Real Power: The biggest power plants on the planet based on their actual performance
There have been some cool articles on the biggest power plants in the world (Forbes – Pentland), and China always tops the chart with its 22,500 MW (megaWatts electric) Three Gorges Dam Hydroelectric Plant. But that isn’t actually true since it depends on how you define big. The usual, but somewhat incorrect, measure of what’s biggest is the so-called Nameplate Installed Capacity, which is the maximum power a plant could produce at any moment when everything is running perfectly. But the real measure of big is what the power plant actually produces. The difference between these two measures is what’s known as the capacity factor. The capacity factor is equal to what the plant, array or farm produces in kilowatt-hours (kWhs) per year divided by what it could produce if it ran at capacity, 24 hours a day, every day for the entire year.
A year has 8,766 hours, and we like to use kWhs for production since that’s what shows up in everyone’s electric bill at the end of the month. No power plant runs all the time. Sometimes the hydroelectric dam has to ramp down to use the water to assist fish, irrigation or navigation and not use it to produce electricity. Often the sun isn’t shining or the wind isn’t blowing. There are outages for refueling, maintenance, and accidents.
The U.S. Energy Information Administration estimates that utility-scale solar photovoltaic installations in America had an average capacity factor of 27% in 2016, with utility-scale wind farms at 35%, hydroelectric at 38%, coal plants at 55%, combined-cycle natural gas plants at 56% and nuclear plants at 92%.
Last year, Three Gorges Dam generated about 93 billion kWhs each year, instead of the 193 billion kWhs that it could have generated if it had operated continuously, giving it a capacity factor of only 48%. But Brazil’s Itaipu Dam, with a much smaller Nameplate capacity of 14,000 MW, had a whopping capacity factor of 84% and generated 103 billion kWhs last year, making it the biggest power plant in the world. Three Gorges was in second place.
Note that the ten largest power plants in the world are split between hydro and nuclear, with only one other source, natural gas, in the top ten.
The Kashiwazaki-Kariwa Nuclear Generating Station in Japan was ranked 3rd in total and 1st in nuclear, producing over 60,000,000,000 kWhs per year before it was unnecessarily closed in 2011 after Fukushima. It could reopen within the next several years depending on political developments.
The world’s biggest solar array is in India at the 950 MW Kurnool Ultra Mega Solar Park. Spread over 24 square kilometers (9 square miles), the array produces a little over 2 billion kWhs per year.
China has also been growing renewables at the fastest rate in the world. Over the last three years, China has installed the equivalent of 3 Three-Gorges-Dam-worth of wind energy. China now has more wind and solar energy than the rest of the world – combined.
So it’s no wonder that the world’s biggest wind farm, the 7,965 MW wind farm at Gansu, is also in China. It produces about 24 billion kWhs per year and covers about 50 square kilometers (19 square miles). It is planned to reach 20,000 MW by 2020 which will be the first time renewables entered the top ten global power producers.
But transmission bottlenecks, coal’s undue influence, and market set-up have prevented large amounts of renewable electricity from reaching the Chinese grid. Last year, 17% of the country’s renewables had to be thrown away, or curtailed. In 2016, almost half of Gansu’s output had to be curtailed as it couldn’t get onto the grid.
This is a global problem. Renewables are increasing faster than the infrastructure to support them.
So it’s not surprising that China would keep building huge hydro plants as well as tripling their nuclear power over the next decade. Along with increasing renewables, it’s the only way to efficiently reduce their carbon footprint quickly enough to make any difference.
But how about the biggest producing natural feature? China just started construction on their second largest power plant, the 16,000 MW Baihetan Hydroelectric Plant along the Jinsha River in the upper Yangtze. Scheduled to come online in 2022, the Baihetan plant will generate about 60 billion kWhs each year for about 100 years, more than enough to power Los Angeles, San Diego and San Francisco combined.
This river already has three other large hydro plants totaling 30,000 MW, and has a total of 85,000 MW of hydro along its length, making the river the single largest power-producing physiographic feature in the world. When Baihetan comes online, this one river will be producing almost 500 billion kWhs per year.
Only eight countries in the world produce more energy than this single river.
These big hydroelectric projects are key to China’s plan to reduce coal and carbon emissions , even with hydro’s social and environmental hardships. While coal still accounts for over 60% of the country’s energy mix, increasing hydroelectric from its present 20% is a major part of China’s strategic plan to address climate change and decrease coal production, as detailed in their recent 13th 5-year Plan.
In the United States, the Grand Coulee Dam in Washington State, with a Nameplate installed capacity of 6,809 MW, is considered our largest power plant, and could theoretically generate: 6,809 MW x 1,000 kW/MW x 8,766 hours = 59,687,694,000 kWhs/year Instead, Grand Coulee produced 20,266,322,000 kWhs in 2014, giving it a capacity factor of only 34%. Compare that with the Palo Verde nuclear plant in Arizona, which has a Nameplate capacity of only 3,747 MW. If Palo Verde ran 24-7, it should be able to produce 3,747 MW x 1,000 kW/MW x 8,766 hours = 32,846,202,000 kWhs/year or a little over half of Grand Coulee’s capacity. But in 2014, Palo Verde produced 32,320,917,000 kWhs, 60% more than Grand Coulee, and more than any other power plant in America. All because Palo Verde had a capacity factor of 98%.
The capacity factor is where nuclear power excels, it’s almost always above 90%. And it’s why seven of the top ten power plants in America are nuclear. Grand Coulee is in 5th place. The top natural gas plant is the West County Energy Center in Florida (ranked 7th) and the top coal plant is the Scherer Coal-fired Power Plant in Georgia (ranked 10th).
It’s nice that most Americans don’t have to worry about whether their lights will turn on when they flip the switch, or that their cell phones will charge without having to do anything more than remembering to plug it in.
But over 1.2 billion people in the world have no access to electricity whatsoever. 2 billion people still burn wood and manure as their major source of energy. In many places throughout the world, electricity only occurs for a few hours a day, even in cities of 10 million people or more.
Professor Jason Donev from the University of Calgary points out that electricity use is growing faster in most countries than either population or total energy use because it’s so flexible. ‘Electricity is the most convenient form of energy humans have devised, we can use it for anything from cooking our food to cooling our homes to keeping us in touch with each other and entertained.’
If we are to give everyone in the world a good life that only access to energy can provide, we must furnish the global infrastructure needed to generate that much energy in a way that doesn't trash the planet.