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Net anthropogenic emissions of carbon dioxide (CO2) must approach zero by mid-century (2050) in order to stabilize the global mean temperature at the level targeted by international efforts1-5. Yet continued expansion of fossil-fuel-burning energy infrastructure implies already 'committed' future CO2 emissions6-13. Here we use detailed datasets of existing fossil-fuel energy infrastructure in 2018 to estimate regional and sectoral patterns of committed CO2 emissions, the sensitivity of such emissions to assumed operating lifetimes and schedules, and the economic value of the associated infrastructure. We estimate that, if operated as historically, existing infrastructure will cumulatively emit about 658 gigatonnes of CO2 (with a range of 226 to 1,479 gigatonnes CO2, depending on the lifetimes and utilization rates assumed). More than half of these emissions are predicted to come from the electricity sector; infrastructure in China, the USA and the 28 member states of the European Union represents approximately 41 per cent, 9 per cent and 7 per cent of the total, respectively. If built, proposed power plants (planned, permitted or under construction) would emit roughly an extra 188 (range 37-427) gigatonnes CO2. Committed emissions from existing and proposed energy infrastructure (about 846 gigatonnes CO2) thus represent more than the entire carbon budget that remains if mean warming is to be limited to 1.5 degrees Celsius (°C) with a probability of 66 to 50 per cent (420-580 gigatonnes CO2)5, and perhaps two-thirds of the remaining carbon budget if mean warming is to be limited to less than 2 °C (1,170-1,500 gigatonnes CO2)5. The remaining carbon budget estimates are varied and nuanced14,15, and depend on the climate target and the availability of large-scale negative emissions16. Nevertheless, our estimates suggest that little or no new CO2-emitting infrastructure can be commissioned, and that existing infrastructure may need to be retired early (or be retrofitted with carbon capture and storage technology) in order to meet the Paris Agreement climate goals17. Given the asset value per tonne of committed emissions, we suggest that the most cost-effective premature infrastructure retirements will be in the electricity and industry sectors, if non-emitting alternatives are available and affordable4,18.

Abstract A carbon dioxide (CO2) based mixture was investigated as a promising solution to improve system performance and expand the condensation temperature range of a CO2 transcritical Rankine cycle (C-TRC). An experimental study of TRC using CO2/R134a mixtures was performed to recover waste heat of engine coolant and exhaust gas from a heavy-duty diesel engine. The main purpose of this study was to investigate experimentally the effect of the composition ratio of CO2/R134a mixtures on system performance. Four CO2/R134a mixtures with mass composition ratios of 0.85/0.15, 0.7/0.3, 0.6/0.4 and 0.4/0.6 were selected. The high temperature working fluid was expanded through an expansion valve and then no power was produced. Thus, current research focused on the analysis of measured operating parameters and heat exchanger performance. Heat transfer coefficients of various heat exchangers using supercritical CO2/R134a mixtures were provided and discussed. These data may provide useful reference for cycle optimization and heat exchanger design in application of CO2 mixtures. Finally, the potential of power output was estimated numerically. Assuming an expander efficiency of 0.7, the maximum estimations of net power output using CO2/R134a (0.85/0.15), CO2/R134a (0.7/0.3), CO2/R134a (0.6/0.4) and CO2/R134a (0.4/0.6) are 5.07 kW, 5.45 kW, 5.30 kW, and 4.41 kW, respectively. Along with the increase of R134a composition, the estimation of net power output, thermal efficiency and exergy efficiency increased at first and then decreased. CO2/R134a (0.7/0.3) achieved the maximum net power output at a high expansion inlet pressure, while CO2/R134a (0.6/0.4) behaves better at low pressure.

In response to climate change, governments are developing policies to move toward ultra-low-energy or ‘zero-energy’ buildings (ZEBs). Policies, codes, and governance structures vary among regions, and there is no universally accepted definition of a ZEB. These variables make it difficult, for countries such as China that wish to set similar goals, to determine an optimum approach. This paper reviews ZEBs policies, programmes, and governance approaches in two jurisdictions that are leading ZEBs development: Denmark and the state of California in the United States. Different modes of governance (hierarchy: principal–agent relations, market: self organizing and network: independent actors) are examined specifically in relation to policy instruments (prescriptive, performance or outcome-based). The analysis highlights differences in institutional conditions and examines available data on energy performance resulting from a building policy framework. The purpose is to identify ZEBs governance and implementation deficits in China and analyse alternative governance approaches that could be employed in China, which is currently developing ZEBs targets and policies. Conclusions suggest that the ZEBs governance structure in China could benefit from widened participation by all societal actors involved in achieving ZEBs targets. China's ZEBs policies would benefit from employing a more balanced hybrid governance approach.

LBNL- Comments on the Joint Proposed Rulemaking to Establish Light- Duty Vehicle Greenhouse Gas Emission Standards and Corporate Average Fuel Economy Standards Docket No. NHTSA–2009–0059 and Docket No. EPA-HQ-OAR-2009-0472 Tom Wenzel, Lawrence Berkeley National Laboratory October 27, 2009 Presented by Tom Wenzel Energy Analysis Department Environmental Energy Technologies Division Lawrence Berkeley National Laboratory Berkeley, CA 94720 October 2009 This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Director of Strategic Planning and Analysis, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

As concerns around water scarcity and energy security increase, so too has interest in the connections between these resources, through a concept called the water–energy nexus. Efforts to improve the integration of water and energy management and to understand their cross-sector relevance are growing. In particular, this paper develops a better empirical understanding on the extent to which governance settings hinder and/or enable policy coherence between the water and energy sectors through a comparative analysis of two case studies, namely, Los Angeles County, California, the United States, and the city of Beijing, China. This paper examines the extent to which the institutional context enables policy coordination within (vertically) and between (horizontally) the water and energy sectors in Beijing and Los Angeles. To do so, we propose a framework for analyzing policy integration for the water energy nexus based on environmental policy integration (EPI). The results highlight the multiple and flexible approaches of EPI in nexus governance, not least with regards to horizontal and vertical policy integration, but also in terms of explicit (i.e., intended) and implicit (i.e., unintended) coordination. The level of nexus-focused policy integration is highly dependent on the motivation at the local context and the criteria to evaluate policy success in each sector.

I. INTRODUCTION II. BACKGROUND ON CLIMATE CHANGE III. HOLDING EMITTERS RESPONSIBLE A. Who Should Pay? B. Designing a System to Shift Costs to Emitters IV. FOUR QUESTIONS ABOUT APPORTIONING RESPONSIBILITY AMONG EMITTERS A. Total or Excess Emissions? B. Average or Marginal Effect? C. Current or Cumulative Emissions? D. Current or Projected Harms? E. The Restitution Measure as an Alternative F. Lessons on Apportioning Responsibility from CERCLA V. CONCLUSION I. INTRODUCTION As most people now realize, our society can no longer postpone serious consideration of how to respond to climate change. Most public attention has been focused on the issue of mitigation--that is, how to reduce greenhouse gas levels and by how much. However, society also needs to consider methods of adapting to climate change. Adaptation will not be cheap. While it is too early to make confident cost estimates, it is clear that the expense for the U.S. will reach the billions of dollars threshold annually over the next few decades. (1) In addition, some of the harms of climate change cannot be avoided by adaptation, and these too may be expensive. The most immediate question is what to do about climate change, but a very closely related question is who should pay. This article is the third in a trilogy addressing the question of how climate change costs should be allocated. The previous articles in the trilogy addressed related aspects of this problem. The first article considered how we might design a scheme where emitters would compensate victims of climate change. Compensation for adaptation costs was a key part of the solution, because of the relative administrative manageability of using this measure of damage. The second article considered the question of how to allocate climate adaptation costs, and concluded that at least some of these costs should be allocated to emitters. Thus, via different paths of reasoning, the two articles converged on the same destination - that emitters should bear at least part of the burden of adaptation costs. A related issue is how mitigation costs should be allocated. Dealing with climate change requires that we reduce total greenhouse emissions to much lower levels. In effect, this goal dictates a cap on emissions. Within that cap, it might be appropriate to allocate emission rights solely on the basis of economic efficiency, or to consider taking other factors into account. Even if emission rights are allocated on the basis of efficiency, side payments could be arranged based on equity or other considerations. Thus, allocation of emission costs could be an issue. The cost allocation issue could arise under any mitigation scheme. For example, if a carbon tax is used to limit emissions, there could well be claims that current emitters deserve to have some compensation from past emitters, on the theory that mitigation is only required because of the cumulative effects of past and present emissions. Similarly, if a cap-and-trade scheme is used to limit emissions, permits might be allocated so as to require emitters with large amounts of past emissions to purchase more permits on the open market. Thus, there could potentially be efforts to shift adaptation costs, mitigation costs, and costs that cannot be avoided through either mitigation or adaptation. In each case, the claim would be that the costs in question should be allocated on the basis of responsibility for climate change rather than falling where they may. Assuming that we did decide that some costs should be shifted to emitters, there are some difficult problems about how to allocate responsibility among the emitting parties. Those problems are the focal point of this paper. Emissions differ greatly between sources. For example, the U.S. was responsible for twenty percent of the world's emissions in 2000, which was about equal to its share of Gross Domestic Product (GDP). …

Wheat (Triticum aestivum L.) is a major global commodity and the primary source for baked products in agri-food supply chains. Consumers are increasingly demanding more nutritious food products with less environmental degradation, particularly related to water and fertilizer nitrogen (N) inputs. While triticale (× Triticosecale) is often referenced as having superior abiotic stress tolerance compared to wheat, few studies have compared crop productivity and resource use efficiencies under a range of N-and water-limited conditions. Because previous work has shown that blending wheat with triticale in a 40:60 ratio can yield acceptable and more nutritious baked products, we tested the hypothesis that increasing the use of triticale grain in the baking supply chain would reduce the environmental footprint for water and N fertilizer use. Using a dataset comprised of 37 site-years encompassing normal and stress-induced environments in California, we assessed yield, yield stability, and the efficiency of water and fertilizer N use for 67 and 17 commercial varieties of wheat and triticale, respectively. By identifying environments that favor one crop type over the other, we then quantified the sustainability implications of producing a mixed triticale-wheat flour at the regional scale. Results indicate that triticale outyielded wheat by 11% (p < 0.05) and 19% (p < 0.05) under average and N-limited conditions, respectively. However, wheat was 3% (p < 0.05) more productive in water-limited environments. Overall, triticale had greater yield stability and produced more grain per unit of water and N fertilizer inputs, especially in high-yielding environments. We estimate these differences could translate to regional N fertilizer savings (up to 555 Mg N or 166 CO2-eq kg ha−1) in a 40:60 blending scenario when wheat is sourced from water-limited and low-yielding fields and triticale from N-limited and high-yielding areas. Results suggest that optimizing the agronomic and environmental benefits of triticale would increase the overall resource use efficiency and sustainability of the agri-food system, although such a transition would require fundamental changes to the current system spanning producers, processors, and consumers.

AbstractMulti-scale macroalgae growth models are required for the efficient design of sustainable, economically viable and environmentally safe farms. Here, we develop a multi-scale model for Ulva sp. macroalgae growth and nitrogen sequestration in an intensive cultivation farm, regulated by temperature, light and nutrients. The model incorporates a range of scales by incorporating spatial effects in two steps: light extinction at the reactor scale (1 m) and nutrient absorption at the farm scale (1 km). The model was validated on real data from an experimental reactor installed in the sea. Biomass production rates, chemical compositions and nitrogen removal were simulated under different seasons, levels of dilution in the environment and water-exchange rate in the reactor. This multi-scale model provides an important tool for environmental authorities and seaweed farmers who desire to upscale to large bioremediation and/or macroalgae biomass production farms, thus promoting the marine sustainable development and the macroalgae-based bioeconomy.

This paper focuses on designing a hybrid generation bioethanol supply chain (HGBSC) that will account for economic, environmental and social aspects of sustainability under various uncertainties. A stochastic mixed integer linear programming model is proposed to design an optimal HGBSC. A case study set in the state of North Dakota in the United States is used as an application of the proposed model. The results suggest that the designs of optimal HGBSC change when different sustainability standards are applied. In addition, sensitivity analysis is conducted to provide deeper understanding of the proposed model.