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Tag Archives: waste -to-energy

The World Bank development indicators 2008 shows that the wealthiest 20% of the world accounts for 76.6% of total private consumption. The poorest fifth just 1.5%.The report further states,

“Today’s consumption is undermining the environmental resource base. It is exacerbating inequalities. And the dynamics of the consumption-poverty-inequality-environment nexus are accelerating. If the trends continue without change — not redistributing from high-income to low-income consumers, not shifting from polluting to cleaner goods and production technologies, not promoting goods that empower poor producers, not shifting priority from consumption for conspicuous display to meeting basic needs — today’s problems of consumption and human development will worsen. The real issue is not consumption itself but its patterns and effects. Inequalities in consumption are stark. Globally, the 20% of the world’s people in the highest-income countries account for 86% of total private consumption expenditures — the poorest 20% a minuscule 1.3%. More specifically, the richest fifth:

  • Consume 45% of all meat and fish, the poorest fifth 5%
  • Consume 58% of total energy, the poorest fifth less than 4%
  • Have 74% of all telephone lines, the poorest fifth 1.5%
  • Consume 84% of all paper, the poorest fifth 1.1%
  • Own 87% of the world’s vehicle fleet, the poorest fifth less than 1%
  • Runaway growth in consumption in the past 50 years is putting strains on the environment never before seen.”

Clearly the above consumption pattern indicates the amount of waste generated worldwide,especially in developed countries. Unfortunately bulk of the waste are not recycled thus creating enormous amount of strain on natural resources. A typical municipal solid waste consists of food, paper, plastic, metal, glass and garden waste etc.For example the amount of MSW collected in Metropolitan Melbourne for the year 2006-2007 was 1.315,119 Mt costing about a$163 million in service cost. Though Government of Victoria follows the policy of reuse, recycle and recover; only 567,117 Mt was recycled and reprocessed.

There are several methods to process waste and such process depends on the quantity , type of waste and the recovery of products. Gasification and Anaerobic digestion to generate syngas are two common methods of converting waste to energy. However a large volume of complex municipal, industrial and biological wastes require  different methods of processing. ‘Desperate problems require desperate solutions’. One such solution is by Plasma Gasification and Vitrification. It  has clear advantages over existing method of incineration.

Plasma is called fourth state of matter after solid, liquid and gas and it is an abundant form of matter in the universe. When the MSW is heated to a high temperature up to 5000C using Plasma torch, it decomposes into syngas  and verified mass. In Plasma gasification, MSW is subject to high temperature  pyrolysis in the absence of air decomposing matter into its elemental state.Vitrification  is a  process in which semi-liquid waste is mixed with glass converting them into a stable glass form. Even radioactive liquids and sludge are converted into vitrified glass. It is similar to Plasma welding electrodes where an Argon gas is heated into a plasma torch of high temperature up to 5000C.This plasma can treat a range of waste materials such as radioactive, biological, MSW, biosolids  from sewage treatment plants and industrial wastes.  The process is highly efficient.The process can be selectively used to generate syngas with high proportion of Hydrogen  by carefully selecting the feedstock and process parameters.

Bulk of the MSW is now sent to landfill. Such landfills generate methane gas over a time and also leach toxic chemicals and material into the soil. Plasma gasification has distinct advantages over other conventional methods of waste-to energy technologies, especially when the volume is large and the waste has highly toxic materials and metals.

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It is clear substituting fossil fuels with Hydrogen is not only efficient but also sustainable in the long run. While efforts are on to produce Hydrogen at a cost in par with Gasoline or less using various methods, sustainability is equally important. We have necessary technology to convert piped natural gas to Hydrogen to generate electricity on site to power our homes and fuel our cars using Fuelcell.But this will not be a sustainable solution because we can no longer depend on piped natural gas because its availability is limited; and it is also a potent greenhouse gas. The biogas or land fill gas has the same composition as that of a natural gas except the Methane content is lower than piped natural gas. The natural gas is produced by Nature and comes out along with number of impurities such as Carbon dioxide, moisture and Hydrogen sulfide etc.The impure natural gas is cleaned and purified to increase the Methane content up to 90%, before it is compressed and supplied to the customers. The gas is further purified so that it can be liquefied into LNF (liquefied natural gas) to be transported to long distances or exported to overseas.

When the natural gas is liquefied, the volume of gas is reduced about 600 times to its original volume, so that the energy density is increased substantially, to cut the cost of transportation. The LNG can be readily vaporized and used at any remote location, where there is no natural gas pipelines are in existence or in operation. Similarly Hydrogen too can be liquefied into liquid Hydrogen. Our current focus is to cut the cost of Hydrogen to the level of Gasoline or even less. Biogas and bio-organic materials are potential sources of Hydrogen and also they are sustianable.Our current production of wastes from industries business and domestic have increased substantially creating sustainability isues.These wastes are also major sources of greenhouse gases and also sources of many airborne diseses.They also cause depletion of valuable resources without a credible recycling mechanisms. For example, number of valuable materials including Gold, silver, platinum, Lead, Cadmium, Mercury and Lithium are thrown into municipal solid waste (MSW) and sewage. Major domestic wastes include food, paper, plastics and wood materials. Industrial wastes include many toxic chemicals including Mercury, Arsenic, tanning chemicals, photographic chemicals, toxic solvents and gases. The domestic and industrial effluents contain valuable materials such as potassium, Phosphorous and Nitrates. We get these valuable resources from Nature, convert them into useful products and then throw them away as a waste. These valuable materials remain as elements without any change irrespective of type of usages.Recyling waste materials and treatment of waste water and effluent is a very big business. Waste to wealth is a hot topic.

The waste materials both organic and inorganic are too valuable to be wasted for two simple reasons. First of all it pollutes our land, water and air; secondly we need fresh resources and these resources are limited while our needs are expanding exponentially. It is not an option but an absolute necessity to recycle them to support sustainability. For example, most of the countries do not have Phosphorous, a vital ingredient for plant growth and food production. Bulk of the Phosphorus and Nitrates are not recovered from municipal waste water and sewage plants. We simply discharge them into sea at far away distance while the public is in dark and EPA shows a blind eye to such activities. Toxic Methane gases are leaking from many land fill sites and some of these sites were even sold to gullible customers as potential housing sites. Many new residents in these locations find later that their houses have been built on abandoned landfill sites. They knew only when the tap water becomes highly inflammable when lighting with a match stick. The levels of Methane were above the threshold limit and these houses were not fit for living. We have to treat wastes because we can recover valuable nutrients and also generate energy without using fresh fossil fuels. It is a win situation for everybody involved in the business of ‘waste to wealth’.

These wastes have a potential to guarantee cheap and sustainable Hydrogen for the future. Biogas is a known technology that is generated from various municipal solid wastes and effluents. But current methods of biogas generation are not efficient and further cleaning and purifications are necessary. The low-grade methane 40-55% is not suitable for many industrial applications except for domestic heating. The biogas generated by anaerobic digestion has to be scrubbed free of Carbon dioxide and Hydrogen sulfide to get more than 90% Methane gas so that it can be used for power generation and even for steam reforming to Hydrogen generation. Fuel cell used for on site power generation and Fuel cell cars need high purity Hydrogen. Such Hydrogen is not possible without cleaning and purifying ‘ biogas’ much. Hydrogen generation from Biogas or from Bioethanol is a potential source of Hydrogen in the future.

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