Energy Transition

Climate Extremes and the Future of the Power Sector in the U.S. Heartland: A Multi-Sector Dynamics Perspective

Abstract: A wide range of electric generation technologies can play a major role in future power production in the heartland of the U.S. for consumption. Different generation technologies have different vulnerabilities to a changing climate and its extremes. The cooling cycle of thermal power plants are vulnerable to rising summer temperatures that increase cooling water temperatures and subsequently add cost and possible curtailments. Drought could limit hydropower availability and further limit thermoelectric cooling. Photovoltaics are less efficient in higher temperatures, and wind resources may change or shift with the changing climate. Rising temperatures are also likely to increase summer peak demands as a result of more intense and broad use of air conditioning, even in currently cooler climates. In addition, high temperatures and high demand pose risks for failure of critical grid infrastructure, such as large power transformers. This combination of stressors raises important research questions: What is the risk of a “perfect storm” that could lead to a tipping point failure of the power system? Are some evolutions of the power sector more or less vulnerable to climate change?

As a preliminary investigation, we review existing word in the area and consider a range of realistic power generation scenarios in the US Heartland (Figure 1). We evaluate the sensitivities of various technologies and demand to climate change and associated extremes, and consider the possible range of changes in their production. We then examine the possible effects on the evolution of the power sector by mid-century in various scenarios, taking a Multi-Sectoral Dynamics perspective by focusing on the interaction of sectors (different supply technologies and different demand sectors) and the effects of multiple stressors (both gradual climate change and changes in extreme events) on the systems. Preliminarily, summer months are a more likely period for a potential “perfect storm,” where a combination of extreme heat, drought, and stagnant meteorological conditions could have significant negative effects on all technologies, while increasing peak power demands across the region. Our results are expected to help develop a research agenda to better resolve future vulnerabilities and suggest strategies to increase power sector resilience.

Exploring Injection Locations for Stratospheric Aerosol Geoengineering to Maximize Particle Lifetime in the Stratosphere

Abstract: Stratospheric Aerosol Injection (SAI) aims to mitigate climate change by releasing aerosols into the stratosphere to reflect incoming shortwave radiation. The radiative efficiency of SAI (i.e., the ratio of injected mass flux to radiative forcing) depends strongly on the stratospheric lifetime of injected particles. In this study, we use a Lagrangian trajectory model (LAGRANTO), modified to account for sedimentation, to analyze the sensitivity of particle lifetime to injection locations.

For the first time, we find that choosing injection longitude could notably increase particle lifetime in the stratosphere, especially for injections below 20 km. For example, the particles injected over the Indian Ocean (60° E to 105° E) in winter have a mean lifetime of 1.33 years, which is 23% larger than particles injected at the same altitude and latitude range (18 km, 10° S to 10° N) over the East Pacific (75° W to 120° W).

We explore four injection strategies to maximize particle lifetime in the stratosphere by selecting injection locations. Selecting injection latitude and longitude can help to achieve a lower injection altitude (more than 1 km lower) without sacrificing lifetime. For example, a uniform injection in the tropical area at 20 km has a mean particle lifetime of 2.0 years, we can select the injection latitude and longitude to lower the injection altitude by 1.5 km (at 18.5 km) to achieve a similar mean lifetime (i.e., 2.0 years). Because maximizing particle lifetime by selecting injection location will increase the interhemispheric imbalance, we designed an injection strategy that can maximize the particle lifetime in the stratosphere subjecting to the interhemispheric balance constraint.

Our results complement SAI studies with GCMs to inform future injection strategy design. The modified LAGRANTO model uses 3-hourly ERA5 data as input, which provides a better estimate of stratospheric transport than GCMs. But the LAGRANTO model cannot model aerosol dynamics nor the response of the climate to SAI.

Implications of Policy Design and Socioeconomic Uncertainties for Energy Transitions and Sectoral Responses

Abstract: Studies exploring energy transitions typically focus on a single or small set of scenarios, often with idealized policy assumptions (e.g. with global carbon pricing and significant negative emissions). However, there are countless possible ways the future could unfold, with different implications for energy transitions. In this work, we develop a probabilistic multi-sector coupled human-natural system model and explore both deep uncertainty about climate policy design and parametric uncertainty about socioeconomic assumptions, and the implications of those uncertainties for energy transitions and sectoral responses. To reflect policy design uncertainty, we utilize a set of increasingly stringent global emissions pathways comprised of increasingly stringent regional GHG constraints, and consider both “Optimistic” and “Pessimistic” design conditions that represent deep uncertainties for climate strategy, including whether or not there is international emissions trading, coverage of land use emissions and availability of carbon dioxide removal technologies. For each of these scenarios, we then run large ensembles of our model, sampling from probability distributions for uncertain socioeconomic parameters (e.g. productivity growth, population, technology costs, fossil resources). Using this approach, we can quantify uncertainty in the future energy mix and sectoral responses (e.g. emissions, output and energy use) and how that uncertainty shifts for different policy design assumptions.

Results suggest many possible energy mixes are consistent with a given global emissions pathway, and the policy design has significant implications for future energy mixes. In particular, whether or not international emissions trading is allowed results in vastly different amounts of BECCS and afforestation pursued globally, which in turn affects how much fossil energy can continue to be used and decarbonization strategies employed in different regions and sectors. This approach demonstrates the importance of considering uncertainty when planning for energy transitions and that planning for a single future is risky.

A Tool for Air Pollution Scenarios (TAPS v1.0) to enable global, long-term, and flexible study of climate and air quality policies

Authors' Summary: Understanding policy effects on human-caused air pollutant emissions is key for assessing related health impacts. We develop a flexible scenario tool that combines updated emissions data sets, long-term economic modeling, and comprehensive technology pathways to clarify the impacts of climate and air quality policies. Results show the importance of both policy levers in the future to prevent long-term emission increases from offsetting near-term air quality improvements from existing policies.

Abstract: Air pollution is a major sustainability challenge – and future anthropogenic precursor and greenhouse gas (GHG) emissions will greatly affect human well-being. While mitigating climate change can reduce air pollution both directly and indirectly, distinct policy levers can affect these two interconnected sustainability issues across a wide range of scenarios.

We help to assess such issues by presenting a public Tool for Air Pollution Scenarios (TAPS) that can flexibly assess pollutant emissions from a variety of climate and air quality actions, through the tool’s coupling with socioeconomic modeling of climate change mitigation. In this study, we develop and implement TAPS with three components: recent global and fuel-specific anthropogenic emissions inventories, scenarios of emitting activities to 2100 from the MIT Economic Projection and Policy Analysis (EPPA) model, and emissions intensity trends based on recent scenario data from the Greenhouse Gas–Air Pollution Interactions and Synergies (GAINS) model.

An initial application shows that in scenarios with less climate and pollution policy ambition, near-term air quality improvements from existing policies are eclipsed by long-term emissions increases – particularly from industrial processes that combine sharp production growth with less stringent pollution controls in developing regions. Additional climate actions would substantially reduce air pollutant emissions related to fossil fuel (such as sulfur and nitrogen oxides), while further pollution controls would lead to larger reductions for ammonia and organic carbon (OC).

Future applications of TAPS could explore diverse regional and global policies that affect these emissions, using pollutant emissions results to drive global atmospheric chemical transport models to study the scenarios’ health impacts.

Decarbonizing the global shipping industry: Evaluating pathways for alternative fuels

Abstract: Achieving net-zero emissions across all sectors, including the shipping industry, which relies heavily on fossil fuels and traditional internal combustion engines for propulsion, is critical to mitigating climate change and limiting global temperature rise. This thesis evaluates decarbonizing pathways for the global shipping industry through alternative fuels.

The decarbonization pathways for shipping are constructed by considering significant system decisions, including powertrains, fuel types, and feedstock. Each pathway is assessed based on cost and multi-attribute utility using system-level metrics relevant to shipping. For alternative fuels, fuel cost models have been developed to estimate the levelized cost of production based on varying electricity prices, natural gas prices, and capital and operating expenditure assumptions. With the fuel cost model results, the total cost of ownership models of bulk carrier vessels has been developed to calculate and compare the lifetime cost for operating vessels for various alternative fuel pathways. The cost models provide insights into the cost markup of alternative fuel pathways relative to the conventional fuels of maritime ships. The MIT’s Economic Projection and Policy Analysis (EPPA) model has been enhanced to represent a low-emission shipping option to assess the economic impact and make projections on the market share of the alternative fuel pathway through 2050. Required investment to enable low-emission shipping to enter the market has been estimated using the EPPA model.

Combining findings from the multiattribute utility, including lifecycle emissions of alternative fuels and economic modeling results, near-term, medium-term, and long-term pathways for low-emission shipping have been proposed.

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