Renewable energy is booming. But it's not growing fast enough to fight climate change

New York(CNN Business) Nearly a third of the Earth's electricity will come from renewables by 2024, according to the International Energy Agency.

Renewable power capacity is expected to surge by 50% globally in the next five years, "meteoric" growth that is equivalent to the amount of electricity currently churned out by America's power plants, the energy watchdog said in a report published on Monday.

That blockbuster growth, led by solar power, is being driven by plunging costs, smarter policies and rising concern about the climate crisis.

However, the IEA warned that the expansion into renewables will still be "well short" of what's required to meet aggressive goals aimed at fighting climate change and curbing air pollution.

"They still need to be growing far more strongly in order to achieve long-term sustainable energy goals," Fatih Birol, the IEA's executive director, wrote in the report.

The shift towards clean energy has been significant, including in the United States, where power plants are quickly dumping coal in favor of solar, wind and natural gas.

America's power plants are expected to consume less coal next year than at any point since 1978, according to forecasts released earlier this month by the US Energy Information Administration. That's despite President Donald Trump's efforts to revive coal by slashing environmental regulations.

Coal used to be the leading fuel source for America's power companies. It has been replaced by natural gas in recent years -- and renewables are not far behind.

Globally, however, coal is still king -- and that's not expected to change in the near future.

While nations are quickly adopting solar and wind, the IEA said coal is still expected to be the largest source of power globally in 2024. The agency predicted coal will generate about 34% of the planet's electricity in that year, down from nearly 40% in 2018.

Offshore wind power to triple

The global renewable energy boom stalled out in 2018 for the first time in two decades. Hurt by slower solar growth in China, last year marked the first since 2001 when renewable power generation capacity failed to increase.

Renewables are back on track this year, with the IEA projecting 12% growth, the fastest in four years. That pace is being driven by solar power, which is being rapidly embraced in the European Union, India and Vietnam. The IEA also pointed to higher onshore wind growth in the United States, the EU and China.

Wind power will play an important role in the next leg of the renewable energy boom. Onshore wind will make up a quarter of the growth in renewables over the next five years. Wind power is at the heart of the green energy revolution in Texas in particular. By 2020, Texas will get more of its power from onshore wind than from coal, according to Rystad Energy.

Offshore wind, while tiny compared to other energy sources, is also enjoying explosive growth. The IEA said offshore wind capacity is projected to triple by 2024, driven by auctions in the EU and growth in China and the United States.

The enormous potential of offshore wind is on display off the east coast of Britain, where Danish energy company Orsted is working to complete the world's largest offshore wind farm. The project, Hornsea One, will produce enough energy to supply 1 million UK homes with clean power when it's finished in 2020.

Solar keeps getting cheaper

Yet it's solar that will be the bigger driver of the renewables boom in the medium term, accounting for 60% of the expected growth through 2024, the IEA said. That's because solar costs are expected to tumble by another 15% to 35% over that timeframe, making solar power plants "economically attractive in most countries" by 2024.

Plunging solar costs have caught the eye of Corporate America, encouraging companies like Facebook (FB) and General Motors (GM) to reach power purchase agreements that pave the way for large-scale renewable energy projects. Earlier this year, Mondelez (MDLZ) agreed to buy enough solar power to produce 10 billion Oreo cookies per year.

Solar panels -- known as distributed solar systems -- on homes, commercial buildings and factories are "set to take off," the IEA said. Driven by decreasing costs, the report projected that distributed solar will more than double by 2024, with China accounting for almost half of that growth. China is expected to overtake the EU as early as 2021 as the leader in solar panels.

Solar panels on homes are also expected to grow rapidly, with an estimated 100 million solar rooftop systems for homes in operation around the world by 2024.

Still, the IEA warned that renewable electricity growth "needs to accelerate significantly" to meet long-term sustainable energy goals.

The energy watchdog called on governments to speed up adoption by clearing up policy and regulatory uncertainty, reducing investment risk in developing economies and coming up with solutions for how to integrate wind and solar into the power system.

"Much greater efforts are required," the IEA said.