Wind energy offers significant potential for greenhouse gas emissions reductions

Wind energy offers significant potential for near-term (2020) and long-term (2050) greenhouse gas (GHG) emissions reductions. A number of different wind power technologies are available across a range of applications, but the primary use of wind energy of relevance to climate change mitigation is to generate electricity from larger, grid-connected wind turbines, deployed either on- or offshore wind farm.

Focusing on these technologies, the wind power capacity installed by the end of 2009 was capable of meeting roughly 1.8% of worldwide electricity demand, and that contribution could grow to in excess of 20% by 2050 if ambitious efforts are made to reduce GHG emissions and to address the other impediments to increased wind energy deployment.

Onshore wind energy is already being deployed at a rapid pace in many countries, and no insurmountable technical barriers exist that preclude increased levels of wind energy penetration into electricity supply systems. Moreover, though average wind speeds vary considerably by location, ample technical potential exists in most regions of the world to enable significant wind energy deployment. In some areas with good wind resources, the cost of wind energy is already competitive with current energy market prices, even without considering relative environmental impacts.

Nonetheless, in most regions of the world, policy measures are still required to ensure rapid deployment. Continued advances in on- and offshore wind energy technology are expected, however, further reducing the cost of wind energy and improving wind energy’s GHG emissions reduction potential.

The wind energy market has expanded rapidly. Modern wind turbines have evolved from small, simple machines to large, highly sophisticated devices, driven in part by more than three decades of basic and applied research and development (R&D). Typical wind turbine nameplate capacity ratings have increased dramatically since the 1980s, from roughly 75 kW to 1.5 MW and larger; wind turbine rotors now often exceed 80 m in diameter and are positioned on towers exceeding 80 m in height.

The resulting cost reductions, along with government policies to expand renewable energy (RE) supply, have led to rapid market development. From a cumulative capacity of 14 GW by the end of 1999, global installed wind power capacity increased 12-fold in 10 years to reach almost 197 GW by the end of 2010. Most additions have been onshore wind farm, but 2.1 GW of offshore capacity was installed by the end of 2009, with European countries embarking on ambitious programmes of offshore wind energy deployment.

From 2000 through 2009, roughly 11% of all global newly installed net electric capacity additions (in GW) came from new wind power plants; in 2009 alone, that figure was likely more than 20%. Total investment in wind power plant installations in 2009 equalled roughly USD2005 57 billion, while direct employment in the wind energy sector has been estimated at 500,000. Nonetheless, wind energy remains a relatively small fraction of worldwide electricity supply, and growth has been concentrated in Europe, Asia and North America.

The top five countries in cumulative installed capacity by the end of 2009 were the USA, China, Germany, Spain and India. Policy frameworks continue to play a significant role in wind energy utilization.

The global technical potential for wind energy exceeds current global electricity production. Estimates of global technical potential range from a low of 70 EJ/yr (19,400 TWh/yr) (onshore only) to a high of 450 EJ/yr (125,000 TWh/yr) (onshore and near-shore) among those studies that consider relatively more development constraints. Estimates of the technical potential for offshore wind energy alone range from 15 EJ/yr to 130 EJ/yr (4,000-37,000 TWh/yr) when only considering relatively shallower and near-shore applications; greater technical potential is available if also considering deeper water applications that might rely on floating wind turbine designs. Economic constraints, institutional challenges associated with transmission access and operational integration, and concerns about social acceptance and environmental impacts are more likely to restrict growth than is the global technical potential. Ample technical potential also exists in most regions of the world to enable significant wind energy deployment relative to current levels.

The wind resource is not evenly distributed across the globe nor uniformly located near population centres, however, and wind energy will therefore not contribute equally in meeting the needs of every country. Research into the effects of global climate change on the geographic distribution and variability of the wind resource is nascent, but research to date suggests that those effects are unlikely to be of a magnitude to greatly impact the global potential for wind energy deployment.

Analysis and operational experience demonstrate that successful integration of wind energy is achievable. Wind energy has characteristics that pose new challenges to electric system planners and operators, such as variable electrical output, limited (but improving) output predictability, and locational dependence. Acceptable wind electricity penetration limits and the operational costs of integration are system-specific, but wind energy has been successfully integrated into existing electric systems; in four countries (Denmark, Portugal, Spain, Ireland), wind energy in 2010 was already able to supply from 10 to roughly 20% of annual electricity demand. Detailed analyses and operating experience primarily from certain Organisation for Economic Co-operation and Development (OECD) countries suggest that, at low to medium levels of wind power electricity penetration (up to 20% of total electricity demand), the integration of wind energy generally poses no insurmountable technical barriers and is economically manageable.

Concerns about (and the costs of) wind energy integration will grow with wind energy deployment, however, and even at lower penetration levels, integration issues must be addressed. Active management through flexible power generation technologies, wind energy forecasting and output curtailment, and increased coordination and interconnection between electric systems are anticipated. Mass market demand response, bulk energy storage technologies, large-scale deployment of electric vehicles, diverting excess wind energy to fuel production or local heating and geographic diversification of wind power plant siting will also become increasingly beneficial as wind electricity penetration rises.

Wind energy technology advances driven by electric system connection standards will increasingly enable wind power plants to become more active participants in maintaining the operability of the electric system. Finally, significant new transmission infrastructure, both on- and offshore, may be required to access areas with higher-quality wind resources. At low to medium levels of wind electricity penetration, the additional costs of managing variability and uncertainty, ensuring generation adequacy and adding new transmission to accommodate wind energy have been estimated to generally be in the range of US cents2005 0.7 to 3/kWh.

Environmental and social issues will affect wind energy deployment opportunities. The energy used and GHG emissions produced in the direct manufacture, transport, installation, operation and decommissioning of wind turbines are small compared to the energy generated and emissions avoided over the lifetime of wind power plants: the GHG emissions intensity of wind energy is estimated to range from 8 to 20 g CO2/kWh in most instances, whereas energy payback times are between 3.4 to 8.5 months. In addition, managing the variability of wind power output has not been found to significantly degrade the GHG emissions benefits of wind energy.

Alongside these benefits, however, wind energy also has the potential to produce some detrimental impacts on the environment and on human activities and well-being. The construction and operation of wind power plants impacts wildlife through bird and bat collisions and through habitat and ecosystem modifications, with the nature and magnitude of those impacts being site- and species-specific. For offshore wind energy, implications for benthic resources, fisheries and marine life must also be considered. Prominent social concerns include visibility/landscape impacts as well various nuisance effects and possible radar interference. Research is also underway on the potential impact of wind power plants on the local climate.

As wind energy deployment increases and as larger wind farm plants are considered, these existing concerns may become more acute and new concerns may arise.

Though attempts to measure the relative impacts of various electricity supply technologies suggest that wind energy generally has a comparatively small environmental footprint, impacts do exist.

Appropriate planning and siting procedures can reduce the impact of wind energy development on ecosystems and local communities, and techniques for assessing, minimizing and mitigating the remaining concerns could be further improved. Finally, though community and scientific concerns should be addressed, more proactive planning, siting and permitting procedures may be required to enable more rapid growth in wind energy utilization.

Technology innovation can further reduce the cost of wind energy. Current wind turbine technology has been developed largely for onshore applications, and has converged to three-bladed upwind rotors, with variable speed operation. Though onshore wind energy technology is already commercially manufactured and deployed on a large scale, continued incremental advances are expected to yield improved turbine design procedures, more efficient materials usage, increased reliability and energy capture, reduced operation and maintenance (O&M) costs and longer component lifetimes. In addition, as offshore wind energy gains more attention, new technology challenges arise and more radical technology innovations are possible (e.g., floating turbines).

Wind turbine nameplate capacity ratings of 2 to 5 MW have been common for offshore wind power plants, but 10 MW and larger wind turbines are under consideration. Advances can also be made through more fundamental research to better understand the operating environment in which wind turbines must operate.

For onshore wind power plants built in 2009, levelized generation costs in good to excellent wind resource regimes are estimated to average US cents2005 5 to 10/kWh, reaching US cents2005 15/kWh in lower resource areas. Offshore wind energy has typical levelized generation costs that are estimated to range from US cents2005 10/kWh to more than US cents2005 20/kWh for recently built or planned wind farm plants located in relatively shallow water.

Reductions in the levelized cost of onshore wind energy of 10 to 30% by 2020 are often reported in the literature. Offshore wind energy is often found to have somewhat greater potential for cost reductions: 10 to 40% by 2020.

Wind energy offers significant potential for near- and long-term GHG emissions reductions. Given the commercial maturity and cost of onshore wind energy technology, wind energy offers the potential for significant near-term GHG emissions reductions: this potential is not conditioned on technology breakthroughs, and no insurmountable technical barriers exist that preclude increased levels of wind electricity penetration.

As technology advances continue, greater contributions to GHG emissions reductions are possible in the longer term. Based on a review of the literature on the possible future contribution of RE supplies to meeting global energy needs under a range of GHG concentration stabilization scenarios, wind energy’s contribution to global electricity supply could rise from 1.8% by the end of 2009 to 13 to 14% by 2050 in the median scenario for GHG concentration stabilization ranges of 440 to 600 and <440 ppm CO2.

At the 75th percentile of reviewed scenarios, and under similarly ambitious efforts to reduce GHG emissions, wind energy’s contribution is shown to grow to 21 to 25% by 2050. Achieving the higher end of this range would be likely to require not only economic support policies of adequate size and predictability, but also an expansion of wind energy utilization regionally, increased reliance on offshore wind energy, technical and institutional solutions to transmission constraints and operational integration concerns, and proactive efforts to mitigate and manage social and environmental concerns.

Additional R&D is expected to lead to incremental cost reductions for onshore wind energy, and enhanced R&D expenditures may be especially important for offshore wind energy technology. Finally, for those markets with good wind resources but that are new to wind energy deployment, both knowledge and technology transfer may help facilitate early wind power plant installations.