Department of Population Health Sciences
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- Canadian hydropower and the U.S. energy transition: controversies, opportunities, and strategic research directionsCalder, Ryan S. D.; Borsuk, Mark E.; Mortazavigazar, A.; Howarth, Richard B.; Jackson, Chloe; Mavrommati, Georgia (2023-12-13)Recent modeling for the northeast United States suggests that the least-cost decarbonization pathway involves a combination of build-out of domestic renewables generation and increased intertie capacity with Canada. U.S. imports of Canadian hydropower have increased by > 1 TWh per year between 2007–2021 because it is a cost-effective and low-carbon alternative to domestic fossil fuel generation. Yet, increased interconnection capacity and imports are controversial and have been opposed by U.S. environmental groups and members of the public. Development of new hydroelectric reservoirs disrupts foodways and lifeways of Indigenous populations and has greenhouse gas impacts greater than wind and solar (though less than fossil fuel alternatives). Two recently cancelled hydropower transmission projects linking New England and Quebec, Canada demonstrate the need to better understand the gap between pathways that appear optimal from the perspective of energy systems modeling and the pathways that will ultimately be socially and environmentally acceptable. The experience of the northeast mirrors that in other parts of the U.S. where substantial resources have been invested in pursuit of renewable projects that are ultimately abandoned following mobilization of stakeholders with adverse interests or values. A research program integrating environmental and economic modeling seeks to resolve controversies surrounding the use of Canadian hydropower in U.S. energy transitions. This includes conceptual disputes over valuation of hydropower from existing reservoirs in cost-benefit analysis; debates over whether new transmission infrastructure stimulates new generation capacity; and analysis of the relative importance of different benefits and impacts to the public.
- Causal inference to scope environmental impact assessment in multisector systems: the case of trans-border hydropower exportsMortazavigazar, Amir; Calder, Ryan S. D. (2022-12-15)Decarbonization of the United States’ electricity sector will require trillions of dollars of investment in generation and transmission infrastructure. The National Environmental Policy Act (NEPA) requires proponents of many major projects to complete environmental impact statements (EIS) that address reasonably foreseeable impacts, regardless of where these impacts occur. There has been controversy over the cause-effect relationships among electrical supply, electrical demand, apparent cost, and other variables given the complex interactions between them. Therefore, the range of environmental impacts attributable to new infrastructure projects is subject to frequent disagreements. In this work, we address increasing U.S. imports of Canadian hydropower in the setting of falling prices and surplus generation. There has been controversy as to whether new transmission capacity stimulates new generation capacity, and thus whether generation-side environmental and health impacts must be assessed in the scope of incremental transmission projects. We have developed a rich longitudinal database of variables related to generation capacity, export volume, retail prices, and climate over the period 1979 to 2021. We have applied a novel multivariable wide neural network machine learning methodology to evaluate alternative causal models for the evolution of the electricity system and the role of new transmission infrastructure. We find no evidence that transmission capacity stimulates generation capacity. Rather, generation capacity growth in Canada is triggered primarily by domestic price signals and climate parameters, with trans-border transmission capacity developed primarily to absorb excess generation potential. This work supports a relatively narrow scope for EIS related to trans-border transmission projects. More generally, this analysis demonstrates how causal inference methods may help build consensus around the appropriate scope of EIS for highly interconnected energy and infrastructure projects.
- Decarbonization via long-distance transmission of hydropower is cost-effectiveCalder, Ryan S. D.; Robinson, Celine; Borsuk, Mark E. (2021-12-14)Hydropower is associated with substantially lower carbon emissions than fossil fuels and can satisfy baseload electricity demand unlike wind and solar power. In the northern United States, imports of Canadian hydropower account for a large and growing share of the electricity portfolio. For example, in New England, Canadian hydropower increased from 10% to 21% of electricity supplied to consumers between 2010 and 2020. These imports are increasingly dependent on capital-intensive long-distance transmission projects between the Canadian border and U.S. urban centers. While costs of these projects are clearly defined in dollars, benefits accrue in diverse forms, ranging from avoided air pollution and greenhouse gas emissions to reduced fuel and operation costs. This severely complicates cost-benefit analysis and has led to controversy over the role of Canadian hydropower in U.S. renewable energy transitions. We develop a probabilistic, multiattribute economic valuation model to explicitly compare direct and environmental costs and benefits of energy transition scenarios. We apply this model to the New York City area, where the recent closure of a ~2,000 MW nuclear power plant has increased demand for fossil fuel generation, and a proposed $4-billion long-distance hydropower transmission project has caused disagreement among environmental groups and other stakeholders. We find that coupling long-distance hydropower transmission with planned build-out of wind and solar reduces net total costs over 2021-2050 on the order of tens of billions of dollars, primarily due to avoided greenhouse gas emissions and air pollution whose economic value outweighs the added upfront capital costs. Long-distance hydropower transmission averts health and property impacts of air pollution from fossil fuel generators associated with an economic value on the order of hundreds of millions of dollars concentrated in vulnerable communities facing disproportionate environmental risks. These findings are robust to an extensive sensitivity analysis. This model provides a novel, transparent framework for supporting decision-making about long-distance hydropower transmission elsewhere.