Greenhouse Gas Emission from Dams

Lower positive impacts are found in the tropical regions, as it has been noted that the reservoirs of power plants in tropical regions may produce substantial amounts of methane. This is due to plant material in flooded areas decaying in an anaerobicenvironment, and forming methane, a greenhouse gas. According to the World Commission on Damsreport,^[24] where the reservoir is large compared to the generating capacity (less than 100 watts per square metre of surface area) and no clearing of the forests in the area was undertaken prior to impoundment of the reservoir, greenhouse gas emissions from the reservoir may be higher than those of a conventional oil-fired thermal generation plant.^[25] Although these emissions represent carbon already in the biosphere, not fossil deposits that had been sequestered from the carbon cycle, there is a greater amount of methane due to anaerobic decay, causing greater damage than would otherwise have occurred had the forest decayed naturally.

ENERGY FROM PLASTIC WASTE

Boston, United States -- Student researchers at Northeastern University have designed an apparatus to convert plastic waste into clean energy while minimizing the release of
harmful emissions. Under the leadership of Yiannis Levendis, distinguished professor of mechanical and industrial engineering, a team of undergraduate and graduate engineering students developed a waste combustor, which breaks down non-biodegradable plastics to
create an alternative source of fuel. Their prototype was featured at the fifth annual MIT Energy Conference this past March.
The team worked for nine months on the research, which, for the undergraduates, was
their senior capstone project. Self-sustainability is the key to the double-tank combustor design. Plastic waste is first
processed in an upper tank through pyrolysis, which converts solid plastic into gas.
Next, the gas flows to a lower tank, where it is burned with oxidants to generate heat
and steam. The heat sustains the combustor while the steam can be used to generate
electric power. “The prototype can be scaled up to drive a large power plant, which could connect to a
plastic recycling center for a constant flow of fuel,” said David Laskowski, an
undergraduate student working on the team.
Levendis, who has pursued research on the combustion of plastics and other post-
consumer wastes for the past 20 years, is currently focusing on the concept of
vaporizing solid plastic waste, which would reduce levels of harmful emissions during the combustion process. “The inspiration behind my research is the quest to develop clean, cost-efficient power
sources in the face of dwindling fossil fuel reserves,” Levendis said. “It will also help get
rid of unsightly, non-biodegradable plastic waste that cannot be recycled.” According to Laskowski, calculations show that the new technology has the potential of
replacing up to 462 million gallons of petroleum in the United States alone, if all recycled
plastics were to be processed. “We are currently consuming highly-priced conventional premium fuels (to produce
electricity). The fuel developed using this system will lower the cost of electricity for
future generations,” Levendis said. The team members included Jeff Young, Shane McElroy, Jason Lee, David Laskowski,
David Garufi, and Paul Conroy, all senior undergraduate students; and Brendan Hall and
Chuanwei Zhuo, who are graduate students. With the success of their prototype, Hall and Zhuo plan to continue working with
Levendis on further development of the project.

BIO GAS

1 Formation First stage consists into making the waste dissolvable by the enzymes secreted from micro organisms.
Then, the acid forming bacteria takes action and transforms these substances into small- structured substances like acetic acid.
After that the methane forming bacteria converts these substances into biogas.
Hydrolysis stage: Long chained complex carbohydrates proteins oils and lipids are transmuted into short chained forms. The first step known as hydrolysis is completed after this transmutation into basic organics.
Acid formation stage: The dissolvable organic materials are transformed into small- structured materials as acetic acid volatile fatty acids hydrogen and carbon dioxide.
Methane formation: The stage of acetic acid disintegration or hydrogen and carbon dioxide synthesis to acquire biogas by bacteria. 2 Factors that effect biogas production The effects of heat: Methanogenic bacteria are inactive at very high or very low temperatures. That’s why the reactor heat effects the biogas production or its speed directly.
The effects of PH: The most suitable PH levels for methane producing bacteria are neutral or have slightly alkali rates.
The effects of toxicity: Antibiotic addition to foods in chicken farming has a toxicity effect in chicken compost using systems in biogas production.
The effects of organic load speed: Organic load speed is daily organic material supply amount to bioreactors. 3 The Economy of biogas Production The most important factors are the economical wastes’ worth and their biogas efficiency. The selected technology takes effects in production efficiency and costs as well as in investment costs. The discounts or limitations on these energy sources by local executives change the convenience of biogas economy. It must be calculated how these investments will pay back and how these values will effect the investment’ cost. 4 Advantages of Biogas In our country animal and herbal wastes are burned directly or they are used as compost agricultural soil. But it is more common to burn wastes for heat production.
Biogas production provides storage or organic wastes under controllable-suitable conditions. The uncontrolled storage of farm originated organic wastes-composts pollutes water earthy and the air. 5 Benefits of biogas production Biogas is a clean and high heat-capacited energy source.
Wastes do not perish. Instead of that, they become a more valuable compost.
The weeds in animal compost cannot germinate.
Biogas has especially positive health effects in rural areas. Smell of animal compost disappears widely after biogas production. Also, disease agents threatening human health coming from animal waste become inactive.