The pillars of green energy

Green energy is a term which is very hard to define. In general it is associated with type of energy sources that are either renewable or "clean". In order to make some sense in the world of green energy, I will discuss the main points and ideas that rule this field.

There are many of places to get information about green energy on the web, as well as on other type of energy sources. To make some order in things we need to first understand what are the current available resources that drive our life. In the past, most of the energy that humans used was the "energy of life"meaning - using men and animals power to work, travel build and produce. But with time, people learned to exploit other energy resources in nature to their will.

In the recent centuries we learned that a huge reservoir of dead biological material buried under the ground, that can be distilled to high energy materials like gasoline and diesel fuel. Soon after that discovery we used these "fossil fuels"in all aspects of modern life - from producing electricity to traveling the ocean.

Now, when we became totally addicted to it, we found two fundamental flaws in the choice to use this "black gold", choice that will surely cause two serious problems in the near future:

1. Fossil fuels are limited - the repository of oil is limited. The lack of supply and constant increase in demand,already causing economical and political havoc, that will soon mature to real energy crisis.

2. Burning these fuels, release toxic gas into our atmosphere and unpredictably affecting the ecology of the entire planed, in ways that can be dangerous to our survival.

There are more problems with fossil fuels, but these are the main problems, that push scientists and economists to seek new forms of energy that will be unlimited (renewable) and fairly clean.

In order to archive that, we need to summarize the basic energy resources that exist on earth and I'll do so below.

The greatest available power source known to us is the sun. The sun bombarding us with very intense radiation all the time. Almost all of the energy of life comes from the sun.

Plants, algae and cyano-bacteria have evolved to harvest the mighty solar power of our sun and use every efficiently to produce electric current in their cells, that is used as energy source to produce all the carbon based materials in living creatures. All the other creatures eat plants in order to survive. In that sense we can say that the fossil fuels are also ancient animals and plants that have got their energy from the sun.

We, as humans have two basic approaches to harvest the sun's energy:

1. Using panels of photo-voltaic (PV) cells that use a simple physical phenomenon to convert the energy of solar radiation to electricity.

2. Using the heat generated by the syn rays to evaporate liquids and use the steam and pressure to move electric generators.

By now, the technology we have for both approaches is very inefficient and expensive. So although the sun is the major source of free, almost unlimited energy, we still far behind plants in using it efficiently.

Moreover, the intensity of the solar power vary in different places and during the day. most plants using the sun so efficiently that they only need a couple of hours every day to produce all the energy they need. But our technology cannot do that, and the hours of night are wasted.

That bring us to a different way to use the sun's energy - biofuels...

Maybe it's sound a bit like cliche "the energy of life" but this is what it really means to use biofuels. In short, since plants and animals are so efficient to use the energy of the sun to produce high energy carbon-based compounds, we can use these organic materials to produce energy. Basically it is exctly like using fossil fuels, but from renewable source.

Unlike fossil fuels, biological fuels are constantly produced(mainly by plants), and it is usually much cleaner when burned. The main waste product of burning biofuels is carbon-dioxide, non-toxic gas, which is recycled by plants to over and over again.

There are two main types of biofuels that come from two main type of biological storage molecules:

1. biodiesel - A fuel that is suited to diesel engines and is produced from plants and animals fats - the process to produce it is by mixing it with strong base that breaks fats into fatty-acids and glycerol. the fatty acids can be used as clean fuel for engines, and the glycerol is an important by-product, useful in the chemical industry.

2. Ethanol - This is a clean substitute to gasoline, and it is produced mainely from plants sugars, the second important energy storage molecules of life. The main process use to produce it is fermentation.

These two main fuels promises cleaner and sustainable fuels, that can be used in our current technology with no need to change the entire transportation and energy market. However it is still imposible to grow enough crops to support both biofuels production and food production. So it is unrealistic to completly move from fossil-fuels to biofuels in the near future.

New agricultural and production techniques are being constantly invented to solve the problems.

Beside solar power and bio-fuels,we can use the energy stored in our own little planet, and one of them is wind power. the changes in climate creates great reservoir of energy we can use by harvesting the wind..

The earth atmosphere store a huge amount of energy in it and provides a good opportunity to leverage it as an energy source. However, this technology is also not so efficient and in not very reliable, since we can't predict the amount of wind all the time.

Another fast growing idea of energy resource is Hydrogen. A well known scientific idea was to use "fuel cells" is which hydrogen and oxygen are combined in a special device to produce water and electricity. These cells are already been used for special need, like space vehicles, but they are still too expansive to be used in commercial engines.

Hydrogen and oxygen are very common materials on earth and can be considered "renewable". This is also a perfect zero-carbon emission technology - very clean.

Another problem of this idea is the amount of money it cost to produce hydrogen today and the sources that are being used. So for now it is still a futuristic immature technology.

The final source of energy is what we called "geothermal energy". Earth is a living planet that produce a lot of heat in his core. We can use this heat to warm liquids and produce energy. In some places this heat just burst out of thee ground, allowing us to use it. This source of energy is cheap and very efficient but it cannot be used everywhere. This form of energy can only be used when streams of hot steam burst out of the ground.