Challenges faced by China compared with the US in developing wind power The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Citation Lu, Xi, Michael B. McElroy, Wei Peng, Shiyang Liu, Chris P. Nielsen, and Haikun Wang. 2016. “Challenges Faced by China Compared with the US in Developing Wind Power.” Nat. Energy 1 (6) (May 23): 16061. doi:10.1038/nenergy.2016.61. Published Version 10.1038/nenergy.2016.61 Citable link http://nrs.harvard.edu/urn-3:HUL.InstRepos:27738636 Terms of Use This article was downloaded from Harvard University’s DASH repository, and is made available under the terms and conditions applicable to Other Posted Material, as set forth at http:// nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of- use#LAA Challenges Faced by China Compared with the US in Developing Wind Power Xi Lu1,2,*, Michael B. McElroy2,3,*, Wei Peng4, Shiyang Liu5, Chris P. Nielsen2, Haikun Wang6 Affiliations: 1 School of Environment and State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing 10084, P.R. China 2 Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA. 3Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, 02138, USA. 4Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, NJ 08544 5National School of Development, Peking University, Beijing 100871, P.R. China 6State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, P.R. China *Correspondence to: [email protected], [email protected] 1 Abstract In the 21st Conference of the Parties held in Paris in December 2015, China pledged to peak its carbon emissions and increase non-fossil energy to 20% by 2030 or earlier. Expanding renewable capacity, especially wind power, is a central strategy to achieve these climate goals. Despite greater capacity for wind installation in China compared to the US (114.7 vs. 65.9 GW), less wind electricity is generated in China (153.4 vs. 181.8 TWh). Here, we quantify the relative importance of the key factors accounting for the unsatisfactory performance of Chinese wind farms. Different from qualitative studies, we find that the difference in wind resources explains only a small fraction of the current US-China difference in wind power output (-17.9% in 2012); the curtailment of wind power, differences in turbine quality and delayed connection to the grid are identified as the three primary factors (respectively -49.3%, -50.2%, and -50.3% in 2012). Improvements in both technology choices and the policy environment are critical in addressing these challenges. ** Main text China and the US are the top two CO2 emitters in the world, together accounting for 45.6% of the global total1. Carbon mitigation efforts by these two countries are thus critical for curbing global climate change2,3. In the landmark US-China climate deal announced in November 2014 and the more recently concluded 21st Conference of the Parties at Paris (https://www.whitehouse.gov/the-press-office/2015/09/25/fact-sheet-united-states-and-china-i 2 ssue-joint-presidential-statement), China pledged to peak its carbon emissions by 2030 or earlier, and to increase low-carbon energy to 20% in its total primary energy mix; the US committed to cut its carbon emissions by 26-28% relative to the 2005 level, following earlier announced long-term target for 2050 to lower its emissions by 83% relative to 2005. Among all the low-carbon technology choices, wind power development is a central strategy for both countries to achieve their climate goals. The US pioneered in the development of wind-powered generation of electricity in the 1980’s and early 1990’s. It lost its lead to Europe in the late 1990’s as cheap oil, coal and gas reduced incentives for US utilities to invest in alternative sources of energy. The US has emerged once again, since the 1990s, as a major player in global wind power development, in part in response to the production tax credit (PTC) incentive introduced in 19924. China, in comparison, has experienced a rapid scale-up of wind power capacity since the passage of the Renewable Energy Law in 2005, and has become the world’s top wind installer since 2010. The wind installation target set in 2006 for 2020 (30GW) was already exceeded by nearly 400% by the end of 2015 (145.1 GW)5,6. China currently accounts for 33.6% of total global installed wind capacity, with US ranking second (17.2%)7. Despite greater total installed capacity, the actual wind-generated electricity output is in China less than in the US (Figure 1). The unsatisfactory performance of Chinese wind farms not only harms the profitability of existing wind investments, but also reduces the economic attractiveness of future investments. 3 Figure 1 A comparison of wind power deployment for China and the US from 2000 to 2014. a) Installed capacity and b) wind-generated electricity. Data were derived from “Global Wind Statistics 2014” edited by the Global Wind Energy Council (GWEC)5. Based on qualitative methods, previous studies indicated a variety of factors that may contribute to the Chinese shortfall: wind power resources may be intrinsically less favorable in China than in the US8,9; the time lag may be longer in China to connect wind farms to the grid10-13; the quality of turbines installed in China may be inferior to those installed in the US 13-15; in addition, for reasons specific for China, wind power curtailment is more pervasive due to an inflexible power generation fleet dominated by coal16-18. Yet the relative importance of these contributing factors is methodologically challenging to quantify. Here we propose a method based on a logarithmic-mean-divisia-index (LMDI) approach19 to quantify their relative importance, and introduce a new parameter to characterise the overall quality of wind turbines. We find that, although the national total wind resources are less favorable in China 4 than in the contiguous US, the available wind resources for the installed wind farms in these two countries are comparable. Our results suggest that curtailment of wind power, differences in turbine quality and delayed connection to the grid are the primary factors accounting for the current US-China difference. Key Factors Determining Wind Energy Production The annual total electricity output from installed wind farms can be calculated as the product of total capacity (C), the fraction of installed capacity connected to the grid (G), the potential capacity factor for wind resources (CFest), the virtual turbine quality (Q), the curtailment rate (Cr) and the total hours of year (see equation 2 in Methods). A methodology to evaluate the overall quality of wind turbines that have been installed is missing in existing literature, despite its significance for the design of future wind development strategies. We introduce therefore a parameter (Q) to characterise the overall quality of existing wind turbines, comparing the actual output with the counterfactual performance if GE 2.5 MW turbines were installed instead. Q is a composite factor reflecting primarily turbine quality, but is affected also by the technical limits on the deployment and operation of wind farms. We use the LMDI decomposition approach to quantify the relative contributions of these factors, in order to explain the discrepancy in wind power output in China as compared to the US for the year of 2012. As illustrated in Figure 2, on the one hand the total capacity of wind farms installed in China exceeds that in the US, which should lead to greater wind-generated electricity in China relative to the US (67.7%); on the other hand, the advantage of greater installed capacity in China is more than offset by the combined effects of delayed 5 grid-connection (negative 50.3%), less favorable wind resources (negative 17.9%) and lower quality of wind turbines (negative 50.2%). China’s high curtailment rate for wind power (negative 49.3%) further reduces the actual wind power generation. In total, wind-generated electricity in China is 39.3 TWh less than that in the US. With other factors fixed, curtailment of wind power in China would contribute to such shortage by 19.37 TWh, the magnitude for which is comparable to the total electricity generated from wind in Canada in 20125. A thorough understanding of the differences in the above-mentioned factors requires further discussion in a broader technical and policy context both for China and for the US. Figure 2 Contribution of different factors in explaining the China-US difference in wind power output. By the scale of the vertical axis, the red bar indicates the total difference of -39.3 TWh of wind-generated electricity in China as compared to the US in 2012, with percentages representing the relative contributions to this difference from the different factors (blue bars). Thus, 50.3%, 17.9%, 50.2% and 49.3% of the lower power output in China is attributed to the differences (Δ) in G, CFest., Q, and (1-Cr) respectively. The reduction in output represented by these influences is offset by the positive contribution from the higher value for the installed capacity (C) in China. Quality of Wind Resources for Existing Wind Farms Total wind resources over the contiguous US are notably superior to those in China8,9. Assuming that GE 2.5 MW turbines were deployed in both countries, we find a mean value 6 for CF in the U.S of 0.286, higher than the value of 0.224 for China.