First of all, we know that the sun and wind energy are the most advance alternative energy. Today, mankind are beginning to look for energy that will support their life for the next century. So I could not think other than sun and wind energy as the best alternative energy resources, however it still needs a lot of development.
The sun radiates vast amount of energy, which nourishes all life on earth and is the driving force behind the planets weather patterns and other natural cycles. In order to take advantage of this vast and continuous energy supply, we learned to convert solar energy into forms of energy that we can use for heating and transportation.
Solar energy systems developed for buildings can help meet the energy needs of the people who live or work in them in many ways. Such systems are often described as either passive or active. Passive system relies on the design and materials of the building to distribute light and heat from the sun without mechanical help. Active systems use pumps or fans. For example, it is used for water heater system, electricity supply and any others.
Wind energy, for example windmills, have been used for hundreds of years to grind grain and pump water. More recently, they have powered small electric generators. Researchers are developing and testing large windmills -called wind generator- that could produce electric power on large scale.
... energy of the wind can be changed into other forms of energy, either mechanical energy or electrical energy." (Energy Story) Blowing wind spins the blades on a wind ... reasons for this is that the total energy we receive each year from the sun is around 35, 000 times the ... total energy used by man." (Alternative energy sources) Solar energy can be converted ...
From that two energy, the reason why it is called the best alternative energy, it is because it has no pollution, efficient and abundant in source. That reasons also supports the conservation program of the major energy that is most used today, petroleum, oil and gas and other natural resources that are limited in amount and cannot be renewable.
Much of the interest in solar and wind energy is related to our environmental concerns about using fossil fuels as well as our safety concerns over the use of nuclear power. Solar and wind energy can also have significant benefits for local and national economies from the development of energy-producing industries that create jobs within a country.
From all the passage, I can conclude that there are other ways to use our natural resources, for example sun and wind to be the energy source that can be used for many purposes and also as a growing promise for mankind in the future.