require large-scale, distributed, cost-effective energy storage, new methods of cost-effective, long-distance electricity transmission, and the management of large amounts of dynamic data.

To a large extent, major deployment of renewable power generation is constrained by location and intermittency issues. In addition, technologies to harness these resources are modular (allowing projects to easily be scaled up or down), and some resources are more amenable to distributed and off-grid applications. Given these conditions, it is clear to the committee that China and the United States will need to transform power delivery systems to accommodate and integrate large amounts of variable-output renewable electric power. Both the United States and China are making sizeable public investments (greater than $7 billion each for 2010) in next-generation grid technologies, with China spending nearly 10 times that amount ($70 billion from its economic recovery package) on new high-voltage transmission infrastructure. This presents a tremendous opportunity for China and the United States to learn from one another. Specific issues that deserve attention are grid stability, load management, system flexibility including MW-scale multiple-hour storage, and compatibility with an electrified transportation infrastructure.

In addition, joint efforts could include the analysis of distributed PV options at a regional level (e.g., metropolitan areas) for both countries. A stronger focus on deploying distributed PV could encourage rapid reduction of balance of system cost and make the overall system more cost effective. China is a world leader in integrating solar thermal technologies for direct use in buildings, and there are lessons from this experience that could transfer well to building-integrated PV. Regional analyses would help optimize PV to best meet peak demand and take advantage of existing electrical distribution infrastructure.

RECOMMENDATIONS

  • China and the United States should cooperate on defining the needs and requirements to transform power delivery systems to accommodate and integrate large amounts of variable-output renewable electric power.

  • China and the United States should cooperate in developing large-scale (>50 MW) physical energy storage systems. Both countries have experience with pumped hydro and are currently investigating options to create additional capacity, which could directly benefit large wind and solar farms. The United States could also work with China to develop and demonstrate a compressed air energy storage system (CAES) in China, which currently has no experience with CAES.

  • China and the United States should share information on, and consider conducting a joint analysis of, experiences with the integration of variable-output renewables (e.g., wind and solar) to gain a better understanding of what has been learned about their impacts and to look into approaches by grid operators in both their countries, and elsewhere, to manage these impacts.



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