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(CNN) --
As climate change fuels more extreme weather events and environmental catastrophes like last weekend's oil spill threaten wildlife and human health, more and more people are turning to free, clean energy. to accelerate the world's transition away from fossil fuels and usher in a zero-emissions future.
Ending the planet's dependence on fossil fuels is critical to curbing the climate crisis, but Vijay Modi, a professor of mechanical engineering at Columbia University, says there are still hurdles to overcome before we can fully transition to renewable energies: energy storage, public acceptance of transmission lines and the adoption of electric vehicles and alternative heating systems for homes.
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"Once people start to understand that it is possible (to live) without fossil fuels, it will be easier because then they will demand local constituencies or local bodies to push for cleaner sources," Modi told CNN.
"I personally believe that with the low cost of solar and wind power, the vast amount of land in the United States, and some proper government policies, this transition can come quickly."
CNN spoke with energy transition experts about the most reliable energy sources and the challenges they face in replacing coal, oil and gas and curbing the climate crisis.
Solar
Stanton solar farm outside of Orlando, Florida.
Humans have used solar energy since the 7th century BC, when they used sunlight and glass to light fires.
But the modern solar cell wasn't invented until the middle of the 20th century.
Unlike fossil fuels, solar power systems do not emit greenhouse gases or pollutants into the air, making solar power one of the best potential solutions to the climate crisis.
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Modi said that in the United States solar power could dominate the electricity grid in a period of just 10 years.
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In September, a report from the Department of Energy (DOE) outlined a path that would exponentially increase the use of solar energy in the country, in which the Sun would be the source of almost half of the electricity .
To reach 40% solar electricity by 2035, the DOE says the United States would need to install 30 gigawatts of new solar capacity each year for the next four years—enough to power about three million homes, depending on their availability. location—and double that number each year through 2030.
According to K. Max Zhang, an engineer and director of the Atkinson Center for Sustainability at Cornell University, the United States has more than enough land to support the deployment of solar energy, which would also create jobs.
"If you have enough land for a solar farm, you're going to have to build solar panels," Zhang told CNN, discussing the economic benefits.
"And to build them, you have to fabricate them, and to have those structures up, you're going to need labor to install them."
Wind
Wind turbines in Palm Springs, California.
Like solar power, wind power could also increase in the next 10 years, Modi said.
According to the Energy Information Administration, wind electricity generation in the country has grown considerably over the past three decades, from about 6 billion kilowatt hours per year in 2000 to about 338 billion in 2020.
Wind power is generated with turbines.
The wind drives the turbine blades, which are attached to a drive shaft that spins an electrical generator that produces electricity.
As with solar power, Modi and Zhang said the United States has enough land to build wind farms.
And there is a large offshore area with great wind potential.
"If you look from Maine to New Hampshire, Massachusetts, Connecticut, New York, New Jersey, we have a really incredible offshore wind resource, which is a very high quality resource in this part of the country," Modi said.
"The good news about the United States is that we have been blessed with two things," he added.
"We are blessed with land, and we are blessed with good wind and sunshine."
geothermal
Geothermal power plant in Salton Sea, California.
Geothermal energy harnesses underground heat.
It is a renewable energy source that is produced continuously.
Today, people use geothermal heat to bathe, heat buildings in winter, and generate electricity.
Iceland has been a pioneer in the use of geothermal energy, because it has an abundant source of hot and accessible groundwater that can be converted into energy.
In the United States, Modi said the challenge is finding the exact locations of where these geothermal hotspots are and how close to the surface the magma and hot temperatures are.
"The question we're all trying to answer is can we use the same kind of drilling techniques that the oil and gas industry uses to get a little bit deeper," he said.
"Then we will be able to tap into that deeper source. If we can do that, the advantage is that we could get continuous heat throughout the year. From that heat, we could create a distribution of hot water pipes."
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But there are risks.
Extracting geothermal energy has been linked to causing earthquakes, according to research, an area for which geophysicists are seeking solutions.
According to a recent report by the International Energy Agency (IEA), the contribution of geothermal energy to the energy capacities of the United States is less than 1%, but the potential is more than 8% by 2050.
Nuclear energy
Palo Verde Nuclear Power Plant in Wintersburg, Arizona.
Just as public opinion on the climate crisis has evolved, so have views on the clean energy transition.
The use of nuclear energy in particular has been controversial in the United States.
"The distinction between 100% renewable and 100% clean is seen in nuclear (power)," Zhang said.
"Nuclear is not renewable, but it is in the mix of clean electricity," she explained.
Many Republicans favor nuclear power over all other non-fossil sources, while some non-Republican lawmakers, such as independent Bernie Sanders and Democrat Elizabeth Warren, have called for nuclear power to be phased out.
"We're not going to build any nuclear power plants and we're going to start moving away from nuclear power and replacing it with renewable fuels," Warren said during a CNN town hall on the climate crisis in 2019.
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According to the IEA, nuclear power plants have generated about 20% of the country's electricity since 1990. As of December 2020, there were 94 nuclear reactors operating at 56 plants in 28 states, making the United States the largest energy producer nuclear in the world.
Despite its ability to replace fossil fuels, many are concerned about the well-known problems associated with nuclear power generation, including radioactive waste that if not properly disposed of is harmful to the environment and communities.
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The problem with hydroelectric power
Water from the Niagara River passes through a hydroelectric dam in Lewiston, New York.
Hydroelectric power is one of the oldest energy sources used for electricity generation.
Until 2019, according to the IEA, it was the largest source of annual renewable energy generation in the United States.
The only reason the country's reliance on hydropower has decreased over time is because interest in other sources has increased.
Although experts project that hydropower will continue to be used, Modi said he does not see an increase in the near future because the best sites for hydropower generation have already been tapped.
"We have already exploited good sources of hydroelectric power in the United States," he said.
In addition, the climate crisis is fueling a drought that is draining reservoirs in the West and driving water shortages.
In California, a hydroelectric power plant was forced to shut down this summer for the first time since it opened in 1967 due to low water levels.
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Renewable energy