Biofuels from waste

Potential for greenhouse gas reduction and energy recovery from MSW through different waste management technologies

The studies on municipal solid waste (MSW) management in Pakistan and its impacts on greenhouse gas (GHG) emissions are glaringly missing. Therefore, this study examines the effect of MSW management on GHG emissions in Pakistan and suggests the best suitable strategies for alleviating GHG emissions. The Intergovernmental Panel on Climate Change (IPCC) 2006 waste model (WM) was used to create inventory of GHG emissions from landfilling. The solid waste management GHG (SWM-GHG) calculator and strengths-weaknesses-opportunities-threat (SWOT) analyses were used as strategic planning tools to reduce GHG emissions by improving MSW management in Pakistan. The IPCC 2006 WM estimated 14,987,113 metric tonnes (Mt) carbon dioxide equivalents (CO2-eq) of GHG emissions in 2016. The SWM-GHG calculator, on the other hand, estimated 23,319,370 Mt CO2-eq of GHG emissions from management of 30,764,000 Mt of MSW in 2016, which included 8% recycling, 2% composting, and 90% disposal in open dumps. To reduce GHG emissions, two strategies including recycling-focused and incineration-focused were analysed. The recycling approach can reduce more GHG emissions than incineration, as it can reduce 36% of GHG emissions (as compared to GHG emission in 2016) by recycling 23% of MSW, anaerobically digesting 10% of MSW, and disposing of 67% of MSW in sanitary landfills (with energy recovery). Moreover, the SWOT analysis suggested integration of the informal sector, adoption of anaerobic digestion and formulation of explicit MSW regulations for improving the current management of MSW which will also result in lower GHG emissions.

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

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

Peru struggles to upgrade its waste management, with landfilling only just overtaking open dumpsters as the main disposal method. Despite the benefits of this transition, including reduced environmental impacts to water and soil, previous studies demonstrated that greenhouse gas (GHG) emissions may increase if adequate levels of technological sophistication are not implemented. Considering that 58% of municipal solid waste (MSW) is organic, it seems plausible that a relevant portion of emissions can be linked directly to food loss and waste (FLW) management. This study aims to determine the GHG emissions mitigation potential in FLW compared to the current baseline scenario in 24 Peruvian cities, by modelling alternative technologies to treat organic MSW. Life cycle modelling was performed using the waste-LCA software EASETECH. Five treatment scenarios were modelled: i) open dumping; ii) landfilling with no gas treatment; iii) landfilling with landfill gas treatment; iv) landfilling with energy recovery; and, v) anaerobic digestion. GHG emissions of FLW generation proved to be substantially higher than those for FLW treatment. However, if sophisticated technologies are implemented in FLW treatment, an annual reduction of up to 1.56 Mt CO2eq could be attained. Moreover, despite the health and environmental benefits of a transition to optimized diets, in which, for example, meat consumption is reduced and vegetables are boosted, an important increase in FLW and, therefore, an increase in GHG emissions in the treatment phase is shown. However, if certain technologies, such as energy recovery or anaerobic digestion, were implemented, most carbon losses would be avoided.

Waste Management Pinch Analysis (WAMPA): Application of Pinch Analysis for greenhouse gas (GHG) emission reduction in municipal solid waste management

GHG emission factors developed for the collection, transport and landfilling of municipal waste in South African municipalities

The Negative Bidirectional Interaction Between Climate Change and the Prevalence and Care of Liver Disease: A Joint BSG, BASL, EASL, and AASLD Commentary

Better information on greenhouse gas (GHG) emissions and mitigation potential in the agricultural sector is necessary to manage these emissions and identify responses that are consistent with the food security and economic development priorities of countries. Critical activity data (what crops or livestock are managed in what way) are poor or lacking for many agricultural systems, especially in developing countries. In addition, the currently available methods for quantifying emissions and mitigation are often too expensive or complex or not sufficiently user friendly for widespread use.The purpose of this focus issue is to capture the state of the art in quantifying greenhouse gases from agricultural systems, with the goal of better understanding our current capabilities and near-term potential for improvement, with particular attention to quantification issues relevant to smallholders in developing countries. This work is timely in light of international discussions and negotiations around how agriculture should be included in efforts to reduce and adapt to climate change impacts, and considering that significant climate financing to developing countries in post-2012 agreements may be linked to their increased ability to identify and report GHG emissions (Murphy et al 2010, CCAFS 2011, FAO 2011).

Landfilling is the most applied solid waste management method in developing countries, which leads to a large amount of greenhouse gas (GHG) emissions. It is thus imperative to develop strategies for evaluating different economically viable waste management scenarios to mitigate GHG emissions. According to the Paris Agreement, Kazakhstan planned to decrease GHG emissions by 25% by 2050 as compared to 1990 levels, while reaching carbon neutrality by 2060. In this context, we herein propose four different scenarios for municipal solid waste (MSW) treatment and three scenarios for sewage sludge (SS) treatment with the aim of evaluating the GHG potential for Astana, the capital city of Kazakhstan, using the (solid waste management) SWM-GHG calculator developed by the Institute for Energy and Environmental Research. The MSW treatment scenarios include: (A) 15% recycling of secondary materials and 85% landfilling of remaining MSW; (B) 30% recycling of secondary materials; 70% sanitary landfilling with biogas collection; (C) 30% recycling and 70% biological stabilization and landfilling without biogas collection; and (D) 30% recycling, 20% composting, and 50% (waste-to-energy) WtE incineration. The sewage sludge management scenarios include (1) 100% landfilling; (2) 100% WtE incineration; and (3) co-incineration of sewage sludge and coal. The results reveal that more complex scenarios lead to extensive ecological benefits; however, there are economic constraints. Based on the analysis of the proposed scenarios, we recommend the optimal strategy for MSW treatment to be 30% recycling with biological stabilization that has a total cost of EUR 16.7 million/year and overall GHG emissions of −120 kt of CO2 eq/year. In terms of sewage sludge management, the addition of coal to sewage sludge simplifies the combustion process due to the higher heat capacity. Considering lower cost and higher energy recovery, it is recommended as a favorable process.

In Malaysia, the rapid growth of population and new consumption trends are causing an increase in municipal solid waste (MSW) generation rate. To make matters worse, the current MSW handling practices in Malaysia are mostly dumping in open landfills with no proper landfill gas collection and energy recovery system, producing greenhouse gas (GHG) emissions to the atmosphere. This handling process undoubtedly causes climate change and is economically unfavourable. In this study, a multi-objective mixed-integer linear programming (MILP) approach was simulated using General Algebraic Modeling System (GAMS) to determine the optimum allocation of MSW on different disposal and treatment facilities (DTF), including sanitary landfills, incineration, recycling, anaerobic digestion, composting, and plasma arc gasification. The mathematical model utilised the augmented e-constraint method to minimise the capital and operational cost, maximise the value of final products, and minimise GHG emissions simultaneously. As compared to the current MSW management situation in Malaysia (total cost: 7.24 M MYR/d, net GHG emissions: 70,465 t CO2-eq/d), the least cost Pareto solution (total cost: 7.23 M MYR/d, net GHG emissions: 24,630 t CO2-eq/d) shows a more than 65 % reduction in GHG emissions without incurring any additional cost. The 9th,10th, and 11th Pareto optimal solutions would be able to achieve the national recycling target of 22 % by 2020 as promulgated by the Malaysia Government. It is hoped that this study can provide guidance on the best allocation of MSW on DTF for decision-makers to plan and design the best in class solution for MSW management not only in Malaysia but also regions that face a similar MSW disposal dilemma.

Circular utilization of urban tree waste contributes to the mitigation of climate change and eutrophication

Emissions of greenhouse gases (GHG) from municipal solid waste (MSW) in North Macedonia are a serious issue for the environment and major efforts are needed to mitigate climate change. In order to determine the current situation with the GHG emissions in North Macedonia, several calculations were made and results and proposals for reduction of GHG emissions, related with waste, are presented in this paper. Municipal solid waste (MSW) management, primarily through landfilling, is a major contributor to GHG emissions in North Macedonia. The anaerobic decomposition of organic waste in landfills generates methane (CH4), a strong greenhouse gas with a high global warming potential, even 25 times more than carbon dioxide (CO2). Furthermore, open waste burning and inadequate waste management techniques lead to the release of CO2, nitrous oxide (N2O) and other pollutants. Despite efforts to mitigate GHG emissions from waste, challenges persist due to inadequate waste management infrastructure, limited waste reduction and recycling initiatives, and failure to implement regulatory frameworks. These challenges exacerbate the environmental impacts of waste management and hinder progress towards sustainable development goals. To tackle GHG emissions from waste in North Macedonia, a comprehensive approach is required that includes legislative interventions, technological advances, and public engagement techniques. Improving waste management infrastructure, promoting waste reduction and recycling, investing in waste-derived renewable energy, and enhancing regulatory enforcement are among the key recommendations.

Legislation to cap and trade greenhouse gas (GHG) emissions was approved by a 219-212 vote of the United States House of Representatives on June 26, 2009. Cap and trade policy articulated in the American Clean Energy and Security (ACES) act of 2009 regulates GHGs including carbon dioxide, methane, nitrous oxide, sulfur hexafluoride, hydrofluorocarbons, perfluorocarbons and nitrogen trifluoride. Debate over the ACES act focused heavily on economic issues contrasted against concerns about climate change1. However, discussion largely ignored the potential for cap and trade legislation to contribute to reductions in levels of other harmful air pollutants, such as sulfur dioxide, particulate matter, and ozone precursors that share emission sources with GHGs. Under the bill, domestic GHG emissions are to be capped at 2005 annual levels, and reduced to 17% of those marks by 20502. The bill provides for an initial round of pollution permits to be made available, some free, others at auction. Subsequently, these permits can be bought and sold in the open market by organizations such as utility companies and manufacturing firms. A key provision in the ACES act requires the president to impose tariffs on countries that do not implement similar regulations on GHG emissions. While other potentially viable legislation, such as a tax on carbon emissions, has been proposed3, the current cap and trade legislation is the first bill to pass in either the House or Senate. The greenhouse gases regulated under the ACES act do not generally pose serious direct health risks. For example, nitrous oxide is used in dental procedures, and carbon dioxide is an ingredient in carbonated beverages. Other GHGs, like nitrogen trifluoride and sulfur hexafluoride, are not harmful at their current concentration levels, but can be hazardous to persons working with them if safety precautions are not taken. Instead, substantial human health benefits from cap and trade legislation could potentially come from reductions in ambient levels of harmful pollutants, such as particulate matter and ozone, that share emissions sources with GHGs. For example, 94% of CO2 emissions in the US result from combustion of fossil fuels, with electricity generation and transportation alone comprising nearly 70%. These are also the leading source of sulfur dioxide, fine particles having diameter small than 2.5 micrometers (PM2.5), and precursors to ozone such as mono-nitrogen oxides (NOx)4. While the time scale for potential impacts of cap and trade legislation on climate change and related health benefits is likely decades or centuries, ancillary air pollution mitigation could have immediate health benefits. In two nationwide epidemiological studies, daily levels of ambient ozone and PM2.5 have been linked to increased risk of cardiovascular and respiratory mortality5 and to increased risk of emergency hospital admissions, especially for heart failure6, respectively. Estimates of the potential health benefits attributable to reductions in harmful air pollutants resulting from mitigation of GHG emissions, at the city, region and national, have been substantial7. While US cap and trade legislation would likely reduce domestic air pollution levels, two caveats deserve consideration. First, methods for reducing GHG emissions typically reduce air pollution levels, but not always. This problem can be highlighted using airplanes as an example8. Two methods to reduce CO2 emissions from airplanes are to decrease aircraft weight or increase engine combustion temperatures. The former reduces both GHG and air pollution emissions, whereas the later reduces GHG emissions at the cost of increasing precursors to ozone. In the broader context of energy production, it is likely cap and trade legislation would drive a shift away from fossil fuel combustion to sources such as solar technology that produce much less air pollution. However, the exact technology development path is still uncertain. A second problem is the potential for domestic cap and trade legislation to transfer US emissions to newly industrialized nations. Countries facing lower production costs associated with looser regulations on GHG emissions would have an economic advantage over manufacturing industries in the US. However, increased air pollution from new manufacturing could be a key public health issue for developing regions, such as China's Pearl River delta, where air pollution levels are already much higher than standards in the US9. The economic and physical systems that would be affected by cap and trade legislation are extremely complex, and impacts on air pollution will have to be considered in a broad context. For example, while the absence of tariffs would likely push manufacturing, air pollution and related negative health effects to developing regions, those regions might experience health benefits associated with increased per capita income. The discussion is similarly complex in the physical domain. For example, some air pollutants, such as sulfate particulate matter, can contribute to short term climate cooling. Though still somewhat unclear, there is an emerging debate over the possibility that air pollution mitigation could actually exacerbate global warming in the short term10. While it faces potentially significant opposition and alteration in the Senate, the cap and trade bill recently passed in the House has progressed further through Congress than any other similar legislation. There is tremendous potential for legislation regulating GHG emissions, via cap and trade or other strategies, to simultaneously decrease emissions of harmful air pollutants and reduce morbidity and mortality attributable to cardiovascular and respiratory illness. Such improvements in public health have been linked to economic benefits from recovered workforce productivity8, and add important support for progress on cap and trade legislation versus delayed action.

The energy system plays an essential role in accounting of greenhouse gas (GHG) emissions from waste management systems and waste technologies. This paper focuses on energy use and energy recovery in waste management and outlines how these aspects should be addressed consistently in a GHG perspective. Essential GHG emission data for the most common fuels, electricity and heat are provided. Average data on electricity provision show large variations from country to country due to different fuels being used and different efficiencies for electricity production in the individual countries (0.007-1.13 kg CO(2)-eq. kWh(-1)). Marginal data on electricity provision show even larger variations (0.004-3 kg CO(2)-eq. kWh( -1)). Somewhat less variation in GHG emissions is being found for heat production (0.01-0.69 kg CO(2)-eq. kWh( -1)). The paper further addresses allocation principles and the importance of applying either average or marginal energy data, and it discusses the consequences of introducing reduction targets on CO( 2) emissions. All discussed aspects were found to significantly affect the outcome of GHG accounts suggesting transparent reporting to be critical. Recommendations for use of average/marginal energy data are provided.