从气候与公平出发,重新审视煤电厂的退役策略

文摘   2024-10-16 19:17   北京  


面对廉价天然气和日益增长的可再生能源市场的竞争,美国的燃煤电厂正在减少。但是,由普林斯顿大学能源系统建模专家领导的新研究表明,基于成本最小化的传统燃煤电厂的退役战略可能忽视了其他气候和公平的潜在效益。


这项研究强调了重新思考以成本为导向的退役战略的价值,表明以气候或公平为重点的战略将降低宾夕法尼亚州及附近各州的碳排放、空气污染及其导致的死亡人数。


 “通常情况下,政策设计并没有将环境正义或气候目标作为明确的目标。”该研究的第一作者、公共与国际事务专业客座研究生Carla Campos Morales说,“研究想要展示,在决定哪些煤电厂应该退役时,如果优先考虑碳强度或环境公平等因素,可能会产生的潜在结果。”


研究人员发现,淘汰宾夕法尼亚州一半的煤电厂可使该州与电力相关的二氧化碳(CO2)排放量减少最多12%,空气污染物排放量减少最多75%,并可避免多达20%的因接触细颗粒物(即PM2.5)暴露引起的死亡。与维持现状、不退役情景相比,这些替代方案中的许多健康益处集中体现在严重受到污染影响的社区。


 “美国有一个独特的政策窗口期,在此期间,我们可以通过设计不同的退役战略,最大限度地为气候和社区带来益处。” 该研究负责人、普林斯顿大学安德林格能源与环境中心(Andlinger Center for Energy and the Environment)公共与国际事务助理教授彭𬀩(Wei Peng)说。


成本、气候和环境公平

研究人员以2019年为基准建立了六种情景,比较在不同优先级下退役宾夕法尼亚州半数煤电厂的结果:首先退役最便宜的电厂、首先退役碳排放最高的电厂,或者首先退役最靠近环境正义地区的电厂。


2023年9月之前,宾夕法尼亚州对环境正义地区的定义是指有20%或以上的人口生活在贫困线或贫困线以下,有30%或以上的人口是非白人少数族裔,或两者兼而有之的人口普查区。


研究人员表示,虽然环境正义地区的定义已经更新,但其研究对环境正义地区附近工厂退役的见解仍然适用,而且这种退役是减轻污染和历史环境不公正的重要机会。


针对这三种优先级,研究人员还研究了在2019年,基于装机容量(即发电厂可产生的最大电力输出)或发电量(即实际发电量)退役一半的煤电厂的影响。彭𬀩认为,虽然装机容量是更直接的衡量标准,但发电量更能反映煤电厂对当地社区和气候的影响。


从健康和环境的结果来看,关键不在于电厂可以烧多少煤,而在于实际上烧了多少煤。退役一个大型但很少使用的煤电厂可以大大减少煤电装机容量,但这对整体减少空气污染的作用可能微乎其微。” 彭𬀩谈到,他同时还是能源与环境政策研究中心(Center for Policy Research on Energy and the Environment)的核心教员。


研究人员发现,与2019年的实际发电量相比,优先考虑气候和环境正义的替代情景在减少碳排放和空气污染物方面带来了显著成效。


例如,首先关闭污染最严重的设施来退役该州一半的煤电装机,将使宾夕法尼亚州的颗粒物污染减少75%。研究小组发现,这种减排效果可以帮助宾夕法尼亚州避免约84例因PM2.5导致的死亡,这比基于2019年实际发电量的情景减少了20%。


研究小组还发现,宾夕法尼亚州下风向的各州,包括新泽西州、马里兰州和特拉华州,也会因为宾夕法尼亚州的电厂退役而减少空气污染。


在同样的情景下,以气候为优先考虑因素,退役一半的煤电装机,不仅能够减少宾夕法尼亚州因 PM2.5导致的死亡人数,还避免了PJM 区域电网(PJM Interconnection,简称:PJM)所覆盖的其他地区(13个州和哥伦比亚特区)52例额外的死亡。


宾夕法尼亚州立大学土木与环境工程系的博士生Campos Morales认为,这些发现强调了在制定能源和气候目标时超越州界的重要性。“我们的研究结果确实突出表明,这些决策并不是孤立进行的。决策者需要考虑政策对整个地区可能产生的连锁反应——无论是积极的还是消极的。”他说。


彭𬀩补充说,他们关于州级决策区域影响的研究结果,代表了能源转型中一个重要但未被充分重视的考虑因素。目前的研究还建立在其研究小组之前关于宾夕法尼亚州加入区域温室气体倡议(Regional Greenhouse Gas Initiative,RGGI)对区域排放和公共健康影响的研究基础之上。RGGI是美国东北部的一个针对能源行业碳排放的限额交易系统。


“去年,在我们举办的一次研讨会上,来自几个州的监管者和政策制定者达成共识,认为区域协调与合作至关重要。但另一方面,我也认为这是一项新兴的工作,需要各州决策者投入更多的时间和精力才能实现。”彭𬀩说。


具有可操作性成果的研究

彭𬀩介绍,这项研究的优势之一在于它与宾夕法尼亚州的政策制定者和监管者息息相关。他的团队在研究过程中与州政府机构和其他利益相关者沟通,以建立能提供最相关信息的模型。


该团队仍在继续扩展他们的模型,以提供其他相关因素的信息,如退役决策对当地就业岗位流失和创造的影响。例如,在目前的模型中,宾夕法尼亚州的煤电退役往往会刺激PJM区域电网中其他地区的能源发电,这意味着当地社区与煤炭相关的工作岗位可能不会被同一社区的新能源行业工作岗位所取代。


人们关心更好的空气质量和更低的污染,但他们也关心自己的工作。因此,不仅要了解这些退役决定会如何影响人们的生计,还要考虑如何帮助那些一直在煤炭行业工作的人转型到可再生能源或其他行业。”Campos Morales说。


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Retiring coal plants with climate and equity in mind


Facing competition from cheap natural gas and a growing renewables market, coal-fired power plants are on the decline in the United States. But new research led by energy systems modelers at Princeton University demonstrates that traditional strategies for retiring coal plants based on minimizing costs could be leaving other climate and equity benefits on the table.


The analysis underscores the value of rethinking cost-driven retirement strategies, showing instead that climate- or equity-focused strategies would lead to lower carbon emissions, air pollution, and pollution-attributable deaths in Pennsylvania and nearby states. Their study was published in Environmental Science & Technology.


"Often, policies aren't designed with environmental justice or climate goals as explicit objectives," said first author Carla Campos Morales, a visiting graduate student in public and international affairs. "We're showing what the potential outcomes could be if we instead prioritize factors like carbon-intensity or environmental equity when making decisions about which coal plants to retire."


The researchers found that retiring half of the coal plants in Pennsylvania could reduce electricity-related carbon dioxide (CO2) emissions in the state by up to 12%, cut air pollutant emissions by up to 75%, and avoid up to 20% of the deaths attributable to fine particulate matter (so called PM2.5) exposure when compared to a business-as-usual, no-retirement scenario. In these alternative scenarios, many health benefits were also concentrated in communities that have been disproportionately impacted by impacts of pollution.


"In the U.S., we have a unique policy window where we can be designing our retirement strategies differently in order to maximize the benefits to the climate and communities," said research leader Wei Peng, assistant professor of public and international affairs and the Andlinger Center for Energy and the Environment.


Cost, climate, and environmental equity


The researchers modeled six scenarios for 2019 to compare the outcomes of retiring half of Pennsylvania's coal plants under different priorities: retiring the cheapest-to-close plants first, the most carbon-intensive plants first, or the plants located closest to environmental justice areas first.


The researchers relied on Pennsylvania's definition of environmental justice areas for the project, which until September 2023 were identified as census tracts with 20% or more individuals living at or below the poverty line, with 30% or more of the population identifying as a non-white minority, or both.


While the definition for environmental justice areas has since been updated, the researchers said their study's general insights about retiring plants near environmental justice areas still apply, and that such retirements are a significant opportunity to mitigate both pollution and historical environmental injustices.


For each of the three priorities, the researchers also studied the impacts of retiring 50% of coal plants in 2019 based on either capacity, which is the maximum electric output a power plant could produce, or generation, which refers to the actual amount of electricity produced. While capacity is the more straightforward metric, Peng said generation is more reflective of the impact that coal power plants can have on local communities and the climate.


"In terms of health and environmental outcomes, it's not about how much coal you could be burning, but instead about how much coal you're actually burning," said Peng, who is also a core faculty member at the Center for Policy Research on Energy and the Environment.


"You could have a large coal plant that is rarely in use. Retiring a plant like that would significantly reduce coal-burning generation capacity, but reductions to overall air pollution might be minimal."


Compared to the actual generation in 2019, the researchers found that the alternative scenarios—especially the ones prioritizing climate and environmental justice—led to significant reductions in carbon emissions and air pollutants.


For instance, retiring half of the state's coal capacity by retiring the most polluting facilities first would cut particulate matter pollution by 75% in Pennsylvania. The team found that such a reduction could help to avoid around 84 PM2.5-attributable deaths in Pennsylvania, which is 20% fewer deaths than the scenario based on the actual electricity generation in 2019.


Through their model, the team also uncovered that states downwind of Pennsylvania, including New Jersey, Maryland, and Delaware, also saw lower air pollution as a result of retiring plants in Pennsylvania. In the same scenario—retiring 50% of coal capacity with climate as the priority—the retirements not only reduced PM2.5-attributable deaths in Pennsylvania but also avoided an additional 52 deaths in the rest of the PJM Interconnection, a regional transmission organization operating across 13 states and the District of Columbia.


The findings, Campos Morales argued, underscore the importance of looking beyond state borders when developing energy and climate targets.


"Our results really highlight that none of these decisions are happening in a vacuum," Campos Morales said, who is a Ph.D. student in Pennsylvania State University's Department of Civil and Environmental Engineering. "Decision-makers need to be thinking about how policies can have ripple effects—positive or negative—across a region."


Peng added that their findings about the regional impacts of state-level decisions represent an important yet underappreciated consideration for the energy transition. The present research also builds on previous work from Peng's group about the regional emissions and public health impacts of Pennsylvania joining the Regional Greenhouse Gas Initiative (RGGI). RGGI is a cap-and-trade system in the northeastern United States that targets carbon emissions from the energy sector.


"Last year, I hosted a workshop with regulators and policymakers from several states, and there was consensus across the state agencies that regional coordination and collaboration is critical," Peng said. "But on the other hand, I do see it as an emerging effort that will require more time and effort from decision-makers across different states to make it happen."


Research with actionable outcomes


According to Peng, one of the strengths of the research is its relevance to Pennsylvania policymakers and regulators. Aligned with her group's mission to develop human-centered energy systems models to inform more realistic and durable climate policies, Peng and her team engaged with state agencies and other stakeholders in the research process to build models that provide the most relevant information.


"Our work is very action-oriented," Peng said. "When we designed the scenarios, we had the Pennsylvania Department of Environmental Protection in mind. With both this paper and our previous one, we thought about the kinds of analyses that would be helpful to them as decision-makers."


Still, the team is continuing to expand their model to provide information about several other relevant factors, such as the impact of retirement decisions on local job loss and creation. In their current model, for example, coal retirements in Pennsylvania often spurred energy generation in other areas of the PJM Interconnection, meaning that jobs in local communities associated with coal may not be replaced with new energy sector jobs in the same community.


"People care about having better air quality and lower pollution, but they also care about their jobs," said Campos Morales. "So not only is it important to understand how these retirement decisions could impact people's livelihoods, but also to think about how we can help people who have been working in the coal industry to transition to careers in renewable energy or other industries."


本文 2024 年 10 月 9 日发布于Phys.org。文章仅代表作者观点,不代表本公众号立场。

封面图源:unsplash

文内图源:Environmental Science & Technology (2024).

翻译 审校/韩迪 吕雅宁     编辑/包林洁

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