Biomass can be used to provide heat, make fuels, and generate electricity. This process is called Bioenergy.
Biomass is derived from the carbohydrates found in plant matter, which can be in the form of agricultural crops, trees or other types of plants such as seaweed. It can also be in the form of crop, plant or tree waste, or animal waste. Paper and plant waste from rubbish dumps can be a source of bio-energy - even the fumes from landfills can be used as an energy source. These are all renewable resources.
Biomass is produced by the action of sunlight on plants and is therefore a concentrated store of solar energy. It can be burned directly to produce heat and generate electricity or it can also be burned to produce methane gas, which can be used as fuel. A third way of using it is to convert it into a liquid fuel: this conversion process is known as pyrolsis, which occurs when the biomass is heated without oxygen being present.
The two main types of liquid fuels in the market, bio-ethanol and bio-diesel, are made from crops such as cereals, corn, soybean, rape seed oil, sugar cane, switch grass and palm oil.
There are two types of liquid fuels: one is a form of alcohol, which can be made from crops high in carbohydrates such as corn or sugar cane. This is known as ethanol. In some parts of the world, ethanol is used as an additive to petroleum in cars and is a way of reducing the production of carbon monoxide and greenhouse gases. Vehicles that run on mixtures of petroleum and ethanol are now available. Some can run on a mixture that is up to 85% ethanol. Another form of alcohol fuel is methanol or wood alcohol.
The other type of liquid fuel is bio-diesel, which is made from vegetable or animal oils and fats. It can also be produced from algae and recycled cooking oils. It is an ester not an alcohol. The ester can solely be used for fuel or it can be used as an additive. It has the effect of reducing harmful emissions.
Advanced biofuels techniques, such as cellulosic ethanol, has the potential to reduce carbon dioxide emissions below those from fossil fuels. Cellulosic ethanol uses microbes to break down the woody bits of plants. The advanced biofuel can be made from low-imput perennial crops, such as switchgrass, that grow on marginal lands. The cellulosic ethanol industry is in its infancy.
The use of biomass to produce these liquid fuels or bio-fuels has tremendous potential for our transportation needs, which at present form a large part of our overall energy consumption. Instead of being wholly reliant on non-renewable fossil fuels such as coal and oil, we could develop bio-energy crops as feed stocks. Biomass energy in gas form can be also be used to produce hydrogen for use in fuel cells.
However there are certain disadvantages concerning bio-energy. Direct burning of biomass adds to greenhouse gases. Also the energy consumed in creating some of the liquid, gas or chemical products may be as great as the energy consumed in manufacturing petroleum-based products.
Wood, which is a very large source of bio-energy, has been used for heating for many thousands of years. Wood is still the most significant energy source for cooking in developing countries. Coal, a fossilized wood, is another form of biomass, but since fossilization takes millions of years, coal is not a recognised renewable resource. However, due to its abundance, coal has evolved over the last few centuries as a popular energy source in many Western countries.
In the West today, energy use from renewable biomass sources is a very small part of the total energy used. For example, only 3% of total US energy consumption is from biomass sources. Some of this is used for transportation and some is used in industry, especially pulp and paper, to provide factory heat and power – only a small amount is used for electricity production. Some companies in the timber industry use wood waste in their boilers, but the energy produced is consumed in manufacturing – only a small amount of excess is sold to the electricity grid.
Examples of bioenergy production
Decomposing landfill rubbish produces methane gas and carbon dioxide; converted into energy, the methane is prevented from escaping into the atmosphere and adding to air pollution and global warming. Australia currently has eight facilities in which the gas is extracted from wells interconnected by a network of buried pipes. In total, they reduce approximately 250,000 tonnes of carbon dioxide and greenhouse gas emissions annually.
In Germany, Austria and Sweden, home heating with ‘pellet boiler systems’ is popular. These pellet systems operate like conventional central heating systems. The boilers are fed wood pellets made mainly of compressed sawdust and shavings from logs processed for lumber and other wood products.
In Queensland, Australia, sugar cane waste (bagasse) is used as boiler fuel in some sugar mills. The electricity generated is mainly for sugar production but some of the excess power is sold to the Queensland electricity grid. With falling world sugar prices, the Queensland government has a Bagasse Integrated Gasification Project, which it hopes will provide a viable alternative for sugar cane growers.
The Bio-diesel Association of Australia has about 500 members, some of whom make their own motor fuel from a mixture of used cooking oil, alcohol, and caustic soda. The Association, which operates approximately 16 plants nation-wide, is proactive in conforming to sustainable environmental principles. The Newcastle City Council has over 200 bio-diesel powered vehicles.
The US Department of Energy’s Office of Renewable Energy has a Biomass Program, which sponsors research and development into both bio-fuels and bio-energy generation. Its objective is to reduce dependence on imported oil and to develop a domestic biomass industry. Over the past few years, its program has quadrupled with 95 ethanol plants which produced 4 billion gallons in 2005.
In Britain, Fibrowatt, which is part of the Energy Power Resources Group, has developed four power stations which use poultry litter as fuel. Over the past 15 years they have burned more than 7 million tons of poultry litter and other biomass. Other work includes a power station at Four Ashes Industrial Estate in the Midlands, which will burn used tyres; as well as several similar projects in the Netherlands. In 2006, Fibrowatt moved into the US market with its Fibrominn plant in Minnesota, which burns more than 500,000 tons of poultry litter annually. Four more plants are currently under construction with three more planned.
However, the US Energy Justice Network points out that the material utilised – high content fertiliser wastes, poultry litter and manure, straw and woodchip by-products – pollutes the atmosphere, water and soil with harmful contaminates inclusive of: arsenic, mercury, sulphuric and hydrochloric acids, dioxins, and carbon dioxide.
Advantages of bioenergy
Table 1: Percentage of production fossil fuel required above ethanol output capacity
Biomass production requires, as with all technological advances, its implementation and use encompasses a ‘holistic’ approach that considers environmental, social and economic long-term sustainability. Bio-fuels can contribute to energy and environmental goals, but only as part of an overall strategy that includes: energy conservation, a diversity of sustainable energy resources, efficient production and transport, and careful environmental
Bio-energy projects should only be supported if there is a genuine overall reduction in the production of greenhouse gases and there are no other adverse affects upon the environment such as the destruction of habitats through the growing of feedstock crops.
Biomass production technologies should be carefully evaluated for potential negative impacts on environmental and human health. Calculations of energy return on investment need to include environmental impacts on soil, water, climate change, and ecosystem services.
Solar and wind power should be promoted as they are much cleaner energy sources and will not utilise large areas of land or incur the problems associated with processing and transport.
Stricter land-use laws, particularly in countries with tropical forests and vulnerable eco-systems, are needed to mitigate potential damage and reap the benefits from biofuels.
An easy immediate step would be to mandate improved fuel efficiency for all forms of transport, beginning with the private automobile. A 20% increase in fuel-efficiency standards is feasible using current technology, and would save far more energy than Europe's biomass could produce.
Governments also need to provide leadership in the form of economic incentives to minimise competition between food and fuel crops, and ensure that water, high-quality agricultural land, and biodiversity are not sacrificed on the altar of our convenience.
What you can do
Use our lobbying service to write a letter or email your government and ask them to replace fossil fuels with biofuels that are produced from sustainable sources and without the input of fossil fuels.
Write a letter or email the editor of your local newspaper; urge him or her to publish your concerns about energy issues.
Join green groups which oppose the development of harmful landfill-burning and other incineration projects, and of air-polluting ethanol and methanol plants. Also, be conscious of how much energy you are using and try to save energy at home.