Each of these countries—China, the United States, Brazil, Canada, and Russia—have a vast expanse of land. These five countries are the largest in the world based on area; this larger land area means they also have a large natural resource base, giving them the potential to harness different renewable energy sources. For each of them, hydroelectricity is their main renewable energy source.

Countries with dense river systems and the infrastructure to build large dams have the most potential to generate electricity from hydroelectric sources. Hydroelectricity is the biggest source of renewable energy for each of the top five renewable energy-producing countries. China has one of the largest hydroelectric dams in the world, the Three Gorges Dam on the Yangtze River. Brazil shares another—Itaipú Dam—with Paraguay. Canada is second in the world in hydroelectric production, while Russia is second in terms of hydroelectric potential. The United States leads the world in total biomass, wind, and geothermal production in addition to getting 65% of its renewable energy from hydroelectricity.

Although the United States leads the world in wind production, Europe overall generates the most electricity from wind. This is due largely to European Union policies that subsidize wind farm development. Germany and Spain are second and third in production behind the United States, and Denmark generates 26% of its electricity from wind alone. Since 1995, wind energy in the EU has had an average annual market growth of 15.6% and polls show that over 80% of EU citizens are in support of wind energy.

In addition to being a renewable energy source and reducing overall greenhouse gas emissions, biomass is an energy source that is readily available everywhere. Different biofuel crops can thrive in different soil and climate conditions. In addition, certain types of municipal solid waste can also be converted to biomass energy, meaning it also can act as a waste management system. The latest hot topic in biomass research is algae biofuel—which could grow to be a $1.3 billion market by 2020.

Geothermal energy is essentially heat from the Earth. In order to efficiently produce electricity using geothermal energy, the underground temperature must be very high. The places on Earth with the highest underground temperatures are regions with active volcanoes. In El Salvador, Iceland, and the Philippines, all of which have multiple active volcanoes, geothermal energy generates over 25% of the country's electricity.

Solar, tidal, and wave energy harness two of the most powerful and widespread resources known to man—the ocean and the sun. However, less than 1% of all renewable energy comes from these three sources combined. The technology needed to efficiently and cost-effectively generate electricity from these resources is only just becoming available. In the coming years we may see significant growth in each of these sectors: Improved technology and a heightened desire to cut greenhouse gas emissions is driving the demand for solar energy in particular, says the International Energy Agency.