Green energy synonymous with renewable enegry is used to describe sources of energy which are considered environment friendly, non-polluting, and therefore may provide a remedy to the global warming, mostly caused by conventional fossil fuel burning. Generally, renewable energy combines that resources which restore themselves over short periods of time and do not diminish. Such fuel sources include the sun, wind, moving water, organic plant and waste material (biomass), and the earth's heat (geothermal).
Few years ago, renewable energy was considered as an alternative power source to the remote areas where regular power line is absent or not cost effective. But, with the changing circumatances from the impacts of climate change, the whole world is now trying to reduce CO2 emissions and thinking more about green energy soureces for its low or no carbon emitting characteristics. Moreover, the extinguishing character of conventaional fuel sources allured the world communities to shift their fuel consumption behaviour. Though, still debabte is going on along with research for the use of renewable energy, but all agree to the point that in the coming decades renewable energy sources will take a significant share in the global fuel market. Many world famous energy companies like BP, Shell are now investing on green energy, which beckons its bright future.
Bangladesh is a mineral resources poor country except natural gas. Disappointingly, this resource is now frought with dangers. Gas based power station, industries now face unanticipated gas shortgae. Consequently, half day or more electrical load-shedding has become a regular event. Though we have no immediate remedy to this huge problem that affects every sector of the economy, yet if we rationally utilize our resources then we have all potentiality to beocme self-sufficient in power within near future.
Bangladesh has a comperative advantage of renewable energy sources like sun, wind ,biomass and tidal forces. But, needs systematic evaluation of these resources and ogranized planning for using the resources to attain stability in its energy sector.
Solar energy: Being situated in the tropical climate zone, Bangladesh has huge opportunity to use solar energy over a long period in the year. Here, daily average solar radiation varies between 4 to 6.5 kWh per square meter with maximum amount of radiation available in the months of March-April and minimum in December-January. Except few days in the rainy season, the sun appears all day for 10 to 12 hours with required radiation that can be used effectively to produce electricity. Earlier, it was thought that solar energy could be used only to electrify some remote and island areas where regular power line is unavailable. But, it is fascinating to note that a few international companies are along with local companies now showing interest to install solar panel in new built up urban and sub-urban areas which will reduce pressure on the national grid and help attain self-sufficiency in power sector as well. Grameen Shakti has already won Ashden Awards-2006 (Global green award, which is generally considered as an alternative nobel prize) for outstanding contribution in the renewable energy sector.
Besides the environmental advantages of individual solar panel, another important advantage is reduction of system loss. Now one third of electricity is misused due to so-called system loss, basically caused from individual extravaganza as well as departmental corruption. In case of solar panel, every panel holder will be responsible for its use so, system loss will come down to nil.
Wind energy: Windmill is a fashionable item showed in western movies used in farm house, many people still think so. But Denmark, being pioneer in wind energy use, changes people's perception and they use free wind to generate a major share of their power consumption. It is beyond imagination but true that in 2007 Denmark generated 3125 megawatts (MW) electricity by windmill (19% of their national consumption) that is almost equal to our national demand, though three times smaller in area than us.
Geographically Bangladesh is blessed with a constant flow of strong trade and monsoon winds. It has 724 km long coastal belt, around 200 km hilly-coast-line and about 50 islands in the Bay of Bengal. The strong south/south-westerly monsoon wind, coming from the Indian Ocean enter into the coastal areas of Bangladesh from March to October. This wind enhances speed onwards V-shaped coastal regions in Bangladesh, as research stated. Based on last 16 years wind speed records at 20m above the ground, assembled by the Bangladesh Meteorological Department, it was known that average wind-blow in areas like Chittagong, Dhaka, Jessore, Patenga and Thakurgaon was between 5.5 to 9.50 m/s almost throughout the year. "This speed has been proved as appropriate for setting up commercial and non-commercial level wind power plants," power experts explained. However, using modern wind turbines, each windmill is capable to generate electricity from 250 watts (W) to 5 megawatts (MW). Besides, 12 other locations in Bangladesh were also identified as moderate wind energy generation sites, where use of non-commercial and household level wind turbines would be pumping water for irrigation, as well as charging batteries, experts added.
Biomass energy: Bangladesh entered into biomass energy technology in 1972 through the bio-gas demonstration plant at Bangladesh Agriculture University. After that, a huge blow to install bio-gas plant in rural areas was found. Unfortunately, lack of government support and improved technology, difficulty in installation and bad smell from the plant made it less attractive to the user. However, recent bonanza of bio-fuel again brings the biomass energy in hot seat. In spite of some criticism, it has to be agreed by all that bio-fuel is the ever best invention that has full potentiality to be an alternative to fossil fuel.
Every year Bangladesh spends about $2 billion to import oil, 15 percent of total national budget. Through bio-fuel production, Bangladesh can save half of its foreign currency from avoided oil import and can allocate the savings to other sectors of the economy. In Bangladesh, other than sugarcane, bio-fuel can be produced from some crops that can be grown in areas not suitable for traditional food crops. Jatropha (verenda), pongamia (caron) can grow under conditions of low fertility and rainfall. The north-western region with low fertility could be put into bio-fuel crop production commercially which may convert the monga-affected area into an important economic zone.
Hydro power: As a riverine country, Bangladesh always has opportunity to go for hydro power. Few hilly rivers with strong current make this opportunity more feasible from economic point of view. As large hydro electricity projects has some environmental impacts, therefore we should go for small scale hydro power project which are more environmentally and ecologically acceptable. Already, in Khagrachori, a member of indigenous community succeeded in producing electricity from small-scale hydro power plant made by indigenous technology.
To explore the possibility of hydropower from small hilly rivers/streams in the country, a working committee was constituted on February 1981 with officers from both Water and Power Development Board (BWDB) and BPDB. The committee explored 19 prospective sites for possible installation of small hydro power plant. Regrettably, their work were only confined to study rather than implementation.
Sea power: Almost every year Bangladesh suffers from cyclone and tidal surges originated in the Bay of Bengal. But, our policy makers seldom thought to use this huge sea power for generating electricity, though many countries are using it.
The normal tidal head rise and fall in the coastal region of Bangladesh is between two and eight meters. This tidal range can easily be converted to pollution free clean renewable energy by using the simple low-cost technology of a "tidal wheel" in the sluice gates. ISTP of Murdoch University, Australia is planning a demonstration tidal power project in Sandwip. ISTP has developed a feasibility plan for rebuilding a recently damaged sluice gate with a trial paddle wheel. If becomes successful, the tidal project of Sandwip can be replicated in the other coastal areas and may usher new light in the region.
Geothermal energy: Geothermal energy is the heat from the Earth. Resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the Earth's surface, and down even deeper to the extremely high temperatures of molten rock called magma. Generally, geothermal reserviors are located in hilly region and exposed by the presence of magma or hot salt water spring. Though we have well defined hilly region in the south and south eastern region, but no fessibilty study has so far been taken to explore the possibility and potentiality of geothermal energy source.
There is a known hot salt-water spring, known as Labanakhya, five kilometres to the north of Sitakunda (40 kilometres from Chittagong). Possibility of extracting energy from this site or any other unknown sites should be carried out by Satellite Remote Sensing or Physical Surveys.
It is imperative to go for green energy not only for combating climate change but also to attain self-sufficiency in the energy sector. We are lucky to have a lot of green energy options; now we need systematic utilization of these. We have no way to stay back further and hope for miraculous solution of our vexing energy problem.
Mohammed Abdul Baten is pursuing higher studies at University of Stockholm, Sweden and Rashedul Tusher is staff reporter- daily Suprobhat Bangladesh, Chittagong.