CO2 emissions and mitigation potential in China’s ammonia industry

Significant pressure from increasing CO₂ emissions and energy consumption in China’s industrialization process has highlighted a need to understand and mitigate the sources of these emissions. Ammonia production, as one of the most important fundamental industries in China, represents those heavy industries that contribute largely to this sharp increasing trend. In the country with the largest population in the world, ammonia output has undergone fast growth spurred by increasing demand for fertilizer of food production since 1950s. However, various types of technologies implemented in the industry make ammonia plants in China operate with huge differences in both energy consumption and CO₂ emissions. With consideration of these unique features, this paper attempts to estimate the amount of CO₂ emission from China’s ammonia production, and analyze the potential for carbon mitigation in the industry. Based on the estimation, related policy implications and measures required to realize the potential for mitigation are also discussed.     

CO2 emissions and reduction potential in China’s chemical industry

GHG (Increasing greenhouse gas) emissions in China imposes enormous pressure on China’s government and society. The increasing GHG trend is primarily driven by the fast expansion of high energy-intensive sectors including the chemical industry. This study investigates energy consumption and CO₂ emissions in the processes of chemical production in China through calculating the amounts of CO₂ emissions and estimating the reduction potential in the near future. The research is based on a two-level perspective which treats the entire industry as Level one and six key sub-sectors as Level two, including coal-based ammonia, calcium carbide, caustic soda, coal-based methanol, sodium carbonate, and yellow phosphorus. These two levels are used in order to address the complexity caused by the fact that there are more than 40 thousand chemical products in this industry and the performance levels of the technologies employed are extremely uneven. Three scenarios with different technological improvements are defined to estimate the emissions of the six sub-sectors and analyze the implied reduction potential in the near future. The results highlight the pivotal role that regulation and policy administration could play in controlling the CO₂ emissions by promoting average technology performances in this industry.     

Examining the driving forces for improving China’s CO2 emission intensity using the decomposing method

This paper examines the driving forces for reducing China’s CO₂ emission intensity between 1998 and 2008, utilizing the logarithmic mean divisia index (LMDI) technique. By first grouping the CO₂ emissions into two categories, those arising from activities related to the electric power industry and those from other sources, emission intensity is further broken down into the effects of the CO₂ emission coefficient, energy intensity of power generation, power generation and consumption ratio, electricity intensity of the gross domestic product (GDP), provincial structural change, and the energy intensity of the GDP for other activities. The decomposition results show that improvements in the energy intensity of power generation, electricity intensity of GDP, and energy intensity of GDP for other activities were mainly responsible for the success in reducing China’s CO₂ emission intensity and that activities related to the electric power industry played a key role. It is also revealed that performance varied significantly at the individual province level. The provinces with higher emission levels contributed the most to China’s improvements in CO₂ emission intensity.     

Multi-regional input–output model for regional energy requirements and CO2 emissions in China

In this study, China is divided into eight economic regions. A multi-regional input–output model for energy requirements and CO₂ emissions in China was established, and employed to perform scenario and sensitivity analysis for each economic region in year 2010 and 2020. Results show that up to year 2020, improvement in energy end-use efficiency for each region could generate intra-regional energy savings. Therefore, continuing efforts should be taken to advance improvements of energy end-use efficiency for each region. At the national level, the effectiveness of inter-regional energy transfers, and efficiency improvements in Central and Northwest regions should be accelerated as much as possible. However, population growth will be an obvious driving force for additional energy requirements and cause greater CO₂ emissions across all regions. This demand will increase with the growth of the economy and improvement in household incomes. Population growth in one region will not only significantly affect energy requirements of the region itself, but also drive up energy requirements of the other regions. During this important period in time when China is making efforts to build a well-rounded society, the basic state policy of family planning should be enforced for each region. Model results indicate that there exists relative error between emissions caused by a region and emissions emitted by that region. Different identification of responsibility will have understandable different impacts on most regions in environmental policy reform.     

Decomposing international polarization of per capita CO2 emissions

The aim of this paper is to analyze the international polarization of per capita CO₂ emissions with exogenous groups based on the Z–K measure (Zhang and Kanbur, 2001), whose main differential advantage lies on its factor-decomposability. In particular, we propose to use the factor decomposition based on Kaya (1989) by applying the methodology suggested by Duro and Padilla (2006). The main empirical results derived can be summarized as follows. First, the international polarization of emissions has significantly decreased over time during the period 1971–2006, when regional sets of nations based on the IEA structure are used; secondly, this decrease can be almost exclusively based on the reduction of the average dissimilarities among sets of countries and not due to a within-group cohesion process. Lastly, this reduction can be mainly attributed to the role of the affluence factor, and to a lesser extent, to the energy intensities. Thus, and given the values achieved for the different components, it seems that further reductions in the international polarization will continue be based on the economic convergence among groups.     

Accounting for energy-related CO2 emission in China, 1991–2006

As the country with the second largest emitter of energy-related CO₂ gas, China experienced a dramatic decline in CO₂ emission intensity from 1991 to 2000, but since then the rate of decline slowed and CO₂ emission intensity actually increased in 2003. In this paper, the complete decomposition method developed by Sun is used to analyze the nature of the factors that influence the changes in energy-related CO₂ emission and CO₂ emission intensity during the period 1991–2006. We find that: (1) energy intensity effect is confirmed as the dominant contributor to the decline in CO₂ emission and CO₂ emission intensity, (2) economic activity effect is the most important contributor to increased CO₂ emission, and (3) economic structure and CO₂ emission coefficient effects are found to contribute little to the changes in CO₂ emission and CO₂ emission intensity, which actually increased CO₂ emission and CO₂ emission intensity over the period 1991–2006 except for several years.     

NOx formation and reduction mechanisms in staged O2/CO2 combustion

The purpose of this study was to investigate the NO_x formation and reduction mechanisms in staged O₂/CO₂ combustion and in air combustion. A flat CH₄ flame doped with NH₃ for fuel-N was formed over the honeycomb, and NO_x formation characteristics were investigated. In addition, chemiluminescence of OH^* distribution was measured, and CHEMKIN-PRO was used to investigate the detailed NO_x reduction mechanism. In general, the NO_x conversion ratio decreases with decreasing primary O₂/CH₄ ratio, whereas NH₃ and HCN, which are easily converted to NO_x in the presence of O₂, increases rapidly. Therefore, a suitable primary O₂/CH₄ ratio exists in the staged combustion. Our experiments showed the primary O₂/CH₄ ratio, which gave the minimum fixed nitrogen compounds in O₂/CO₂ combustion, was lower than in air combustion. The NO_x conversion ratio in O₂/CO₂ combustion was lower than in air combustion by 40% in suitable staged combustion. This could be explained by high CO₂ concentrations in the O₂/CO₂ combustion. It was shown that abundant OH radicals were formed in O₂/CO₂ combustion through the CO₂ + H → CO + OH, experimentally and numerically. OH radicals produced H and O radicals through H₂ + OH → H + H₂O and O₂ + H → OH + O, because a mass of hydrogen source exists in the CH₄ flame. O and OH radicals formed in the fuel-rich region enhanced the oxidation of NH₃ and HCN. NO_x formed by the oxidation of NH₃ and HCN was converted to N₂ because the oxidation occurred in the fuel-rich region where the NO_x reduction effect was high. In fact, the oxidation of NH₃ and HCN in the fuel-rich region was preferable to remaining NH₃ and HCN before secondary O₂ injection in the staged combustion. A significant reduction in NO_x emission could be achieved by staged combustion in O₂/CO₂ combustion.     

Impact of inter-sectoral trade on national and global CO2 emissions: An empirical analysis of China and US

This paper attempts to discuss the CO₂ emissions embodied in Sino-US international trade using a sector approach. Based on an input–output model established in this study, we quantify the impact of Sino-US international trade on national and global CO₂ emissions. Our initial findings reveal that: In 2005, the US reduced 190.13 Mt CO₂ emissions through the consumption of imported goods from China, while increasing global CO₂ emissions by about 515.25 Mt. Similarly, China reduced 178.62 Mt CO₂ emissions through the consumption of US goods, while reducing global CO₂ emissions by 129.93 Mt. Sino-US international trade increased global CO₂ emissions by 385.32 Mt as a whole, of which the Chemical, Fabricated Metal Products, Non-metallic Mineral Products and Transportation Equipment sectors contributed an 86.71% share. Therefore, we suggest that accelerating the adjustment of China’s trade structure and export of US advanced technologies and experience related to clean production and energy efficiency to China as the way to reduce the negative impact of Sino-US trade on national and global CO₂ emissions. This behavior should take into account the processing and manufacturing industries as a priority, especially the Chemical, Fabricated Metal Products, Non-metallic Mineral Products and Transportation Equipment sectors.     

Impact of the economic recession on the European power sector’s CO2 emissions

This paper investigates the impact of the economic recession on CO₂ emissions in the European power sector, during the years 2008 and 2009. Three main determinants of the power sector’s emissions are identified: the demand for electricity, the CO₂ price, and fuel prices. A counterfactual scenario has been set up for each of these, i.e., what these parameters would have been if not affected by the recession. A simulation model of the European power sector is then employed, comparing a historical reference simulation (taking the parameters as actually occurred) with the counterfactual scenarios. The lower electricity demand (due to the recession) is shown to have by far the largest impact, accounting for an emission reduction of about 175 Mton. The lower CO₂ price (due to the recession) resulted in an increase in emissions by about 30 Mton. The impact of fuel prices is more difficult to retrieve; an indicative reduction of about 17 Mton is obtained, mainly as a consequence of the low gas prices in 2009. The simulated combined impact of the parameters results in an emission reduction of about 150 Mton in the European power sector over the years 2008 and 2009 as a consequence of the recession.     

Long-term CO2 emissions reduction target and scenarios of power sector in Taiwan

This study analyses a series of carbon dioxide (CO₂) emissions abatement scenarios of the power sector in Taiwan according to the Sustainable Energy Policy Guidelines, which was released by Executive Yuan in June 2008. The MARKAL-MACRO energy model was adopted to evaluate economic impacts and optimal energy deployment for CO₂ emissions reduction scenarios. This study includes analyses of life extension of nuclear power plant, the construction of new nuclear power units, commercialized timing of fossil fuel power plants with CO₂ capture and storage (CCS) technology and two alternative flexible trajectories of CO₂ emissions constraints. The CO₂ emissions reduction target in reference reduction scenario is back to 70% of 2000 levels in 2050. The two alternative flexible scenarios, Rt4 and Rt5, are back to 70% of 2005 and 80% of 2005 levels in 2050. The results show that nuclear power plants and CCS technology will further lower the marginal cost of CO₂ emissions reduction. Gross domestic product (GDP) loss rate in reference reduction scenario is 16.9% in 2050, but 8.9% and 6.4% in Rt4 and Rt5, respectively. This study shows the economic impacts in achieving Taiwan's CO₂ emissions mitigation targets and reveals feasible CO₂ emissions reduction strategies for the power sector.     

Grey forecasting model for CO2 emissions: A Taiwan study

Among the various greenhouse gases associated with climate change, CO₂ is the most frequently implicated in global warming. The latest data from Carbon Monitoring for Action (CARMA) shows that the coal-fired power plant in Taichung, Taiwan emitted 39.7 million tons of CO₂ in 2007 – the highest of any power plant in the world. Based on statistics from Energy International Administration, the annual CO₂ emissions in Taiwan have increased 42% from 1997 until 2006. Taiwan has limited natural resources and relies heavily on imports to meet its energy needs, and the government must take serious measures control energy consumption to reduce CO₂ emissions. Because the latest data was from 2009, this study applied the grey forecasting model to estimate future CO₂ emissions in Taiwan from 2010 until 2012. Forecasts of CO₂ emissions in this study show that the average residual error of the GM(1,1) was below 10%. Overall, the GM(1,1) predicted further increases in CO₂ emissions over the next 3 years. Although Taiwan is not a member of the United Nations and is not bound by the Kyoto Protocol, the findings of this study provide a valuable reference with which the Taiwanese government could formulate measures to reduce CO₂ emissions by curbing the unnecessary the consumption of energy.     

Decomposition of CO2 emissions change from energy consumption in Brazil: Challenges and policy implications

This study evaluates the changes in CO₂ emissions from energy consumption in Brazil for the period 1970–2009. Emissions are decomposed into production and consumption activities allowing computing the full set of energy sources consumed in the country. This study aims to develop a comprehensive and updated picture of the underlying determinants of emissions change from energy consumption in Brazil along the last four decades, including for the first time the recently released data for 2009. Results demonstrate that economic activity and demographic pressure are the leading forces explaining emission increase. On the other hand, carbon intensity reductions and diversification of energy mix towards cleaner sources are the main factors contributing to emission mitigation, which are also the driving factors responsible for the observed decoupling between CO₂ emissions and economic growth after 2004. The cyclical patterns of energy intensity and economy structure are associated to both increments and mitigation on total emission change depending on the interval. The evidences demonstrate that Brazilian efforts to reduce emissions are concentrated on energy mix diversification and carbon intensity control while technology intensive alternatives like energy intensity has not demonstrated relevant progress. Residential sector displays a marginal weight in the total emission change.     

The future choice of technologies and co-benefits of CO2 emission reduction in Bangladesh power sector

This paper examines the impacts of CO₂ emission reduction on future technology selection and energy use in Bangladesh power sector up to 2035 considering the base year 2005. It also examines the implications of CO₂ emission reduction targets on energy security of the country. The analysis is based on a long-term energy system model of Bangladesh using the MARKAL framework. The results show that the introduction of the CO₂ emission reduction targets directly affect the shift of technologies from high carbon content fossil-based to low carbon content fossil-based as well as clean, renewable energy-based technologies compared to the base scenario. With the CO₂ emission reduction target of 10–30%, the cumulative net energy imports during 2005–2035 would be reduced in the range of over 1400 PJ to 4898 PJ compared to the base scenario emission level. The total primary energy requirement would be reduced in the range of 5.5–15.2% in the CO₂ emission reduction targets and the primary energy supply system would be diversified compared to the base scenario.     

Assessment of CO2 emissions reduction in a distribution warehouse

Building energy use accounts for almost 50% of the total CO₂ emissions in the UK. Most of the research has focused on reducing the operational impact of buildings, however in recent years many studies have indicated the significance of embodied energy in different building types. This paper primarily focuses on illustrating the relative importance of operational and embodied energy in a flexible use light distribution warehouse. The building is chosen for the study as it is relatively easy to model and represents many distribution centres and industrial warehouses in Europe.A carbon footprinting study was carried out by conducting an inventory of the major installed materials with potentially significant carbon impact and material substitutions covering the building structure. Ecotect computer simulation program was used to determine the energy consumption for the 25 years design life of the building. This paper evaluates alternative design strategies for the envelope of the building and their effects on the whole life emissions by investigating both embodied and operational implications of changing the envelope characteristics. The results provide an insight to quantify the total amount of CO₂ emissions saved through design optimisation by modeling embodied and operational energy.     

Assessment of CO2 emissions and its reduction potential in the Korean petroleum refining industry using energy-environment models

We assessed potential future CO₂ reduction in the Korean petroleum refining industry by investigating five new technologies for energy savings and CO₂ mitigation using a hybrid SD-LEAP model: crude oil distillation units (CDU), vacuum distillation units (VDU), light gas-oil hydro-desulfurization units (LGO HDS), and the vacuum residue hydro-desulfurization (VR HDS) process. The current and future demand for refining industry products in Korea was estimated using the SD model. The required crude oil input amounts are expected to increase from 139 million tons in 2008 to 154 million tons in 2030 in the baseline scenario. The current and future productivity of the petroleum refining industry was predicted, and this prediction was substituted into the LEAP model which analyzed energy consumption and CO₂ emissions from the refining processes in the BAU scenario. We expect that new technology and alternative scenarios will reduce CO₂ emissions by 0.048% and 0.065% in the national and industrial sectors, respectively.     

Technoeconomic assessment of China’s indirect coal liquefaction projects with different CO2 capture alternatives

ICL (Indirect coal liquefaction), an alternative fuel-supplying technology, has drawn much attention and caused considerable debate in China’s energy sector. The hurdles to its development include the high risk of investment into large-scale installations, the high CO₂ emissions and water resource consumption. A comprehensive assessment of ICL is urgently needed. This study provides an economic assessment and a technical analysis based on process simulations. To address the future challenge of curbing CO₂ emissions, three absorption methods are compared for capturing the CO₂ released from the ICL process: DMC (a novel absorbent), MEA and Rectisol. The comparative results suggest that physical absorbents, represented by Rectisol and DMC, have a remarkable advantage over chemical absorption processes, represented by MEA. The Rectisol process costs the least, while the DMC process is close to the same level. As a novel absorbent, DMC has the potential to be widely used in the future. The economic analysis of ICL predicted a high capital cost of over 35 billion yuan and an overall product cost of approximately 3800 yuan/ton for the baseline. In addition, via a sensitivity analysis, coal price, electricity price and capacity factor were identified as the three most influential factors affecting the overall product cost.     

Will restrictions on CO2 emissions require reductions in transport demand?

In this paper, the potential for the transportation sector to develop in a way that is consistent with long-term climate targets will be discussed. An important question is whether technical measures will be sufficient for reaching long-term climate targets. Although there is a large potential to significantly increase the use of bioenergy from today's level, there will be severe restrictions to its use within the transportation sector. Other renewable energy sources such as wind and solar are much more abundant and could provide the majority of the necessary transportation fuel in the long run. Although potentially much more expensive than current fuels they could, in combination with strong efficiency improvements, provide transport services at costs that could be acceptable in a growing economy. Transport levels as high as today or even higher could be consistent from a climate perspective if such fuels and technologies are utilised. Relying only on technical measures would, however, be risky, as there is no guarantee that the technology will develop at a sufficient rate. Furthermore, the existence of other negative environmental effects would argue for the implementation of measures affecting transport demand as well.     

Estimating marginal CO2 emissions rates for national electricity systems

The carbon dioxide (CO₂) emissions reduction afforded by a demand-side intervention in the electricity system is typically assessed by means of an assumed grid emissions rate, which measures the CO₂ intensity of electricity not used as a result of the intervention. This emissions rate is called the “marginal emissions factor” (MEF). Accurate estimation of MEFs is crucial for performance assessment because their application leads to decisions regarding the relative merits of CO₂ reduction strategies. This article contributes to formulating the principles by which MEFs are estimated, highlighting the strengths and weaknesses in existing approaches, and presenting an alternative based on the observed behaviour of power stations. The case of Great Britain is considered, demonstrating an MEF of 0.69 kgCO₂/kW h for 2002–2009, with error bars at +/−10%. This value could reduce to 0.6 kgCO₂/kW h over the next decade under planned changes to the underlying generation mix, and could further reduce to approximately 0.51 kgCO₂/kW h before 2025 if all power stations commissioned pre-1970 are replaced by their modern counterparts. Given that these rates are higher than commonly applied system-average or assumed “long term marginal” emissions rates, it is concluded that maintenance of an improved understanding of MEFs is valuable to better inform policy decisions.     

Incentives for subcontractors to adopt CO2 emission reporting and reduction techniques

We investigate the incentives for subcontractors (couriers) of a transport and logistics company to report about their CO₂ emissions and to implement CO₂ reducing technologies. Furthermore, we try to find out whether these incentives differ between British and Dutch couriers. We find that several incentives play a significant role. Subcontractors in the Netherlands predominantly are extrinsically motivated to engage in CO₂ reporting and reduction techniques. This is because they are mainly driven by regulatory compliance, energy costs and implementation costs. In contrast, British subcontractors are much more intrinsically motivated to comply. They are predominantly driven by energy costs, environmental awareness, relationship building and reputation building. The contractor will have to account for these differences in making its policies work.     

Role of CO2 in the CH4 oxidation and H2 formation during fuel-rich combustion in O2/CO2 environments

The effect of CO₂ reactivity on CH₄ oxidation and H₂ formation in fuel-rich O₂/CO₂ combustion where the concentrations of reactants were high was studied by a CH₄ flat flame experiment, detailed chemical analysis, and a pulverized coal combustion experiment. In the CH₄ flat flame experiment, the residual CH₄ and formed H₂ in fuel-rich O₂/CO₂ combustion were significantly lower than those formed in air combustion, whereas the amount of CO formed in fuel-rich O₂/CO₂ combustion was noticeably higher than that in air. In addition to this experiment, calculations were performed using CHEMKIN-PRO. They generally agreed with the experimental results and showed that CO₂ reactivity, mainly expressed by the reaction CO₂ + H → CO + OH (R1), caused the differences between air and O₂/CO₂ combustion under fuel-rich condition. R1 was able to advance without oxygen. And, OH radicals were more active than H radicals in the hydrocarbon oxidation in the specific temperature range. It was shown that the role of CO₂ was to advance CH₄ oxidation during fuel-rich O₂/CO₂ combustion. Under fuel-rich combustion, H₂ was mainly produced when the hydrocarbon reacted with H radicals. However, the hydrocarbon also reacted with the OH radicals, leading to H₂O production. In fact, these hydrocarbon reactions were competitive. With increasing H/OH ratio, H₂ formed more easily; however, CO₂ reactivity reduced the H/OH ratio by converting H to OH. Moreover, the OH radicals reacted with H₂, whereas the H radicals did not reduce H₂. It was shown that OH radicals formed by CO₂ reactivity were not suitable for H₂ formation. As for pulverized coal combustion, the tendencies of CH₄, CO, and H₂ formation in pulverized coal combustion were almost the same as those in the CH₄ flat flame.