Atmospheric stabilization of CO2 emissions: Near-term reductions and absolute versus intensity-based targets

This study analyzes CO₂ emissions reduction targets for various countries and geopolitical regions by the year 2030 to stabilize atmospheric concentrations of CO₂ at 450 ppm (550 ppm including non-CO₂ greenhouse gases) level. It also determines CO₂ intensity cuts that would be required in those countries and regions if the emission reductions were to be achieved through intensity-based targets without curtailing their expected economic growth. Considering that the stabilization of CO₂ concentrations at 450 ppm requires the global trend of CO₂ emissions to be reversed before 2030, this study develops two scenarios: reversing the global CO₂ trend in (i) 2020 and (ii) 2025. The study shows that global CO₂ emissions would be limited at 42 percent above 1990 level in 2030 if the increasing trend of global CO₂ emissions were to be reversed by 2020. If reversing the trend is delayed by 5 years, global CO₂ emissions in 2030 would be 52 percent higher than the 1990 level. The study also finds that to achieve these targets while maintaining expected economic growth, the global average CO₂ intensity would require a 68 percent drop from the 1990 level or a 60 percent drop from the 2004 level by 2030.     

CO2 emissions embodied in international trade: evidence for Spain

The objective of this paper is to analyse the sectoral impacts that Spanish international trade relations have on present levels of atmospheric pollution using an input–output model. We try to evaluate the exports and imports of the Spanish economy in terms of the direct and indirect CO₂ emissions (CO₂ embodied) generated in Spain and abroad. The results show a slightly exporting behaviour in the Spanish economy which, nevertheless, hides important pollution interchanges. Moreover, the sectors transport material, mining and energy, non-metallic industries, chemical and metals are the most relevant CO₂ exporters and other services, construction, transport material and food the biggest CO₂ importers, and those whose final demands also embody more than 70% of the CO₂ emissions.     

CO2 utilization options, part II: Assessment of dimethyl carbonate production

In this paper, the potential to reduce CO₂ emissions from dimethyl carbonate production by switching from the traditional phosgene-based production to a urea-based CO₂ utilization process is assessed. The total CO₂ emission for each process is estimated, including emissions related to the carbon content of the products, energy consumption in the production process, and energy consumption in the production processes of the required reactants. Implementation of the CO₂ utilization process probably will reduce total CO₂ emissions. However, in order to achieve substantially reduced CO₂ emissions, serious consideration must be given to the optimization and design of the CO₂ utilization process. Furthermore, the fuel-mix employed is one of the factors that influences the total CO₂ emission the most.     

Cost effective integration of hydrogen in energy systems with CO2 constraints

The integration of hydrogen in national energy systems is illustrated in four extreme scenarios, reflecting four technological mainstreams (energy conservation, renewables, nuclear and CO₂ removal) to reduce C emissions. Hydrogen is cost-effective in all scenarios with higher CO₂ reduction targets. Hydrogen would be produced from fossil fuels, or from water and electricity or heat, depending upon the scenario. Hydrogen would be used in the residential and commercial sectors and for transport vehicles, industry, and electricity generation in fuel cells. At severe (50–70%) CO₂ reduction targets, hydrogen would cost-effectively supply more than half of the total useful energy demands in three out of four scenarios. The marginal emission reduction costs in the CO₂ removal scenario at severe CO₂ reduction targets are DFL 200/tCO₂ (ca $ 100/t). In the nuclear, renewable and energy conservation scenarios these costs are much higher. Whilst the fossil fuel scenario would be less expensive than the other scenarios, the possibility of CO₂ storage in depleted gas reservoirs is a conditio sine qua non.     

Integrated biomass energy systems and emissions of carbon dioxide

Electric Power Research Institute (EPRI) and the US Department of Energy (DOE) have been funding a number of case studies under the initiative entitled “Economic Development through Biomass Systems Integration”, with the objective of investigate the feasibility of integrated biomass energy systems, utilizing a dedicated feedstock supply system (DFSS) for energy production. This paper deals with the full fuel cycle for four of these case studies, which have been examined with regard to the emissions of carbon dioxide, CO₂. Although the conversion of biomass to electricity in itself does not emit more CO₂ than is captured by the biomass through photosynthesis, there will be some CO₂ emissions from the DFSS. External energy is required for the production and transportation of the biomass feedstock, and this energy is mainly based on fossil fuels. By using this input energy, CO₂ and other greenhouse gases are emitted. However, by utilizing biomass with fossil fuels as external input fuels, we would get about 10–15 times more electric energy per unit fossil fuel, compared with a 100% coal power system. By introducing a DFSS on former farmland the amount of energy spent for production of crops can be reduced, the amount of fertilizers can be decreased, the soil can be improved and a significant amount of energy will be produced compared with an ordinary farm crop. Compared with traditional coal-based electricity production, the CO₂ emissions are in most cases reduced significantly by as much as 95%. The important conclusion is the great potential for reducing greenhouse gas emissions through the offset of coal by biomass.     

CO2 emissions per individual based on a survey of university students

The amount of CO₂ produced by the daily activities of university students is estimated on the basis of statistical, questionnaire, and measurement data. The results reveal that a large proportion of CO₂ emissions occurs during energy consumption, food preparation and transport, and that the CO₂ emissions of dormitory residents are lower than those of students living in other situations. Practical methods for reducing student CO₂ emissions are also examined.     

Prediction of cost and emission from Indian coal-fired power plants with CO2 capture and storage using artificial intelligence techniques

Coal-fired power plants are one of the most important targets with respect to reduction of CO₂ emissions. The reasons for this are that coal-fired power plants offer localized large point sources (LPS) of CO₂ and that the Indian power sector contributes to roughly half of all-India CO₂ emissions. CO₂ capture and storage (CCS) can be implemented in these power plants for long-term decarbonisation of the Indian economy. In this paper, two artificial intelligence (AI) techniques—adaptive network based fuzzy inference system (ANFIS) and multi gene genetic programming (MGGP) are used to model Indian coal-fired power plants with CO₂ capture. The data set of 75 power plants take the plant size, the capture type, the load and the CO₂ emission as the input and the COE and annual CO₂ emissions as the output. It is found that MGGP is more suited to these applications with an R² value of more than 99% between the predicted and actual values, as against the ~96% correlation for the ANFIS approach. MGGP also gives the traditionally expected results in sensitivity analysis, which ANFIS fails to give. Several other parameters in the base plant and CO₂ capture unit may be included in similar studies to give a more accurate result. This is because MGGP gives a better perspective toward qualitative data, such as capture type, as compared to ANFIS.     

CO2 savings in Brazil The importance of a small contribution

Brazil's development process could lead potentially to a doubling of CO₂ emissions per capita over the next four decades. This paper shows that the implementation of policy measures promoting energy efficiency and fuel switching could reduce Brazil's energy-related CO₂ per capita by 11% by 2025 with respect to their 1985 level without necessitating any significant change in lifestyles. While Brazil's total reductions would be equivalent to only 1% of present global carbon emissions, capturing these savings opportunities would both allow Brazil to participate in global efforts to curtail the generation of greenhouse gases into the atmosphere and support Brazil's own economic development process.     

China’s pre-2020 CO2 emission reduction potential and its influence

China achieved the reduction of CO₂ intensity of GDP by 45% compared with 2005 at the end of 2017, realizing the commitment at 2009 Copenhagen Conference on emissions reduction 3 years ahead of time. In future implementation of the “13th Five-Year Plan (FYP),” with the decline of economic growth rate, decrease of energy consumption elasticity and optimization of energy structure, the CO₂ intensity of GDP will still have the potential for decreasing before 2020. By applying KAYA Formula decomposition, this paper makes the historical statistics of the GDP energy intensity decrease and CO₂ intensity of energy consumption since 2005, and simulates the decrease of CO₂ intensity of GDP in 2020 and its influences on achieving National Determined Contribution (NDC) target in 2030 with scenario analysis. The results show that China’s CO₂ intensity of GDP in 2020 is expected to fall by 52.9%–54.4% than the 2005 level, and will be 22.9%–25.4% lower than 2015. Therefore, it is likely to overfulfill the decrease of CO₂ intensity of GDP by 18% proposed in the 13th FYP period. Furthermore, the emission reduction potentiality before 2020 will be conducive to the earlier realization of NDC objectives in 2030. China’s CO₂ intensity of GDP in 2030 will fall by over 70% than that in 2005, and CO₂ emissions peak will appear before 2030 as early as possible. To accelerate the transition to a low-carbon economy, China needs to make better use of the carbon market, and guide the whole society with carbon price to reduce emissions effectively. At the same time, China should also study the synergy of policy package so as to achieve the target of emission reduction.     

System analysis of hydrogen production from gasified black liquor

Hydrogen produced from renewable biofuel is both clean and CO₂ neutral. This paper evaluates energy and net CO₂ emissions consequences of integration of hydrogen production from gasified black liquor in a chemical pulp mill. A model of hydrogen production from gasified black liquor was developed and integration possibilities with the pulp mill's energy system were evaluated in order to maximize energy recovery. The potential hydrogen production is 59 000 tonnes per year if integrated with the KAM reference market pulp mill producing 630 000 Air dried tonnes (ADt) pulp/year. Changes of net CO₂ emissions associated with modified mill electric power balance, biofuel import and end usage of the produced hydrogen are presented and compared with other uses of gasified black liquor such as electricity production and methanol production. Hydrogen production will result in the greatest reduction of net CO₂ emissions and could reduce the Swedish CO₂ emissions by 8% if implemented in all chemical market pulp mills. The associated increases of biofuel and electric power consumption are 5% and 1.7%, respectively.     

Conceptual study of distributed CO2 capture and the sustainable carbon economy

Capture of carbon dioxide from distributed sources is often neglected as a viable solution to the global problem of CO₂ emissions management. Small scale power plants, including those applicable to the transportation sector, can be designed to capture their CO₂ exhaust stream, provided it is not heavily diluted with air. Liquefaction of carbon dioxide allows the captured CO₂ to be stored densely, with a minimal energetic penalty and space requirement, until it can be permanently sequestered. In this short-term solution, the energetic penalty for CO₂ capture can be further offset by exploiting novel energy conversion processes involving regeneration of the reaction product stream – a simple strategy that is not exploited in conventional systems. More importantly, in the long-term, as the renewable energy infrastructure is built up, the collected CO₂ can be recycled into synthetic carbon-based liquid fuels which act as energy carriers in the sustainable carbon economy.     

The Carbon-tax debate

This paper discusses recent topics related indirectly to energy production and marketing and related highly to energy policy and economy. These topics are: (1) background to carbon taxes including environmental issues — global warming and CO₂ emissions, fuel substitution and the encouragement of non-hydrocarbon fuel use; (2) climate-change convention and related conferences including those at Rio de Janeiro — objectives and achievements, and Kyoto-objectives; (3) carbon-tax proposals, including implications for oil, coal and gas: (4) The OECD view including evolution of general taxes on hydrocarbons, the carbon tax as a government revenue-raising objective, CO₂ emissions in the OECD; (5) the oil-producer's view including discrimination against oil, the impact on the incentives to use oil and gas; (6) the developing countries' view, including the need to increase fuel use for industrialisation, financial constraints on energy use, and CO₂ emissions in the developing countries.     

Recovery of fluorocarbons in Japan as a measure for abating global warming

The objective of this study is to evaluate the potential for recovering fluorocarbons as measures for the abatement of global warming. In this study, we focused on the three different kinds of fluorocarbons: CFCs, HCFCs and HFCs, and targeted refrigerant use because of the availability of relevant data. We first estimated future fluorocarbon emissions from the targeted appliances; we next compared those emissions in the units of CO₂ equivalent to the level of CO₂ emissions in 1990 from a quantitative point of view. As the result of this study, it was found that fluorocarbon emissions in 1999 and 2010 would be equal to approximately 7 and 3% of the level of CO₂ emissions in 1990 respectively. Moreover, if we implement a 100% recovery rate in every recovery route, we can reduce a large amount of emissions which correspond to approximately 2–5% of the level of CO₂ emissions in 1990, even if we take into account the energy-related CO₂ emissions by the transportation and decomposition of fluorocarbons.     

Coal gasification system using nuclear heat for ammonia production

Utilization of nuclear energy is an effective way of solving the global warming resulting from CO₂ emissions. Thermal energy accounts for more than two thirds of total energy utilization at present and therefore it is significant to extend the utilization of nuclear heat for the effective reduction of CO₂ emissions in the world. This paper describes a coal gasification system using HTGR nuclear heat in an ammonia production plant in terms of industrial utilization of the nuclear heat. The system uses the nuclear heat directly in addition to generating electricity. A steam reforming method using a two-stage coal gasifier is employed: it improves the heat utilization efficiency of the secondary helium gas from the HTGR. Finally, the paper clarifies that the nuclear gasification system can reduce CO₂ emissions by about five hundred thousand tons per year from that of a conventional system using fossil fuel.     

Mitigation of carbon dioxide from Indonesia's energy system

In Indonesia, energy consumption (excluding non-commercial energy) increased from 328 MBOE in 1990 to 478 MBOE in 1995. As a consequence, energy sector CO₂ emissions increased from 150 million tons to over 200 million tons during the same period. The present rapid economic growth Indonesia is experiencing (7–8%) will continue in the future. Based on a BAU scenario, primary energy supply for the year 2020 will be 18,551 PJ, an increase of 5.9% annually from 1990 CO₂ from the energy system will increase from 150 Teragrams in 1990 to 1264 Teragram in 2020. The mitigation scenario would reduce total CO₂ emissions from the BAU scenario by 10% for the year 2000 and 20% by 2020. Some demand side management and energy conservation programs are already included in the BAU scenario. In the mitigation scenario, these programs are expanded, leading to lower final energy demand in the industrial and residential sectors.

Indonesia's total primary energy supply in 2020 is approximately 5% lower for the mitigation scenario than for the BAU scenario. In the BAU scenario, coal and oil have the same contribution (25%). In the mitigation scenario, natural gas and nonfossil fuels such as hydropower, geothermal, and nuclear have higher contributions.     

Optimal climate protection strategies for space heating: The case of Austria

The debate over the costs of climate protection policies still focuses on the question of whether strategies to significantly reduce greenhouse gas emissions at zero or negative net cost (‘no regrets’ strategies) can be found. This article describes a carbon dioxide (CO₂) reduction strategy for space and water heating in Austria relying on net present value analyses of 43 climate protection measures. The cost-benefit analyses include investment costs, the savings from energy conservation, the administrative costs of policy instruments and estimates of the external costs. An efficient CO₂ reduction strategy was developed on the basis of energy supply curves which were adapted so that interactions between the CO₂ reduction technologies could be considered. A cost-efficient CO₂ reduction strategy could lower the CO₂ emissions for the provision of space and water heating in Austria by up to 2.7% per year relative to the official ‘business as usual’ scenario.     

2020年我国钢铁行业CO_2排放趋势和减排路径分析

我国钢铁行业CO_2排放占全国排放总量的近20%,分析钢铁行业的CO_2排放趋势和减排路径对我国控制温室气体排放有着重要的现实意义。本文从影响钢铁行业排放的主要影响因素着手,分析了钢铁产量和工序能耗的现状及未来发展趋势,测算了2010～2020年钢铁行业排放趋势和减排潜力,同时给出了减排途径和各种减排措施的贡献度,并提出了相关政策建议。     

Combined heat and power in the Swedish district heating sector—impact of green certificates and CO2 trading on new investments

Combined heat and power (CHP) has been identified by the EU administration as an important means of reducing CO₂-emissions and increasing the energy efficiency. In Sweden, only about one third of the demand for district heat (DH) is supplied from CHP. This share could be significantly larger if the profitability of CHP generation increased. The objective of this study was to analyse the extent to which the profitability for investments in new CHP plants in the Swedish DH sector have changed thanks to the recently implemented trading schemes for green certificates (TGCs) and CO₂ emissions (TEPs). The analysis was carried out using a simulation model of the Swedish DH sector in which the profitability of CHP investments for all DH systems, with and without the two trading schemes applied, is compared. In addition, a comparison was made of the changes in CHP generation, CO₂ emissions, and operation costs if investments are made in the CHP plant shown to be most profitable in each system according to the model. The study shows that the profitability of investments in CHP plants increased significantly with the introductions of TGC and TEP schemes. If all DH utilities also undertook their most profitable CHP investments, the results indicate a major increase in power generation which, in turn, would reduce the CO₂ emissions from the European power sector by up to 13 Mton/year, assuming that coal condensing power is displaced.     

A model analysis of clean development mechanisms to reduce both CO2 and SO2 emissions between Japan and China

It is necessary for Japan to support the development of desulfurization policies of China to solve global and local environmental problems. This study proposes a “double clean development mechanism” to reduce both CO₂ and SO₂ emissions at the same time. The purpose of this study is to investigate the consequences for both countries' energy economies of following double clean development mechanism between Japan and China. A dynamic optimization model is developed to estimate the effects of Japanese investments in China for carbon dioxide recovery-disposal and emission desulfurization technologies. The simulation results suggest that a double clean development mechanism can effectively mitigate the damage caused by SO₂ emissions because the clean development mechanism itself can reduce SO₂ emissions, e.g. by switching to fuels. However, China might not be willing to accept restrictions on SO₂ emissions. This study also examines whether China will be able to maintain high growth rates with a clean development mechanism under the CO₂ and SO₂ restriction. The analysis shows that increasing the upper limit of investment from Japan to China can enhance the economies of the both nations. The effect of nuclear power installation on economic performance is also investigated for the both nations.     

A comparison of CO2 emissions from fossil and solar power plants in the United States

We present estimates of the lifetime carbon dioxide emissions from coal-fired, photovoltaic, and solar thermal power plants in the United States. These CO₂ estimates are based on a net energy analysis derived from both operational systems and detailed design studies. It appears that energy-conservation measures and shifting from fossil to renewable energy sources have significant long-term potential to reduce CO₂ production caused by energy generation. The implications of these results for a national energy policy are discussed.