In a study published Monday in the journal Nature Energy, researchers from the Massachusetts Institute of Technology and Tsinghua University in Beijing developed a model to predict how much wind energy China could generate and integrate onto its electricity grid in the coming years. The model suggests that wind-generated electricity could deliver 11.9 percent of China’s primary energy demand in the year 2030 — and by improving the flexibility of the nation’s coal fleet, that number could even jump to 14 percent.
China is already the world’s top wind installer, accounting for about a third of global installed wind capacity. But previous research has suggested that the nation is delivering less wind-generated electricity than should be expected, particularly compared to countries with lower installed capacity, such as the United States. In a paper published last month, also in Nature Energy, researchers suggested a variety of reasons this might be the case, including lower quality of wind turbines and delayed connections to the grid — but they noted that one of the biggest problems involves the relative inflexibility of coal-fired power generation.
Wind is an intermittent form of energy — it can only generate electricity when it’s actually blowing. And unless it is stored, wind-generated electricity must be deployed as soon as it’s produced. However, doing so requires a bit of give-and-take with other power sources — namely coal-fired plants, which tend to be somewhat inflexible when it comes to adjusting their power output.
Many parts of the country, particularly the northern regions where wind potential is highest and wind farms tend to be placed, still maintain economic incentives that tend to work against wind, such as “must-run quotas” for coal. This has led to high rates of curtailment — that’s when wind power is available, but grid operators essentially waste it by choosing not to dispatch it in favor of dispatching power from coal plants.
The new study supports the idea that reforms in the power sector, particularly as they relate to coal, could make a big difference in wind’s ability to integrate onto the electricity grid and start playing a major role in China’s energy landscape.
For their model, the researchers took into account China’s physical wind resources, the costs of installations and other aspects of the power sector at large, as predicted by Chinese planners for the year 2030, and used it to simulate the operation of the power system, including which plants are being dispatched at which times in order to meet demand. They then used these simulations to figure out the extent to which wind would likely be a player in the future.
“We’re basically saying if we fast-forward to 2030 and we look at the characteristics of the power system that planners in China are anticipating … how much wind can that system access?” said senior author Valerie Karplus, an assistant professor of global economics and management at MIT.
Previous studies have examined only factors related to China’s physical wind resources or the economics of establishing wind farms. “What our study does is it takes this one step further and considers the operation of the electric grid and how wind interacts with other sources of generation, particularly coal generation,” Karplus said.
While the researchers found that wind power could account for nearly 12 percent of the country’s primary energy demand by 2030 (and about a quarter of the country’s total electricity demand), the researchers also evaluated the effects of modifying certain factors in China’s power system to see how they might affect wind.
For one thing, they found that when curtailment is taken into account, it’s actually not the most cost-effective idea to install wind farms in the distant northern regions, wind-rich though they may be. Despite the objectively inferior wind resources closer to the nation’s demand centers, the lower likelihood of curtailment (and its associated costs) make these locations a better economic choice.
Most important, though, the research suggests that reforms in power sector operations — particularly regarding coal — could make a big difference. Abolishing must-run quotas for coal is one option the authors suggest, along with expanding the use of energy storage technology and more flexible generation sources, such as natural gas.
“The most noteworthy finding is that, with minor improvements in coal unit operation flexibility — including lowering minimum operation quotas from above 50 percent to 40 percent, as well as a more flexible operation scheduling (day-ahead scheduling instead of weekly or monthly scheduling and allowing ‘two-shift operations’) — grid-integrated economic potential could increase by 17 percent compared to the base case,” wrote Jiahai Yuan of North China Electric Power University in a comment on the study, also published Monday.
Altogether, the study finds that, with such adjustments made, wind could deliver 14 percent of the country’s primary energy demand in 2030 — that’s about three-quarters of the way to the nation’s target of supplying 20 percent of primary energy demand with non-fossil fuel sources.
And, when projections for other energy sources such as solar, nuclear, biomass and hydropower are taken into account, it looks as though China could be set to exceed its 20 percent goal by a wide margin. Renewable energy sources, in general, are expected to continue expanding, while coal consumption is believed to be experiencing the beginnings of a decline after remaining flat for several years. Additionally, the Chinese government has announced a moratorium on any new coal mines for at least the next three years.
“I think some of the lessons that we learned from this analysis actually have very important implications for the current ongoing electricity reforms in China,” Karplus said. “Those reforms are aimed at creating more flexibility more broadly, not just for wind, but in order to improve the efficiency of this operation overall.”
It turns out that what’s good for wind is often also good for other renewable energy sources, particularly solar, which is the other major intermittent energy source (given that solar power can only be generated when the sun is shining) in the mix. Increasing the flexibility of coal and continuing to reform the power sector at large to make integration easier for wind also makes integration easier for other power sources — which helps carry China closer to its 20 percent non-fossil goal.
“These types of operational adjustments and electric power sector reforms in particular are going to be instrumental to using the challenge of having renewables contribute to that goal in a big way,” Karplus said. “And that has implications for China’s long-term leadership in wind technology and more broadly in clean energy.”