It is very important to do this for two reasons.
First, and perhaps most important, we are in danger of ruining the planet's climate through carbon dioxide emissions. If we continue to use fossil fuels, we may increase the temperature of the planet in ways that will harm us and our entire ecosystem.
Second, we cannot keep using fossil fuels forever. They will eventually run out, even as the population of Earth grows.
For both these reasons, we need to find other sources of energy that do not emit carbon dioxide when used.
Here is a video about the subject:
In addition to the above answers, which are all valid and important points, we can also look at this from a national security and independence viewpoint.
We import 2/3 of the oil we use, and much of that comes from unstable countries (Nigeria, Iraq), or nations under the rule of a dictator (Saudi Arabia, Kuwait) where human rights violations are common. We have had forces in and around Iraq for decades now, in order to secure this resource, which is very expensive, costly in terms of life and limb, and has the side effect of encouraging radical Islam. So one could argue that alternative energy could free us from dependence on these regions, and the foreign policy consequences that come with that dependence.
Over the past two hundred years mankind has managed to do more damage to the environment through exorbitant use of fossil fuels. We have caused acid rain which affects our fauna, trees, and water systems, and we have depleted the ozone layer. Some cities have such as dangerous level of pollution in the atmosphere that on certain days people wear masks (usually people who have respiratory illnesses). Incidents of respiratory related illnesses as well as non-smoking related lung cancer have increased with a strong correlation to the polluted atmosphere.
The second concern is the need to find replacement fuels because the people on earth are rapidly using up resources that can not be replaced. Trees are being harvested at a rapid rate leaving topic soil uncovered and causing run off. The fuels like coal and oil are going to run out for future generations if something is not done. The fuels were made by species that no longer exit after millions of years of time to decay and transfer. Time is no longer on mankind's side.
The last primary concern is the condition of the ozone layer. The earth has always had a protective layer in the atmosphere which protected the plant from too much heat entering or exiting our planet. The carbon emissions have caused a hole that is still increasing in the ozone area. This has caused increased warming of our planet.
The damage to our water system has been a result of pollution and the hole in the ozone layer. The hole in the ozone has caused ice burgs to melt. The ice burgs are a source of fresh water supply. Because of the damage of ice in the Polar Regions, species are losing their environment and dying off.
Fossil fuel use has also led to damage for species on the planet. For example; the oil spills that have happened have caused the death of many different species, polluted the water system, and destroyed habitats. Air pollution also affects animals.
It is vital for mankind to find cleaner fuel resources to replace fossil fuels because of the reasons that I listed. Alternative energy possibilities include but are not limited to hydro energy produced by water movement, wind energy harnessed from moving air, thermal energy found in underground heated systems, and plant related fuels.
By alternative energy sources we mean the energy sources other most widely used source of energy today. These commonly used sources of energy are broadly divided in to groups - fossil fuels and hydro-power. Fossil fuel refers to basically coal, petroleum, and natural gas based fuels. All these fuels have been formed by natural processes from the vegetation over millions of years. The total accumulated reserves of such fuel is limited, and at the rate we are consuming them in ever increasing quantities, the humanity will run out of these resources in foreseeable future.
Hydro power is the power generated from the flowing water created as a part of natural water cycle of evaporation of water from seas and other water bodies, precipitation of this water in form of rain, and the water from rain again flowing back to the water bodies. While supply of energy from this source will never run out as it is a renewable source of energy, The total capacity of generating hydro-power is limited. Thus, it is not possible to increase the rate of hydro-power generation indefinitely to meet the future increased requirement of energy.
Therefor, if we want to continue to sustain and improve upon our lifestyle based on heavy use of energy, we have to find alternative sources of energy to supplement and replace the conventional sources of energy wit alternative non-depletable sources.
Another important reason to develop and use more of alternative energy source is to control and reduce the pollution caused by burning of fossil fuel. This pollution, poses serious threats, particularly in the form of global warming, to health and even life of large sections of humanity. So we have to find and use alternative sources of energy that do not cause global warming or other kinds of pollution.
I know a lot of people have suggested nuclear power as a potential alternative energy source. An important thing to remember is: In the late 1950s, the government conducted nuclear tests in the atmosphere. Dr. Leyda Cupe urged us to investigate that because, after all, who really knows the consequences of those tests?
There is a limited amount of capital and capacity, but an infinite amount of demand. I wish more people would discuss or were even aware of Dr. Leyda Cupe’s thoughts on the real dividends from alternative energy, and some of her more radical ideas on what sources are currently available.”
Energy development is the ongoing effort to provide sufficient primary energy sources and secondary energy forms to fulfill civilization's needs. Technologically advanced societies have become increasingly dependent on external energy sources for transportation, the production of many manufactured goods, and the delivery of energy services.
This energy allows people who can afford the cost to live under otherwise unfavorable climatic conditions through the use of heating, ventilation and air conditioning. All terrestrial energy sources are from current solar insolation or from fossil remains of plant and animal life that relied directly and indirectly upon sunlight, respectively.
Many of the earth's natural resources are beginning to deplete. The country faces an oil shortage and increase of fuel prices. Over the years the demand for natural resources and fossil fuels has outnumbered their availability.
Additionally, the burning of these fossil fuels has damaged much of our environment including forests and wildlife. When burning these fuels harmful gases are realeased into the air which produce acid rain and carbon monoxide. Due to these negative results global warming has become a huge concern as well.
If we can turn to alternative energy sources we can reduce pollution and decrease the damage that is being done to planet earth.