تجزیه و تحلیل هزینه - فایده زیست محیطی و اقتصادی از انرژی باد فراساحلی

Wind energy has experienced dramatic growth over the past decade. A small fraction of this growth has occurred offshore, but as the best wind resources become developed onshore, there is increasing interest in the development of offshore winds. Like any form of power production, offshore wind energy has both positive and negative impacts. The potential negative impacts have stimulated a great deal of opposition to the first offshore wind power proposals in the U.S. and have delayed the development of the first offshore wind farm in the U.S. Here we discuss the costs and benefits of offshore wind relative to onshore wind power and conventional electricity production. We review cost estimates for offshore wind power and compare these to estimates for onshore wind and conventional power. We develop empirical cost functions for offshore wind based on publicly reported projects from 2000 to 2008, and describe the limitations of the analysis. We use this analysis to inform a discussion of the tradeoffs between conventional, onshore and offshore wind energy usage.

Over the past 10 years, the onshore wind industry in the U.S. has grown dramatically and as a result developers, citizens and the U.S. Congress have expressed interest in the development of an offshore wind industry. Several companies have developed plans for offshore wind projects and the U.S. Mineral Management Service (MMS) is in the process of reviewing these applications and developing regulations for the industry while the state of Texas has already leased lands for at least one and possibly several additional offshore wind farms. Lawmakers, government agencies, corporations, non-governmental organizations and private individuals are deciding whether or not to support or participate in the development of an offshore wind industry, and the relative level of support or encouragement to give this new industry. In making these decisions, stakeholders will have to balance the ecological costs and benefits of offshore wind against its economic costs and compare to offshore wind energy's most realistic competitors. The decision is complex and requires balancing local and global environmental issues, historical conservation and economic costs. Offshore wind energy competes with both onshore wind energy and conventional fossil-fueled electricity. Onshore wind power and natural gas fired power are the two fastest growing segments of the electricity market. Coal power is the largest current producer of electricity in the U.S. Offshore wind will thus displace either coal, natural gas or onshore wind. Given the uncertainties associated with global climate change, it is difficult to compare the societal costs and benefits of wind energy to fossil-fueled energy. However, one way to develop a first-order comparison of these costs would be include the costs of market based carbon offsets in the costs of conventional electricity. This assumes that the costs of carbon emission credits accurately reflect their ecological value which would occur if carbon credits actually represent a reduction of the specified amount of carbon dioxide from the atmosphere. It is perhaps less difficult to compare the costs of onshore and offshore wind energy since they both have similar carbon emissions. In this case, one could simply compare the economic and ecological costs of onshore and offshore wind. There are several reasons why developers or lawmakers might prefer offshore wind power over fossil-fueled power or onshore wind power. Offshore wind power could be less expensive than its competitors, either at a local or national scale, it could have the potential to be less expensive than its competitors, or it could have less severe social and environmental impacts than its competitors. In this paper, we seek to address the question, “Is investment in offshore wind power preferred over investments in fossil-fueled or onshore wind power?” We focus primarily on coal-fired power as representative of fossil-fueled power since it is the dominant source of electricity in the U.S. and it is both inexpensive and a major source of greenhouse gases. We begin with an overview of the commonly expressed criticisms and benefits of offshore wind power. We discuss cost models for offshore wind power and compare them to onshore wind power and conventional power. We also discuss the factors that lead to higher costs through a first-order empirical cost function and discuss how these costs can be decreased. We discuss the environmental impacts of offshore wind power and how these factors can be mitigated. We end the paper with the conclusions of the analysis.

The higher economic costs of offshore wind power relative to onshore wind power could be justified if the ecological or social costs of offshore wind were significantly different from onshore wind power, but this seems not to be the case. Both on and offshore wind power face local opposition due to user conflicts. The ecological impacts of offshore wind power affect a very different ecosystem than onshore wind power and, as a result, their ecological impacts are not directly comparable. However, like onshore wind, it is clear that offshore wind power does have ecological impacts with the potential for population level effects. Decreasing commodity costs or legislation capping greenhouse gas emissions could increase the profitability of offshore wind but would not change the fact that onshore wind will be a less expensive alternative, even when transmission costs are included. Until land use conflicts in high-wind onshore sites become severe, or the technology develops so that the higher offshore winds balance the higher costs of installation, there seems to be little incentive for a large offshore wind industry in the U.S. In sum, we do not envision offshore wind producing a significant portion of the U.S. electricity production until at least 2020. It is much more difficult to analyze the ecological and economic costs and benefits of offshore wind power relative to fossil-fueled power. Including a premium on coal-fired power of $25/MW h to offset emissions may make coal and offshore wind power nearly price competitive, depending on the specific capital costs of offshore wind. This $25/MW h premium would give coal and offshore wind similar greenhouse gas emissions, however, coal would still use more water than offshore wind and would be associated with significant health effects. However, this would be balanced against the ecological impacts of offshore wind in terms of bird and bat mortality and marine mammal impacts. Thus, it is not clear that offshore wind is preferable to coal-fired power, if the emissions from the coal plant are offset. Based on the analysis in this paper, it seems clear that the economic and ecological costs of offshore wind power are site specific. These costs can be mitigated with current technology and detailed site selection. It therefore seems imprudent to conclude that all offshore wind development is inferior to all onshore wind development or fossil-fueled power. Instead, a more nuanced approach which weighs the site specific costs and benefits of offshore wind power is necessary. In some cases, offshore wind power may be able to cheaply produce electricity with negligible environmental impacts, however, in many more cases, offshore wind power will be more expensive than its competitors, even when the costs of carbon offsets are included.