Energy today is one of the most important issues that concerns humans, and may be it is the most important of all. The main source of all energy is the sun. It supplies plants with light energy, which is used during photosynthesis and stored in the form of organic materials inside the plant. This energy has either two paths to follow, animals might use it directly by eating these plants and using some of the energy in their activities. The rest is stored in their bodies until they die and the decomposing bacteria changes it into some organic materials again that either stays in the soil and get used by plants or get to be stored and starts to form petroleum on long ages. The other path is after the death of the plants where, these plants themselves decompose and either form petroleum. Or get used by other plants during their lifetime!
However, the humans have been always using petroleum or its derivatives as the main source of energy and in different functions. After about two centuries from the start of the industrial revolution, humans realized that the amount of the fuel they have isn’t enough for the human activity especially with the permanent increase in the human population.
Biomass is the organic matter contained in plants and produced by photosynthesis. For most of the world’s population, biomass, in the form of wood used for fuel, is the main energy supply. In industrialized countries, biomass supplies only a small proportion of energy needs, but developed countries have shown considerable interest in biomass energy in recent years for several reasons:
Most biomass is burned for heat. Wood is the primary source of energy for cooking and heating for half of the world’s population and for 80% of the population of the developing countries. The wood is either burned directly or made into charcoal, which is sold in cities.
Fuel wood is being harvested faster than it can grow in many countries and is causing the destruction of many tropical forests. More than 1 billion people don’t have access to enough wood to supply their energy needs or to alternative sources of energy. Possible the most pressing item on the world’s energy agenda is finding the substitute for the biomass energy in developing countries.
In countries where wood reserves are adequate, the use of wood to heat homes and produce steam and electricity in industrial processes has increased in the last 30 years. For instance, the use of wood burning stoves to heat homes has increased enormously in the United States since 1970. Wood as much single- family homes as oil does. Wood is bulky and heavy for its energy content, so it is inefficient to transport over long distances. Thus, most of the fuel used in developed countries is cut by people in rural areas who pay little or nothing for it and don’t carry it far.
In the next table a represented data of percentages of people that use fuel-wood in 3 countries:
(Ton/year)
Country
Per capita
% people use fuel-wood
Tanzania
1.8
99
Gambia
1.2
99
Thailand
1.1
87
Wood’s main disadvantage as fuel is the particles and carbon added to the air when it burns. Several states with pollution problems from burning wood passed laws requiring that wood burners be fitted with catalytic combusters, which curb air pollution and also make wood burning stoves more efficient. In 1992 the U.S Environmental protection Agency established national emissions standards for stoves.
Manufacturers have responded by producing several varieties of clean- burning stoves:
Finding replacement for biomass energy in developing countries would slow the destruction of tropical rain forests. In developed countries the use of biomass energy is increasing.
When we produce energy from biomass, it is more economical to use biomass that is formed as a waste product of other processes than it is to grow plants especially for energy production. One study showed that Virginia produces enough sawdust, logging residues, and unsalable trees to replace nearly half of the gas and oil consumed by its industries. It would make sense for the state to generate energy from its waste.
Biomass is used in many American factories. For instance, the U.S pulp and paper industry meets about half of its energy needs by burning its own waste products. This also solves part of the industry’s disposal problem. The Hawaiian sugar growing started selling electricity in the late 1970s. It uses bagasse, the plant residue left after juice is extracted from sugarcane, to power its generating plants.
And some examples of companies generating electricity from waste biomass in the following table:
Plant location
Fuel
Start-up date
Union camp(Virginia)
Pulp waste, peanut shells
1937
Champion Intl (Florida)
Pulp waste, bark
1961
Lihue plantation (Hawaii)
Bagasse
1980
Louisiana pacific (California)
Wood waste
1983
Farmer rice milling (Louisiana)
Rice husks
1984
Wheelaborator (California)
Orchard pruning
1989
The most efficient way for an industry to make use of energy from waste biomass is to install cogeneration units. Cogeneration means electricity generation together with some other use of the energy. The industry burns the biomass for purposes such as heating buildings or boilers. In addition, it uses any excess heat to generate electricity. It may use the electricity itself or sell it to the local utility company.
The simplest way to get energy from biomass is to burn it. To generate electricity, the heat has been traditionally used to produce steam that powers a steam turbine. However it is more efficient to use hot gases from burning biomass directly to power a gas turbine. Improved gas turbines are now being produced, and some experts believe that they will revolutionize the production of energy from biomass. One study showed that developing countries that grow sugarcane could use this biomass (with gas turbines) to produce as much electricity, at lower coast, as they now produce from oil.
U.S government agencies estimate that biomass should supply up to 18% of this country’s energy with adequate research and development, tax, and other incentives. The department of energy has awarded a number of grants for research in this area in recent years.
Sometimes it makes sense to convert waste biomass into liquid or gaseous fuel instead of electricity. Organic matter can be converted into fuels by decomposer organisms with the assistance of various chemical processes. The main liquid fuels produced from biomass are methanol and ethanol. The main gaseous fuel is biogas, a mixture of methane and carbon dioxide. Biogas digesters are fermenting vats where bacteria convert plant and animal waste into biogas used for heating and cooking. They have been widely used in China to recycle a village waste. When the bacteria have released all the methane from the organic matter, the waste is removed and used to fertilize the crops. Biogas digesters are vulnerable to the same problems that may beset a garden compost heap or anything else powered by living organisms: they work best at particular pH values and temperatures and can be poisoned by detergents, heavy metals, pesticides, and industrial wastes. These factors mean that gas production is unpredictable, and the process will probably continue to be used only in small scale local plants.
Methane is produced naturally by anaerobic decomposers in any pile of organic matter not exposed to air. As a result, garbage dumps invariably contain methane, which can be collected merely by inserting pipes. Hundreds of plants for recovering gas from landfills are now in operation in U.S.A and most of them in California. Methane can be recovered from thousands of other landfills.
Methane is also being produced by the anaerobic decomposition of sludge produced by sewage treatment plants and manure from feedlots. Part of Chicago’s gas supply comes from this source. Again this tends to be a local solution, since it takes a lot of energy to collect and transport sludge and manure any distance.
One major advantage of alcohol in vehicles is that they produce less air pollution. Colorado has tackled its air pollution problems partly by requiring motorists in major cities to use gasohol during winter months when air pollution is the worst. As a result carbon monoxide emissions have been reduced. An even cleaner solution is vehicles powered by electricity from fuel cells that run on methanol. The U.S department of energy has awarded contracts to two teams that will build buses powered by methanol fuel cells,
Brazil has experimental airplanes flying on a fuel called prosene, a vegetable oil derivative. Biologists for years have thought that fuel for transportation might be made of various plants that produce high yields of oil. Vegetable oils similar to prosene have been already developed for tractors, where they substitute for diesel fuel made from petroleum. Prosene technology may prove a valuable substitute for expensive imported petroleum, particularly in tropical countries that don’t have their own oil reserves.
A major problem with energy and biomass all over the world, however the problem is much more affective for developing countries than for developed countries. Also generating energy from waste biomass is something that should be followed and recognized world wide, as a future substitute for the sources of energy.
However, there should be a cheap way of extracting this energy so that all countries would be able to follow up the procedure, and may be that is what we should aim for now. Finding cheap , easy and efficient ways of obtaining this energy.
Biofuels of many kinds are becoming wide spread. Their use will undoubtedly continue to increase.