Wind Power
Wind energy is a form of indirect solar power. Winds are caused by the uneven heating of the atmosphere by the sun, the irregularities of the earth's surface, and rotation of the earth. As a result, winds are strongly influenced and modified by the earth's terrain, bodies of water, vegetation and other factors. Humans use this wind flow for many purposes: sailing, flying a kite, and even generating electricity.
How it Operates
A wind turbine operates in the opposite way to a fan. The wind turns the blades, which then spins a shaft that is connected to a generator. Wind turbines convert the kinetic energy in wind into electricity.
A large wind turbo generator can be more than 110 metres tall with blades spanning 130 metres and needs a minimum average wind speed of about 25 km/h.
Location Needs
Sites cannot contain any tall plants and are often placed on outstanding hills and headlands or in coastal areas.
A large wind farm may consist of several dozen to about 100 individual wind turbines, and cover an area of hundreds of square kilometers. The land between the turbines may be used for agricultural or other purposes. A wind farm may be located off-shore to take advantage of strong winds blowing over the surface of an ocean or lake.
Costs
The cost for a wind turbine really depends on 5 factors; location, how big you want it, how much money you have, how much electricity you want to produce and if you require a VAWT (vertical axis wind turbine) or a HAWT(horizontal axis wind turbine). The average cost for a wind turbine is approximately AU$1050 per Kilowatt. Also, big wind farms could be placed on someones land, so the owners of the land would be payed a fee for the use of their land.
Biomass
Biomass is the name given to any material which is recently derived from plants that use sunlight to grow. It is the mass of biological matter on earth. Biomass is sometimes classified as "combustible renewable and waste".
Converting biomass energy into usable energy has many environmental benefits. It uses waste products which are usually disposed of, and it also uses up methane (a greenhouse gas). Methane has higher energy levels than any other source of biomass energy.
Fuels like Ethanol can be produced from biomass and used as an alternative to petrol in cars.
How it Operates
Biomass can be converted to energy in 2 ways; directly by creating electricity, normally done by burning the biomass (e.g. wood or waste products) in steam generators or indirectly by converting it to a liquid or gas fuel.
Main Sources of Biomass
- Wood from natural forests and woodlands
- Forestry plantations
- Forestry residues
- Agricultural residues such as straw, bagasse (crushed sugar cane), animal slurries and green agricultural wastes
- Livestock residues
- Black liquor from paper manufacturing
- Sugar and grain grown to make alcohol for use as a fuel
- Grains and oil seeds grown for production of biodiesel
- Sewage wastes
| Type of biomass | Energy available (megajoules per kilogram) |
| green wood | 8 |
| oven dry plant matter | 20 |
| methane gas | 55 |
Figure 1: Sludge digesters at Woodmans Point sewage treatment plant, Western Australia.
Location Needs
A biomass plant needs about 20 acres of land. But most plants are just added on to a sewage treatment plant.
Costs
The cost for a high-tec biomass plant in India is approximately $11,150,000 AUD. Another “cost” for a biomass plant is getting enough of the needed resources to run it.
Hydropower
Hydropower is currently the most used renewable energy source to generate electric power. Hydropower is clean. It prevents the burning of 120 million tons of coal each year. Like other energy sources, the use of water for generation has limitations, including environmental impacts caused by damming rivers and streams, which affects the habitats of the local plant, fish, and animal life.
How it Operates
A power source (falling water) turns a propeller-like object called a turbine, which then turns a metal shaft in a generator, which is the motor that creates electricity. Power lines which are connected to the generator carry electricity to lots of homes. The water continues past the propeller through the tailrace into the river past the dam.
Location Needs
The water used by hydro plants can be flowing in natural streams or rivers, or contained in man-made facilities such as reservoirs, pipelines, or canals. A good source for hydroelectric energy is a dam that is tall and has a high amount of water flowing through the river.
Costs
For a very powerful new hydro plant that can power 115,000 homes the price can be up to $250 million. The cost to produce power at a hydro plant will vary depending on the size of the plant. In general, the larger the hydroelectric plant, the cheaper the cost per kilowatt to produce the electricity.
