Integrating high penetration variable renewables in economically and operationally plausible ways is a current clean energy challenge facing many countries and regions, including California. Renewable energy deployment is a relevant pathway to decarbonize the electricity sector and reduce greenhouse gas emissions (GHGs) and mitigate the harmful effects of climate change. This paper highlights the key findings from a recently completed study, funded by the California Solar Initiative, to develop and investigate strategies to integrate high penetration renewable energy and solar photovoltaic (PV) systems using distributed energy resources (DER). We develop hypothetical operating strategies that utilize the DER present in campus microgrids, such as combined heat and power (CHP) systems and thermal energy storage, and evaluate these based on economic criteria. Our host site is the University of California, San Diego (UCSD) microgrid, which has a rich DER base that includes a 2.8 MW fuel cell powered by directed biogas, 30 MW of onsite generation, steam and electric chillers, thermal storage and roughly 1.5 MW of onsite solar PV. We develop and evaluate three types of strategies for integrating renewable generation: peak load shifting , on-site PV firming , and grid support . We analyze these strategies with an hourly dispatch optimization model and one year of data. We define a successful renewable integration strategy as one that is operationally plausible and economically viable. We find all three classes of strategies are technically feasible and can be cost-effective under certain conditions. However, we find that the value proposition to customers such as the UCSD campus, under current tariff structures and market prices, will need to be higher to motivate such customers to offer these services, given the risks associated with changing microgrid operations from regular practice. Our findings suggest alternative incentive mechanisms and engagement strategies beyond those pathways currently available are needed to leverage the potential of DER at campuses for renewables integration purposes. Such efforts are relevant not only to campus resources but to similar commercial and industrial loads across California, including the vast combined heat and power resources.

Smart grid has become linked with topics of energy efficiency, renewables integration and climate policy. A smarter grid is one that utilizes communications and information systems to achieve more flexible grid operations. Energy storage and more broadly, load shifting, is one mechanism for achieving flexible grid operations. Unlike demand response, permanent load shifting moves energy on a regular basis, from peak to off-peak. Technologies that can deliver load shifting include thermal storage, electrical and mechanical storage and process shifting. This paper highlights findings from a recent study, mandated by a California Public Utilities Commission order, of permanent load shifting (PLS) opportunities located at customer sites in California. We developed a cost-effectiveness framework to estimate the costs and benefits of PLS technologies, demonstrated the framework with an analysis of PLS systems, and evaluated the market for PLS, including an assessment of challenges to expanding PLS. The cost-effectiveness analysis included a technology-neutral scenario analysis and an evaluation of technology-specific cases. Grid-level benefits of load shifting range from approximately $500–$2500/peak kW. Among the case studies, some approaches, such as refrigerated warehouse precooling, are cost-effective for both the utility and the consumer, while others, such as flow batteries, are not yet cost-effective and can be viewed as emerging technologies. Due to the wide range of technology costs and performance, these results are unsurprising. Still, PLS technologies can be one tool that can help set the stage for integrating large amounts of renewables in the future, a road California is paving.

Energy “sustainability” and energy supply have again emerged as central public policy issues and are at the intersection of the economic, environmental, and security challenges facing the nation and the world. The goal of significantly reducing greenhouse gas (GHG) emissions associated with energy production and consumption, while maintaining affordable and reliable energy supplies, is one of the most important issues. Among the strategies for achieving this goal, increasing the efficiency of energy consumption in buildings is being emphasized to a degree not seen since the 1970s. “End-use” efficiency is the core of the State of California’s landmark effort to reduce its GHG emissions, of other state and local climate-change initiatives, and is emphasized in emerging federal GHG abatement legislation. Both economic and engineering methods are used to analyze energy efficiency, but the two paradigms provide different perspectives on the market and technological factors that affect the diffusion of energy efficiency. These disparate perspectives influence what is considered the appropriate role and design of public policy for leveraging not just efficient end-use technology, but other sustainable energy technologies. We review the two approaches and their current roles in the GHG policy process by describing, for illustrative purposes, the U.S. Environmental Protection Agency’s assessment of energy efficiency in the American Clean Energy and Security Act of 2009 Discussion Draft. We highlight opportunities and needs for improved coordination between the engineering, economic and policy communities. Our view is that a better understanding of disciplinary differences and complementarities in perspectives and analytical methods between these communities will benefit the climate change policy process.