City-scale geothermal energy everywhere to support renewable resilience – A transcontinental cooperation

Abstract

Cities have important and varying incentives to transform their energy sector to all-electric with low carbon emissions. However, they often encounter a number of impediments when attempting to implement such a change. For example, while urban areas have the highest energy demand-density, cities often lack the space for installing additional energy generation and/or long-duration energy storage systems. Cities also have existing environmental issues from energy sources (e.g., pollution from dust, waste heat or noise) that make residents sensitive to energy infrastructure development. Utilizing power from conventional sources, such as natural gas, biomass and hydropower, which usually are distanced from the urban areas, also make cities more vulnerable to supply disruptions. One promising de-carbonizing energy option for cities focuses on their heating and cooling needs, which constitutes around 1/3 of U.S. and 1/2 of European energy consumption (including industrial processes like drying, pasteurization, etc.; Jadun and others, 2017; EU Commission 2022). If heating and cooling loads can be met by geothermal direct-use technologies, then the need for new electric sources can be greatly lessened. Despite the proven efficacy of geothermal energy as a city/community-scale heating and cooling resource, it is currently only a niche resource in the heating and cooling sector, though has significant potential for future growth. Historically, emphasis has been placed on geothermal electricity generation potential that requires higher temperature (greater than 90 °C) resources at drillable depths, but potentially viable areas are geographically limited and typically well removed from urban centers. Key drivers for investments were represented by greater political interest in renewable electricity production, higher revenues and less effort in distributing the produced energy via grids. In contrast, low-temperature (less than 90 °C) geothermal resources can be used directly for heating and cooling almost everywhere and are cost-effective in urban/suburban settings. In addition, the increased prominence of renewable electricity sources, such as wind and solar onto city-scale electric grids, has led to new urgency around questions of energy storage. Underground thermal energy storage (UTES), wherein surplus or waste heat is stored underground for later use, could present a long-duration energy storage solution. From October 2022 through September 2024, a transcontinental consortium consisting of geological surveys, geoscience organizations, industry representatives and universities aims to develop an understanding of the global potential for city-scale geothermal, proposing guidelines to aid in promoting the economic utilization of low temperature geothermal resources. Efforts will focus on providing city managers and other decision makers with the information needed to evaluate and implement suitable city/community-scale geothermal technologies. Funded by the U.S. Geological Survey’s John Wesley Powell Center for Analysis and Synthesis, this interdisciplinary consortium will showcase tools, datasets, and scientific recommendations to accelerate the broader understanding and adoption of renewable energy systems that access geothermal resources. The collaborative research activities include standardization of nomenclatures, resource description and characterization strategies globally. The results from these activities will be combined with a preliminary climate-driven, city-based energy needs related analysis to perform energy supply/demand matching analysis. The identification of city-specific applications that would benefit from the geothermal technologies provides the basis to up-scale city-specific determinations to regional and national assessments of resource estimates. The city-scale geothermal energy research initiative will ultimately provide the synergies and management analysis that can address benefits, environmental impacts, regulatory frameworks, sustainability, and suitability in retrofitted buildings or new as well as existing heating networks.