Sunday, March 23, 2008

Hydrogen Fuel Cell Bicycles

Several companies in the past have showcased their plans to use hydrogen fuel cell technology to power a bicycle. Recently, Chinese company Pearl Hydrogen became the latest company to showcase the idea, at a recent technology convention in Shanghaimart. The 20″ wheel prototype weighs 32kg and is powered by a PEM fuel cell and brushless electric motor. The top speed is 25km/hour and the 600L twin cylinder fuel cells have a maximum range of 100km. Some trial orders have already been placed for 20,000 Yuan (about US$2,650). The company is optimistic that their hydrogen bike will be successful enough to begin mass producing bikes for the mainstream Chinese market, for a more affordable 4,000 Yuan (US$530).

Of course there are still technical challenges to overcome, like where people will refill the fuel cells. At present there is no hydrogen refueling infrastructure in China, so customers will have to purchase refills from local suppliers. However, there is talk of expanding the fuel network in China to accommodate future hydrogen powered cars. The electric bicycle industry still has a long way to go in terms of battery technology and efficiency, so there are likely to be many electrical and mechanical flaws to discover and overcome as they produce more bikes. Bicycles take a beating, so the systems will have to be rugged enough to endure the daily commute.

Thursday, March 20, 2008

Reseach initiatives for Solar Thermal from Germany

The development of a new generation of large-scale, low-cost solar thermal power plants is the focus of a joint research agreement signed between Algeria and Germany.

Researchers will be sharing data and expertise to speed up the market introduction of large-scale solar thermal plants. The plants could supply up to 200 megawatts (MW) of electricity and desalinate water for 50,000 people.

Electricity from solar thermal plants could cost as little as €0.04/kilowatt hour (kWh) [US $0.06/kWh] by 2015 to 2020, Bernhard Milow from the German Aerospace Center (DLR) said. And using solar thermal power to desalinate seawater could cost the same.

"The technology and science is all there. It's just a question of transferring that knowledge to those who have the sunshine and optimizing the technology to make it competitive," Milow said.
Electricity from solar thermal plants currently costs €0.20 to 0.30/kWh [US $0.31 to 0.47/kWh], depending on the location of the plant and the amount of sunshine it receives. But with improvements in the performance of plants and better sites, solar thermal electricity could soon be cheaper than coal, and so generate huge amounts of reliable, clean electricity in hot desert regions, Milow said.

Even factoring in high steel prices and other costs, a kWh of electricity could still be as low as €0.06-0.07/kWh [US $0.09-0.11/kWh] if the power plants are in prime locations, Milow said.
By 2050, he estimated that 10 - 25 percent of Europe's electricity needs could be supplied by North African solar thermal plants.

The agreement between the DLR in Germany and the New Energy Algeria (NEAL) in Algeria will allow German researchers access to data from the 150 MW hybrid solar-gas plant at Hassi R'mel, 420 kilometers south of Algiers. The plant is due to go into operation in 2009 and has a 25 MW solar energy capacity with a parabola trough design. The DLR researchers will look at ways of optimizing the design and manufacture of the component parts and the efficiency of the collectors and absorbers.

Another area for research will be thermal storage technology. "The DLR has 30 years of experience in solar thermal power technology while Algeria has the right sites for these plants, and has committed itself developing the technology for its own use and for export to Europe, so we can help each other out," Milow said.

Algeria has introduced a feed-in tariff for electricity from solar thermal plants to boost the use of the technology, and NEAL plans to build pure solar thermal plants without gas as soon as the technology allows it. The typical solar thermal plant of the future could be as large 200 MW and supply electricity to 250,000 people and fresh water to 50,000 people.

In fact, solar thermal desalination plants could turn as much as 100,000 m³ / day of sea water into fresh, clean water — and so help boost agriculture and secure the supply of drinking water in a region increasingly hit by drought. According to a German study, there is already a shortfall of 50 billion cubic meters of fresh water in the region and that shortfall is set to grow to 150 billion by 2050. Algeria is particularly rich in sites suitable for solar thermal desalination plants.

The DLR has identified the best locations for plants using satellite images to encourage investment. "80 percent of the finance for solar thermal projects will come from private investors who will be looking for the best return. That means finding places where there are as few clouds as possible," said Milow.

The DLR has used weather data going back for decades to identity locations with the most sunshine. An average of 2200 kWh of solar radiation falls on each square meter of Algeria with 2650 kWh falling on the Sahara desert region; this compares to just 1000 kWh falling on a square meter in Germany. One study estimated that solar energy harnessed just from Algeria could supply 60 times the electricity needs of Europe.

To transport the electricity to Europe, a 1,875 mile high voltage direct current cable is to be built between Algeria and Germany, running through Sardinia, Italy and Switzerland.

"Getting permission from all these countries to build this cable could slow down the project for years because of all the red tape. But the cable will be able to carry electricity to Europe with only about a 10 percent loss," Milow said. He said small quantities of electricity could be imported into Germany as early as 2010.

The DLR is also carrying out parallel research on a pilot 1.5 MW solar tower power plant in Julich in northern Germany.

"We need to do research on several solar thermal technologies to find the best one," Milow said.
He said that the same model could be used in Australia for electricity and water desalination.
"Plants in Australia could even supply enough fresh water to ensure good, reliable harvests in key crop growing areas that have seen yields drop dramatically because of drought. Israel already successfully uses desalinated water for agriculture, so it has been shown to work in practice, " said Milow.

The southern states of America could also expand their solar thermal plants and eventually export electricity to the northern states, Milow said. Solar thermal power plants have been in commercial use in southern California since 1985. Last year, the 64 MW parabola trough Nevada Solar One plant went into operation.

In Spain, 10 new solar thermal plants are being planned. Spain, which introduced a 25-year guaranteed feed-in tariff of €0.26/kWh [US $0.40/kWh] for solar thermal electricity, is building Europe's two biggest parabola trough solar power plants, Andasol I and II, in Andalusia. The 11 MW PS10 solar power tower has also started operating close to Seville in southern Spain.

New plants are also being planned in Abu Dhabi, Eygpt, Iran, Israel, Mexico, and Morocco. Milow said Morocco and the Red Sea region could also tap wind power in addition to the sunshine to generate clean energy.

"Energy in the future will come from many different sources, including biomass and geothermal, but solar thermal power plants can definitely play a big part when they become cost competitive," he said.

Looking into the future, networks of decentralized and overlapping renewable energy technologies complemented by irrigation networks and water desalination plants could power economies — and large-scale solar thermal power plants could be playing a key role in the energy supply of many regions.

Sunday, March 09, 2008

Global Status of Renewables in 2007

In 2007, more than $100 billion was invested in new renewable energy capacity, manufacturing plants, and research and development -- a true global milestone. Yet perceptions lag behind the reality of renewable energy because change has been so rapid in recent years. This report captures that reality and provides an overview of the status of renewable energy worldwide in 2007. The report covers trends in markets, investments, industries, policies, and rural (off-grid) renewable energy. (By design, the report does not provide analysis, discuss current issues, or forecast the future.) Many of the trends reflect increasing significance relative to conventional energy.

Renewable electricity generation capacity reached an estimated 240 gigawatts (GW) worldwide in 2007, an increase of 50 percent over 2004. Renewables represent 5 percent of global power capacity and 3.4 percent of global power generation. (Figures exclude large hydropower, which itself was 15 percent of global power generation.)

Renewable energy generated as much electric power worldwide in 2006 as one-quarter of the world's nuclear power plants, not counting large hydropower. (And more than nuclear counting large hydropower.)

The largest component of renewables generation capacity is wind power, which grew by 28 percent worldwide in 2007 to reach an estimated 95 GW. Annual capacity additions increased even more: 40 percent higher in 2007 compared to 2006.

The fastest growing energy technology in the world is grid-connected solar photovoltaics (PV), with 50 percent annual increases in cumulative installed capacity in both 2006 and 2007, to an estimated 7.7 GW. This translates into 1.5 million homes with rooftop solar PV feeding into the grid worldwide.

Rooftop solar heat collectors provide hot water to nearly 50 million households worldwide, and space heating to a growing number of homes. Existing solar hot water/heating capacity increased by 19 percent in 2006 to reach 105 gigawatts-thermal (GWth) globally.

Biomass and geothermal energy are commonly employed for both power and heating, with recent increases in a number of countries, including uses for district heating. More than 2 million groundsource heat pumps are used in 30 countries for building heating and cooling.

Production of biofuels (ethanol and biodiesel) exceeded an estimated 53 billion liters in 2007, up 43 percent from 2005. Ethanol production in 2007 represented about 4 percent of the 1,300 billion liters of gasoline consumed globally. Annual biodiesel production increased by more than 50 percent in 2006.

Renewable energy, especially small hydropower, biomass, and solar PV, provides electricity, heat, motive power, and water pumping for tens of millions of people in rural areas of developing countries, serving agriculture, small industry, homes, schools, and community needs. Twenty-five million households cook and light their homes with biogas, and 2.5 million households use solar lighting systems.

Developing countries as a group have more than 40 percent of existing renewable power capacity, more than 70 percent of existing solar hot water capacity, and 45 percent of biofuels production.

Including all these markets, an estimated $71 billion was invested in new renewable power and heating capacity worldwide in 2007 (excluding large hydropower), of which 47 percent was for wind power and 30 percent was for solar PV. Investment in large hydropower was an additional $15-20 billion. Investment flows became more diversified and mainstreamed during 2006/2007, including those from major commercial and investment banks, venture capital and private equity investors, multilateral and bilateral development organizations, and smaller local financiers.

The renewable energy industry saw many new companies, huge increases in company valuations, and many initial public offerings. Just counting the 140 highest-valued publicly traded renewable energy companies yields a combined market capitalization of over $100 billion. Companies also broadened expansion into emerging markets. Major industry growth is occurring in a number of emerging commercial technologies, including thin-film solar PV, concentrating solar thermal power generation, and advanced/second generation biofuels (with first-ever commercial plants completed in 2007 or under construction). Jobs worldwide from renewable energy manufacturing, operations, and maintenance exceeded 2.4 million in 2006, including some 1.1 million for biofuels production.

Policy targets for renewable energy exist in at least 66 countries worldwide, including all 27 European Union countries, 29 U.S. states (and D.C.), and 9 Canadian provinces. Most targets are for shares of electricity production, primary energy, and/or final energy by a future year. Most targets aim for the 2010-2012 timeframe, although an increasing number of targets aim for 2020. There is now an EU-wide target of 20 percent of final energy by 2020, and a Chinese target of 15 percent of primary energy by 2020. Besides China, several other developing countries adopted or upgraded targets during 2006/2007. In addition, targets for biofuels as future shares of transport energy now exist in several countries, including an EU-wide target of 10 percent by 2020.

Policies to promote renewables have mushroomed in recent years. At least 60 countries-37 developed and transition countries and 23 developing countries-have some type of policy to promote renewable power generation. The most common policy is the feed-in law. By 2007, at least 37 countries and 9 states/provinces had adopted feed-in policies, more than half of which have been enacted since 2002. Strong momentum for feed-in tariffs continues around the world as countries enact new feed-in policies or revise existing ones. At least 44 states, provinces, and countries have enacted renewable portfolio standards (RPS), also called renewable obligations or quota policies.

There are many other forms of policy support for renewable power generation, including capital investment subsidies or rebates, tax incentives and credits, sales tax and value-added tax exemptions, energy production payments or tax credits, net metering, public investment or financing, and public competitive bidding. And many developing countries have greatly accelerated their renewable electricity promotion policies in recent years, enacting, strengthening, or considering a wide array of policies and programs.

Policies for solar hot water and biofuels have grown substantially in recent years. Mandates for incorporating solar hot water into new construction represent a strong and growing trend at both national and local levels. Many jurisdictions also offer capital subsidies and/or conduct solar hot water promotion programs.

Mandates for blending biofuels into vehicle fuels have been enacted in at least 36 states/provinces and 17 countries at the national level. Most mandates require blending 10-15 percent ethanol with gasoline or blending 2-5 percent biodiesel with diesel fuel. Fuel tax exemptions and/or production subsidies have become important biofuels policies in more than a dozen countries.
Below the national and state/provincial level, municipalities around the world are setting targets for future shares of renewable energy for government consumption or total city consumption, typically in the 10-20 percent range. Some cities have established carbon dioxide reduction targets. Many cities are enacting policies to promote solar hot water and solar PV, and are conducting urban planning that incorporates renewable energy.

Market facilitation organizations (MFOs) are also supporting the growth of renewable energy markets, investments, industries, and policies through networking, market research, training, project facilitation, consulting, financing, policy advice, and other technical assistance. There are now hundreds of such organizations around the world, including industry associations, nongovernmental organizations, multilateral and bilateral development agencies, international partnerships and networks, and government agencies.

Wednesday, March 05, 2008

Solar Architecture

The term solar architecture refers to an approach to building design that is sensitive to Nature and takes advantage of climatic conditions to achieve human comfort rather than depending on artificial energy that is both costly and environmentally damaging. Unlike the conventional design approach that treats climate as the enemy which has to be kept out of the built environment, solar architecture endeavours to build as part of the environment using climatic factors to our advantage and utilising the energy of Nature itself to attain required comfort levels. Nature’s energies can be utilised in two ways - passiveand active and consequently solar architecture is classified as passive solar and active solar architecture.

Passive solar architecture

It relies upon the design or architecture of the building itself to ensure climate control by way of natural thermal conduction, convection and radiation. The rudiments of solar passive design were developed and used through the centuries by many civilisations across the globe; in fact, many of these early civilisations built dwellings that were better suited to their climatic surroundings than those built today in most developed and developing countries. This has been largely due to the advent of cheap fossil fuels that allowed for artificial temperature and light control at the cost of natural light and cooling. A substantial share of world energy resources is therefore being spent in heating, cooling and lighting of such buildings. The use of solar passive measures such as natural cross ventilation, sufficient day-lighting, proper insulation, use of adequate shading devices coupled with auxiliary energy systems that are renewable and environment friendly can considerably bring down the costs as well as the energy needs of the building.

Passive solar systems The term passive solar refers to systems that absorb, store and distribute the sun’s energy without relying on mechanical devices like pumps and fans, which require additional energy. Passive solar design reduces the energy requirements of the building by meeting either part or all of its daily cooling, heating and lighting needs through the use of solar energy.
Passive heating Heating the building through the use of solar energy involves the absorption and storage of incoming solar radiation, which is then used to meet the heating requirements of the space. Incoming solar radiation is typically stored in thermal mass such as concrete, brick, rock, water or a material that changes phase according to temperature. Incoming sunlight is regulated by the use of overhangs, awnings and shades while insulating materials can help to reduce heat loss during the night or in the cold season. Vents and dampers are typically used to distribute warm or cool air from the system to the areas where it is needed. The three most common solar passive systems are direct gain, indirect gain and isolated gain. A direct gain system allows sunlight to windows into on occupied space where it is absorbed by the floor and walls. In the indirect gain system, a medium of heat storage such as wall, in one part of the building absorbs and stores heat, which is then transferred to the rest of the building by conduction, convection or radiation. In an isolated gain system, solar energy is absorbed in a separate area such as greenhouse or solarium, and distributed to the living space by ducts. The incorporation of insulation in passive systems can be effective in conserving additional energy.

Passive cooling Passive solar technology can also be used for cooling purposes. These systems function by either shielding buildings from direct heat gain or by transferring excess heat outside. Carefully designed elements such as overhangs, awnings and eaves shade from high angle summer sun while allowing winter sun to enter the building. Excess heat transfer can be achieved through ventilation or conduction, where heat is lost to the floor and walls. A radiant heat barrier, such as aluminium foil, installed under a roof is able to block upto 95% of radiant heat transfer through the roof. Water evaporation is also an effective method of cooling buildings, since water absorbs a large quantity of heat as it evaporates. Fountains, sprays and ponds provide substantial cooling to the surrounding areas. The use of sprinkler systems to continually wet the roof during the hot season can reduce the cooling requirements by 25%. Trees can induce cooling by transpiration, reducing the surrounding temperature by 4 to 14 degrees F. Active cooling systems of solar cooling such as evaporative cooling through roof spray and roof pond and desiccant cooling systems have been developed alongwith experimental stratergies like earth-cooling tubes and earth-sheltered buildings. Desiccant cooling systems are designed to dehumidify and cool air. These are particularly suited to hot humid climates where air-conditioning accounts for a major portion of the energy costs. Desiccant materials such as silica gels and certain salt compounds naturally absorb moisture from humid air and release the moisture when heated, a feature that makes them re-useable. In a solar desiccant system, the sun provides the energy to recharge the desiccants. Once the air has been dehumidified, it can be chilled by evaporative cooling or other methods to provide relatively cool, dry air. This can greatly reduce cooling requirements.

Evaporative cooling Evaporation occurs whenever the vapour pressure of water is lesser than the water vapour in the surrounding atmosphere. The phase change of water from liquid to the vapour state is accompanied by the release of a large quantity of sensible heat from the air that lowers the temperature of air while its moisture content increases. The provision of shading and the supply of cool, dry air will enhance the process of evaporative cooling. Evaporative cooling techniques can be broadly classified as passive and hybrid.

Passive direct systems include the use of vegetation for evapotranspiration, as well as the use of fountains, pools and ponds where the evaporation of water results in lower temperature in the room. An important technique known as ‘Volume cooler’ is used in traditional architecture. The system is based on the use of a tower where water contained in a jar or spray is precipitated. External air introduced into the tower is cooled by evaporation and then transferred into the building. A contemporary version of this technique uses a wet cellulose pad installed at the top of a downdraft tower, which cools the incoming air.

Passive indirect evaporative cooling techniques include roof spray and roof pond systems.
Roof spray The exterior surface of the roof is kept wet using sprayers. The sensible heat of the roof surface is converted into latent heat of vaporisation as the water evaporates. This cools the roof surface and a temperature gradient is created between the inside and outside surfaces causing cooling of the building. A reduction in cooling load of about 25% has been observed. A threshold condition for the system is that the temperature of the roof should be greater than that of air. There are, however, a number of problems associated with this system, not least of which is the adequate availability of water. Also it might not be cost effective, as a result of high maintenance costs and also problems due to inadequate water proofing of the roof.

Roof pond The roof pond consists of a shaded water pond over an non-insulated concrete roof. Evaporation of water to the dry atmosphere occurs during day and nighttime. The temperature within the space falls as the ceiling acts as a radiant cooling panel for the space, without increasing indoor humidity levels. The limitation of this technique is that it is confined only to single storey structure with flat, concrete roof and also the capital cost is quite high.

Earth cooling tubes These are long pipes buried underground with one end connected to the house and the other end to the outside. Hot exterior air is drawn through these pipes where tit gives up some of its heat to the soil, which is at a much lower temperature at a depth of 3m to 4m below the surface. This cool air is then introduced into the house. Special problems associated with these systems are possible condensation of water within the pipes or evaporation of accumulated water and control of the system. The lack of detailed data about the performance of such systems hinders the large-scale use of such systems.

Earth-sheltered buildings During the summer, soil temperatures at certain depths are considerably lower than ambient air temperature, thus providing an important source for dissipation of a building’s excess heat. Conduction or convection can achieve heat dissipation to the ground. Earth sheltering achieves cooling by conduction where part of the building envelope is in direct contact with the soil. Totally underground buildings offer many additional advantages including protection from noise, dust, radiation and storms, limited air infiltration and potentially safety from fires. They provide benefits under both cooling and heating conditions, however the potential for large scale application of the technology are limited; high cost and poor day-lighting conditions being frequent problems.

On the other hand, building in partial contact with earth offer interesting cooling possibilities. Sod roofs can considerably reduce heat gain from the roof. Earth berming can considerably reduce solar heat gain and also increase heat loss to the surrounding soil, resulting in increase in comfort.

Active solar architecture
It involves the use of solar collectors and other renewable energy systems like biomass to support the solar passive features as they allow a greater degree of control over the internal climate and make the whole system more precise. Active solar systems use solar panels for heat collection and electrically driven pumps or fans to transport the heat or cold to the required spaces. Electronic devices are used to regulate the collection, storage and distribution of heat within the system. Hybrid systems using a balanced combination of active and passive features provide the best performance.

Active solar systems

Active heating In active systems, solar collectors are used to convert sun’s energy into useful heat for hot water, space heating or industrial processes. Flat-plate collectors are typically used for this purpose. These most often use light-absorbing plates made of dark coloured material such as metal, rubber or plastic that are covered with glass. The plates transfer the heat to a fluid, usually air or water flowing below them and the fluid is used for immediate heating or stored for later use. There are two basic types of liquid based active systems- open loop and closed loop. An open loop system circulates potable water itself, through the collector. In closed loop systems, the circulating fluid is kept separate from the system used for potable water supply. This system is mainly used to prevent the freezing of water within the collector system. However, there is no need to go in for such a system in India, as freezing of water is not a possibility. Also closed loop systems are less efficient as the heat exchanger used in the system causes a loss of upto 10 degrees in the temperature of water, at the same time, one has to reckon with the extra cost of the heat exchanger as well as the circulating pumps. Compared to these, thermosiphon systems are more convenient and simple. In Thermosiphon systems, the water circulates from the collector to the storage tank by natural convection and gravity. As long as the absorber keeps collecting heat, water keeps being heated in the collector and rises into the storage tank, placed slightly above (at least 50 cm). The cold water in the tank runs into the collector to replace the water discharged into the tank. The circulation stops when there is no incident radiation. Thermosyphon systems are simple, relatively inexpensive and require little maintenance and can be used for domestic applications. Solar ponds have been developed ,which harness the sun's energy that can be used for various purposes including production of electricity. Other devices such as solar cookers, water distillation systems, solar dryers, etc. have been developed which can be used to reduce energy requirements in domestic households and in industrial applications.

Active cooling Absorption cooling systems transfer a heated liquid from the solar collector to run a generator or a boiler activating the refrigeration loop which cools a storage reservoir from which cool air is drawn into the space. Rankine steam turbine can also be powered by solar energy to run a compressed air-conditioner or water cooler. Solar refrigeration is independent of electric supply and without any moving parts, for example, Zeolite refrigerator.
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