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Potential Climatic Impacts and Reliability of Very Large-Scale Wind Farms

Meeting future world energy needs while addressing climate change requires large-scale deployment of low or zero greenhouse gas (GHG) emission technologies such as wind energy. The widespread availability of wind power has fueled substantial interest in this renewable energy source as one of the needed technologies. For very large-scale utilization of this resource, there are however potential environmental impacts, and also problems arising from its inherent intermittency, in addition to the present need to lower unit costs. To explore some of these issues, we use a three-dimensional climate model to simulate the potential climate effects associated with installation of wind-powered generators over vast areas of land or coastal ocean. Using wind turbines to meet 10% or more of global energy demand in 2100, could cause surface warming exceeding 1 °C over land installations. In contrast, surface cooling exceeding 1 °C is computed over ocean installations, but the validity of simulating the impacts of wind turbines by simply increasing the ocean surface drag needs further study. Significant warming or cooling remote from both the land and ocean installations, and alterations of the global distributions of rainfall and clouds also occur. These results are influenced by the competing effects of increases in roughness and decreases in wind speed on near-surface turbulent heat fluxes, the differing nature of land and ocean surface friction, and the dimensions of the installations parallel and perpendicular to the prevailing winds. These results are also dependent on the accuracy of the model used, and the realism of the methods applied to simulate wind turbines. Additional theory and new field observations will be required for their ultimate validation. Intermittency of wind power on daily, monthly and longer time scales as computed in these simulations and inferred from meteorological observations, poses a demand for one or more options to ensure reliability, including backup generation capacity, very long distance power transmission lines, and onsite energy storage, each with specific economic and/or technological challenges.
 

Potential Climatic Impacts and Reliability of Very Large-Scale Wind Farms

Meeting future world energy needs while addressing climate change requires large-scale deployment of low or zero greenhouse gas (GHG) emission technologies such as wind energy. The widespread availability of wind power has fueled legitimate interest in this renewable energy source as one of the needed technologies. For very large-scale utilization of this resource, there are however potential environmental impacts, and also problems arising from its inherent intermittency, in addition to the present need to lower unit costs. To explore some of these issues, we use a three-dimensional climate model to simulate the potential climate effects associated with installation of wind-powered generators over vast areas of land or coastal ocean. Using windmills to meet 10% or more of global energy demand in 2100, could cause surface warming exceeding 1oC over land installations. In contrast, surface cooling exceeding 1°C is computed over ocean installations, but the validity of simulating the impacts of windmills by simply increasing the ocean surface drag needs further study. Significant warming or cooling remote from both the land and ocean installations, and alterations of the global distributions of rainfall and clouds also occur. These results are influenced by the competing effects of increases in roughness and decreases in wind speed on near-surface turbulent heat fluxes, the differing nature of land and ocean surface friction, and the dimensions of the installations parallel and perpendicular to the prevailing winds. These results are also dependent on the accuracy of the model used, and the realism of the methods applied to simulate windmills. Additional theory and new field observations will be required for their ultimate validation. Intermittency of wind power on daily, monthly and longer time scales as computed in these simulations and inferred from meteorological observations, poses a demand for one or more options to ensure reliability, including backup generation capacity, very long distance power transmission lines, and onsite energy storage, each with specific economic and/or technological challenges.

Potential Direct and Indirect Effects of Global Cellulosic Biofuel Production on Greenhouse Gas Fluxes from Future Land-use Change

The production of cellulosic biofuels may have a large influence on future land emissions of greenhouse gases. These effects will vary across space and time depending on land-use policies, trade, and variations in environmental conditions. We link an economic model with a terrestrial biogeochemistry model to explore how projections of cellulosic biofuels production may influence future land emissions of carbon and nitrous oxide. Tropical regions, particularly Africa and Latin America, are projected to become major producers of biofuels. Most biofuels production is projected to occur on lands that would otherwise be used to produce crops, livestock and timber. Biofuels production leads to displacement and a redistribution of global food and timber production along with a reduction in the trade of food products. Overall, biofuels production and the displacement of other managed lands increase emissions of greenhouse gases primarily as a result of carbon emissions from deforestation and nitrous oxide emissions from fertilizer applications to maximize biofuel crop production in tropical regions. With optimal application of nitrogen fertilizers, cellulosic biofuels production may enhance carbon sequestration in soils of some regions. As a result, the relative importance of carbon emissions versus nitrous oxide emissions varies among regions. Reductions in carbon sequestration by natural ecosystems caused by the expansion of biofuels have minor effects on the global greenhouse gas budget and are more than compensated by concurrent biofuel-induced reductions in nitrous oxide emissions from natural ecosystems. Land policies that avoid deforestation and fertilizer applications, particularly in tropical regions, will have the largest impact on minimizing land emissions of greenhouse gas from cellulosic biofuels production.

Potential Land Use Implications of a Global Biofuels Industry

In this paper we investigate the potential production and implications of a global biofuels industry. We develop alternative approaches to the introduction of land as an economic factor input, in value and physical terms, into a computable general equilibrium framework. Both approach allows us to parameterize biomass production in a manner consistent with agro-engineering information on yields and a "second generation" cellulosic biomass conversion technology. We explicitly model land conversion from natural areas to agricultural use in two different ways: in one approach we introduce a land supply elasticity based on observed land supply responses and in the other we consider only the direct cost of conversion. We estimate biofuels production at the end of the century will reach 220 to 270 exajoules in a reference scenario and 320 to 370 exajoules under a global effort to mitigate greenhouse gas emissions. The version with the land supply elasticity allows much less conversion of land from natural areas, forcing intensification of production, especially on pasture and grazing land, whereas the pure conversion cost model leads to significant deforestation. The observed land conversion response we estimate may be a short-term response that does not fully reflect the effect of long-run pressure to convert land if rent differentials are sustained over 100 years. These different approaches emphasize the importance of reflecting the non-market value of land more fully in the modeling of the conversion decision.

Potential land use implications of a global biofuels industry

In this paper we investigate the potential production and implications of a global biofuels industry. We develop alternative approaches to consistently introduce land as an economic factor input and in physical terms into a computable general equilibrium framework. The approach allows us to parameterize biomass production consistent with agro-engineering information on yields and a "second generation" cellulosic biomass conversion technology. We explicitly model land conversion from natural areas to agricultural use in two different ways: in one approach we introduced a land supply elasticity based on observed land supply responses and in the other approach we considered only the direct cost of conversion. We estimate biofuels production at the end of the century could reach 221 to 267 EJ in a reference scenario and 319 to 368 EJ under a global effort to mitigate greenhouse gas emissions. The version with the land supply elasticity allowed much less conversion of land from natural areas, forcing intensification of production, especially on pasture and grazing land, whereas the pure conversion cost model led to significant deforestation. These different approaches emphasize the importance of somehow reflecting the non-market value of land more fully in the conversion decision. The observed land conversion response we estimate may be a short turn response that does not fully reflect the effect of long run pressure to convert land if rent differentials are sustained over 100 years.

© 2007 Berkeley Electronic Press

Precipitation Recycling in the Amazon Basin

Precipitation recycling is the contribution of evaporation within a region to precipitation in that same region. The recycling rate is a diagnostic measure of the potential for interactions between land surface hydrology and regional climate. In this paper we present a model for describing the seasonal and spatial variability of the recycling process. The precipitation recycling ratio, p, is the basic variable in describing the recycling process. p is the fraction of precipitation at a certain location and time which is contributed by evaporation within the region under study. The recycling model is applied in studying the hydrologic cycle in the Amazon basin. It is estimated that about 25% of all the rain that falls in the Amazon basin is contributed by evaporation within the basin. This estimate is based on analysis of a data set supplied by the European Centre for Medium-range Weather Forecasts. The same analysis is repeated using a different data set from the Geophysical Fluid Dynamics Laboratory. Based on this data set, the recycling ratio is estimated to be 35%. The seasonal variability of the recycling ratio is small compared with the yearly average. The new estimates of the recycling ratio are compared with results of previous studies, and the differences are explained.

© 1996 Royal Meteorological Society

Precipitation, Recycling, and Land Memory: An Integrated Analysis

A synthesis of several approaches to quantifying land–atmosphere interactions is presented. These approaches use data from observations or atmospheric reanalyses applied to atmospheric tracer models and stand-alone land surface schemes. None of these approaches relies on the results of general circulation model simulations. A high degree of correlation is found among these independent approaches, and constructed here is a composite assessment of global land–atmosphere feedback strength as a function of season. The composite combines the characteristics of persistence of soil moisture anomalies, strong soil moisture regulation of evaporation rates, and reinforcement of water cycle anomalies through recycling. The regions and seasons that have a strong composite signal predominate in both summer and winter monsoon regions in the period after the rainy season wanes. However, there are exceptions to this pattern, most notably over the Great Plains of North America and the Pampas/Pantanal of South America, where there are signs of land–atmosphere feedback throughout most of the year. Soil moisture memory in many of these regions is long enough to suggest that real-time monitoring and accurate initialization of the land surface in forecast models could lead to improvements in medium-range weather to subseasonal climate forecasts.

© 2009 American Meteorological Society

Pricing Carbon - The European Union Emissions Trading Scheme

About the book: The European Union's Emissions Trading Scheme (EU ETS) is the world's largest market for carbon and the most significant multinational initiative ever taken to mobilize markets to protect the environment. It will be an important influence on the development and implementation of trading schemes in the US, Japan, and elsewhere. However, as is true of any pioneering public policy experiment, this scheme has generated much controversy. Pricing Carbon provides the first detailed description and analysis of the EU ETS, focusing on the first 'trial' period of the scheme (2005-7). Written by an international team of experts, it allows readers to get behind the headlines and come to a better understanding of what was done and what happened based on a dispassionate, empirically based review of the evidence. This book should be read by anyone who wants to know what happens when emissions are capped, traded, and priced.

Publisher's Link to Book

Op-Ed: E.U. Greenhouse Gas Plan: Better Than It Sounds by A. Denny Ellerman (Forbes.com, March 18, 2010)

Primary Aluminum Production: Climate Policy, Emissions and Costs

Climate policy regarding perfluorocarbons (PFCs) may have a significant influence on investment decisions in the production of primary aluminum. This work demonstrates an integrated analysis of the effectiveness and likely economic consequences of different climate policy options. In our study we first compare atmospheric observations to the available estimates of PFC emissions for the baseline years 1990 and 1995. We then present projections for regional emissions of PFCs from the aluminum industry using the MIT Emissions Projection and Policy Analysis model under different policy scenarios. Abatement costs for emissions of PFCs and CO2 are compared in the context of the Kyoto Protocol.

Probabilistic Emissions Scenarios

We provide a set of three emissions scenarios with known probability characteristics generated using an uncertainty technique known as the deterministic equivalent modeling method (DEMM), which requires distributions for uncertain parameter inputs and then uses a statistical sampling technique to generate parameter sets, and the MIT Emissions Prediction and Policy Analysis (EPPA) model. Emissions of CO2, CH4, N2O, SF6, PFC, HFC, NOx, SOx, CO, NMVOC, NH3 and carbonaceous particulates from 1995 through 2100 at 5 year intervals are provided on a 1° by 1° latitude-longitude grid. These scenarios do not include emissions from natural sources or sinks of carbon, other GHGs, or other substances. They include emissions of carbon and other substances from land use change (deforestation) and agriculture (waste burning, livestock, rice production, soils) but do not include carbon sinks due to forest regrowth. The scenarios were selected by chosing parameter sets that produced the median (50 percentile value) and 97.5 percentile value (upper) and 2.5 percentile value (lower) limit for CO2 emissions in 2100 (i.e. a range covering 95 percent of the distribution). Conditional on these values, we then chose parameter sets that produced 50 percentile values for each of the other emissions. This scenario selection design was chosen so that the resulting scenarios are approximately 2.5, 50, 97.5 percentile outcomes yet retain the characteristic that the scenarios for all substances are the result of internally consistent scenarios given the structure of the EPPA model.

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