Net Environmental Impactsof Transmission Systems

摘要

Transmission system capacity is a critical issue in many parts of the country,rnparticularly for new market participants such as wind power. In the Upper Midwest significantrnnew transmission has not been built for nearly two decades while electricity consumption hasrncontinued to grow at a steady pace. Several major new transmission proposals are imminentrnin the Midwest.rnEach state makes decisions on new transmission proposals on several levels including policy,rnregulatory, and siting/routing. Achieving regional consensus on the policy level prior tornundertaking the regulatory and siting proceedings is critical to success. This requires a clearrnunderstanding of the purpose of and need for proposed new transmission lines over time. Thernprimary drivers for new transmission are reliability of the power system, economics of therndelivered electricity, and regional environmental impacts. Reliability criteria for newrntransmission are well established. Economic criteria for new transmission are underrndevelopment in many regions including California, PJM, and the Midwest. However, regionalrnenvironmental criteria have not been incorporated to date to any significant degree inrntransmission planning.rnThis paper outlines a scope and an initial method for estimating net environmental impacts,rnbased on regional air emissions, of new transmission expansion and demonstrates the methodrnon a set of exploratory transmission lines in the 2003 Midwest Independent System Operatorrn(MISO) Transmission Expansion Plan. The method applies an integrated production costrnmodel that produces hourly dispatch throughout the year for generators in the region. Thisrnallows estimation of the net environmental impacts of the proposed transmission line basedrnupon the new regional generation mix facilitated by the line and the resulting change inrnregional air emissions. The method can provide quantitative regional environmentalrninformation regarding particular transmission proposals for decision makers such as publicrnutilities commissioners. The case study results illustrate the potential for a significant reductionrnin regional air emissions with the addition of remote wind power and new transmission to movernit to market. The proposed methodology could be developed further to include evaluation ofrnother environmental impacts besides air emissions, including potential impacts fromrntransmission and generation such as land-use, water, wildlife/biodiversity, habitatrnfragmentation, wetlands, and from mining, transporting, and burning coal.