Ever since the industrial revolution, man has used many sources and methods to meet his energy needs. These energy sources can be classified into two major categories. Energy from fossil fuels form the first category and is the first choice when energy is required on the move, like in vehicles. The other major category is electrical energy which is generated through a variety of methods. It is used for lighting and to power equipments in factories and homes.

The depleting fossil fuel reserves, global warming and many other frightening consequences of traditional methods of energy generation has fortunately shifted the focus to sustainable, renewable and clean energy systems.

While it could be many years before a clean replacement for fossil fuels for transportation is available, the scenario is much brighter for using environmentally friendly methods for the generation of electricity. There are six main clean energy ideas, hydropower, ocean energy, solar energy and geothermal energy. Let us take a look at each of these methods.

The World’s Most Used Clean Energy – Hydropower

Hydropower is obtained when kinetic energy of moving water is converted into electricity. Flowing water has a lot of energy. Perennial rivers and streams are ideal for power generation. This method involves building a dam across the river.

There are two options. The first option is suitable for huge rivers with continuous water inflow. In such cases no reservoir is made, and the water just flows through the powerhouse turning generator turbines for electricity generation. The other option is to stop the flow of water, create a reservoir and then use that water to generate electricity as needed.

Hydropower is the most widely used renewable method to generate electricity. In the United States about 10% of the total energy produced is hydro powered.

Ocean energy

The power hidden in the world’s oceans are enormous. Ocean power is a vast untapped storehouse of energy and may one day power all our energy requirements. There are three main sources and methods of tapping ocean energy. They are wave energy, tidal energy and ocean thermal energy conversion.

Wave energy systems use the up and down motion of the water as waves move through a point to rotate a turbine. The power to rotate the turbine either comes from the up and down movement of a piston caused by the wave or the force of air escaping from a chamber as the wave fills it with water. Wave energy systems can be used for modest applications like powering a small lighthouse.

Tidal energy can be used in areas where the difference between the water levels during high and low tide is significant. The method is to allow water to flow into a reservoir during high tide and then preventing it from flowing out during low tide by using a dam. At this time the trapped water in the reservoir can be used to generate electricity like hydropower projects. This method is not a new discovery; its use is known since approximately the 11th Century. In France, the La Rance Station uses this method to produce 240 MW of power.

Ocean thermal energy conversion is a technology that generates power from the difference of temperature between water at different depths of the ocean.

One major obstruction is the impact tidal energy has on ecosystems and wildlife.

Clean Energy From The Earth – Geothermal energy

The interior of the earth is very hot. The typical increase in temperature is around 3C for every 100 meters. Deep down the temperature is high enough to melt rocks, making the earth a perfect thermal clean energy idea. Thermal energy comes to the surface at certain locations such as hot springs. The temperature of water and steam that comes out of these springs can be in excess of 130C.

The hot water from the springs is used to generate electricity. There are at least 14 areas in California where this idea is used. The technology is the same as a regular thermal power plant except that the source of heat is the hot steam from the earth. The geothermal generators of California produce a major share of the total geothermal energy produced.

Clean Energy Ideas From The Wind

Wind power is generated by harnessing the force of the wind to rotate turbines which produce electricity. Though wind farms and wind power may seem newer entrants on the energy generation scene, their actual use dates back to centuries ago. Wind was used to power sail ships, wind mills and water pumps much before fossil fuel engines came to the scene.

A wind turbine looks like a child’s toy, a sort of pin wheel over a tall mast. Blowing wind rotates the blades of wind turbines. The speed of rotation is increased by using a gearbox which then spins the shaft of the generator which produces electricity. A wind farm usually has rows and rows of wind turbines spread over a large piece of land. There are offshore wind farms too which take advantage of the continuous windy conditions at sea.

The power rating for modern wind turbines usually ranges from 600 KW to 5 MW. For commercial use a rating of 1.5 to 3 MW is considered optimal. The power output of a wind turbine increases exponentially with the increase in wind speed.

Wind power is most viable in areas with round the year windy conditions like coastal areas, off shore locations and on hilltops. Though the capacity utilization of wind turbines is around 30% in average installations, if properly harnessed, the potential for energy production is estimated to be 40 times the current electricity demand!

Clean Energy From The Sun – Solar Energy

Sun is the nuclear power plant provided by nature. Most of the energy sources that we have owe their existence to the sun in one way or other. Sun gives us a continuous supply of heat and light during the day. This energy source is so dependable that all the artificial satellites that orbit the earth use it to generate the energy for their operation. The only drawback of this energy source is that it is not available during the night and not available in full strength on cloudy days.

This clean energy idea revolves around the fact that the sun provides heat in the form of radiation. Using the heat from the sun to run a solar thermal power plant is one way of tapping solar energy. The method is to focus the sun’s energy onto pipes carrying water using parabolic mirrors. The heat converts the water into steam which can then be used to run turbines to generate electricity. One such facility in the Mojave Desert in California powers over 300,000 homes.

The other way to generate electricity from the sun is by converting the sunlight directly into electricity. This is accomplished by photovoltaic cells. This technology is commonly used to power calculators, watches and street lights to name a few. However the technology has not yet reached a stage where large scale generation of electricity by this method becomes commercially viable.

There are many advantages and disadvantages of solar energy which contribute to a situation where although it’s becoming more popular, solar still isn’t a mainstream method, and it doesn’t receive unified encouragement from policy makers.

Clean Energy Today

There are two things common among the many clean energy ideas that we use today. One is that they are sustainable and will never get exhausted. The other aspect is that they are clean energy methods because they don’t produce environment damaging byproducts or harm it in any way.

Below is a diagram that nicely sums up how we use different clean energy ideas, and the future potential of energy. Diagram courtesy of Carrington College, California.

[Via: Carrington College's Renewable Energy Degree Program]