WGII LESS scenarios
WGII LESS scenarios refer to five distinct approaches developed to assess low-emissions supply systems in the context of climate change. These scenarios were created by Working Group II of the Intergovernmental Panel on Climate Change (IPCC) to explore the impacts of climate change and evaluate various adaptation and mitigation strategies. The five scenarios include Nuclear-intensive (NI), Natural-gas-intensive (NGI), Coal-intensive (CI), Biomass-intensive (BI), and a High-demand variant (HD), each examining different energy sources and their potential roles in reducing greenhouse gas emissions.
The WGII analysis highlights the technical and economic feasibility of increasing energy efficiency and transitioning to cleaner technologies, particularly in energy generation, while acknowledging that significant upfront investments are often required. While options like biomass and renewable energy sources show promise, reliance on fossil fuels remains a concern due to rising global energy demands. The scenarios emphasize that no single solution will be sufficient globally; instead, a combination of different technologies tailored to regional needs will be essential for stabilizing emissions. By providing a framework for understanding various possibilities, the WGII LESS scenarios aim to guide nations in selecting appropriate clean energy strategies that align with their specific circumstances and developmental goals.
WGII LESS scenarios
- DATE: Published as part of the Second Assessment Report in 1995
Definition
WGII LESS scenarios were developed for the Second Assessment Report of Working Group II (WGII) of the to assess low-emissions supply systems (LESS). The mission of Working Group II was to study the physical, ecological, human-health-related, and socioeconomic impacts of climate change. The overall goal of the IPCC is to determine the history, present situation, and likely future of Earth’s climate and to make recommendations as to the best climate policies to preserve the health and welfare of the world’s peoples and ecosystems. As part of that mission, WGII was tasked to review the technical and economic feasibility of various adaptation and mitigation strategies relevant to climate change.
Significance for Climate Change
WGII examined various cost-effective adaptation and mitigation techniques, beginning with existing commercial-scale technologies that would increase efficiencies in energy generation and distribution by 10-30 percent with little net cost increases. Gains of 50-60 percent in are technically feasible in the developed world, but they would require significant capital expenditures on the global commercial-energy system. Such costs would be prohibitive for the developing world. Even a switch to more efficient energy technology might not lead to an overall reduction in total greenhouse gas (GHG) emissions, given the rising global demand for energy.
The five LESS scenarios explored by WGII are:
- • Nuclear-intensive (NI)
- • Natural-gas-intensive (NGI)
- •Coal-intensive (CI)
- • Biomass-intensive (BI)
- • High-demand variant (HD)
WGII considered the options involved in switching to low-carbon fossil fuels. This switch would favor electric power generation using oil or natural gas rather than coal. Sufficient technologies exist to allow for the decarbonization of fossil fuel and the storage of for use in producing hydrogen fuels. Technologies also exist to capture methane emissions in the energy-generation-and-distribution process. Commercial-scale implementation of decarbonization and methane capture are not, however, economically attractive solutions.
WGII considered energy generation by means of nuclear power. This option is technically and economically possible and cost-effective, but it is very unattractive to a segment of the public as a result of problems with reactor safety, radioactive-waste transfer and storage, and a lack of clear authority to force nuclear-reactor builders and operators to adhere to international quality-control standards.
WGII also considered energy generation by means of renewable sources of energy, either exclusively or in combination with fossil-fuel sources. In this area, WGII constructed five scenarios using varying degrees of renewable energy technologies that were then available or could become available on a commercial scale at an economically justifiable cost. Technologies that were not cost competitive for CO2 LESS up to the year 2100 were eliminated from consideration.
WGII investigated the coal-intensive option using an experimental stem-injected aeroderivative gas turbine developed by General Electric. In comparing the efficiencies of coal and energy generation, WGII found that either a steam-injected or an oxygen-blown gasifier turbine used in conjunction with coal would result in “hot gas” clean-up costs without removing any sulfur in the combustion process. Available technologies do not allow coal to be burned as cleanly as biomass fuels. Research in this area continues, however.
The natural-gas-intensive is based on estimates of recoverable natural gas resources provided by the 1994 U.S. Geological Survey. Should these estimates prove inaccurate, or should the resources prove too expensive to recover, the natural-gas-intensive option will decrease in feasibility. LESS natural-gas-intensive practices include CO2 sequestration, an additional cost factor.
The high-demand variant scenario is based on a fourfold increase in global energy demand. The HD variant involves a mixture of coal, biomass, and alternative energy sources such as wind and solar power. It also includes decarbonization of coal and natural gas and high degrees of energy efficiency across the board. It was judged to be cost prohibitive given current levels of technology in the developing world.
The biomass-intensive scenario shows much promise for reducing global GHG emissions in a cost-effective manner. Biomass feed stocks must be high-density materials, such as wood chips. In order to combust with maximum efficiency, the wood chips produced from fast-growing trees must be dried using superheated steam, which can then be recovered and utilized in the energy production process. Biomass power plants can be smaller in scale than traditional coal plants and possibly located nearer to energy consumers, thus increasing efficiency in distribution networks.
WGII also considered the use of intermittent renewable energy sources such as solar and wind in combination with other fuels for electricity generation. It determined that up to 30 percent of electrical energy can by produced by renewable sources without significant cost increases in electrical storage capacity.
Information and results from the WGII Second Assessment Report indicate that a combination of different low-emission energy-generating methods, all operating at maximum achievable efficiency in different regions of the world, will be necessary to stabilize and possibly reduce global GHG emissions. Energy demands will increase in the foreseeable future as a result of global population growth and economic development, and no single technology will satisfy those demands, nor is any single technology suitable for universal adoption by all nations. However, the WGII LESS scenarios may help each nation in evaluating the proper combination of clean energy technologies for its needs and increase the global adoption of clean energy.
Bibliography
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Houghton, John. Global Warming: The Complete Briefing. 4th ed. New York: Cambridge University Press, 2009.
Pittock, A. Barrie. Climate Change: Turning up the Heat. Sterling, Va.: Earthscan, 2005.
"Summary for Pilcymakers Headline Statements." IPCC Sixth Assessment Report, 28 Feb. 2022, www.ipcc.ch/report/ar6/wg2/resources/spm-headline-statements/. Accessed 21 Dec. 2024.