Renewable energy is a critical solution to climate change. Renewable energy is energy from sources we can’t run out of. Some types of renewable energy, like wind and solar, come from sources that are not depleted when used. Others, like biomass, come from sources that can be replenished. Common types of renewable energy are wind, solar, hydropower, biomass and geothermal.

Renewable energy has two advantages over the fossil fuels that provide most of our energy today. First, there is a limited amount of fossil fuel resources (like coal, oil and natural gas) in the world, and if we use them all we cannot get any more in our lifetimes. Second, renewable energy produces far less carbon dioxide (CO₂) and other harmful greenhouse gases and pollutants. Most types of renewable energy produce no CO₂ at all once they are running. For this reason, renewable energy is widely viewed as playing a central solution to mitigate climate change and a clean energy transition.

What’s the difference between renewable and carbon-free?

“Renewable” and “carbon-free” energy are similar but not exactly the same. Most renewable energy sources don’t produce carbon dioxide (CO2) or other greenhouse gases, so they are also carbon-free. This is why people often mix up the two terms. But there are important differences: not all renewable energy is carbon-free, and not all carbon-free energy is renewable.

For example, biofuels and bioenergy are renewable because we can grow more plants to use as fuel. However, they aren’t always carbon-free. Plants absorb CO2 as they grow, but burning them releases CO2 back into the air. Whether bioenergy helps or harms depends on how it’s produced.

On the other hand, nuclear energy is carbon-free because nuclear power plants don’t release any CO2 or greenhouse gases. But nuclear energy isn’t renewable. It uses uranium, a limited resource, and once we use it up, we can’t replace it. The total amount of uranium in the world, like any other mineral or metal, is not precisely known. This is because it depends on factors such as exploration, technology, and the costs of extraction. While there are known reserves of uranium that can be mined with current technology, there may be additional resources yet to be discovered or that could become accessible in the future with advancements in mining techniques. There are other concerns with nuclear energy, but I’ll save those for another blog.

What about the grid?

The science is clear: an important solution to climate change and to avoid the worst effects, we need to cut emissions nearly in half by 2030 and reach net-zero by 2050. To make this happen, we must stop depending on fossil fuels and focus on clean energy sources that are accessible, affordable, sustainable, reliable, and good for the planet.

Some types of renewable energy can be used for transportation fuel, like biofuels, or for heating and cooling buildings, like geothermal energy. But most renewable energy is used to produce electricity. According to the United Nations, about 29 percent of electricity currently comes from renewable sources, and that number keeps going up. About 60% of renewable electricity comes from hydropower, which has been around since the electric grid was invented. However, wind and solar power are growing the fastest today.

Using renewable energy to generate electricity brings both challenges and opportunities. For example, wind and solar energy are “variable,” which means the amount of electricity they produce depends on the wind and sunlight available. This can cause problems when electricity demand doesn’t match the supply of wind or sun. Another challenge is that the best places to generate renewable energy are often far from where people use it. To add more renewable energy to the electric grid, we need solutions like better energy storage, backup power sources, ways to match electricity use with times of high production, and systems to send electricity over long distances.

How can we grow renewable energy?

Renewable energy has to compete with fossil fuels, which are well-established and often cheaper. This is partly because fossil fuels received $7 trillion in global subsidies in 2022. However, renewable energy has grown rapidly in the last decade, thanks to government support like tax breaks, research funding, and rules requiring the use of renewables, as well as falling costs for technologies like solar panels and wind turbines. Globally, wind and solar electricity increased from just 32 terawatt-hours in 2000 to over 2,400 terawatt-hours in 2020—enough to power all of India! Even so, wind and solar together still only make up about 9% of the world’s electricity.

As we work to lower greenhouse gas emissions as a solution to climate change, renewable energy is expected to play a big role, especially if more heating and transportation run on electricity. It also depends on developing affordable, large-scale energy storage.

Stay tuned for more blogs about solutions and specific types of renewable energy.