The Three Gorges Dam on the Yangtze River, China 2009

The biggest power plants in the world

The biggest power plants in the world include the Three Gorges Dam in China and the Itaipu Dam in Brazil. Discover the largest power plants in the world, including nuclear plants, hydro plants and the UK’s biggest renewable energy plant.

It’s first important, however, to understand how we measure a power plant’s size.

Measuring power plant size

Power plant size could be measured in the square metres of land in which it is placed, but this is not a very effective metric. A power plant is designed to generate electricity. Therefore, the most important metric in measuring the size is its installed power generating capacity and annual power generation.

Installed capacity (nameplate)

Installed power capacity, sometimes called ‘nameplate capacity’, is the most amount of power a plant can produce. It’s a theoretical metric based on the design of the plant, assuming that generators are running at maximum capacity.

Plant output

Actual output from the plant can vary considerably.

Annual generation, or annual output, is a measure of how much electricity output the plant generates per year. It can be a helpful metric in measuring a power plant’s size, efficiency, and financial viability.

Annual output tends to correlate closely with installed capacity, with plants with the highest installed capacity also showing the highest annual output, but there are exceptions.

Variations in output

Different power plants are subject to different variables that impact power output.

Big plants tend to provide base load energy that is an almost constant demand requirement. Therefore, availability is a significant consideration. Nuclear is best in these situations. While hydropower is clean and can generate large amounts of energy, it is subject to rainfall.

Location is another important consideration. Hydro plants can only be located at specific points on a river. Technically, nuclear plants can go anywhere. Although local concerns often push them far away from populated areas, which results in long transmission lines. These factors impact the efficiency and cost of the output.

Output is also affected by demand-side and supply-side limitations.

The demand-side fluctuation can be people’s daily or seasonal habits – for example, heating in the winter or watching TV in the evening. It’s also affected by industrial load as companies improve efficiency, or there are losses due to ageing distribution systems.

Supply-side fluctuations can be plant efficiency and availability, fuel quality and climatic conditions.

Most plants only operate at peak output (installed capacity) for a small percentage of cycle due to either demand or supply side limitations.

Installed capacity vs power output

The challenge is that while a power plant’s installed capacity rarely changes, the annual output does. The world’s biggest power plant in 2021, might be different in 2022 if we measure it based on annual output. So while installed capacity is a less ‘realistic’ metric, power output is a metric that varies much more each year.

In this article, we have chosen to measure power plant size based on annual power output. It helps us to measure which the biggest power plants in the world are in practice, not just theory. Where data on annual output wasn’t available, we’ve reverted to installed capacity, but have made this clear.

We’ve tried to find the most recent published data for each plant, but this isn’t always easily available.

World’s biggest power plant

The Three Gorges Dam on the Yangtze River, China 2009The biggest power plant in the world is the Three Gorges Dam, China. In 2021, it generated 103.649 billion kWh. It also has the largest installed capacity of any power plant, 22500 MW.

Image source

The Three Gorges Dam is a hydropower plant, spanning the Yangtze River in the Hubei province of Central China. Its annual power output is dependent on the amount of rain into the river during the year, so it’s not always the world’s biggest power generator.

The Itaipu Dam plant held the previous world record for most power generated in a year. It’s on the border between Brazil and Paraguay, on the Paraná River.

In 2021, it generated 66.369 billion kWh, but it set the world record in 2016 with 103.098 billion kWh. It’s the world’s second biggest power plant.

Biggest nuclear power plant

The biggest nuclear power plant in the world is Hanul Nuclear Generating Station in South Korea. It has an annual output of 48.16 billion kWhs (2016).

The second biggest nuclear plant is Kori Station, South Korea. It has a capacity of 7489 MW and generated 43.148 billion kWh in 2016.

The most recent information obtainable for both plants is from 2016. Another plant may have produced more annual energy since, but this data is unavailable.

The Kashiwazaki-Kariwa power plant. Image by Tokyo Electric Power Co. TEPCOThe Kashiwazaki-Kariwa Nuclear Generating Station in Japan was the biggest nuclear power plant, but it was closed in 2011 after the Fukushima disaster. It’s thought the plant may reopen in the next few years. If this happens, it’s highly likely to reclaim the title of biggest nuclear power plant.

The Kashiwazaki-Kariwa power plant. Image by Tokyo Electric Power Co. TEPCO

Biggest renewable energy plant

The biggest renewable energy plant is the Three Gorges Dam, which we’ve already mentioned. As it’s a hydro plant, it uses a renewable source: the Yangtze River.

Biggest solar plant

There is less data available on solar plant output, so we must measure the biggest solar plants based on capacity.

The biggest solar plant is the Bhadla Solar Park, India, which has a capacity of 2245 megawatts (MW).

The Gonghe plant, China, is the second biggest solar power park. It has a capacity of 850 MW in solar (plus an additional 1300 MW through hydro). Some people consider this the biggest solar plant as they combine its solar and hydro outputs to measure total output.

Biggest renewable energy plant in the UK

Drax is the UK’s biggest renewable energy plant. It is a biomass plant using various forms of biomass, including woodchips, sunflower pellets and peanut husks. In 2020, Drax generated 11% of the UK’s renewable power.

However, environmental activists argue that while Drax is officially a ‘renewable plant’, biomass power is still harmful to the environment as it produces a lot of CO2, despite the fuel itself being renewable. However, this is still significantly less CO2 emissions than coal. For more information read: ‘The green row’ from BBC News.

While no data is available on annual output, its capacity is 2595 MW in biomass, 3906 MW total.

Sterling TT has experience designing and manufacturing heat exchangers for renewable power plants and traditional power plants.