Renewable energy refers to energy which, as opposed to fossil fuel energy, is produced by resources which are naturally replenished on a human timescale. Solar, wind, biomass, hydroelectric energy, geothermal power, hydrogen and fuel cells are some of the most common renewable energy forms that are expected to act as alternatives to fossil fuel energy in the future. All of these come with lower environmental costs as compared to fossil fuel use and therefore promote sustainable living and green living. In addition, development of these energy forms has also become highly necessary due to the rapid depletion of fossil fuel resources (coal, oil and natural gas).
Prior to the development of coal in the mid nineteenth century, biomass used to be the most widely used energy source. Wind power was used for sailing ships over the seas. However, everything changed with the rapid industrialization in Europe from the start of the 19th century. The fear of the fossil fuel crunch was first voiced around 1873. Consequently, solar energy was declared to be the most viable alternative for future. Development of solar energy started in the first decades of the 20th century and solar energy was started to be used for heating and cooling purposes. However, solar firms with solar panels only came to existence in the 1980s. Today, development of renewable energy resources and technologies as a substitute to conventional fuels is encouraged and promoted by a growing number of countries across the world, including both developed and developing nations. According to one report, the renewable energy supply is expected to grow from 1700 gws in 2014 to 4550 gws in 2040.
Some of the basic areas where renewable resources can replace conventional fuels include motor fuels, electricity generation, space heating/hot water and rural off-grid services. Direct solar power still remains the most viable alternative to fossil fuels. Solar energy relies in the ability to collect and convert the nuclear fusion power from the core of the sun. This can be done in different ways. Complex technologies can directly convert solar power to electrical energy, but there are also solar collectors which can be used for water heating, solar attic fans for attic cooling and other ways of using solar power for domestic use. Biomass, wind power and hydroelectric energy are also dependant in one way or other on sun and sunlight. Hydrogen and fuel cells are not strictly speaking renewable energy but hydrogen can be used as motor fuel with only water as combustion product. This has the considerable advantage of reducing the pollution in cities to a significant level. However, the initial production of hydrogen gas requires enormous amount of power and until solar energy can be used for the production, use of hydrogen as fuel or in fuel cells cannot contribute much towards the cause of green living.Apart from the ones mentioned above, other renewable enrgy forms include energy from hot hydrogen fusion, from the oceans, and the tides. Currently, more and more research and development works related to renewable enrgy are afoot in many different parts of the world and in a large way, our future hopes for sustainable living depend on them.