Nowadays global warming has become a global issue, how we slowly destruct our only home in this universe the mother Earth by choking it up with carbons, methane, water vapor, nitrous oxide and other dangerous materials. In the other hand we also threatened by fosil energy crisis. This irrecoverable energy is running out and the price is also getting higher and higher every time. We need to find alternative renewable energies to replace fosil energy as well as to safe the earth from the use of energy which produce too much polution.

But the question is can we or have we found an alternative energy that suits all the goals ? because the challenge is the new energy source must be cheaper than the one we used before and also it must be environmental and ecological friendly. The scientists and experts all over the world have thought about this for many years and came up with some ideas, but none of them are perfectly applicable or in other words they all still have weaknesses. But still their efforts to make this earth a better place to live deserve our highest appreciation and we hope that not in a long time in the future these people will find the perfect alternative energies for us.

Here are 10 of the most popular and already obtained alternative energies :

* Wind Power (Using A Wind Turbines)
USA is probably the number one country in the world in using this alternative energy, a US government study found that energy from the wind would supply 20 percent of the electricity by 2030.The wind capacity in this country increased every year as they continously installing new turbines, and in order to reach their 20 percent goal they will have to install 75,000 additional new turbines. the weakness of this project is the turbines which are big and so many, very disturbing the view and also they could be deadly for migrating birds so they're not ecological friendly.

* Ebb and Tide Flow Turbine
This turbine has the same operation principal with the wind turbine, only it uses water / tidal flow power, and since water is denser than the wind it will take fewer turbines to produce the same power as the wind turbines. But since it's operated under the water it could impact the living environment there and it could also alter tidal flows.

* Nuclear Power
Many countries in the world have developed this kind of energy as a solution for their energy problems, in many ways it's an effective way to solve the problems but there are always many concerns about the use of this energy. We still remember the accidents happened at Pennsylvania and of course the chernobyl accident in 1986. There are also concerns about the nuclear waste which is extremely dangerous for every living thing, and beside all that it's very expensive to build a nuclear reactor.

* Geothermal Power
This is a way to produce electricity using heat from Earth's depths. to get this energy we have to dig miles beneath the earth's surface and then connect them with water to produce steam that spins electricity turbines. it seems like a good solution, but the critics say the construction to costs are very high, there are also some seismic risks and consume too much valuable water.

* Solar Energy
This could be the most popular alternative energy because nowadays many people have used it in their homes especially in developed countries. however, solar energy accounts for less than 1 percent of the nation's electricity mix. the weakness include the high cost and low efficiency of the silicon chips that convert sunlight to electricity and unreliability of clear skies at any one location.

* Hydroelectric Dam
Hydroelectric dams are seen as an important source of cheap and abundant electricity without carbon.the level of water behind the concrete wall flows through a turbine to generate electricity. large dams however, could drown landscapes, rivers, and damage the life of fish. But it also helps the farmers to supply irrigation water, so it has lots of plus and minus points.

* Coal
It's cheap and very much applicable but the problem is it still produces carbon dioxide emission. Many experts say that it just need to be "clean" in order to limit the contribution to global warming. several Technologies are being developed in order to capture and store coal's carbon dioxide emissions underground.

* Bio Ethanol
This one seems very promising, it's actually biofuels distilled from crops such as corn and soybeans. But since it's helping drive up food prices and, according to some studies, doing little if anything to reduce greenhouse-gas emissions, researchers are trying to find more acceptable feedstock and they come up with algal fuel.The scraps can be transformed into ethanol and animal feed. The problem is the cost : A gallon of algal fuel today is about $20, which is expensive compared to $4 gasoline.

* Gas / Electric hybrid vehicle
It could extremely decrease the polution and it's powered by a cheap energy source. The only problem is the price of this kind of vehicle is unbelievebly expensive, which means the financial payback comes several years down the road. this probably because no car industries have decided to produce this kind of vehicles massively.

* Hydrogen and Air Powered Car
This car uses fuel cell stacks as an alternative energy to create electricity by combining hydrogen and air, so there would be no gases or fumes linked with global warming or pollution. And nowadays there are already few roadside hydrogen filling stations. The problem is the same as No. 9, the price is still too high in a cause of no mass production yet.