solar concentration technology, provides energy for air conditioning on the Southern California Gas Co. Energy Resource Center located in Downey, Calif. The system is part of a comparative program to use heat generated by the sun to power an absorption chiller that feeds cold water to the air conditioning loop.
The HelioDynamics solar concentrator is available for the generation of industrial-grade heat at temperatures in excess of 185 degrees C. It uses EnergyMixx-developed Technology, employing simple flat-glass mirrors held within a lightweight, low-cost but robust aluminum frame.
The best way to go green: carbon taxes, cap-and-trade -- and white paint.
IF THE NATION IS GOING GREEN, THEN CONGRESS AND THE administration should go for a jolting, life-altering transition in a logical, cost-effective manner. However, the evidence so far is that logic will play second fiddle to fashion.
Scientist-businessman Arnold Leitner points to tax subsidies for hybrid cars and photovoltaic systems as being especially inefficient applications of tax dollars to alter consumer behavior.
"Right now, the entire environmental discussion is driven by the affluent do-gooder who want to save the planet," he says. "The result is a complete misallocation of our tax money."
Government programs supporting weatherization and white paint make sense, he says; they'd provide more bang for the buck in helping utilities meet peak demand than would support for expensive, relatively inefficient photovoltaic systems.
And funding light-rail systems powered by clean energy is also going to have greater impact than giving tax breaks to people who buy hybrids, which still require gasoline.
Leitner, who was reared in Germany, holds a doctoral degree in physics from the University of Colorado and runs a highly innovative alternative-energy outfit called SkyFuel.
LEITNER ASSERTS THAT APPLYING WHITE paint to the roofs of commercial buildings in warm and sunny places like Los Angeles would cut their air-conditioning costs by 15% to 20%.
"We now consume twice as much energy in this country as we have to, because we are wasteful and not smart," he says. He also recommends widespread use of roof-top solar hot water systems to significantly cut electric demand.
If it sounds as though Leitner has an axe to grind against photovoltaics (PV), he does and he doesn't.
He spent his early years as a physicist trying to develop PV film -- until government funding for the program was cut. He went on to research superconductors, elements that conduct electricity with little resistance. Now his company, based in New Mexico, may eventually go public; it competes against the PV industry for business and tax dollars.
Leitner is now hawking a technology called parabolic-trough solar collection. The trough system generates electric power by using highly reflective, mirrorlike polymer-based film to concentrate sunlight and heat a conducting fluid above 700 degrees Fahrenheit. The fluid, in turn, makes the steam that drives a plant's generators. Enough of that superheated water can be stored by a utility in an insulated container the size of an oil tank to produce electricity 24/7. By contrast, PV converts sunlight into power and has more limited storage capacity, so it is used in smaller applications.
Like photovoltaic power and other forms of green energy, Leitner's industry could not exist without government subsidies such as tax breaks and research credits. (He says that trough systems require a subsidy of 50 cents per kilowatt, versus $3 per kilowatt for PV). It is impossible in today's marketplace for renewable energy to compete against coal, as long as the cost for putting emissions into the atmosphere is free, Leitner adds.
SO HOW DOES THE GOVERNMENT GET its citizens to go green?
"If you want to change behavior, then you only get there when it hurts," he says. This means setting a floor price for carbon -- a base cost of doing business that shows the real cost of using carbon in the various things we do. The tax might have to be high enough to raise the cost of a barrel of oil back over $150. Last time oil hit that mark, gasoline shot up to $4-a-gallon (or higher in many regions) and commuters abandoned their cars for public transportation.
Leitner also says the government must avoid establishing a "renewable-energy portfolio" dictating the percent of power than must come from various sources like solar and wind. "Let the market respond to the price signal," he urges Congress.
Leitner favors a regime that would have a cap-and-trade system for registered, fixed-place emitters and a simple carbon tax for the rest of us.
The public will not stand for such a tax if it does not perceive that it's getting something in return. He suggests using the proceeds to fund "sacred programs" like benefits for veterans, something no future politician in his right mind would consider rolling back.
Leitner sees a payoff for our children and grandchildren. Although the start-up costs for solar-trough and wind power are high, longer term, the cost of producing energy in these systems is practically free, he says. He points to the big dams built by the U.S. in the 1930s. They were paid off long ago, but are still operating and producing power at nearly zero cost.
(May 5, 2009) -- DuCool is launching the DuHybrid air-conditioning system which is powered by solar thermal energy or electricity to reduce the energy required for cooling by up to 60% compared to standard air conditioning. The DuHybrid system combines desiccant dehumidification with evaporative or geothermal cooling to eliminate the need for conventional mechanical cooling. It utilizes solar thermal energy when available and automatically switches to electric power when needed. The DuHybrid system can also be integrated with a cogeneration system and can be powered by other renewable energy sources or waste heat.
The DuHybrid system operates in one of two modes. The renewable energy mode is the default mode of operation. Based on the application, in this mode the unit can generate over 20 TR (tons of refrigeration) of cooling and dehumidification using renewable energy sources such as solar thermal and geothermal water. In the electric mode of operation an embedded compressor is activated to enable efficient cooling and dehumidification by utilizing the waste heat of the compressor as an internal energy source. The DuHybrid system can be supplied in one of the three configurations, 1400CFM, 2400CFM and 3400CFM, that cover a broad range of commercial and industrial needs for air conditioning and dehumidification.
Additional benefits of the DuHybrid system include the ability to control humidity and temperature independently (variable sensible heat ratio). This guarantees that the required conditions, both temperature and humidity, are achieved in the most energy efficient way. The DuHybrid's liquid desiccant cooling process eliminates 91% of the bacteria in the air in a single pass and removes over 80% of all particles larger than five microns including allergens such as pollen, dust and other airborne particles. These air scrubbing qualities are inherent to all of DuCool's cooling and dehumidification systems.
About DuCool DuCool's systems cool, heat, dehumidify, disinfect and clean the air while providing independent control of temperature and humidity. DuCool's solutions are powered by renewable energy sources such as solar thermal panels, geothermal water or available low grade waste heat, providing considerable savings to commercial and industrial users. DuCool systems utilize a patented liquid desiccant process for dehumidification and air conditioning that is considerably more efficient and effective than other air conditioning and /dehumidifying solutions. DuCool systems can be configured as a standalone solution or they can be coupled with existing conventional systems to provide a superior energy saving solution.
Starfish has joined with five other managers to establish an equity funding facility for Ausra.
Venture capital manager Starfish Ventures has reinvested in California-based solar thermal energy company Ausra.
The Melbourne-headquartered manager is part of a group of five that has ploughed $25.5 million into an equity funding facility for the company.
Other members of the group are Al Gore-founded Generation Investment Management, Ausra founding investors Khosla Ventures and Kleiner Perkins Caufield & Byers, and Kern Partners.
Funds from the equity facility will be available to Ausra for acceleration of the company's solar thermal energy equipment supply business.
Ausra said the group had committed the funds to support global expansion opportunities for existing power generation and industrial steam applications.
Starfish Ventures has had a number of institutional investors, including Westscheme and MTAA Super.
Many readers have expressed interest in learning more about the water consumption of concentrating solar power and how measures to reduce it might impact system efficiency and cost. After my recent CSP post, "World's largest solar power plants with thermal storage to be built in Arizona," Michael Hogan wrote in the comments (here) about a low-water-consuming cooling system he had experience with. I asked Hogan, a long-time power industry executive and currently the Power Programme Director for the European Climate Foundation (bio here), to write a longer piece for Climate Progress. Here is what he put together, with links and figures (click to enlarge).
EXECUTIVE SUMMARY: If concentrating solar power ("CSP") is a core climate solution, indirect dry cooling systems (also known as "Heller" systems) will be a crucial enabling technology, since large-scale CSP will be located in desert regions. US power companies have long favored direct dry cooling systems for fossil plants, probably because of the visual impact of Heller systems. But Heller systems have long experience in certain regions and will probably play an important role in the success of large-scale CSP. This is due to their higher efficiency, smaller footprints, quieter operation, lower maintenance, higher availability, and more flexible site layout. Heller systems can reduce water consumption in a CSP plant by 97% with minimal performance impact. The height of the cooling towers should be less of an issue in remote desert locations, especially since the central tower in power tower facilities will be of comparable height.
Concentrating solar thermal power plants ("CSP") have been identified a number of times in Climate Progress as a core climate solution due to their almost unique potential to replace coal as the dominant supplier of baseload and/or firm dispatchable capacity to the world's power grids. It is said that CSP could represent 3 of the 12-14 wedges in the 450ppm solution –- 20-25% of global mitigation potential. I concur wholeheartedly with that view, and I applaud CP for its efforts to educate readers on the singular challenges of eliminating coal-fired power production at scale. But if CSP is a core climate solution, dry cooling technologies, and in particular Heller systems, will be a crucial enabler (see note at the end regarding the status of the name "Heller" system).
One of the concerns often cited about CSP is water consumption, particularly because the technology's reliance on direct normal insolation means that it is most economically located in desert regions. Because most CSP systems rely on Rankine cycle steam turbine-generators to produce electricity, they face the same requirements as fossil-fired power plants for condensing large volumes of saturated steam back into boiler feedwater. (Parabolic dish systems use Stirling or Brayton engines to produce useful energy, each of which has its own advantages and disadvantages) Where an abundant and cheap supply of water is available, the most efficient way to accomplish this is by evaporation (or "wet cooling"), which is what produces the large plume of water vapor one often sees rising from power stations. Convective cooling using ambient air ("dry cooling") requires higher capital costs and can reduce plant performance, and thus planners of fossil plants have sought to locate them close to adequate supplies of cooling water whenever possible.
In the desert areas where CSP will thrive, the consumption of large amounts of water by conventional wet cooling systems is clearly unsustainable. Dry cooling alternatives will be required, and CSP will have to demonstrate its commercial viability despite the capital cost and performance penalties this will entail. Fortunately this is an eminently manageable problem.
Deutsches Zentrum fur Luft- und Raumfahrt e.V. ("DLR"), a German government research agency, presented a study in 2007 comparing a particular dry cooling technology, the Heller system, with wet cooling for CSP plants in Spain and in the California desert (see figures above). Water consumption was reduced by 97%, and the performance impact was quite minimal. Indeed the impact on performance in the higher desert temperatures of California was overwhelmed by the benefits of better annual insolation. They also noted that the potentially negative impact of high daytime temperatures is mitigated by the use of thermal storage, which uses energy collected during peak daytime insolation to produce electricity when temperatures are considerably lower. One interesting aspect of the DLR study was their focus on Heller systems over more familiar (at least in the US) direct dry cooling systems, and that is worth a closer examination.
Two basic types of dry cooling systems have long been employed where necessary -– "direct" air cooling (usually called an "air-cooled condenser" or "ACC") and "indirect" air cooling (often referred to as the "Heller system", after Laszlo Heller, the Hungarian thermodynamics professor who pioneered this approach in the 1950s). In ACC systems, the saturated steam from the steam turbine exhaust is carried directly to a very large array of A-framed fin-tube bundles, where large mechanical fans force air over the tubes, convectively condensing the steam.
ACC system
In Heller systems, the steam is condensed by spraying water directly into the exhaust flow in a ratio of about 50:1 (called "direct contact jet condensing"), creating a large volume of warm water, some of which is pumped back to the boiler as the working fluid and the rest of which is pumped to bundles of tubes arrayed at the base of a natural-draft hyperbolic cooling tower. The warm water circulating around the base of the tower and the cooler air at the top of the tower, combined with the tower's hyperbolic shape, stimulate a powerful updraft that draws ambient air over the tube bundles, thereby convectively cooling the water before it is returned to the condenser. Both are closed systems.
Heller system [Acronyms: "CW" = cooling water; "DC" = direct contact]
While the Heller system has been widely used elsewhere, there are none in the US. This is probably because the much lower auxiliary power requirements of Heller systems come with the visual impact of a large hyperbolic cooling tower (typically 150m high and 120m in base diameter), often a difficult sell given that most fossil power stations are located in the vicinity of the populated demand centers they're intended to serve. The auxiliary power required to run an ACC system is roughly twice the power required run a Heller system, and the Heller system is considerably quieter, but these have apparently been considered prices worth paying for the lower profile (a typical ACC system can be 40m high), particularly when it was cheap coal-fired power. Simple lack of familiarity could be another factor in the hidebound world of US power utilities.
The Electric Power Research Institute has kicked off a comparative study of indirect dry cooling (due to be completed in mid 2010), on the theory that it is the most economic dry cooling solution for large-scale thermal applications. The prospect of large amounts of CSP being built in the world's deserts calls for a reconsideration of the relative merits of these two approaches, since it would require dry cooling to be deployed in a different application and to a far larger extent than has ever been the case.
Three Bechtel engineers published a paper in 2005 (Digital Object Identifier reference DOI:10.1115/1.1839924) (originally presented at an American Society of Mechanical Engineers conference in 2002) that compared cooling technologies for combined-cycle gas power plants. They cited the following comparison of installed costs for various cooling systems, including ACC and Heller.
[Acronyms: "WSAC" – wet-surface air condenser]
They also note that the footprint of an ACC system is larger than that required for a Heller system, though specific data is not offered. Overall system efficiency of a Heller system is in the range of 2% better than an ACC system. That performance improvement meant one thing in a fossil power plant in the bad old days of cheap dirty power, but when it means 2% less land area covered by solar collectors, and lower auxiliary consumption of much more costly power, it takes on a much greater significance. The same sources note that since the Heller systems are mechanically far simpler than ACC systems, maintenance is much less of an issue and system availability is significantly greater. In the remote areas where these plants will be located, and given the large land areas over which they will spread, these are far more significant considerations than they were for compact fossil power plants located close to the populations they served. Another factor noted in these sources is that an ACC must be located next to the steam turbine it serves, because of the cost of transporting saturated steam over any distance, whereas the Heller system has much more flexibility in where the cooling tower is located. This will be much more important to CSP, where one can envision clusters of power tower complexes in a given area each with its own steam turbine, than it was with fossil plants. And finally, the feature that most worked against Heller systems in US fossil plant applications – visual impact – should be far less of an issue in remote desert sites, especially with solar power tower complexes where the central towers will likely be of similar height.
I should note that as a senior executive of the private power company InterGen in the late 1990s I oversaw the deployment of a Heller system on our 2,400 MW gas-fired combined cycle plant in Adapazari, Turkey (see below), which is still the world's largest installation of an indirect dry cooling system and continues to work extremely well. I trace my enthusiasm for the technology to that personal experience.
One final note on the term "Heller" system. A German engineering company, GEA, appears to own the trademark rights to the name "Heller", which they acquired when the bought EGI, the Hungarian company that commercialized indirect dry cooling systems. Indirect dry cooling is a generic technical solution that is often referred to as "the Heller system". I have no affiliation with GEA.
I am happy to see it pointed out that large amounts of water are not needed for solar power. Thanks.
There seem to be two design decisions here: whether to use direct or indirect condensation, and whether to use a cooling tower or forced cooling. Only 2 of the possible 4 combinations are discussed. Lets say I've decided I will use a cooling tower. What advantage is there to using the Heller system over placing a direct condensing system in my tower? (Other than less steam piping, I get that).
I see one advantage to direct: The steam is hotter than the water will be in the Heller system, so the fluid to air heat exchanger will be smaller, and hence cheaper.
In 2013 the world will see the real future of solar technology. That's when the world's largest dispatchable power plant, the 290 MW Starwood 1 will start producing power day and night, on cloudy or sunny days.
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