ALTERNATE ENERGY RESOURCES
DR. S.M. ALAM
Apr 25 - May 1, 2011
Alternate energy flows involve natural phenomena such as sunlight, wind, tides, plant growth, and geothermal heat, as explained by the International Energy Agency. Renewable energy is derived from natural processes. In its various forms, it derives directly from the sun, or from heat generated deep within the earth. Included in the definition is electricity and heat generated from solar, wind, ocean, hydropower, biomass, geothermal resources, and bio-fuels and hydrogen derived from renewable resources. Renewable energy replaces conventional fuels in four distinct areas: power generation, hot water, space heating, transport fuels, and rural (off-grid) energy services.
Power generation. Renewable energy provides 18 per cent of total electricity generation worldwide. Renewable power generators spread across many countries, and wind power alone already provides a significant share of electricity in some areas: for example, 14 per cent in the U.S. state of Iowa, 40 per cent in the northern German state of Schleswig-Holstein, and 20 per cent in Denmark. Some countries get most of their power from renewable, including Iceland and Paraguay (100 per cent), Norway (98 per cent), Brazil (86 per cent), Austria (62 per cent), New Zealand (65 per cent), and Sweden (54 per cent).
Solar hot water makes an important contribution in many countries, most notably in China, which now has 70 per cent of the global total (180 GW). Most of these systems are installed on multi-family apartment buildings and meet a portion of the hot water needs of an estimated 50-60 million households in China. Worldwide, total installed solar water heating systems meet a portion of the water heating needs of over 70 million households. The use of biomass for heating continues to grow as well. In Sweden, national use of biomass energy has surpassed that of oil. Direct geothermal for heating is also growing rapidly.
Transport fuels. Renewable bio-fuels have contributed to a significant decline in oil consumption in the United States since 2006. The 93 billion liters of bio-fuels produced worldwide in 2009 displaced the equivalent of an estimated 68 billion liters of gasoline, equal to about five per cent of world gasoline production.
MAINSTREAM FORMS OF ALTERNATE ENERGY: Airflows can be used to run wind turbines. Modern wind turbines range from around 600 kW to five MW of rated power, although turbines with rated output of 1.5-3 MW have become the most common for commercial use; the power output of a turbine is a function of the cube of the wind speed, so as wind speed increases, power output increases dramatically. Areas where winds are stronger and more constant, such as offshore and high altitude sites, are preferred locations for wind farms. Typical capacity factors are 20-40 per cent, with values at the upper end of the range in particularly favorable sites.
Globally, the long-term technical potential of wind energy is believed to be five times total current global energy production, or 40 times current electricity demand. This could require wind turbines to be installed over large areas, particularly in areas of higher wind resources. Offshore resources experience mean wind speeds of 90 per cent greater than that of land, so offshore resources could contribute substantially more energy.
HYDROPOWER: Energy in water can be harnessed and used. Since water is about 800 times denser than air, even a slow flowing stream of water, or moderate sea swell, can yield considerable amounts of energy. There are many forms of water energy:
* Hydroelectric energy is a term usually reserved for large-scale hydroelectric dams. Examples are the Grand Coulee Dam in Washington State and the Akosombo Dam in Ghana.
* Micro hydro systems are hydroelectric power installations that typically produce up to 100 kW of power. They are often used in water rich areas as a remote-area power supply (RAPS). There are many of these installations around the world, including several delivering around 50 kW in the Solomon Islands.
* Run-of-the-river hydroelectricity systems derive kinetic energy from rivers and oceans without using a dam.
* Ocean energy describes all the technologies to harness energy from the ocean and the sea. This includes marine current power, ocean thermal energy conversion, and tidal power.
* SOLAR ENERGY: Solar energy is the energy derived from the sun through the form of solar radiation. Solar powered electrical generation relies on photovoltaics and heat engines. A partial list of other solar applications includes space heating and cooling through solar architecture, day lighting, solar hot water, solar cooking, and high temperature process heat for industrial purposes. Solar technologies are broadly characterized as either passive solar or active solar depending on the way they capture, convert and distribute solar energy. Active solar techniques include the use of photovoltaic panels and solar thermal collectors to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light dispersing properties, and designing spaces that naturally circulate air.
BIOMASS: Biomass (plant material) is a renewable energy source because the energy it contains comes from the sun. Through the process of photosynthesis, plants capture the sun's energy. When the plants are burned, they release the sun's energy they contain. In this way, biomass functions as a sort of natural battery for storing solar energy. As long as biomass is produced sustainably, with only as much used as is grown, the battery will last indefinitely. In general, there are two main approaches to using plants for energy production: growing plants specifically for energy use, and using the residues from plants that are used for other things. The best approaches vary from region to region according to climate, soils, and geography.
BIO-FUELS: Liquid bio-fuel is usually either bio-alcohol such as bio-ethanol or oil such as bio-diesel. Bio-ethanol is an alcohol made by fermenting the sugar components of plant materials and it is made mostly from sugar and starch crops. With advanced technology being developed, cellulosic biomass, such as trees and grasses, are also used as feedstock for ethanol production. Ethanol can be used as a fuel for vehicles in its pure form, but it is usually used as a gasoline additive to increase octane and improve vehicle emissions. Bio-ethanol is widely used in the USA and in Brazil. Biodiesel is made from vegetable oils, animal fats or recycled greases. Biodiesel can be used as a fuel for vehicles in its pure form, but it is usually used as a diesel additive to reduce levels of particulates, carbon monoxide, and hydrocarbons from diesel-powered vehicles. Biodiesel is produced from oils or fats using transesterification and is the most common bio-fuel in Europe. Bio-fuels provided 1.8 per cent of the world's transport fuel in 2008.
GEOTHERMAL ENERGY: Geothermal energy is energy obtained by tapping the heat of the earth itself, both from kilometers deep into the Earth's crust in volcanically active locations of the globe or from shallow depths, as in geothermal heat pumps in most locations of the planet. It is expensive to build a power station but operating costs are low resulting in low energy costs for suitable sites. Ultimately, this energy derives from heat in the Earth's core.
Three types of power plants are used to generate power from geothermal energy: dry steam, flash, and binary. Dry steam plants take steam out of fractures in the ground and use it to directly drive a turbine that spins a generator. Flash plants take hot water, usually at temperatures over 200 ∞C, out of the ground, and allows it to boil as it rises to the surface then separates the steam phase in steam/water separators and then runs the steam through a turbine. In binary plants, the hot water flows through heat exchangers, boiling an organic fluid that spins the turbine. The condensed steam and remaining geothermal fluid from all three types of plants are injected back into the hot rock to pick up more heat.
The geothermal energy from the core of the Earth is closer to the surface in some areas than in others. Where hot underground steam or water can be tapped and brought to the surface it may be used to generate electricity. Such geothermal power sources exist in certain geologically unstable parts of the world such as Chile, Iceland, New Zealand, United States, the Philippines, and Italy. The two most prominent areas for this in the United States are in the Yellowstone basin and in northern California. Iceland produced 170 MW geothermal power, and heated 86 per cent of all houses in the year 2000 through geothermal energy. Some 8000 MW of capacity is operational in total. There is also the potential to generate geothermal energy from hot dry rocks. Holes at least 3 km deep are drilled into the earth. Some of these holes pump water into the earth, while other holes pump hot water out. The heat resource consists of hot underground radiogenic granite rocks, which heat up when there is enough sediment between the rock and the earths surface. Several companies in Australia are exploring this technology.
In the present day world, the winnowing wind has been proved as a powerful natural source for generating electricity in most countries of the world, where the powerful wind resource is available. Around the world, the renewable energies targets have been set and the last decade saw an immense increase in the world wind energy output. To generate any measurable power from wind, we need strong wind speed, of more than five meters per second. Another problem with the speed of the wind is that it should be steady and consistent throughout the day.
Pakistan has yet to embark towards the generation of renewable energy. The country is far behind on electricity generation through wind energy. The Alternate Energy Development Board (AEDB) was founded in May 2003 for supplying wind/solar energy in remote regions of the provinces. Pakistan has a long coastal belt of 1050 kilometers from Sindh to Balochistan, which is highly suitable for wind energy generation. To generate power from wind, we need strong wind speed of more than six meters per second. In the long coastal areas, the dispersing wind blows from March to November in almost normal speed. Due to its ideal geographical location, Pakistan possesses immense potential to harness unlimited solar and wind energy. The average wind speeds of 5 to 7 meters per second are available in most of the coastal areas in Sindh and Balochistan as well as in a few northern valleys of K-P and AJK which are suitable for producing electricity.
WIND POWER MARKET: Global wind power installations increased by 35,800 MW in 2010, bringing total installed capacity up to 194,400 MW, a 22.5 per cent increase on the 158,700 MW installed at the end of 2009. For the first time more than half of all new wind power was added outside of the traditional markets of Europe and North America, mainly driven, by the continuing boom in China which accounted for nearly half of all of the installations at 16,500 MW. China now has 42,300 MW of wind power installed. Wind power accounts for approximately 19 per cent of electricity generated in Denmark, 9 per cent in Spain and Portugal, and 6 per cent in Germany and the Republic of Ireland.
TOP 10 WIND POWER COUNTRIES
|COUNTRY||TOTAL CAPACITY END 2009 (MW)||TOTAL CAPACITY JUNE 2010 (MW)|
|Rest of world||21,698||24,500|