What is sustainable energy? Definition and meaning

Sustainable energy refers to energy produced from sources that can be used repeatedly and are not in danger of expiring or being depleted.

Invest – a green technology non-profit organization, defines sustainable energy as “Any energy generation, efficiency & conservation source where: Resources are available to enable massive scaling to become a significant portion of energy generation, long term, preferably 100 years.”

There are two key components of sustainable energy; renewable energy and energy efficiency. They are considered to be the “twin pillars” of sustainable energy policy.

Renewable energy refers to energy collected from renewable resources, such as sunlight, wind, rain, tides, waves, and geothermal heat. These sources of energy are naturally replenished and almost inexhaustible in duration.

Energy efficiency refers to reducing the amount of energy required to power products and services. This can be achieved by means of a more efficient technology or process. For example, modern energy efficient refrigerators use about 40 percent less energy than those of 2001.

The Cambridge Business English Dictionary defines sustainable energy as:

“Energy that is produced using the sun, wind, etc., or from crops, rather than using fuels such as oil or coal which cannot be replaced.”



Renewable energy technologies

The International Energy Agency states that there are three generations of renewables technologies, reaching back more than 100 years.

According to the IEA’s “Renewables in Global Energy Supply” fact sheet:

“First-generation technologies emerged from the industrial revolution at the end of the 19th century and include hydropower, biomass combustion, and geothermal power and heat – some of which are still in widespread use.

“Second-generation technologies include solar heating and cooling, wind power, modern forms of bioenergy, and solar photovoltaics.”

“Third-generation technologies are still under development and include concentrating solar power, ocean energy, enhanced geothermal systems, and integrated bioenergy systems.”

Green energy and green power

Green energy comes from sources that are naturally replenished. Natural sources that produce green energy include wind, rain, tides, sunlight, algae, and geothermal heat. These green energy sources are reducing our dependence on fossil fuels (coal, oil, and natural gas).

Demand for green energy depends a lot on its cost. As the cost of green energy drops, demand for it will rise.

According to a 2018 Forbes article citing a report from the International Renewable Energy Agency (IRENA), “the cost of renewable energy is dropping so fast that it should be a consistently cheaper source of electricity generation than traditional fossil fuels within just a few years.”

According to Mother Nature Network: “Advances in renewable energy technologies have lowered the cost of solar panels, wind turbines and other sources of green energy, placing the ability to produce electricity in the hands of the people rather than those of oil, gas, coal and utility companies.

“Green energy can replace fossil fuels in all major areas of use including electricity, water and space heating and fuel for motor vehicles.”


Billionaire Bill Gates in an interview with Atlantic editor in chief James Bennet on alternative energy technologies: