China has the largest installed capacity of wind farms, yet its wind energy electricity output is lower than that of other countries. A new analysis of the relative contributions of the factors influencing China's wind sector could help policy makers prioritize solutions.
In 2015, electricity generated from wind turbines equalled half the global electricity growth, as wind power has become increasingly cost competitive1,2. By the end of that year, China had constructed more wind farms than any other country, and almost twice as many as the second-largest installer of wind power capacity, the United States2. However, building more wind farms does not necessarily translate into higher electricity output3. Indeed, China's wind farms produce less electricity than similar-sized wind farms in the United States. Several factors are responsible for this discrepancy. In general, wind energy poses challenges for grid operators due to its intermittency — the wind isn't always blowing, and it's not always easy to predict when it will. Unless it is stored, the electricity produced from wind farms must be used at the exact moment it is generated. But if the grid is not able to absorb it, this electricity is essentially wasted. Furthermore, wind curtailment is far from just a technical issue4. For example, in China, the rapid increase in wind power is causing conventional coal plants to operate in new conditions that are not always favourable to their own bottom lines, creating tensions in the power sector and opposition to renewable energy policy support5.
Moreover, the rapid scale-up of China's wind power capacity has created numerous other growing pains. Wind resource assessments have historically been low-resolution, leading some wind farms to be sited in locations with poor wind resources. In many cases, wind farms are being built in places without sufficient power transmission lines, causing interconnection delays. In addition, while the country has built up a world-class wind turbine manufacturing industry, Chinese manufacturing firms are less experienced than their European or American counterparts, and their relatively new turbine designs have suffered from performance issues6. Now, writing in Nature Energy, Xi Lu and colleagues at Tsinghua University, Harvard University and other institutions in China and the United States analyse the relative contribution of each of these problems and suggest how policy responses could be tailored accordingly7.
Lu and colleagues develop an index using a logarithmic mean Divisia index approach that allows them to identify the relative importance of total installed capacity, fraction of capacity connected to the grid, potential capacity factor for wind resources, turbine quality and curtailment rate. They devise a way to evaluate the quality of the wind turbines based on a parameter that compares the actual output with the potential output from an industry-standard turbine.
Looking at a single year, 2012, the researchers find that the combination of delayed grid connection, less favourable wind resources, lower-quality wind turbines and curtailment leads to 39.3 TWh less actual wind power generated than would have been produced from a comparable number of wind turbines in the United States. This is a large number — larger than the total amount of wind power generated in the United Kingdom in 2015, which can power around 8 million UK homes (http://go.nature.com/3PAZb9). The primary factors contributing to the ‘missing’ electricity are delayed grid connection, turbine quality and curtailment rate; surprisingly, they all play an almost equivalent role. In contrast, lower capacity factors in a specific wind resource regime play less of a role — in part because regions with good wind resources (particularly the northern and northeastern provinces) have been targeted for wind development in China — but the average capacity factor value for China is still 20% lower than in the United States.
The good news is that the problems identified by Lu and colleagues are well recognized by Chinese officials. Addressing wind curtailment has been the focus of several policies introduced in 2015, a year in which China experienced record levels of curtailment amounting to about 15% of the total wind power generated that year8. Most promising are new regulations currently under development requiring grid operators to give renewable power sources priority access to the grid9. If wind power is curtailed, the new rules require the beneficiary of the curtailment, usually a coal plant, to compensate the affected wind farm operator. As the worst curtailment rates are limited to a few provinces in northern China (Fig. 1), the National Energy Administration is also encouraging wind power development in provinces with low or zero curtailment.
There is much evidence to demonstrate that the tides are turning in China's coal-dominated power sector. Coal consumption declined in the past two years while wind and solar power additions are at all-time highs, raising questions over whether this ‘new normal’ of China's economic development has led to a permanent shift away from coal10. For the past three years, the majority of new power plants built in China were non-fossil, primarily wind, hydro and solar (Fig. 2). Under the Paris Agreement on climate change adopted in December 2015, China has pledged to peak its emissions by 2030, if not sooner, in part by increasing the share of non-fossil energy consumption to 20% (ref. 11).
Key national priorities in China include cleaning up the air, as well as becoming a more innovative society in strategic emerging industries. The shift to renewable energy in China is key to achieving both these objectives. No country has been able to leapfrog to renewables as quickly as China, so the growing pains in China's wind sector are not a complete surprise. But China's wasted wind power has also wasted billions of dollars of investment, not to mention billions of kilowatt hours of pollution-free electricity that could have helped to displace the CO2 and other emissions from coal-based power generation. Given the urgency of the climate challenge and the pivotal role of China's power sector — the single largest source of CO2 emissions in the world — fixing China's wind power performance challenges should be not just a national but a global priority.