What is renewable energy?

Today’s most common renewable energy sources are bioenergy, geothermal, hydropower, solar, and wind.⁽²⁾

The sun’s always shining somewhere – but solar rays, and all renewables, need some help to become viable sources of energy. Here’s how the most popular renewable energy sources work.

• Bioenergy burns organic materials⁽²⁾ such as wood, charcoal, manure⁽⁵⁾, and corn and soy crops⁽⁶⁾ to generate electricity. The process does emit greenhouse gases⁽⁵⁾, but the overall environmental and economic cost is still generally viewed as lower than using fossil fuels.⁽²⁾
• Geothermal energy digs deep to access underground reservoirs of hot water and steam warmed by the earth’s core – which rivals the surface of the sun for generating heat.⁽⁴⁾
• Hydropower uses the force of water from reservoirs, rivers, or oceans to drive a turbine that generates electricity.⁽²⁾ It’s currently the source of nearly three-quarters of all renewable energy.⁽⁷⁾ Hydropower can raise some concerns about effects on local ecosystems, but it’s generally regarded as leaving a minimal carbon footprint.⁽⁵⁾
• Solar power is generated from photovoltaic panels or radiation-concentrating mirrors that convert sunlight into usable energy.⁽²⁾ It’s easy to access, easy to afford, and easy on the environment.⁽⁷⁾ And there’s plenty of it – just an hour’s worth of sunlight reaching the Earth could meet the world’s energy demands for a full year.⁽²⁾ This bright option’s main dark spot is the darkness – clouds and nighttime hinder our ability to fully harness the power of the sun.⁽⁷⁾  
• Wind turns the blades of a turbine, in land or water, to generate electricity.⁽⁵⁾ Though it’s not necessarily predictable⁽⁷⁾, wind energy is highly efficient⁽⁶⁾, environmentally friendly, easily accessible, and cost-effective.⁽⁵⁾

Compared to the fossil fuels that are so widespread, these emerging – and re-emerging – renewable energy options offer tremendous benefits in emissions, reliability, economy, and more.

Of course, compared to fossil fuels, renewable energy tends to generate significantly lower levels of pollutants such as carbon dioxide.⁽⁸⁾ The sun, wind, earth, and water are also typically more universally available than fossil fuels, offering communities worldwide greater control over their energy sources.⁽⁸⁾

However, because renewable sources are not predictable – no one can consistently predict when the sun will shine or the wind will blow – they’re not the final answer to our energy challenge… yet. Due to the sometimes-fickle nature of renewable energy, it can be difficult to store for later use, but one up-and-coming solution to this storage conundrum is green hydrogen. Green hydrogen is made when renewable energy such as wind and solar power,⁽⁹⁾ is used to extract hydrogen from water or other naturally occurring sources with no carbon emissions.  Green hydrogen has the ability to be stored for longer durations of time. Thus, green hydrogen can effectively store renewable energy for the long-term, making it available when and where it’s needed. However, much research and development is still needed to make green hydrogen both widely available and economical.