Hybrid Renewable Energy System

Hybrid renewable energy systems (HRES) are becoming popular for remote area power generation applications due to advances in renewable energy technologies and subsequent rise in prices of petroleum products. A hybrid energy system usually consists of two or more renewable energy sources used together to provide increased system efficiency as well as greater balance in energy supply.

Biomass-wind-fuel cell

For example, let us consider a load of 100% power supply and there is no renewable system to fulfil this need, so two or more renewable energy system can be combined. For example, 60% from a biomass system, 20% from a wind energy system and the remainder from fuel cells. Thus combining all these renewable energy systems may provide 100% of the power and energy requirements for the load, such as a home or business.


Block diagram of a PV/wind hybrid energy system

Another example of a hybrid energy system might be a photovoltaic array coupled with a wind turbine. This would create more output from the wind turbine during the winter, whereas during the summer, the solar panels would produce their peak output. Hybrid energy systems oftentimes yield greater economic and environmental returns than wind, solar, geothermal or trigeneration stand-alone systems by themselves.


To get constant power supply, the output of the renewable may be connected to the rechargeable battery bank and then to the load. If the load is alternating current (AC), then an inverter is used to convert the direct current (DC) supply from the battery to the AC load. Consideration about voltage transition among modules starting from Wind Generator,Battery Charger Controller and Inverter should be subject to voltage standard which mainly focus about voltage compatibility.

Need for research

The key to cost reductions of this order is, of course, the right sort of support for innovation and development - something that has been lacking for the past and, arguably, is still only patchy at present. Research and development efforts in solar, wind, and other renewable energy technologies are required to continue for:

  • improving their performance,
  • establishing techniques for accurately predicting their output
  • reliably integrating them with other conventional generating sources

Economic aspects of these technologies are sufficiently promising to include them in developing power generation capacity for developing countries.

Third Generation Technologies of Renewable Energy

Third-generation renewable energy technologies are still under development and include advanced biomass gasification, biorefinery technologies, hot-dry-rock geothermal power, and ocean energy. Third-generation technologies are not yet widely demonstrated or have limited commercialization. Many are on the horizon and may have potential comparable to other renewable energy technologies, but still depend on attracting sufficient attention and RD&D funding.

New bioenergy technologies

According to the International Energy Agency, cellulosic ethanol biorefineries could allow biofuels to play a much bigger role in the future than organizations such as the IEA previously thought. Cellulosic ethanol can be made from plant matter composed primarily of inedible cellulose fibers that form the stems and branches of most plants. Crop residues (such as corn stalks, wheat straw and rice straw), wood waste, and municipal solid waste are potential sources of cellulosic biomass. Dedicated energy crops, such as switchgrass, are also promising cellulose sources that can be sustainably produced in many regions of the United States.

Selected Commercial Cellulosic Ethanol Plants in the U.S.
(Operational or under construction)
Company Location Feedstock
Abengoa Bioenergy Hugoton, KS Wheat straw
BlueFire Ethanol Irvine, CA Multiple sources
Gulf Coast Energy Mossy Head, FL Wood waste
Mascoma Lansing, MI Wood
POET LLC Emmetsburg, IA Corn cobs
Range Fuels Treutlen County, GA Wood waste
SunOpta Little Falls, MN Wood chips
Xethanol Auburndale, FL Citrus peels

Ocean energy

First proposed more than thirty years ago, systems to harvest utility-scale electrical power from ocean waves have recently been gaining momentum as a viable technology. The potential for this technology is considered promising, especially on west-facing coasts with latitudes between 40 and 60 degrees:

In the United Kingdom, for example, the Carbon Trust recently estimated the extent of the economically viable offshore resource at 55 TWh per year, about 14% of current national demand. Across Europe, the technologically achievable resource has been estimated to be at least 280 TWh per year. In 2003, the U.S. Electric Power Research Institute (EPRI) estimated the viable resource in the United States at 255 TWh per year (6% of demand).

Funding for a wave farm in Scotland was announced in February 2007 by the Scottish Executive, at a cost of over 4 million pounds, as part of a £13 million funding packages for ocean power in Scotland. The farm will be the world's largest with a capacity of 3 MW generated by four Pelamis machines.

The world's first commercial tidal power station was installed in 2007 in the narrows of Strangford Lough in Ireland. The 1.2 megawatt underwater tidal electricity generator, part of Northern Ireland's Environment & Renewable Energy Fund scheme, takes advantage of the fast tidal flow (up to 4 metres per second) in the lough. Although the generator is powerful enough to power a thousand homes, the turbine has minimal environmental impact, as it is almost entirely submerged, and the rotors pose no danger to wildlife as they turn quite slowly.

Enhanced geothermal systems

As of 2008, geothermal power development was under way in more than 40 countries, partially attributable to the development of new technologies, such as Enhanced Geothermal Systems. The development of binary cycle power plants and improvements in drilling and extraction technology may enable enhanced geothermal systems over a much greater geographical range than "traditional" Geothermal systems. Demonstration EGS projects are operational in the USA, Australia, Germany, France, and The United Kingdom.

Nanotechnology thin-film solar panels

Solar power panels that use nanotechnology, which can create circuits out of individual silicon molecules, may cost half as much as traditional photovoltaic cells, according to executives and investors involved in developing the products. Nanosolar has secured more than $100 million from investors to build a factory for nanotechnology thin-film solar panels. The company expects the factory to open in 2010 and produce enough solar cells each year to generate 430 megawatts of power.

Second Generation Technologies of Renewable Energy

Markets for second-generation technologies of renewable energy have been strong and growing over the past decade, and these technologies have gone from being a passion for the dedicated few to a major economic sector in countries such as Germany, Spain, the United States, and Japan. Many large industrial companies and financial institutions are involved and the challenge is to broaden the market base for continued growth worldwide.

Solar Heating

Solar heating systems are a well known second-generation technology and generally consist of solar thermal collectors, a fluid system to move the heat from the collector to its point of usage, and a reservoir or tank for heat storage. The systems may be used to heat domestic hot water, swimming pools, or homes and businesses. The heat can also be used for industrial process applications or as an energy input for other uses such as cooling equipment.

In many warmer climates, a solar heating system can provide a very high percentage (50 to 75%) of domestic hot water energy. As of 2009, China has 27 million rooftop solar water heaters.


Photovoltaic (PV) cells, also called solar cells, convert light into electricity. In the 1980s and early 1990s, most photovoltaic modules were used to provide remote-area power suppy, but from around 1995, industry efforts have focused increasingly on developing building integrated photovoltaics and photovoltaic power plants for grid connected applications.

As of October 2009, the largest photovoltaic (PV) power plants in the world are the Olmedilla Photovoltaic Park (Spain, 60 MW), the Puertollano Photovoltaic Park (Spain, 50 MW), the Moura photovoltaic power station (Portugal, 46 MW), and the Waldpolenz Solar Park (Germany, 40 MW). The largest photovoltaic power plant in North America is the 25 MW DeSoto Next Generation Solar Energy Center in Florida. The plant consists of over 90,000 solar panels.

At the end of 2008, the cumulative global PV installations reached 15,200 MW. Photovoltaic production has been doubling every two years, increasing by an average of 48 percent each year since 2002, making it the world’s fastest-growing energy technology. The top five photovoltaic producing countries are Japan, China, Germany, Taiwan, and the USA.

Wind power

Some of the second-generation renewables, such as wind power plant, have high potential and have already realised relatively low production costs. At the end of 2009, worldwide wind farm capacity was 157,900 MW, representing an increase of 31 percent during the year, and wind power supplied some 1.3% of global electricity consumption. Wind power is widely used in European countries, and more recently in the United States and Asia. Wind power accounts for approximately 19% of electricity generation in Denmark, 11% in Spain and Portugal, and 9% in the Republic of Ireland. These are some of the largest wind farms in the world, as of January 2010:
Wind farm Installed
Capricorn Ridge Wind Farm 662 USA
Fowler Ridge Wind Farm 750 USA
Horse Hollow Wind Energy Center 736 USA
Roscoe Wind Farm 781 USA
San Gorgonio Pass Wind Farm 619 USA
Tehachapi Pass Wind Farm 690 USA

Solar thermal power stations

Solar thermal power plants include the 354 MW Solar Energy Generating Systems power complex in the USA, Nevada Solar One (USA, 64 MW), Andasol 1 (Spain, 50 MW) and the PS10 solar power tower (Spain, 11 MW). Many other plants are under construction or planned, mainly in Spain and the USA. In developing countries, three World Bank projects for integrated solar thermal/combined-cycle gas-turbine power plants in Egypt, Mexico, and Morocco have been approved.

Modern forms of Bioenergy

Global ethanol production for transport fuel tripled between 2000 and 2007 from 17 billion to more than 52 billion litres, while biodiesel expanded more than ten-fold from less than 1 billion to almost 11 billion litres. Biofuels provide 1.8% of the world’s transport fuel and recent estimates indicate a continued high growth. The main producing countries for transport biofuels are the USA, Brazil, and the EU.

Brazil has one of the largest renewable energy programs in the world, involving production of ethanol fuel from sugar cane, and ethanol now provides 18 percent of the country's automotive fuel. As a result of this and the exploitation of domestic deep water oil sources, Brazil, which for years had to import a large share of the petroleum needed for domestic consumption, recently reached complete self-sufficiency in liquid fuels.

Most cars on the road today in the U.S. can run on blends of up to 10% ethanol, and motor vehicle manufacturers already produce vehicles designed to run on much higher ethanol blends. Ford, DaimlerChrysler, and GM are among the automobile companies that sell flexible-fuel cars, trucks, and minivans that can use gasoline and ethanol blends ranging from pure gasoline up to 85% ethanol (E85). By mid-2006, there were approximately six million E85-compatible vehicles on U.S. roads. The challenge is to expand the market for biofuels beyond the farm states where they have been most popular to date. Flex-fuel vehicles are assisting in this transition because they allow drivers to choose different fuels based on price and availability. The Energy Policy Act of 2005, which calls for 7.5 billion gallons of biofuels to be used annually by 2012, will also help to expand the market.

The growing ethanol and biodiesel industries are providing jobs in plant construction, operations, and maintenance, mostly in rural communities. According to the Renewable Fuels Association, the ethanol industry created almost 154,000 U.S. jobs in 2005 alone, boosting household income by $5.7 billion. It also contributed about $3.5 billion in tax revenues at the local, state, and federal levels.