Greenhouse Gas Emissions from Energy Systems, Comparison, and Overview

Radley Horton,1,a Daniel Bader,1,a Yochanan Kushnir,2 Christopher Little,3 Reginald Blake,4 and Cynthia Rosenzweig5 1Columbia University Center for Climate Systems Research, New York, NY. 2Ocean and Climate Physics Department, Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY. 3Atmospheric and Environmental Research, Lexington, MA. 4Physics Department, New York City College of Technology, CUNY, Brooklyn, NY. 5Climate Impacts Group, NASA Goddard Institute for Space Studies; Center for Climate Systems Research, Columbia University Earth Institute, New York, NY

Climate change is a complex and contentious public issue, but the risk-management options available to us are straightforward and have well-characterized strengths and weaknesses.

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Energy-related activities are a major contributor of greenhouse gas (GHG) emissions. A growing body of knowledge clearly depicts the links between human activities and climate change. Over the last century the burning of fossil fuels such as coal and oil and other human activities has released carbon dioxide (CO2) emissions and other heat-trapping GHG emissions into the atmosphere and thus increased the concentration of atmospheric CO2 emissions. The main human activities that emit CO2 emissions are (1) the combustion of fossil fuels to generate electricity, accounting for about 37% of total U.S. CO2 emissions and 31% of total U.S. GHG emissions in 2013, (2) the combustion of fossil fuels such as gasoline and diesel to transport people and goods, accounting for about 31% of total U.S. CO2 emissions and 26% of total U.S. GHG emissions in 2013, and (3) industrial processes such as the production and consumption of minerals and chemicals, accounting for about 15% of total U.S. CO2 emissions and 12% of total ...

Lentic waters are biogeochemical reactors, producing and receiving carbon (C) originally fixed by the terrestrial and aquatic biosphere, which is then buried in sediments or respired back to the atmosphere in the forms of carbon dioxide (CO2) and one of the more potent greenhouse gas (GHG) methane (CH4). Additionally, lakes serve as archives of terrestrial and aquatic carbon processes within their sediments, enabling the reconstruction of historical changes spanning thousands of years. These changes encompass alterations in land cover, indicated by pollen records, soil carbon erosion and shifts in lake productivity resulting from changes in land use and climate. Both the burial of C in lakes and the emissions of GHGs are recognised as important components of Earth's climate system, yet they remain poorly understood and constrained due to inadequate quantities and qualities of observations. In the case of GHG emissions from lakes, observations are often sporadic, failing to capture the significant spatial and temporal variations in emissions across diverse lentic systems. To address this challenge, process-based models that incorporate the interconnected biogeochemical processes occurring within lakes and their watersheds would arguably be the best tool to extrapolate from site-level observations to regional and finally global scales, to quantify the anthropogenic impact on these fluxes and to reconstruct long-term shifts in emissions and burial due to changes in land cover and climate. However, the development and evaluation of such models is hampered by the lack of observations in sufficient quality. In this project, we bring together a unique consortium of specialists in aquatic ecology, biogeochemistry, palynology, sedimentology and modelling of terrestrial and aquatic biogeochemistry. This project will put forth a national programme of systematic, long-term observations of lake GHG and C cycling processes of unmet detail, consistency and quality. First, at 40 pilot sites spanning typological and environmental gradients, there will be a comprehensive data acquisition endeavour to evaluate biological processes and mesological factors influencing the sequestration or recycling of organic carbon. This effort will be complemented with a synthesis of existing data (WP1). Second, based on well-dated sediment records, which include both newly-acquired and synthesised existing data, variability of lake C burial and their climate and land-use controls will be reconstructed over the past 150 years (WP2). For 15 of these pilot sites, reconstruction will go back until the mid-Holocene (5,000 years BP), allowing us to shed light on the anthropogenic perturbation of the C cycle in this earlier part of human history, which is commonly excluded from this type of research due to lack of information. The activities of these first two WPs will result in an open-source national database, guaranteeing valorisation of our research far beyond this project. In WP3, we will use the land surface model (LSM) ORCHIDEE C-lateral to assess C cycling in the terrestrial biosphere and the mobilisation of biospheric C into lakes, which is possible due to an explicit representation of soil C leaching and erosion processes and a downscaling scheme permitting us to assess C exports from watersheds at sub-grid scale. While LSMs are used to assess evolution of biospheric C budgets from the beginning of the Industrial Period, we will use it to hindcast the evolution since the mid-Holocene, using lake sediment records for model validation. Moreover, we will develop a new process-based lake C model supported by the database established in WPs 1 and 2, which we will couple to ORCHIDEE C-lateral to simulate lake C burial and GHG emissions in response to climate and processes in the lake watershed. This model set-up will first be used to better constrain contemporary large-scale lake GHG emissions and to disentangle the anthropogenic perturbation of these fluxes from the natural background flux. These estimates will be revolutionary, as they will allow attributing part of lake GHG emissions to anthropogenic emissions for national GHG budget reporting. Then, these models will be emulated to reconstruct evolution of lake GHG budgets and C budgets of the whole lake watershed since the mid-Holocene. While simulations will first be performed at the scales of France and Europe, the development of international partnerships to implement observations from other biomes (WP4) will finally support simulations at the global scale.

Imposing versus Enacting Commitments for the Long‐Term Energy Transition: Perspectives from the Firm

Modelling food demand in the 21st century

Energy supply utilities release significant amounts of greenhouse gases (GHGs) into the atmosphere. It is essential to accurately estimate GHG emissions with their uncertainties, for reducing GHG emissions and mitigating climate change. GHG emissions can be calculated by an activity-based method (i.e., fuel consumption) and continuous emission measurement (CEM). In this study, GHG emissions such as CO2, CH4, and N2O are estimated for a heat generation utility, which uses bituminous coal as fuel, by applying both the activity-based method and CEM. CO2 emissions by the activity-based method are 12–19% less than that by the CEM, while N2O and CH4 emissions by the activity-based method are two orders of magnitude and 60% less than those by the CEM, respectively. Comparing GHG emissions (as CO2 equivalent) from both methods, total GHG emissions by the activity-based methods are 12–27% lower than that by the CEM, as CO2 and N2O emissions are lower than those by the CEM. Results from uncertainty estimation show that uncertainties in the GHG emissions by the activity-based methods range from 3.4% to about 20%, from 67% to 900%, and from about 70% to about 200% for CO2, N2O, and CH4, respectively, while uncertainties in the GHG emissions by the CEM range from 4% to 4.5%. For the activity-based methods, an uncertainty in the Intergovernmental Panel on Climate Change (IPCC) default net calorific value (NCV) is the major uncertainty contributor to CO2 emissions, while an uncertainty in the IPCC default emission factor is the major uncertainty contributor to CH4 and N2O emissions. For the CEM, an uncertainty in volumetric flow measurement, especially for the distribution of the volumetric flow rate in a stack, is the major uncertainty contributor to all GHG emissions, while uncertainties in concentration measurements contribute a little to uncertainties in the GHG emissions.Implications:Energy supply utilities contribute a significant portion of the global greenhouse gas (GHG) emissions. It is important to accurately estimate GHG emissions with their uncertainties for reducing GHG emissions and mitigating climate change. GHG emissions can be estimated by an activity-based method and by continuous emission measurement (CEM), yet little study has been done to calculate GHG emissions with uncertainty analysis. This study estimates GHG emissions and their uncertainties, and also identifies major uncertainty contributors for each method.

Introduction: To date, a variety of studies have been published on the topic of long term energy system transition. Most studies on future energy systems, however, have a shorter time frame or adopt a supranational focus (e.g. the Energy Roadmap, 2011 or the World Energy Outlook, 2015). It then constitutes a sincere challenge to perform a national energy system transition study with as time horizon 2050 and covering a far-reaching transformation of the energy system. VITO, together with the FPB (Federal Planning Bureau) and ICEDD, performed a study to scrutinise the transition of the Belgian national energy system towards a future mix entirely based on renewable energy sources. The focus on renewable energy sources and on building a national energy system completely running on renewable energy can be traced back to three main concerns: – Climate change: Renewable energy sources (RES) are a major instrument in the fight against climate change as RES do not release (net) greenhouse gas emissions. – Security...

Achieving the international climate community's current objective of limiting global warming to no more than 1.5°C will require CO2 emissions to be cut in half by 2030 and to be eliminated by 2050. According to Vaclav Smil, these goals for the rapid decarbonization of human activities are impossible to achieve. This controversial conclusion carries weight because Smil is one of the world's leading experts on energy who has written dozens of books and hundreds of articles on a wide range of topics related to natural resources and their use by humans. Smil is an astute observer of the relationships between the human and the natural worlds and is known for his incisive analysis of complex problems, his trenchant criticisms of wrong-headed thinking, and his desire to reform misguided policy ideas. To the uninitiated reader, the subject of this book may not be clear from the title. How the World Really Works could be the title of a book written by an economist or a political scientist. The content becomes clearer when Smil identifies ammonia, plastics, steel, and concrete as the “four pillars of modern civilization.” This choice of topic may seem surprising, but several chapters are devoted to explaining why these fundamental substances are indispensable to the functioning of modern societies and are needed in vast quantities. The production of these pillars depends heavily on the combustion and conversion of fossil fuels. Understanding their roles is essential in making sound policy. The first half of the book is devoted to a detailed discussion of the complex global energy, food, and material production systems that support our current high standards of living. The food system involves good soil, water, fertilizer (mostly from ammonia), herbicides and insecticides, irrigation, heavy farm machinery, cattle ranches, factory farming of animals, huge distribution networks of trucks, trains and ships, and a range of middlemen, including truckdrivers and grocery store workers. The energy system is even more complicated and depends on several sources, including coal, oil, gas, wood, nuclear, wind, solar and hydro, each with its unique extraction and production processes. These energy sources feed into refineries and electric power plants with distribution systems involving transmission lines, pipes, ships, trucks, and so on. Another chapter covers the production and uses of a wide range of materials. Smil aims to educate his readers about how steaks end up on their dinner plate, where the electricity from the outlets in their home comes from and why cement is ubiquitous in our infrastructure. This may seem a rather quixotic objective, and economists will argue that Adam Smith's “invisible hand” takes care of all these minutiae without the consumers’ need to know. Smil disagrees and believes that a lack of fundamental knowledge about the real world is the cause of misguided and wishful thinking on the part of the public, scientists, and politicians. How the World Really Works next tackles the central issue: the threat of global warming and what can be done about it. A concise summary of climate science is followed by a critique of the current consensus plan to decarbonize human activities by 2050. These goals are embedded in the Glasgow Climate Pact agreed to at the 26th United Nations Climate Change Conference held in Glasgow last fall. They are essential to keep the global temperature from rising more than 1.5°C above preindustrial levels. Smil claims that these goals are unattainable for two reasons. The main obstacle to rapid decarbonization is the enormous scale of the infrastructure humanity has built to feed, house, transport, and pamper humans and the impossibility of quickly turning this around. Our food, energy and material industries are full of cumbersome and heavy man-made objects such as irrigation systems, refineries, electricity generating plants, and distribution systems that require a long time to build and are expected to last decades. People are accustomed to extremely rapid technological change in tools such as cell phones and computers. Some believe that switching to renewable energy resources is not much more difficult than updating to a new phone. Smil emphatically disagrees. Many nations have already made large investments in renewable electricity production with solar panels and windmills. This is important, but the intermittent nature of these sources requires back-up from fossil fuel or nuclear plants. Moreover, electricity today supplies only 18 percent of global energy consumption. Most of the remaining energy is derived from fossil fuels and used for transportation (cars, airplanes, trucks, etc.), households (heating and cooking) and industry (including the production of steel, ammonia, cement, and plastics). Despite recent efforts to introduce renewables, the global consumption of fossil fuels rose by 45 percent in the first two decades of this century, and the share of fossil fuels in the world's energy supply declined only slightly. Smil's position is clear: “…we are a fossil-fueled civilization whose…prosperity rests on the combustion of huge quantities of fossil carbon and we cannot simply walk away from this critical determinant of our fortunes in a few decades…” (5) and “the scale of our dependence on fossil carbon make any rapid substitutions impossible” (42). “We will be eating transformed fossil fuels…for decades to come” (75) and “modern economies will always be tied to massive material flows and …will remain fundamentally dependent on fossil fuels used in the production of these indispensable materials” (102). Cutting emissions in half in eight years indeed looks impossible. The other fundamental obstacle to the rapid elimination of CO2 and other greenhouse gasses is the large and growing demand for food, energy, and materials from low- and middle-income countries. Even if the affluent world somehow manages to reach net zero emissions soon, there are still a billion people who are undernourished or malnourished, and billions more whose energy and material use is only a tiny fraction of levels consumed in the rich world. These people need much more ammonia to feed increasing populations a better diet and huge quantities of steel, cement, and plastics to build their infrastructure to support higher living standards. All of this requires massive amounts of fossil fuels, which in part is why India, China, and other low- and middle-income countries are rapidly building new coal plants. China's fossil fuel consumption nearly tripled between 2000 and 2019; there are billions of people living in poorer parts of the world who want to do the same. All of this is unwelcome news for the international climate community that has for decades tried to negotiate international agreements to reduce and eventually eliminate greenhouse gas emissions. The response from this community was not long in coming. In fact, it arrived before the book's publication date in the form of a blog by Bill McKibben, a highly influential environmental activist (https://billmckibben.substack.com/p/who-gets-to-define-reality?sxr). Interestingly, he largely agrees with Smil's main point: “of course he's right: it is on the bleeding edge of the technically possible to cut emissions in half by 2030, but it's almost certainly not politically possible to get all the way there.” However, McKibben disagrees with Smil about the desirability of trying anyway: “pressing to make that change happen—pushing for the most rapid possible change—could get us further sooner.” He also accuses Smil of assisting “self-interested oil companies and intellectually lazy politicians.” The book's main conclusions are well supported, but several important issues could have been given more attention to provide the reader with a fuller understanding of the ongoing climate policy debate. Missing from this scientific account is a true sense of urgency. To McKibben and his colleagues, global climate change is a catastrophic existential crisis that demands a radical change in the way we live. They would even be willing to accept a decline in standards of living among the well-off. Smil says he is neither an optimist nor a pessimist and discusses how past predictions of global crises have gone wrong thanks to technical innovations. He is essentially uncertain about what lies ahead and refuses to make forecasts. To him, the most likely prospect is that we will muddle through with “a mixture of progress and setbacks, of insurmountable difficulties and near-miraculous advances” (229). However, he neglects to note that when faced with a highly uncertain critical situation, it is better to give more weight to very bad outcomes. In the future, we will regret not having taken more insurance in the 2020s if the pessimists turn out to be right. If no drastic changes are made in greenhouse gas emissions in the coming decades, it will be too late to avoid catastrophic outcomes later in the century. Once carbon concentrations have reached multiple preindustrial levels, large future temperature increases and their dire consequences for humans and the environment become essentially unavoidable due to inertia in our global temperature regulation system. A second issue is a lack of an alternative solution. If turning around our energy supply system in the next decades is not feasible, then what should be done? This question is not addressed in detail, but Smil half-heartedly offers a controversial solution: the “greedy” affluent should consume less. Rapidly rising incomes (made possible by the four pillars) have led to extraordinary levels of consumption of material goods. Many households in OECD countries can afford multiple cars or SUVs, large homes, vacations to exotic places, and food and drink that is flown in from around the world. Smil wants everyone to live a simpler life with a smaller environmental footprint. This recommendation has been made by environmentalists for many years with little success because most people do not want to make sacrifices. It is also not clear how much of a difference cutting luxuries will make. In theory, consumers could be coaxed into changing to more environmentally friendly behaviors and consumption patterns (e.g., by introducing a substantial carbon tax), but for now, this is not a viable political option in many countries. The third is the absence of a discussion or even mention of geoengineering solutions such as blocking sunlight. Geoengineering is still in its early stages of development, but in theory, it could be a relatively inexpensive option. If humanity is facing a catastrophic future, why not consider all options no matter how controversial? PDR readers may be disappointed that Smil has not much to say about population throughout the book. However, on the last page of the last chapter, he states, “Despite the recent preoccupation with the impact of global warming and for the need for rapid decarbonation, few uncertain outcomes will be as important in determining our future as the trajectory of the global population during the remainder of the 21st century.” This is a sound statement, but he does not elaborate his thinking on the causes and consequences of population growth. It would be interesting to learn his views on how to slow the still rapid expansion of human numbers in the poorest regions of the world. This book has become a NYT bestseller for a good reason. It is essential reading for anyone with an interest in the impact future climate change will have on our human and natural worlds. The text is packed with interesting and sometimes startling facts, statistics, and conclusions and is written to be accessible to a wide audience (although it helps to know what mega-joules, gigawatt-hours, and yotta-bytes are). Environmental and climate scientists will encounter a fair amount of familiar material but still find much of interest. In any case, they may want to read the book to understand the fine points of Smil's arguments and to take part more effectively in the lively ongoing debate about his conclusions.

Taking Stock of Strategies on Climate Change and the Way Forward: A Strategic Climate Change Framework for Australia

The construction sector is a central source of greenhouse gas (GHG) emissions. Reducing environmental impacts along the life cycle of buildings is therefore an important target. Given recent innovations in low-energy buildings and energy supply systems with low climate impacts, additional reduction potential can mainly be found in mitigating GHG emissions in other life cycle stages. The focus of mitigation has thus shifted to emissions related to material input, and comparative life cycle analyses of buildings constructed with different material types are becoming increasingly relevant in guiding regulations to achieve emission reduction targets. This paper performs comparative life cycle assessments for 48 non-residential buildings, comparing GHG emissions according to the current European standardised calculation methods. A substitution potential is introduced to evaluate the advantage of using timber as a building material. Furthermore, a comparative method is presented for assessing the substitution potential on the building level. The results show that the substitution potential for the construction of the studied buildings ranges from 5 to 48%. Specific substitution potentials are differentiated between four subcategories of non-residential buildings. The lowest substitution potential was identified for agricultural buildings and the highest for office and administration buildings. Moreover, the current research shows that the specific materials, construction, the geometry and design all affect the substitution potential of a building. On the basis of these values, it is possible to make projections regarding GHG reduction potential in the construction sector on a national scale.

Major US electric utility climate pledges have the potential to collectively reduce power sector emissions by one-third

Drained peat soils contribute significantly to global human-caused CO2 emissions and reducing peat degradation via rewetting is high on the political agenda. Ceasing agricultural activities on rewetted soils might lead to land owner resistance and high societal expenses to compensate farmers. Continued biomass production adapted for wet conditions on peat soils potentially minimizes these costs and helps supplying the growing demand for e.g. materials, fuels and feed. Here we used a life cycle assessment approach (cradle to farm gate) to investigate the greenhouse gas (GHG) emissions related to three cases by applying IPCC (Intergovernmental Panel on Climate Change) emission factors and specific site conditions at a bog and a fen site that represent widely distributed temperate peat soils. Besides soil emissions, upstream emissions from input, operational emissions and emission related to rewetting construction work were included. The analyzed systems were deeply drained cash cropping on agricultural bog (potatoes (Solanum tuberosum L.), spring barley (Hordeum vulgare L.) and oat (Avena sativa L.), permanent Reed canary grass (RCG) (Phalaris arundinacea L.) production on non-drained bog and permanent RCG production on shallow-drained fen. The annual mean water table depths (WTD) were −70, −38 (estimated) and −13 cm, respectively. Results showed estimated GHG emissions of 40.5, 26.1 and 20.6 Mg CO2eq ha−1, respectively, corresponding to a 35% GHG reduction for the non-drained bog case as compared to the drained bog case, despite that the obtained WTD due to ceased drainage did not adhere to the IPCC rewetting threshold of −30 cm. Emissions related to crop management represented 7, 14 and 19% of total emissions. In the RCG cultivation on fen case, the WTD were controlled primarily by the water table of the nearby stream and total GHG emissions were even lower as compared to the RCG production on the non-drained bog reflecting the difference in WTD. Rewetting projects need to include careful knowledge of the specific peat area to foresee the actual reduction potential.

Globally, agriculture is directly responsible for 14% of annual greenhouse gas(GHG) emissions and induces an additional 17% through land use change, mostlyin developing countries (Vermeulen et al 2012). Agricultural intensification andexpansion in these regions is expected to catalyze the most significant relativeincreases in agricultural GHG emissions over the next decade (Smith et al 2008,Tilman et al 2011). Farms in the developing countries of sub-Saharan Africa andAsia are predominately managed by smallholders, with 80% of land holdingssmaller than ten hectares (FAO 2012). One can therefore posit that smallholderfarming significantly impacts the GHG balance of these regions today and willcontinue to do so in the near future.However, our understanding of the effect smallholder farming has on theEarth’s climate system is remarkably limited. Data quantifying existing andreduced GHG emissions and removals of smallholder production systems areavailable for only a handful of crops, livestock, and agroecosystems (Herrero et al2008, Verchot et al 2008, Palm et al 2010). For example, fewer than fifteenstudies of nitrous oxide emissions from soils have taken place in sub-SaharanAfrica, leaving the rate of emissions virtually undocumented. Due to a scarcity ofdata on GHG sources and sinks, most developing countries currently quantifyagricultural emissions and reductions using IPCC Tier 1 emissions factors.However, current Tier 1 emissions factors are either calibrated to data primarilyderived from developed countries, where agricultural production conditions aredissimilar to that in which the majority of smallholders operate, or from data thatare sparse or of mixed quality in developing countries (IPCC 2006). For the mostpart, there are insufficient emissions data characterizing smallholder agricultureto evaluate the level of accuracy or inaccuracy of current emissions estimates.Consequentially, there is no reliable information on the agricultural GHG budgetsfor developing economies. This dearth of information constrains the capacity totransition to low-carbon agricultural development, opportunities for smallholdersto capitalize on carbon markets, and the negotiating position of developingcountries in global climate policy discourse.Concerns over the poor state of information, in terms of data availability andrepresentation, have fueled appeals for new approaches to quantifying GHGemissions and removals from smallholder agriculture, for both existing conditionsand mitigation interventions (Berry and Ryan 2013, Olander et al 2013).Considering the dependence of quantification approaches on data and the currentdata deficit for smallholder systems, it is clear that in situ measurements must bea core part of initial and future strategies to improve GHG inventories and