RENEWABLE ENERGY RESOURCES AND TECHNOLOGIES: GLOBAL PERSPECTIVE

 

Dr. Shahida Rafique, Hasan Sarwar

Department of Applied Physics, Electronics and Communication Engineering

University of Dhaka

Dhaka-1000, Bangladesh

 

Abstract

•           Global renewable energy resources are identified as the radiant energy from the Sun in visible, invisible and IR region, wind energy, bio-energy, marine renewable, tidal waves, hydropower, lubricants from renewable resources, renewable hydrogen, geothermal energy, etc.

•           Hydroelectric, wind power, bio-energy and non-solar environmental energy resources have been found to be solar-powered.

•           Efficient solar technologies have been developed are solar photovoltaic, which uses solar cells to convert sunlight into electricity, to produce heat, light, hot water, even cooling for homes, business centers and industries.

•           Wind is the fuel source for wind energy, which is considered as a green power technology.

•           Thermal energy of the sun is converted to the kinetic energy of the air, which moves the air masses.

•           Biomass is the result of photosynthetic conversion of solar energy and CO2 into the chemical and physical components of plant material.

•           It has been found that about 11% of world primary energy use at present is derived from bio-energy.

•           Geothermal is the heat energy of the earth, a major renewable energy resource for many countries.

•           At present 39 countries are 100% geothermal powered, 4 countries are 50% geothermal powered.

•           It is suggested that the renewable energy transition must start now in all the countries both developing and developed.

•           Let solar energy, the source of all lives on earth, is the sustainable and safe future energy for all of us.

Introduction

Any naturally occurring source of energy that is theoretically inexhaustible, such as, solar, wind, tidal and hydropower, which has finite supply levels that cannot be replenished except over a geological time-scale, is known as renewable energy. In the history of human civilization, RE resources were the sole world supplies of energy for all living beings. The electromagnetic energy from the sun can be used directly to heat or light buildings, to heat water to steam for industrial processing, to produce electricity through PV effect, to produce fresh water from the sea through desalination plant, to detoxify contaminated water, to cook food in solar cookers and to covert sun's energy into electricity. This electricity can be used to produce heat, light, hot water or even cooling for homes. Passive solar heating, cooling and day lighting involve building design features and building materials for natural ventilation.

Concentrating solar power technologies consist of reflecting materials to concentrate sun’s energy to produce heat. This heat energy is converted to electricity. The most recognizable solar energy technologies aim to produce electricity by SPV system. BIPV systems with modest amount of storage can provide light and heat to buildings.

 

Solar Energy

 

The energy received by the earth from the sun in the form of radiation is known as solar energy. The energy from the sun can be used directly

•           to heat or light buildings

•           to heat water to provide very hot water or steam for industrial processing

•           to heat fluids through concentration to temperatures needed to produce electricity in

  thermal electric generators

•           to run heat engines directly

•           to produce electricity through PV effect. It can be used directly

☼ to enhance public safety

☼ to bring light and the refrigeration of food and medicine to provide

   communications to all regions of the world

☼ to produce fresh water from the seas

☼ to pump water and power irrigation systems

☼ to detoxify contaminated waters

☼ to cook food with solar box cookers, etc.

 

The indirect uses of solar energy such as, hydroelectric, wind power and bio-energy and non-solar environmental energy resource, geothermal and their combined outputs are all direct applications of radiant solar energy. It is this diversity of opportunities that makes solar energy such an attractive option for so many applications and is important for all culture’s regions, economies and people of the world. The annual solar resource is uniform within a factor of two throughout all the populated regions of the world.

 

 

 

 

 

 

 

 

 

                                             

Solar PV Electric Energy Production

The most recognizable solar energy technology is the solar PV system for electricity production. Although it is expensive in terms of energy production, it is the most versatile, simplest to install and cheapest to maintain, and provides electricity at the point of use. PV modules can be used

•          to power telephones or traffic and warning signs

•          to reduce corrosion in metal bridges

•          to power water pumps and wells

•          to provide light and power for remote houses and villages

•          to refrigerate medicine

•          to reduce purchased energy in grid connected homes and commercial establishments

•          to provide both power and shade in parking lots

•          to charge electric cars and many more applications

•          to power on-board satellite LEO, GEO, MEO.

 

PV roofing shingles, standing seam roofing with “stick-on” PV, PV shading overhangs, PV curtain wall glazing, and PV skylights are already commercially available. Flat hotels and commercial roofs are being decked over with PV that produces electricity and reduces the cooling load for the building.

 

Building integrated PV (BIPV) systems with modest amount of storage can provide emergency operations and maintain safety. The PV is sold by the watt.

 

 

Technology

The most popular PV technologies are mono-crystalline and poly-crystalline silicon cells. New PV cell compounds are being developed and marketed such as, single or multi-junction amorphous silicon, mixed-phase microcrystalline silicon, copper indium deselenide or cadmium telluride. However, 95% of worldwide solar cell is silicon-based. Japanese manufacturer reached a solar to electric energy conversion efficiency of 20% for large-area crystalline silicon cells for module production in 2003. The most popular application of PV today is on roofs.

 

 

Global Scenario

 

PV is an industry that is growing worldwide at an amazing pace over 560MWp of PV modules were manufactured and sold in 2002. The average rate of growth of the industry at the beginning of this millennium has been 36.6% and it has increased by 44% in 2002. In India, by the end of 2002, 5084 solar PV water pumps have been installed in rural areas with a total capacity of 5.55MWp. About 2,400 villages had been electrified in India with PV. Japan has produced 123.07MWp in 2002 and is producing 100MWp annually. Europe produced 135MWp of the world’s PV module in 2002. US produced 120.6MWp and the rest of the world produced 55MWp. The three most significant national PV programs are

 

1. Residential PV system dissemination program in Japan

2. 100,000 roof solar electric program in Germany

3. Million roofs solar program in US

 

 

One million solar, thermal or electric systems by 2010 have been announced by a company of US. Japanese program exceeded for 32000 private housing alone, with a total of 40000 application for the year. Japanese Government’s near term goal for manufacturing 500 MWp of pv annually with 250 MWp  for internal consumption and rest of export. the rate of growth in PV application in Germany has reached upto 100000 roof program. total installed PV system power in Germany is about 278 MWp (1999) and it reached upto 190 MWp in 2002. By the end of 2002 55000 rooftop PV systems had been installed in Germany. 98% of those are grid connected. The total installed power on residential roofs reached upto 200 MWp. Switzerland reached the EU installations at 2.8 Wp per capita., Germany at 2.3 and Netherlands at 1.1. The measured average daily energy production from the German rooftop PV system is about 2.33 KWh/KWp. It has been forecasted that at the end of this decade the world market will reach 10000 MW annually. An average PV production growth of 25% from 2000 to 2010 would lead to annual production of 2500 MW. An average growth rate of 50% would lead to annual production of 16000 MW by 2010.

 

Solar photovoltaic technology, in concert with energy efficient and sustainable design of building and integrated into the electrical grid, can make a substantial contribution to the basic energy needs of almost all countries of the world. But the societal value of PV and the worthiness of public support and governmental stimulus goes well beyond the KW produced by PV systems. PV system in both developed and developing nation can enhance local employment, strengthen local economics, improved local environment, increase system and infrastructure reliability and provides better economic security for the society. The PV industry growing by a rate of 40% per year globally with opportunities for economics advancement and international marketing competitiveness by all the nations.

 

Solar Thermal Electric energy generation

When solar energies concentrated by reflection surface, the energy densities dramatically increases. This produces high temperatures to be received by fluids that can be transferred to generate electricity in thermal electric generators. This technology generally referred to CSP of concentrating solar power. CSP falls into 3 categories. 

Parabolic troughs

                                              Long parabolic shaped mirrors mounted in roofs to heat the fluid that flows in energy collecting receiver pipes to heat the fluid that flows in energy collecting receiver maintain d alone their lines of focus by adjustment the position of the receiver. The hot fluid is then flashed to steam in a conventional low temperature turbine generator.

Power towers

                                              Power towers represents fields of mirrors that focus their energy onto the top of the tower where it is collected and sent by very high temperature fluid to the thermal power generator. 

Heat engines

                                              Heat engines direct solar energy with very highly focus Heliostats onto a piston, which then drives n engine through air expansion. Each Stirling Engine directly mounted onto its own 3 axes tracking Heliostat. The technical target for the Stirling engine is to be maintenance free for 50000 –100000 hours of operation.

 

 

Global Scenario

The world’s largest set of solar electric generators 354 MW of parabolic trough technology in 3-phase are operating in the US. New and New CSP projects are underway in US, Spain, Israel, South Africa, Mexico, Egypt, Morocco and India. Iran, Algeria and Jordan are in process. CSP viabilities have been tested for Greece, Italy, Portugal, Australia, Brazil, Liberia, Tunisia and China. The cumulative world total of over 100000 MW of CSP electricity generations is expected in next 25 years.

 

 

Solar, Water and Space Heating

Solar water heating is a new technology. Gas fired and electric water heaters are convenient and technologically simple but thermodynamic work potential of this energy resource is wasted. For developing nations, solar water heating is simple passive tank-type units. The value of solar water heating to society is greater. Calculations show that solar water heating can make a significant contribution for the reduction of CO2 emission. Solar water heating is fully matured technology.

 

Global Scenario

 

About 12.3 million/m2 of solar water heater have been installed in EU member countries. The annual rate of installation is about 1.5 million/m2/yr in 2001 and 1.2 million/m2 in 2002. Three countries, Germany, Greece and Austria have developed markets.

·  EU has set a goal of 100 million/m2 of solar collectors installed by 2010 in Austria, Belgium, Britain, Denmark, France, Germany, Greece, Italy, Netherlands and Spain.

·  The rate of growth is over 35% per year.

·  Estimated EU countrywide potential is 1.4 billion/m2, which could generate 683 TWh of thermal energy per year.

·  China installed 26 million/m2 of solar water heaters in 2000 and manufactured 1,000 solar water heating components and systems in 2001.

·  Chinese Govt. goal is for 65 million/m2 of solar water heaters in 2005.

·  By 2010 China would reach 3 billion/m2/yr.

Thus globally solar water heating competes with electric water heating and is the cheaper alternative.

 

 

Passive Solar heating and day lighting of buildings

•           In industrial nations, 35%~40% of total national primary energy is consumed in buildings.

•           In US building sector accounts for 48% of primary energy consumption and 46% of CO2 emission.

•           In Europe 30% of national energy use is for space and water heating representing 75% of total energy use.

•           Buildings can account for one-third of a nation’s greenhouse gas emission and one-third of a nation’s production of waste.

From thermodynamic standpoint, letting the sunshine into buildings in winter to heat them and letting diffused daylight enter the buildings can safe electrical power. These are pre-historic concepts of natural heating, cooling and ventilation design. Passive solar design and building integrated PV are the technology for this.

 

Bio-Energy

Biomass is the result of photosynthetic conversion of solar energy and CO2 into the chemical and physical components of plant material. Energy produced from various ways from biomass is the bio-energy. Biomass is the only combustible carbon resource that is carbon neutral. 11% of world primary energy use is derived from bio-energy. Estimates for world bio-energy potential appeared to be 450 EJ in 2050. Biomass can be mixed with coal to reduce environmental emissions. Technical efficiency is enhanced when bio-energy is used in combined heat and power (CHP) applications. Bio-energy works within the Earth's carbon balance and can contribute to the maintenance of biodiversity. Biogas production from biomass is shown in Figure 1. Production process of biogas is shown in Figure 2. From production to consumption of biogas is shown in Figure 3. Organic waste is mixed up with water. The mixture is heated and placed in the digester tanks where bacteria transform the nutritive substratum into methane and CO2. Methane is the component that is used to produce biogas. The biogas is cleaned from the CO2, vapor, H2S and then compressed. The pipeline then conveys biogas.

 

Production of Biogas :

Biogas can be produced from solid wastes, sewage, agro-industrial wastewaters by microbes during methanogenic anaerobic fermentation. Other types of bio-fuels such as, methyl esters may be mixed with standard patrol or diesel to give bio-diesel. Bio-fuels can be produced locally with local resources and technology. There are different technologies available for methane production and to recover biogas. To use it in vehicles, it must be purified to 96 to 100% methane by removing or separating CO2, moisture, H2S and other corrosive components in the gas. The purified gas is then compressed to a pressure of 200 to 250 bars for use in the vehicles.

 

Biogas is produced from organic waste being decomposed by microorganisms. Decomposition is anaerobic that it takes place in an oxygen-free atmosphere. The digestion process of organic waste produces mainly methane and CO2. Several types of organic waste can be used provided that the amount of N2 and carbon are sufficient.

 

Production Process of Biogas

•           The waste is composed of low-risk material.

•           The waste material is mixed up with sufficient water. In order to slow down the digestion process, the waste is mixed with manure from farms.

•           The mixture is then heated and placed in digestion tanks, where bacteria transform the nutritive substratum into methane and CO2.

•           Methane is the component that is used to produce biogas. Biogas is then cleaned from CO2, vapor and trace-levels of H2S. The cleaning technique is absorption technique.

•           When cleaned, biogas is conveyed by pipeline at a pressure of 4 bars to the compression center.

•           It is then compressed to 200 bars.

 

 

 

 

Biogas Production from Biomass.

 

 

From Production to Consumption of Biogas.

 

 

 

 

 

 

 

Production Process of Biogas.

Biomass is the only combustible carbon resource that is “carbon neutral”. Bio-energy remains critically important to the life support systems of developing nations. In the industrial nations, bio-energy remains, as a percentage of national primary energy needs.

 

Global Scenario

 

•           80% of primary energy of US comes from bio-energy.

•           A recent estimate shows that bio-power generation in Europe could grow to 55,000 MW by 2020.

•           Vision for bio-energy and bio-based products in the US sets goals for 2020 of 5% of US electricity and industrial heat demand from bio-energy, 20% of all transportation fuels from bio-fuels, and for bio-based products to represent 25% of US commodities.

•           Bio-power plants in the 30MW to 40MW range have been announced by Australia and Thailand.

•           The Finnish Govt. in 2002 raised investment subsidies for bio-energy by 40%.

The actual percentage of world primary energy demands in 2050 that 450EJ of bio-energy meet depends on the successful implementation of bio-energy. Bio-energy also works within the earth’s carbon balance and can contribute to the maintenance of bio-diversity. Bio-energy and other renewable energy resources are much more economic than traditional energy sources.

 

 

 

 

Wind Energy

Wind energy uses the energy in the wind for generating electricity charging batteries, pumping water, grinding grains, etc. Modern wind turbines operate in wind farms to produce electricity for utilities. Wind energy technologies consist of wind turbines. Giant blades are turned by the winds to spin powerful generators converting wind energy into electricity. The power density of a 40kmh wind is equivalent to the power density of the bright sun.

•           Wind energy is solar energy once removed. The energy to move air masses comes from the unequal solar heating of the atmosphere and the earth’s surface, resulting in unequal air pressure distribution.

•           These inequalities produce the flows of air from local micro levels to massive global levels.

•           Thermal energy of the sun is converted to the kinetic energy of the air.

•           These winds can be used to turn giant blades to spin powerful generators that convert wind energy into electricity.

•           The power density of a 40kmh wind is equivalent to the power density of the bright sun, which is 1,000W/m2.

•           Total energy carried by the wind on earth is huge.

•           The energy can be extracted from the wind for human use, for generating electricity, charging batteries, pumping water, grinding grains, etc.

 

 

 

 

Technologies

Wind energy technologies consist of wind turbines. They are divided into two major categories: horizontal axis turbines and vertical axis turbines. For high level of wind power integration, a number of key technologies are required and those are AC and DC transmission technologies, network load flow and dynamic stability mitigation, storage technologies and flexible AC transmission systems. Wind network stabilization circuit is shown in Figure 4. Figure 5 shows the development of wind power projects. Fixed speed wind generation with STATCOM is shown in Figure. 6.

 

 

Figure 4: Wind Network Stabilization Circuit.

 

Figure 5: Development of Wind Power Projects.

 

 

Figure 6: Fixed Speed Wind Generation with Statcom

 

Global Scenario

1. Over 60,000 utility scale wind turbines are now operating in 45 countries and in 27 states in US.

2. Total installed global wind power capacity exceeding 32,000MW (by 2002).

3. Wind electric generation by the 12,000MW of installed wind electric capacity in Germany produced about 20 billion KWh at the end of 2002, which met 4.7% of Germany’s national electricity needs.

4. 20% of Danish electricity is coming from wind electric generation.

5. Some area of Germany has already surpassed its 2010 target of 25% electrical energy needs from wind power (2003).

6. This is a low-cost and readily available RE resource which is growing at a 32% rate per year globally.

7. By 2007 wind power installation could represent 24% of all new world power installations.

8. A goal of 12% of the world’s electricity demand from the wind is expected by 2020 without requiring energy storage.

 

In Bangladesh wind power has been estimated to be ........... in some coastal areas.

 

 

 

The dramatic growth in world installed wind capacity, from 1980 through 2002.

 

Hydropower

Approximately 70% of the earth’s surface is covered with water. It is a resource that has been exploited for many centuries. Due to the continuous technical development of hydropower system, this has become a leading renewable energy source in the world. Hydropower now accounts for about 84% of the electricity generation from renewable sources and for 13% of total electricity production in EU. Hydropower system belongs to two categories; small hydropower plants and large hydropower schemes. Micro hydropower schemes are more suitable for rural communities. Small hydropower schemes generate electricity by converting the energy available in the flowing water of rivers, canals and streams. It is offering a very good alternative to conventional sources of electricity to both developed and developing countries. They can be designed with a small head with gentle gradients or with a high head with steep gradients. Specific equipment is necessary to meet fundamental requirements.

Large hydropower schemes with over 100MW of installed capacity and small hydropower schemes up to 100MW of installed capacity. Micro hydropower schemes can be used for agro-processing, local lighting, water pumps, small businesses and industries, farms and household in rural communities. Principal technical requirements are:

·  Suitable rainfall catchments area.

·  Hydraulic head.

·  A means of transporting water from the intake to the turbine, such as a pipe or a millrace.

·  A turbine house containing the power generation equipment and valve gear.

•             A tailrace to return the water to its natural course.

 

 

Advantages of Small Hydropower

•           A sustainable resource. It meets the needs of the present without compromising the ability of future generations to meet their own needs.

•           An efficient resource. It can satisfy energy demand with no depletion of the resource and with little impact on the environment.

•           A secure resource. Small hydropower is available within the borders of one country, and is not subject to disruption by international political events. This guarantees its security of supply.

•           A clean resource. It does not involve a process of combustion, thus avoiding polluting and greenhouse gas emissions.

•           A renewable resource. The fuel for hydropower is water, which is not consumed in the electricity generation process.

 

Marine Renewable

Marine renewable has become a new energy option all over the world. Tidal current, turbines, tidal barrages, wave energy converters, offshore wind turbines are the required technologies. Wave energy technologies include oscillating water column, shoreline device, wavegen, floating "Sea-snake" which is articulated cylinder system, floating wave field reservoir system, wave dragon device, etc. Most advance technology for tidal current is

•           The propeller type device to grab marine current to produce power

•           Windmill like turbine installed on the seabed

•           Storm device with propellers and blades of 15-16m long mounted on towers

•           Hydro venturi which consist of vertical axis turbines, helical turbines, H-shaped vertical axis turbines mounted on a modular frame structure

These are known as blue energy from the blue sea.

 

 

 

Geothermal (GT) Energy

•           It is the energy contained as heat under the surface of the planet.

•           This heat is found in enormous and practically inexhaustible quantities, but it is highly dispersed.

•           It can be exploited if it is sufficiently concentrated.

•           When this concentrations are closed to the surface, at the depth of 5-10km, the heat contained in the masses of magma in liquid or solid form, is released in the process of cooling.

•           When the magma makes its way back to the surface, they cause phenomena like volcanoes, geysers, earthquakes and fumaroles.

•           The GT energy is brought to the surface either through water or steam, that circulates through the hot subterranean rock, minerals, absorbing heat along the way.

Energy from GT source is natural, clean and renewable. This is the 2nd largest non-hydro RE source.

 

Technology

Technologies are

•           Geophysical prospecting technique

•           Geological model of GT system

•           Drilling technology; drill upto 5,000 meter depth where steam pressure is sufficiently high

•           Design of geothermal fields that consist of water-steam-gas(CO2) dominated reservoirs

 

 

Methodology

1. Drilling of GT wells in reservoirs with temperature upto 4000C – surveying and site selection (using µω technology)

2. Providing drilling services, such as, cementing, pumping, logging and GT well logging

3. Gathering feedback on well operation

4. Undertaking turn-key projects that involve well design, drilling engineering, well testing and analysis and finally OAM

5. Developing odor-abatement technology to stop annoying smells 

 

 

 

Global Scenario

•           GT energy has been used globally to provide heat for human use for 1,000 of years

•           It has been used to produce electricity to many countries around the world. Central and South America are particularly reach in potential GT resources

•           It has been predicted that GT energy can be a major RE resource for at least for 58 countries; 39 countries could be 100% GT-powered; 43 countries could be 50% GT-powered; 44 could be 20% and 47 could be 10%.

•           Upto now 67 nations are using GT energy including Japan, Italy, New Zealand, Mexico and United States.

The direct worldwide use of GT energy was estimated to be 15,200 MWt delivering 53,000 GWht/yr for the year 2002. Reasonable projections suggest that at least a 10% per year growth in GT energy applications should occur through 2010, which would lead to 20,100 MWe and 39,250 MWt of GT power worldwide by 2010. Using advanced technology, 35,000 and 72,000 MWe generation capacity could be installed.

 

GT energy can provide economically beneficial energy to many countries of the world. It has no pollutions. The 95% availability factor for GT electric power generation can along with bio-energy can serve as stabilizing base load resource of RE.

 

 

Hydrogen Energy

The most likely long-term candidate for energy storage from the intermittent RE source is the hydrogen. This can convert electricity derived from RE into fuel. Remote sources of RE in areas of reach wind, solar or GT energy potential can be hydrogen factories. The reasons to consider hydrogen as the source of RE energy are multiple:

1. It protects air quality, climate and has energy security

2. It can address all the issues of sustainable energy based on quality and services

3. Hydrogen could provide a fundamental means for energy storage from intermittent energy sources, such as, wind and solar and could be a key element in exploiting the full potential of RE

4. It offers flexibility in terms of volume of energy and power stored and released

5. It can be used as a transport-fuel

6. Hydrogen may provide a means of tackling greenhouse gas emissions from the transport sector

 

Renewable Hydrogen Production

There are wide ranges of potential options for the production of hydrogen from renewables. Hydrogen production could vary widely in terms of scale installations and geographic distributions. The main supply options of hydrogen from renewables are from wind-generated electricity and biomass from woody energy crops. Other renewable resources for the production of hydrogen are agricultural and forestry residues, biodegradable municipal solid waste, wave, tidal and photovoltaic.

Onshore and offshore winds are considered to have the great potential for direct renewable hydrogen generation. Wind farms could be 30 MW for onshore and 60 MW for offshore. The electricity generated could be used either to power on-site electrolysis to produce hydrogen directly. It requires hydrogen transport infrastructure.

Electrolysis

Large-scale alkaline electrolysis is the mature commercial technology. Small-scale electrolysers are also commercially available. There are number of possible routes for hydrogen from woody energy crops, such as, electrolytic hydrogen production using biomass electricity, biomass liquid fuel reforming to hydrogen and on-site reforming of biomass gases from gasification.

 

Production of Hydrogen by Gasification Process

•           The biomass feedstock is first dried and sized.

•           The feedstock is then gasified to produce syngas, mainly composed of CO, hydrogen, CO2, steam, some methane and small quantities of hydrocarbons.

•           The syngas is then cleaned, and hydrocarbons are converted to CO and hydrogen by steam reforming.

•           The reformed gas then undergoes shift reactions. Two shift reactors in series, the first at 4500C and the second at 2300C are used to react the CO with steam to form hydrogen.

•           Hydrogen is then recovered from the gas steam by pressure swing absorption (PSA - PSA desorbs all the gases except hydrogen).

•           97% of the hydrogen passing through the PSA is recovered which has 99.999% purity.

•           The hydrogen can then be liquefied or compressed for transport.

Gasification and gas cleaning equipment is still at the pre-commercial stage. Reforming, shift reaction and PSA equipment is commercially available at large-scale, and is widely used for industrial hydrogen production, mainly from natural gas.

 

Hydrogen Storage

•           The main storage options for hydrogen are as compressed gas at low and high pressure, or as liquid hydrogen.

•           Underground storage is suitable for very large gas volumes.

•           Compressed hydrogen can be stored above ground in pressure vessels at various ranges of sizes and pressures.

 

Hydrogen Transport

•           Hydrogen can be transported as a compressed gas either in dedicated pipelines or by container or as liquid hydrogen by tanker.

•           Transport of both compressed and liquid hydrogen by road is used in industry. Liquid hydrogen is favored for long distances and compressed gas is suitable for short distances.

 

 

Use of Hydrogen

Hydrogen can be used as fuel in internal combustion engine vehicles (ICEV), in fuel cell vehicles (FCV). Three basic hydrogen production changes have been assessed globally. Two of them are based on offshore wind electricity and one based on biomass gasification. The use of renewable hydrogen in fuel cell vehicles has better prospect for zero emission fuel chain. Hydrogen and its use in fuel cell is likely to play a major role in a sustainable energy future.

 

Conclusion

•           It has been realized that no single RE technology can be more important than other in terms of delivering useful energy to the society.

•           It has been estimated that one sq. meter of surface area can deliver 100 AC watts of peak electrical power with PV technology.

•           One sq. meter of mirror can deliver about 100 watts of peak electrical energy through solar thermal technology.

•           200 watts of electricity is available with heat engines.

•           One sq. meter of intercepted solar energy can deliver 300 watts of thermal power for domestic heating or for active solar space heating.

•           One sq. meter of intercepted solar radiation can deliver over 600 watts of heating energy.

•           One sq. meter of glass can deliver daylight with an efficiency of about twice the lumens/watt, which is equivalent to 100 watts of electrical lighting energy.

The earth surface captures solar energy, giant blades convert power of the wind into electrical energy, geo-thermal wells deliver earth’s thermal energy, seawater delivers the energy of the water flows, waves and tides deliver the energy of the tidal wave, etc. Using them in hybrid relationship with RE resources will contribute to cleaner, stronger, safer societies and economies. Therefore, the RE transition must start now before it is too late. Governments, companies, academicians and technologists must cooperate in moving it knowing that societal environmental and personal reward will come. Let solar energy, the source of all life on earth, is the sustainable, safe and sane energy for us all.

 

References

Rafique, S. et al (2004), Renewable Energy Scenario in Bangladesh, World Renewable Energy Congress (WREC) VIII, Denver, Colorado, USA.