The main source for Renewable Energy comes from Wind, Solar and Water. There are others such as Biomass and Biofuel but these are the main ones. Nuclear power although when its safe is not a renewable energy. It doesn't produce global warming gasses like the others (coal, gas, oil), it produces a lot of waste fuel that needs to be stored because it is radioactive. The waste has to be secured and guarded from terrorists. A power plant can't be dismantled once it has come to the end of its lifetime, it has to be decontaminated and that can be hazardous and take years to do. Once all the Uranium that is used in nuclear power stations is used up then there's no more.
Wind is generated by large turbines that are pushed round as the wind travels across the land or sea. Wind Turbines can be located on either land or off-land if the country is located on the coast. On-Land Turbines are hated and are the source of a lot of dislike because they can look ugly and they can be noisy. A single can generate enough energy for 300 homes, a more efficient one could power more. Some people have put wind turbines on their houses but they can look ugly. There are other sources of renewable power if that's not to your liking.
Solar power is generating power from the Sun and the most common place you can see those are with calculators. The same principle can be used to power houses. Near where I live is a solar power plant and I'm in the United Kingdom. Solar power doesn't mean it needs heat, it just needs light that gets turned into energy for consumption.
Energy can be generated by water as it rushes for example to the mouth or delta of the river. Dams can be placed along a river and energy generated as the water is flows through the dam's generator. At night, the water is pushed back up to the reservoir and allowed to flow through again. You can see an illustration of what I mean at the U.S. Geological Survey site.
Even if you are a Climate Sceptic who believes that humans are making no impact on the weather, we should begin to Start using renewable sources of energy. Coal, Gas and Oil are finite resources, one day they will run out. We have about enough coal to probably last until 2088. However we are using more and more and that 2088 is only an estimate. We have a few years to start reducing our addiction to these dirty substances. The sooner we move to renewables, the better, that way we'll be best placed to cope when they do go. New sources of fuel might be being found but they're quite rare and they distract from the point. As fuels become scarce, countries will be less likely to sell to other countries, protectionism will begin. Some countries are already using renewable energy, below is only a couple.
The United States generates 14.20% of its net energy generation using renewable energy (i.e., biomass, geothermal, hydropower, solar, wind). 9 This is an increase of 0.63 from the following year. Its small but growing. The United States is well placed to increase the renewable energy considerably, it has a large area of land that it can use to generate electricity from renewables without affecting people. Interesting facts on Wind Power in the U.S. can be found on the Wind Energy Foundation
Norway produces 99% of its energy needs from Hydropower (power generated from water). It is well placed to deal with any future energy consumption crisis in the future. However this doesn't actually go as far as cars though. Economical cars that can travel long distances without a recharge are still not there yet but one day, they will hopefully will be.2
Wind renewable is slowly taking off but is lagging behind European nations. In terms of amount generated from Wind power, it is fifth in Europe with Germany generating the most 29,060MW of energy for end of 2011 5. The UK is on 6,540. Whilst most wind power in Germany will have been through on-shore, there is much more resistance to on-shore wind power in the UK and most wind power is generated offshore. Hydropower is responsible for 21% of renewable energy in the UK with most of the hydro plants (1000kw+) in either Scotland or Wales 7. The RenewablesUK trade association found 25% of energy in the UK was generated by wind power. 11. Scotland produces more energy through renewables and still can go further.
Germany generates more solar power than any other nation on this planet. 36% of the worlds solar power generated is generated in Germany 10.
India's power generated from renewable energy is 29%, 17% of all energy produced is produced through hydropower plants with the remaining 12% from the other renewable resources. Coal still makes up 50% of all power generated but its a start.8
Despite hearing that China is building a new power station each week, China generates 30% of its energy needs through renewable energy, 69% is from coal though. 3. China is still a large polluter of the environment through energy generation but that should not come as a surprise given its large population, the second largest after India. China built 44% of wind renewable energy turbines for 2011. 6