Advantages and disadvantages using renewable energy resource

1. solar
advantages:Solar energy is free - it needs no fuel and produces no waste or pollution.
In sunny countries, solar power can be used where there is no easy way to get electricity to a remote place. Handy for low-power uses such as solar powered garden lights and battery chargers
disadvantages: Doesn't work at night. Very expensive to build solar power stations.
Solar cells cost a great deal compared to the amount of electricity they'll produce in their lifetime.Can be unreliable unless you're in a very sunny climate. In the United Kingdom, solar power isn't much use except for low-power applications, as you need a very large area of solar panels to get a decent amount of power. However, for these applications it's definitely worthwhile.

2.wind
advantages:Wind is free, wind farms need no fuel. Produces no waste or greenhouse gases. The land beneath can usually still be used for farming. Wind farms can be tourist attractions. A good method of supplying energy to remote areas.
disadvantages:The wind is not always predictable - some days have no wind. Suitable areas for wind farms are often near the coast, where land is expensive.Some people feel that covering the landscape with these towers is unsightly. Can kill birds - migrating flocks tend to like strong winds.Can affect television reception if you live nearby. Can be noisy. Wind generators have a reputation for making a constant, low, "swooshing" noise day and night, which can drive you nuts.

3.Hydro-electric power
advantages:Once the dam is built, the energy is virtually free. No waste or pollution produced.Much more reliable than wind, solar or wave power. Water can be stored above the dam ready to cope with peaks in demand.Hydro-electric power stations can increase to full power very quickly, unlike other power stations. Electricity can be generated constantly.
disadvantages:The dams are very expensive to build.However, many dams are also used for flood control or irrigation, so building costs can be shared.Building a large dam will flood a very large area upstream, causing problems for animals that used to live there. Finding a suitable site can be difficult - the impact on residents and the environment may be unacceptable. Water quality and quantity downstream can be affected, which can have an impact on plant life.

4.Geothermal Energy
advantages:Geothermal energy does not produce any pollution, and does not contribute to the greenhouse effect.The power stations do not take up much room, so there is not much impact on the environment.No fuel is needed. Once you've built a geothermal power station, the energy is almost free.It may need a little energy to run a pump, but this can be taken from the energy being generated.
disadvantages:The big problem is that there are not many places where you can build a geothermal power station. You need hot rocks of a suitable type, at a depth where we can drill down to them. The type of rock above is also important, it must be of a type that we can easily drill through. Sometimes a geothermal site may "run out of steam", perhaps for decades. Hazardous gases and minerals may come up from underground, and can be difficult to safely dispose of.

2007-01-21 17:18:32 補充：
Advantages:-energy source is free and renewable, once the technologies are intalled to produce electricty from renewable energy, the fuel is free because it comes from wind and sun which is available to us everyday.

2007-01-21 17:18:51 補充：
-no polluting gases are emitted-start-up time is short-electricity can be generated in remote places

2007-01-21 17:20:54 補充：
Disadvantages:-High cost of delivering electricity to the user.-set up of some kind of renewable electricity generator such as dams and Wind generators may cause environmental problems.