Call it one of the hazards of rapid urban growth, mega-cities of the world are facing a new challenge of disposing massive wastes. According to an estimate, over 2.1 billion tons of municipal waste is produced all over the world annually. The most common method of disposing this waste has been through the development of organized landfills. Experience has shown that these landfills end up producing harmful gases, particularly methane and carbon dioxide in large amounts. However, researchers have successfully shown that the gases emanating from vast landfills could be trapped for creative purposes like generation of electricity, bio-fuels, and fertilizers.
Still, there are various pros and cons associated with the practice of harvesting energy from landfills. Here we have discussed all such issues in detail.
Waste to Energy:
Waste materials of a landfill can be used to produce electricity for domestic consumption. In fact, data from the International Energy Agency shows that many countries have started to harvest energy from municipal and industrial wastes that were earlier dumped in large landfills. Presently, over 400 terawatt of electricity all over the world, is produced this way.
Landfills contain large amount of organic wastes like discarded food scraps, paper, textiles and yard trimmings. They produce large amount of green house gases like methane and CO2. The US Environment Protection Agency (EPA) says that landfills are the third-largest source of human-related methane emissions in the United State, amounting to 17 percent of total methane emissions.
With the development of new technologies, it has now become possible to use such large amount of methane to produce clean electricity. This is done by burning the methane for producing electricity. Water and less potent CO2 is produced as the byproduct. This process doesn’t require any extra fossil fuels for burning methane as this gas is itself highly inflammable.
Apart from electricity, new technologies have shown that cellulosic ethanol can also be derived from the landfills. It is organically produced because of the degradation of cellulose found in grass trimmings, fallen tree branches and corn stalks etc. This bio-fuel produces more energy and emits less greenhouse gases as compared to other bio-fuels produced today.
Burning landfill methane for energy is a bad Idea:
While the amount of global waste is increasing, a fool-proof method for harvesting energy from them is still alluding scientists and policy makers. Experience at some places, has shown that the existing technology could cause more harm than good. The reason for this is that a large amount of gas actually leaks into the environment which not only contributes to global warming but also causes some health hazards. As, methane is 75 percent more powerful greenhouse gas in the first 20-years of its existence than the CO2.
Most of the landfills are sealed from the top to help prevent the leakage of gases. However, these gases find different routes to escape. For example: Landfill experiment in Ontario has shown that the potential damage by leaked gases could be far more than the useful production of about 5000 MW of electricity from them. Also, it has been found that existing technology succeeds in treating only about 20-25 percent of the total waste.
Landfill Gas and awful affects of landfills:
Apart from methane, the land fills also produce other gases with heavy odor – that not only affect the environment but are substantial health hazards. While about 50 percent of the gases produced in a landfill is methane, 40 percent of CO2 and some other harmful gases like sulfur dioxide, nitrogen oxides and other particulate matters are produced.
The sulfur dioxide causes acid rain, particulate matters cause respiratory problems and fatigue among people living in proximity to these landfills. Also, the nitrogen oxides cause local ozone and smog formation. The heavy odor of these gases may also cause headache and nausea among people. These gases can travel through the soil and sometimes enter nearby buildings, putting them to significant fire risks as methane is highly inflammable.
However, harvesting energy from the gases organically produced in landfills, is still the most effective way of reducing some of the hazards discussed above. And, on a positive note, many new initiatives have been taken up to this effect in many cities in recent times.