DISADVANTAGES

• It changes the coastline completely and the estuaries are flooded so any mud flats or habitats that birds or animals live on are destroyed

• Initial building cost is very expensive
• Water is not replenished, it cannot flow away so any dirt or pollution lingers around the coast much longer
• Silt builds up behind the barrage
• Disrupts creatures’ migration in the oceans
• Needs a very big piece of sea to be cost effective
• Not many sites suitable for this kind of power generation; building the barrage
• Only produces power for about 10 hours of the day

WHAT IS BIOMASS?

In the developed world biomass is becoming more important for dual applications such as heat and power generation.

Biomass is a clean renewable energy resource derived from the waste of various human and natural activities. It excludes organic material which has been transformed by geological processes into substances such as coal or petroleum.

The energy of biomass is extracted from three distinct sources:

Wood Waste Alcohol fuels Crops Landfill gases

Wood is the largest energy source of biomass: contributors include the timber industry, agricultural crops and raw materials from the forest.

Waste energy is the second largest source of biomass energy. The main contributors are: municipal solid waste and manufacturing waste.

Alcohol fuels is the third largest contributor and is derived mainly from corn.

Any source can be used to fuel biomass energy production. We can use rubbish, animal manure, woodchips, seaweed, corn stalks and other wastes. Biomass is matter usually thought of as garbage. Some of the sources are just lying around: dead trees, left-over crops, woodchips, sawdust from lumber mills, even used tires and livestock manure will do.

In California, USA, more than 60 million tons of energy sources for biomass energy are collected each year. If all these sources were used to create biomass energy, California could make up to 2000 megawatts of electricity. That is enough to make electricity for about 2 million homes.

HOW DOES IT WORK?

The harnessing of energy from biological mass (biomass) is a simple process. The waste wood and other sources are gathered in big trucks. The waste is then transported to a biomass plant. Here, the waste is fed into furnaces where it is burned. The heat created is used to boil water and the energy from the steam is used to rotate turbines and generators.

The second method, through which energy is created, is called Landfill Gas. When garbage is burned or is allowed to decompose it gives off methane gas. Pipelines are put into the landfills (pits in which garbage is burned) and the methane gas is collected. It is then used to make energy in power plants.

The use of biomass can help reduce Global Warming. Plants use and store carbon dioxide (CO2) when they grow. When it burns or decomposes, it releases the CO2. Replanting plants, crops or trees etc. ensures that the C02 is reused. If the plants are not replanted the biomass will disrupt the natural carbon equilibrium and thus continue to contribute towards Global Warming.

IS IT RENEWABLE?

Biomass is renewable; we are going to carry on making waste products, plants and trees are going to die and the cycle will continue. This ensures that the sources contributing to biomass are always available.

The use of biomass can be environmentally friendly because the biological mass is reduced, recycled and then re-used.

Innovations and ideas in which biomass can be used are continually being invented. One such way is the production of ethanol, a liquid alcohol fuel. Ethanol can be used in special types of cars that have been manufactured to accept alcohol fuels instead of petrol. This innovation helps reduce our dependence on oil.