Plasma Gasification

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Clean Energy Diary

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…

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Waste-to-Energy Initiative in Vietnam

Vietnam Environment

Tu Ngoc An, board chairman of Kien Giang Composite Co. (KGC), has paid a visit to Australia to finalize the whole plan of building a plant generating power from garbage in HCMC with Australian partner Trisun International Development Co.

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The Incineration Debate

Remsol

On Easter Monday, 9th April 2012, the front page of The Times newspaper carried a story about the debate that’s currently raging over whether the UK ought to be building more and bigger incinerators to burn our household rubbish.

Opponents of waste-to-energy incineration insist that it discourages recycling, adds to CO2 emissions at a time when we’re trying to reduce them, and that incineration plants themselves are an ugly blot on the urban landscape.

Proponents, on the other hand, often dismiss these claims as fiction.

I tend to come down on the “for” side of the waste incineration argument, for several reasons, but chief amongst these is the belief that the argument only exists because we, as a society, create waste and crave energy.

According to statistics released by the Department of Energy and Climate Change (DECC) UK electricity consumption for consumer electronics soared by 576% between 1970 and 2010.

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Thermal Conversion of Wastes

Thermal (or thermochemical) conversion systems consist of primary conversion technologies which convert the waste into heat or gaseous and liquid products. These technologies can be classified according to the principal energy carrier produced in the conversion process. Carriers are in the form of heat, gas, liquid and/or solid products, depending on the extent to which oxygen is admitted to the conversion process (usually as air).

Combustion

Direct combustion is the best established and most commonly used technology for converting wastes to heat. During combustion, waste is burnt in excess air to produce heat. The first stage of combustion involves the evolution of combustible vapours from wastes, which burn as flames. Steam is expanded through a conventional turbo-alternator to produce electricity. The residual material, in the form of charcoal, is burnt in a forced air supply to give more heat. The main products of efficient combustion are carbon dioxide and water vapor, however tars, smoke and alkaline ash particles are also emitted. Minimization of these emissions and accommodation of their possible effects are important concerns in the design of environmentally acceptable waste combustion systems.

Co-Firing

Co-firing or co-combustion of biomass wastes with coal and other fossil fuels can provide a short-term, low-risk, low-cost option for producing renewable energy while simultaneously reducing the use of fossil fuels. Co-firing involves utilizing existing power generating plants that are fired with fossil fuel (generally coal), and displacing a small proportion of the fossil fuel with renewable biomass fuels. Co-firing has the major advantage of avoiding the construction of new, dedicated, waste-to-energy power plant. An existing power station is modified to accept the waste resource and utilize it to produce a minor proportion of its electricity. Co-firing may be implemented using different types and percentages of wastes in a range of combustion and gasification technologies. Most forms of biomass wastes are suitable for co-firing. These include dedicated municipal solid wastes, wood waste and agricultural residues such as straw and husk.

Gasification

Gasification systems operate by heating wastes in an environment where the solid waste breaks down to form a flammable gas. The gasification of biomass takes place in a restricted supply of air or oxygen at temperatures up to 1200–1300°C. The gas produced—synthesis gas, or syngas—consists of carbon monoxide, hydrogen and methane with small amounts of higher hydrocarbons.  Syngas may be burnt to generate heat; alternatively it may be processed and then used as fuel for gas-fired engines or gas turbines to drive generators. In smaller systems, the syngas can be fired in reciprocating engines, micro-turbines, Stirling engines, or fuel cells. There are also small amounts of unwanted by-products such as char particles, tars, oils and ash, which tend to be damaging to engines, turbines or fuel cells and which must therefore first be removed or processed into additional fuel gas. This implies that gasifier operation is significantly more demanding than the operation of combustion systems.

Pyrolysis

Pyrolysis is thermal decomposition occurring in the absence of oxygen. During pyrolysis process, waste is heated either in the absence of air (i.e. indirectly), or by the partial combustion of some of the waste in a restricted air or oxygen supply. This results in the thermal decomposition of the waste to form a combination of a solid char, gas, and liquid bio-oil, which can be used as a liquid fuel or upgraded and further processed to value-added products. High temperature and longer residence time increase the waste conversion to gas and moderate temperature and short vapour residence time are optimum for producing liquids. Pyrolysis technologies are generally categorized as “fast” or “slow” according to the time taken for processing the feed into pyrolysis products. Using fast pyrolysis, bio-oil yield can be as high as 80 percent of the product on a dry fuel basis. Bio-oil can act as a liquid fuel or as a feedstock for chemical production.

Hydrogen from Organic Waste

Clean Energy Diary

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…

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Denver zoo test-drives elephant-poop-powered vehicle

Grist

The Denver Zoo has to deal with a lot of waste. A good deal of that waste comes from visitors, but the zoo also produces hundreds of thousands of pounds of animal poo each year. Now, zoo engineers have found a positive use for it: They rigged up a poo-powered tuk-tuk. (A tuk-tuk is a motorized rickshaw.)

“We want to show people that we’re not crazy for wanting to take elephant poop and turn it into energy,” one engineer told the Denver Post.

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Biogas Strorage

English: Author: Alex Marshall
Image via Wikipedia

Selection of an appropriate biogas storage system makes a significant contribution to the efficiency and safety of a biogas plant. A biogas storage system also compensates fluctuations in the production and consumption of biogas as well as temperature-related changes in volume. There are two broad categories of biogas sto

Biogas plant Strem

rage systems: Internal Biogas Storage Tanks are integrated into the anaerobic digester while External Biogas Holders are separated from the digester forming autonomous components of a biogas plant.

The simplest and least expensive storage systems for on-site applications and intermediate storage of biogas are low-pressure systems. Floating gas holders on the digester form a low-pressure storage option for biogas systems. These systems typically operate at pressures below 2 psi. Floating gas holders can be made of steel, fiberglass, or a flexible fabric. A separate tank may be used with a floating gas holder for the storage of the digestate and also storage of the raw biogas. A major advantage of a digester with an integral gas storage component is the reduced capital cost of the system.

The least expensive and most trouble-free gas holder is the flexible inflatable fabric top, as it does not react with the H2S in the biogas and is integral to the digester. These types of covers are often used with plug-flow and complete-mix digesters. Flexible membrane materials commonly used for these gas holders include high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low density polyethylene (LLDPE), and chlorosulfonated polyethylene covered polyester. Thicknesses for cover materials typically vary from 0.5 to 2.5 millimeters.

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Trends in Food Waste Management

Food waste is an untapped energy source that mostly ends up rotting in landfills, thereby releasing greenhouse gases into the atmosphere. Food waste is difficult to treat or recycle since it contains high levels of sodium salt and moisture, and is mixed with other waste during collection. Major generators of food wastes include hotels, restaurants, supermarkets, residential blocks, cafeterias, airline caterers, food processing industries, etc.

In United States, food waste is the third largest waste stream after paper and yard waste. Around 12.7 percent of the total municipal solid waste (MSW) generated in the year 2008 was food scraps that amounted to about 32 million tons. According to EPA, about 31 million tons of food waste was thrown away into landfills or incinerators in 2008. As far as United Kingdom is concerned, households throw away 8.3 million tons of food each year. These statistics are an indication of tremendous amount of food waste generated all over the world.

The proportion of food waste in municipal waste stream is gradually increasing and hence a proper food waste management strategy needs to be devised to ensure its eco-friendly and sustainable disposal. Food waste can be recycled via:

  • In-vessel composting (IVC): A treatment that breaks down biodegradable waste by naturally occurring micro-organisms with oxygen, in an enclosed vessel or tunnel;
  • Anaerobic digestion (AD): A treatment that breaks down biodegradable waste in the absence of oxygen, producing a renewable energy (biogas) that can be used to generate electricity and heat.

Currently, only about 3 percent of food waste is recycled throughout U.S., mainly through composting. Composting provides an alternative to landfill disposal of food waste, however it requires large areas of land, produces volatile organic compounds and consumes energy. Consequently, there is an urgent need to explore better recycling alternatives. Anaerobic digestion has been successfully used in several European and Asian countries to stabilize food wastes, and to provide beneficial end-products. Sweden, Austria, Denmark, Germany and England have led the way in developing new advanced biogas technologies and setting up new projects for conversion of food waste into energy.

Of the different types of organic wastes available, food waste holds the highest potential in terms of economic exploitation as it contains high amount of carbon and can be efficiently converted into biogas and organic fertilizer. Food waste can either be used as a single substrate in a biogas plant, or can be co-digested with organic wastes like cow manure, poultry litter, sewage, crop residues, abattoir wastes, etc.

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Global Waste-to-Energy Market

English: Waste to Energy Plant

The global market for WTE technologies was valued at US$19.9bn in 2008. This has been forecasted to increase to US$26.2bn by 2014. While the biological WTE segment is expected to grow more rapidly from US$1.4bn in 2008 to approximately US$2.5bn in 2014, the thermal WTE segment is nonetheless estimated to still constitute the vast bulk of the entire industry’s worth. This segment was valued at US$18.5bn in 2008 and is forecasted to expand to US$23.7bn in 2014.

The global market for waste to energy technologies has shown substantial growth over the last five years, increasing from $4.83 billion in 2006, to $7.08 billion in 2010 with continued market growth through the global economic downturn. Over the coming decade, growth trends are expected to continue, led by expansion in the US, European, Chinese, and Indian markets. By 2021, based on continued growth in Asian markets combined with the maturation of European waste management regulations and European and US climate mitigation strategies, the annual global market for waste to energy technologies will exceed $27 billion, for all technologies combined.

Asia-Pacific’s waste-to-energy market will post substantial growth by 2015, as more countries view the technology as a sustainable alternative to landfills for disposing waste while generating clean energy. In its new report, Frost & Sullivan said the industry could grow at a compound annual rate of 6.7 percent for thermal waste-to-energy and 9.7 percent for biological waste-to-energy from 2008 to 2015.

The WTE market in Europe is forecasted to expand at an exponential rate and will continue to do so for at least the next 10 years. The continent’s WTE capacity is projected to increase by around 13 million tonnes, with almost 100 new WTE facilities to come online by 2012. In 2008, the WTE market in Europe consisted of approximately 250 players due in large to the use of bulky and expensive centralized WTE facilities, scattered throughout Western Europe.

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