There are many sources of environmentally friendly, renewable energy. This post is a brief roundup covering most of them. I’ll cover each one and their general uses in more detail in other posts, linking to them from this post in the process. Feel free to leave a comment if you think I forgot one!
The Sun/Solar energy
If you ask someone to name examples of environmentally friendly and renewable energy sources, the Sun will probably come up pretty quickly. And for good reason: the Sun radiates enormous amounts of energy in our direction. In one year, the Earth’s oceans, land masses and atmosphere absorbs somewhere around 3.850.000 exajoules of solar energy. To put that ridiculously large number into perspective; in one hour, the Sun delivers more energy to us than the whole world used in the whole year of 2002. Another equally dazzling perspective: The energy delivered by the Sun in one year is about twice as much as the Earth’s stored non-renewable resources combined. That’s right; if we spend every last bit of oil, coal, natural gas and mined uranium we can squeeze out of the planet, we’ll get the energy equivalent of about half a year’s radiation from the Sun. You’ll find more about solar energy in Solar energy uses.
Flowing or falling water/Hydroelectricity
Water is another source that would feature in one of the top spots of a list of renewable energy sources. In fact, if widespread use were the main criterion, it would feature very high indeed – hydroelectricity is one of the most widely used forms of renewable energy. More than half of the world’s energy production from renewable sources in 2005 was from hydroelectricity. It could be argued that the source of the power we can harvest from flowing or falling water is actually the Sun – since the Sun drives the water cycle. In fact, the same could be said about almost any energy source, since they can all ultimately be traced back to the Sun – except for tidal power and some types of geothermal power. I’m going to ignore this for the purposes of this post, though. A List Of Three Does Not A Decent Roundup Make, after all. You’ll find more about water power in Water power uses
Wind/Wind power
Wind is the third source that is likely to be mentioned quickly if you ask someone to list a few sources of renewable energy. Although only about 1.5% of worldwide electricity use in 2008 was from wind power, it’s growing at a healthy pace. Between 2005 and 2008, the worldwide percentage doubled. The potential of wind power is high compared to the world’s total consumption. While the numbers aren’t quite as spectacular as with solar energy, they still reach respectable heights: the Earth’s total commercially viable wind power resources has been estimated to 72 terawatts. That’s almost five times as much as the 15 terawatts that was the average global consumption from all sources in 2005.
Waves/Wave power
The near-constant undulations of ocean waves holds a great deal of energy. The problem so far has been harvesting that power in a reliable and economical way. While many experimental techniques have been tested since the end of the 17th century, the first commercial wave power plants have only begun appearing the last few years – consequently the amount of energy generated from wave power at the moment is close to negligible.
Tides/Tidal power
Water streaming in and out of straits and other narrow necks of water during tides can be used to generate energy. Few commercial scale facilities exist, although the field is the subject of extensive research and show great promise as the technology developed becomes sturdier. Tidal power is far more dependable than solar power and wind energy. After all, tides are the result of the Earth’s position relative to the Sun and the Moon, which follows a predictable cycle. This eliminates a common disadvantage of renewable energy sources – intermittency – making it easier to plan for a dependable energy supply.
Geothermal
The Earth itself holds a lot of energy, stored as heat. This heat has several origins: solar energy absorbed by the Earth’s surface, radioactive mineral decay and the original formation of the planet. Regardless of origins, this heat can be used for several purposes, the main ones being the heating of spaces and water and energy generation. For energy generation, about 10 gigawatts of capacity were installed worldwide as of 2007 – about 0.3% of the world’s electricity demand. For heating and other uses, about 28 additional gigawatts were installed.
Biofuels and biomass
While technically two different things, I’ll lump these two together in one brief definition: biological material and/or waste that in some way or another can be converted to something we can burn to produce energy. This includes – among others – manure, garden waste, chips from forestry and crop stalks. While burning biofuels and biomass releases carbon dioxide and other greenhouse gases to the atmosphere, these are gases that were already bound by the biological processes that produced them. Therefore, their production are considered carbon neutral.
That concludes my roundup of renewable energy sources – I can’t think of any more. If you can, let me know in the comments!
This post was tagged with: biofuel, biomass, geothermal, hydroelectricity, hydropower, solar energy, solar power, tidal energy, tidal power, wave energy, wave power, wind energy, wind power