Life cycle GHG assessment of fossil fuel power plants with carbon capture and storage

The evaluation of life cycle greenhouse gas emissions from power generation with carbon capture and storage (CCS) is a critical factor in energy and policy analysis. The current paper examines life cycle emissions from three types of fossil-fuel-based power plants, namely supercritical pulverized coal (super-PC), natural gas combined cycle (NGCC) and integrated gasification combined cycle (IGCC), with and without CCS. Results show that, for a 90% CO₂ capture efficiency, life cycle GHG emissions are reduced by 75–84% depending on what technology is used. With GHG emissions less than 170 g/kWh, IGCC technology is found to be favorable to NGCC with CCS. Sensitivity analysis reveals that, for coal power plants, varying the CO₂ capture efficiency and the coal transport distance has a more pronounced effect on life cycle GHG emissions than changing the length of CO₂ transport pipeline. Finally, it is concluded from the current study that while the global warming potential is reduced when MEA-based CO₂ capture is employed, the increase in other air pollutants such as NO_x and NH₃ leads to higher eutrophication and acidification potentials.     

Examining carbon emissions economic growth nexus for India: A multivariate cointegration approach

The study probes cointegration and causality between carbon emissions and economic growth for India using ARDL bounds testing approach complemented by Johansen–Juselius maximum likelihood procedure in a multivariate framework by incorporating energy supply, investment and employment for time span 1971–2006. The study fails to establish long-run equilibrium relationship and long term causality between carbon emissions and economic growth; however, there exists a bi-directional short-run causality between the two. Hence, in the short-run, any effort to reduce carbon emissions could lead to a fall in the national income. This study also establishes unidirectional short-run causality running from economic growth to energy supply and energy supply to carbon emissions. The absence of causality running from energy supply to economic growth implies that in India, energy conservation and energy efficiency measures can be implemented to minimize the wastage of energy across value chain. Such measures would narrow energy demand–supply gap. Absence of long-run causality between carbon emissions and economic growth implies that in the long-run, focus should be given on harnessing energy from clean sources to curb carbon emissions, which would not affect the country’s economic growth.     

Carbon emissions by rural energy in China

Carbon emissions due to rural energy consumption in China have not yet been sufficiently addressed or quantified. In this work systematic accounting with a life cycle perspective was used to estimate both the direct CO₂ emissions from fuel combustion and the indirect emissions from the production and provision of rural energy carriers. The results indicate that the total direct CO₂ emissions resulting from rural energy consumption have nearly tripled, from 0.79 billion metric tons (hereafter ton) in 1979 to 1.98 billion tons in 2008, whilst indirect emissions have nearly quadrupled, from 0.27 billion tons to 0.85 billion tons for the same period. This finding quantitatively illustrates the importance of rural energy consumption as a contributor to China's overall carbon emission. In addition, the analysis of per capita emission from rural energy revealed significant regional disparities and similarities in emission and energy sources used. Both total and per capita CO₂ are significantly higher in the North China, which is largely due to the colder climate and the relatively high economic development levels for multi-demands of energy utilisation. The analysis and results presented here provide substantial information for policy makers in relation to energy and emission targets in China.     

Trade-off in emissions of acid gas pollutants and of carbon dioxide in fossil fuel power plants with carbon capture

This paper investigates the impact of capture of carbon dioxide (CO₂) from fossil fuel power plants on the emissions of nitrogen oxides (NO_X) and sulphur oxides (SO_X), which are acid gas pollutants. This was done by estimating the emissions of these chemical compounds from natural gas combined cycle and pulverized coal plants, equipped with post-combustion carbon capture technology for the removal of CO₂ from their flue gases, and comparing them with the emissions of similar plants without CO₂ capture. The capture of CO₂ is not likely to increase the emissions of acid gas pollutants from individual power plants; on the contrary, some NO_X and SO_X will also be removed during the capture of CO₂. The large-scale implementation of carbon capture is however likely to increase the emission levels of NO_X from the power sector due to the reduced efficiency of power plants equipped with capture technologies. Furthermore, SO_X emissions from coal plants should be decreased to avoid significant losses of the chemicals that are used to capture CO₂. The increase in the quantity of NO_X emissions will be however low, estimated at 5% for the natural gas power plant park and 24% for the coal plants, while the emissions of SO_X from coal fired plants will be reduced by as much as 99% when at least 80% of the CO₂ generated will be captured.     

Alternative fuel buses currently in use in China: Life-cycle fossil energy use,GHG emissions and policy recommendations

The Chinese government has enacted policies to promote alternative vehicle fuels (AVFs) and alternative fuel vehicles (AFVs), including city bus fleets. The life cycle (LC), energy savings (ES) and GHG reduction (GR) profiles of AVFs/AFVs are critical to those policy decisions. The well-to-wheels module of the Tsinghua-CA3EM model is employed to investigate actual performance data. Compared with conventional buses, AFVs offer differences in performance in terms of both ES and GR. Only half of the AFVs analyzed demonstrate dual benefits. However, all non-oil/gas pathways can substitute oil/gas with coal. Current policies seek to promote technology improvements and market creation initiatives within the guiding framework of national-level diversification and district-level uniformity. Combined with their actual LC behavior and in keeping with near- and long-term strategies, integrated policies should seek to (1) apply hybrid electric technology to diesel buses; (2) encourage NG/LPG buses in gas-abundant cities; (3) promote commercialize electric buses or plug-in capable vehicles through battery technology innovation; (4) support fuel cell buses and hydrogen technology R&D for future potential applications; and (5) conduct further research on boosting vehicle fuel efficiency, applying low-carbon transportation technologies, and addressing all resultant implications of coal-based transportation solutions to human health and natural resources.     

Multi-period emissions trading in the electricity sector—winners and losers

In the context of controlling greenhouse gas emissions, the directive on a Europe-wide trading scheme may be perceived as one of the most important milestones in recent years. Prior to its start, however, a number of very specific design features have to be agreed upon. Regarding the allocation of allowances, a distribution (almost) free of charge seems to be the most likely choice. An aspect that has interestingly attracted little attention in the past is the question of how to allocate emission rights over time. The following paper analyses different allocation options in multi-period emissions trading that are currently discussed in the European context. The options are applied for the electricity sector which is simulated over two periods. The paper distinguishes between a market effect of emissions trading and compliance costs for meeting the emission reduction obligation. The market effect results from a price increase which is due to the fact that opportunity costs for using allowances must be considered. It turns out that the electricity sector as a whole gains from the introduction of the instrument due to the increase of the electricity price. With regard to the different allocation options, it is found that utilities have different preferences depending on the fuel used.     

Biomass and China's carbon emissions: A missing piece of carbon decomposition

A number of previous studies on China's carbon emissions have mainly focused on two facts: (1) the continuous growth in emissions up till the middle of the 1990s; (2) the recent stability of emissions from 1996 to 2001. Decomposition analysis has been widely used to explore the driving forces behind these phenomena. However, since 2002, China's carbon emissions have resumed their growth at an even greater rate. This paper investigates China's carbon emissions during 1971–2003, with particular focus on the role of biomass, and the fall and resurgence in emissions since the mid-1990s. We use an extended Kaya identity and the well-established logarithmic mean Divisia index (LMDI I) method. Carbon emissions are decomposed into effects of various driving forces. We find that (1) a shift from biomass to commercial energy increases carbon emissions by a magnitude comparable to that of the increase in emissions due to population growth, (2) the technological effect and scale effect due to per-capita gross domestic products (GDP) growth are different in the pre-reform period versus the post-reform period, (3) the positive effect of population growth has been decreasing over the entire period, and (4) the fall in emissions in the late 1990s and resurgence in the early 2000s may be overstated due to inaccurate statistics.     

Reduction potentials of energy demand and GHG emissions in China's road transport sector

Rapid growth of road vehicles, private vehicles in particular, has resulted in continuing growth in China's oil demand and imports, which has been widely accepted as a major factor effecting future oil availability and prices, and a major contributor to China's GHG emission increase. This paper is intended to analyze the future trends of energy demand and GHG emissions in China's road transport sector and to assess the effectiveness of possible reduction measures. A detailed model has been developed to derive a reliable historical trend of energy demand and GHG emissions in China's road transport sector between 2000 and 2005 and to project future trends. Two scenarios have been designed to describe the future strategies relating to the development of China's road transport sector. The ‘Business as Usual’ scenario is used as a baseline reference scenario, in which the government is assumed to do nothing to influence the long-term trends of road transport energy demand. The ‘Best Case’ scenario is considered to be the most optimized case where a series of available reduction measures such as private vehicle control, fuel economy regulation, promoting diesel and gas vehicles, fuel tax and biofuel promotion, are assumed to be implemented. Energy demand and GHG emissions in China's road transport sector up to 2030 are estimated in these two scenarios. The total reduction potentials in the ‘Best Case’ scenario and the relative reduction potentials of each measure have been estimated.     

Contributing to local policy making on GHG emission reduction through inventorying and attribution: A case study of Shenyang,China

Cities consumed 84% of commercial energy in China, which indicates cities should be the main areas for GHG emissions reduction. Our case study of Shenyang in this paper shows how a clear inventory analysis on GHG emissions at city level can help to identify the major industries and societal sectors for reduction efforts so as to facilitate low-carbon policy-making. The results showed total carbon emission in 2007 was 57 Mt CO₂ equivalents (CO₂e), of which 41 Mt CO₂e was in-boundary emissions and 16 Mt CO₂e was out-of-boundary emissions. The energy sector was dominant in the emission inventory, accounting for 93.1% of total emissions. Within energy sector, emissions from energy production industry, manufacturing and construction industry accounted for 88.4% of this sector. Our analysis showed that comparing with geographical boundary, setting system boundary based on single process standard could provide better information to decision makers for carbon emission reduction. After attributing electricity and heating consumption to final users, the resident and commercial sector became the largest emitter, accounting for 28.5% of total emissions. Spatial analysis of emissions showed that industrial districts such as Shenbei and Tiexi had the large potential to reduce their carbon emissions. Implications of results are finally discussed.     

A long-term global energy- economic model of carbon dioxide release from fossil fuel use

In this paper the authors develop a long-term global energy-economic model which is capable of assessing alternative energy evolutions over periods of up to 100 years. The authors have sought to construct the model so that it can perform its assigned task with as simple a modelling system as possible. The model structure is fully documented and a brief summary of results is given.     

Border carbon adjustments: Addressing emissions embodied in trade

Approximately one fourth of global emissions are embodied in international trade and a significant portion flows from non-carbon-priced to carbon-priced economies. Border carbon adjustments (BCAs) figure prominently as instruments to address concerns arising from unilateral climate policy. Estimating the volume of emissions that could be potentially taxed under a BCA scheme has received little attention until now. This paper examines how a number of issues involved in the implementation of BCAs can affect their ability to cover emissions embodied in trade and thus address carbon leakage. These issues range from ensuring compliance with trade provisions and assumptions on the carbon intensity of imports, to determining which countries are included and whether intermediate and final demand are considered. Here we show that the volume of CO₂ captured by a scheme that involved all Annex B countries could be significantly reduced due to these issues, particularly by trade provisions, such as the principle of ‘best available technology’ (BAT). As a consequence, the tariff burdens faced by non-Annex B parties could dwindle considerably. These findings have important policy implications, as they question the effectiveness and practicalities of BCAs to reduce carbon leakage and alleviate competitiveness concerns, adding further arguments against their implementation.     

Assessing the impact of US ethanol on fossil fuel markets: A structural VAR approach

Despite the growing importance of biofuels, the effect of biofuels on fossil fuel markets is not fully understood. We develop a joint structural Vector Auto Regression (VAR) model of the global crude oil, US gasoline, and US ethanol markets to examine whether the US ethanol market has had any impact on global oil markets. The structural VAR approach provides a unique method for decomposing price and quantity data into demand and supply shocks, allowing us to estimate the distinct dynamic effects of ethanol demand and supply shocks on the real prices of crude oil and US gasoline. Ethanol demand in the US is driven mainly by government support in the form of tax credits and blending mandates. Shocks to ethanol demand therefore reflect changes in policy more than any other factor. In contrast, ethanol supply shocks are driven by changes in feedstock prices. A principle finding is that a policy-driven ethanol demand expansion causes a statistically significant decline in real crude oil prices, while an ethanol supply expansion does not have a statistically significant impact on real oil prices. This suggests that even though US ethanol market is small, the influence of US biofuels policy on the crude oil market is pervasive. We also show that ethanol demand shocks are more important than ethanol supply shocks in explaining the fluctuation of real prices of crude oil and US gasoline.     

Mitigation potential of greenhouse gas emission and implications on fuel consumption due to clean energy vehicles as public passenger transport in Kathmandu Valley of Nepal: A case study of trolley buses in Ring Road

This paper estimates the consequences in fuel consumption and greenhouse gas emission due to the possible intervention of the electric run trolley buses in the existing public transport system in a particular road up to the year 2025 in Kathmandu Valley. It projects the scenarios on the basis that the passenger travel demand is the function of population and income. Basically, it uses the Long Range Energy Alternatives Planning System software to develop Business as Usual scenario and the five alternative scenarios. The alternative scenarios are 100% replacement of vehicles catering to mass-transit in the concerned routes, 50% replacement, 25% replacement, stopping future growth of other vehicles catering to mass-transit in the concerned routes and 25% replacement in the first year, and combination scenarios. The results estimate that the passenger travel demand will increase by three folds from the year 2003 to the year 2025. It projects the three-fold increase of the existing vehicle activity by the year 2025 in Business as Usual scenario. The fuel consumption will increase by 2.4 times compared to the year 2003. It estimates the total greenhouse gas (GHG) emission as 8.5 thousands tons in year 2003 which will increase by more than 3 times in year 2025. It estimates that 174.3 thousands t CO₂e can be avoided in combination scenario. The paper concludes that the intervention of clean energy transport in the existing public transport can have a significant positive impact on the GHG emission and current fuel consumption.     

Effects of future fossil fuel use on CO2 levels in the atmosphere

A model based on fossil fuel use per capita and United Nations population predictions has been developed to predict global fossil fuel use and the resulting levels of CO₂ in the atmosphere. The results suggest levels of CO₂ will increase to between 415 and 421 ppm by 2025. Countries with energy-intensive economies will be responsible for the majority of CO₂ emissions, while nations with large populations but low energy consumption per capita will have less of an effect. A major increase in nuclear power generation will not have a significant impact on CO₂ levels over this time scale.     

Carbon dioxide emission trends in cars and light trucks: A comparative analysis of emissions and methodologies for Florida's counties (2000 and 2008)

This paper investigates methodologies to quantify CO₂ emissions from cars and light trucks in Florida. The most widely used methodology to calculate greenhouse gas emissions in the transportation sector at the local level uses a harmonic average (HA) methodology based on nationally averaged fuel economies that assume 55% city and 45% highway VMTs. This paper presents a local condition (LC) methodology that accounts for county-level variations in city and highway VMTs, as opposed to assumed uniform driving conditions. Both HA and LC methodologies were used to estimate and compare absolute and per capita CO₂ emissions both statewide and counties for 2000 and 2008. From 2000 to 2008, statewide absolute and per capita CO₂ emissions increased similarly using HA and LC methodologies; however, the percent change varied considerably among counties. Statewide CO₂ emissions calculated from HA and LC methodologies differed by only −0.2% (2000) and 1.7% (2008); however, the differences in the county-level emissions ranged from −8.0% to 14.9% (2000) and from −5.6% to 17.0% (2008). While either the HA or the LC methodology yields a similar result statewide, significant variation exists at the county level, warranting the need to consider local driving conditions when estimating county-level emissions.     

Policies for improving the efficiency of the Brazilian light-duty vehicle fleet and their implications for fuel use,greenhouse gas emissions and land use

The increase in greenhouse gas concentrations in the atmosphere, energy security issues and competition for land use are putting pressure on governments and policymakers. However, these three subjects are not usually treated in integrated form. This paper shows that the implementation of energy efficiency policies combined with policies to encourage use of biofuels can help reduce greenhouse gases emissions while easing land use competition from sugarcane ethanol in Brazil. By adapting the ADVISOR (Advanced Vehicle Simulator) software to evaluate vehicle efficiency, and by estimating the Brazilian light-duty vehicle market share based on historical data, this paper estimates the possible levels of GHG emissions and area planted with sugarcane in 2030 in the country. The findings indicate that reductions from 8% to 20% in greenhouse gas emissions and 0.9–1.8 million ha in sugarcane planted area are possible with no significant technological breakthroughs over the horizon to 2030 in comparison with a baseline scenario.     

A decarbonization strategy for the electricity sector: New-source subsidies

An expedient phase-out of carbon emissions in the electricity sector could be facilitated by imposing carbon fees and applying the revenue exclusively to subsidize new, low-carbon generation sources. Since there would initially be no “new sources,” fees would be substantially zero at the outset of the program. Nevertheless, the program would immediately create high price incentives for low-carbon capacity expansion. Fees would increase as new, low-carbon sources gain market share, but price competition from a growing, subsidized clean-energy industry would help maintain moderate retail electricity prices. Subsidies would automatically phase out as emitting sources become obsolete.     

State-scale evaluation of renewable electricity policy: The role of renewable electricity credits and carbon taxes

We have developed a state-scale version of the MARKAL energy optimization model, commonly used to model energy policy at the US national scale and internationally. We apply the model to address state-scale impacts of a renewable electricity standard (RES) and a carbon tax in one southeastern state, Georgia. Biomass is the lowest cost option for large-scale renewable generation in Georgia; we find that electricity can be generated from biomass co-firing at existing coal plants for a marginal cost above baseline of 0.2–2.2 cents/kWh and from dedicated biomass facilities for 3.0–5.5 cents/kWh above baseline. We evaluate the cost and amount of renewable electricity that would be produced in-state and the amount of out-of-state renewable electricity credits (RECs) that would be purchased as a function of the REC price. We find that in Georgia, a constant carbon tax to 2030 primarily promotes a shift from coal to natural gas and does not result in substantial renewable electricity generation. We also find that the option to offset a RES with renewable electricity credits would push renewable investment out-of-state. The tradeoff for keeping renewable investment in-state by not offering RECs is an approximately 1% additional increase in the levelized cost of electricity.     

A novel direct carbon fuel cell by approach of tubular solid oxide fuel cells

A direct carbon fuel cell based on a conventional anode-supported tubular solid oxide fuel cell, which consisted of a NiO-YSZ anode support tube, a NiO-ScSZ anode functional layer, a ScSZ electrolyte film, and a LSM-ScSZ cathode, has been successfully achieved. It used the carbon black as fuel and oxygen as the oxidant, and a preliminary examination of the DCFC has been carried out. The cell generated an acceptable performance with the maximum power densities of 104, 75, and 47 mW cm⁻² at 850, 800, and 750 °C, respectively. These results demonstrate the feasibility for carbon directly converting to electricity in tubular solid oxide fuel cells.     

Operation of solid oxide fuel cells on glycerol fuel: A thermodynamic analysis using the Gibbs free energy minimization approach

Solid oxide fuel cells (SOFCs) are very flexible, unlike other fuel cells. In principle, SOFCs can operate on almost any fuel. Currently much effort is invested in the development of SOFCs for portable applications operating directly on liquid fuels such as methanol and ethanol rather than hydrogen. However, there are very few publications dealing with the direct use of glycerol in SOFCs for portable systems. A recently published study shows that the performance achieved for an SOFC fueled by pure glycerol is quite interesting even when there is a thick electrolyte membrane, indicating that glycerol is a promising fuel for portable applications. For this reason a thermodynamic analysis for SOFCs operating directly on glycerol fuel is performed in the present study. The Gibbs energy minimization method computes the equilibrium compositions of the anode gas mixture, carbon deposition boundaries and electromotive forces (EMFs) as a function of fuel utilization and temperature. Moreover, the minimum amounts of H₂O, CO₂ (direct internal reforming case) and air (partial oxidation case) to be added to glycerol in the feedstock to avoid carbon deposition at the open circuit voltage (OCV) are calculated. Finally, a thermodynamic analysis is performed, taking into account the experimental conditions employed in a previous study. Experimental observations concerning carbon deposition in an SOFC operating on glycerol can be explained by the theoretical analysis developed in the present study. Additionally, the effect of mixed electronic-ionic conduction of the electrolyte on carbon deposition at the anode is discussed based on the thermodynamic analysis of the C-O system.