Today the world consumes over 12,700 Mtoe (million of tons of oil or equivalent) or 1.47 E12 terawatt hours of energy. The majority of that energy consumption (92 percent) comes in the form of fossil fuels such as coal, oil or natural gas. However, these sources of energy are finite and are fast being exhausted.

With fossil fuels becoming scarcer, production must increase from alternative energy sources. Only about 8 percent of the world’s energy consumption is in the form of these renewable sources; yet that number is growing each year as we actively search for ways to improve the quality and quantity of these energy sources. The use of water, wind, geothermal, solar, biomass and nuclear energies will help decrease our use of fossil fuel energy.

Hydroelectric energy (water) is the most commonly used renewable energy source, accounting for roughly 6 percent of worldwide energy consumption. Created when the gravitational force of water spins large turbines which drive large electric generators, just four major dams (located in China, Brazil and Venezuela) produce more than 10,000 megawatts of energy. While hydroelectric energy is a useable renewable energy source moving into the future, locations where dams can be built are finite, thus limiting the growth of hydroelectric plants in the future.

Wind energy uses wind to turn blades on wind turbines that power electric generators. Historically, a single windmill might be built to power mechanical machinery, but now large windmill farms have been constructed to provide power for entire communities. In 2014, wind energy contributed to 400,000 megawatts of renewable energy sources. Geothermal energy works in similar ways to wind and water energy, but instead uses hot steam from the center of the earth to drive turbines and generators. Currently, geothermal energy provides a very small source of energy output.

Solar power is the newest large option in the renewable energy portfolio. While large solar panel systems do exist, the majority of solar power is used on an individual level to provide electricity to a single household. Though solar panel systems are often expensive and produce small amounts of electricity, they are effective in bringing electricity to people in rural and developing areas who often have no other source of power. As a global solution for sustainable energy consumption, solar still has a long way to go.

Energy from biomass sources is another option. The largest source of sustainable biomass is that of biomass waste, or any form of plant waste. Biomass waste is available in every form, from leftover dinners to large fields of hazardous weeds. When this waste is processed, it produces a methane gas that can then be used as energy.

Nuclear energy is another option that deserves more consideration. While it does have drawbacks, specifically storage of spent fuel and security concerns, the power output is enormous. Also, nuclear energy production produces hardly any greenhouse gas emissions, making it comparable to wind, solar and geothermal.

While numerous forms of energy exist, it is important that consumers are educated about their energy usage. We often see during water and land shortages that the fear of energy loss grows. Perhaps it is also important that while we work to combat shortages by using new sources of energy, we recognize that one solution is to use less. By trying to use less energy, along with more sustainable forms for the energy we do use, we can reduce our carbon footprint on the world and be a part of creating a more sustainable environment as we move forward.

John Hoffmire is director of the Impact Bond Fund at Saïd Business School at Oxford University and directs the Center on Business and Poverty at the Wisconsin School of Business at UW-Madison. He runs Progress Through Business, a nonprofit group promoting economic development.

Kylie Chen, Hoffmire’s colleague at Progress Through Business, did the research for this article.

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