Can ‘negative net CO2 emissions’ from decarbonised biogas-to-electricity contribute to solving Poland’s carbon capture and sequestration dilemmas?

The article analyses to what extent ‘negative net CO₂ emissions’ from decarbonised biogas-to-electricity can contribute to solving Poland’s carbon capture and sequestration dilemmas. From the criteria-based evaluation of low-carbon power technologies it is found, that biogas-to-electricity is among technologies having increasing production potential in Poland. Therefore, in future biogas will be able to contribute to solving Poland’s CCS dilemmas, because it offers carbon-neutral electricity. Moreover, by applying CCS into biogas-to-electricity the ‘negative net CO₂ emissions’ can be achieved. The article examines three biogas-to-electricity technologies involving CO₂ capture, i.e. biogas-to-biomethane, biogas-to-CHP and biogas-to-electricity via the ORFC cycle. It is emphasised that the ORFC cycle offers low-cost CO₂ separation from a CO₂-H₂ mixture, low O₂-intensity, and the opportunities for advanced mass and energy integration of involved processes. Besides, energy conversion calculations show that the ORFC cycle can offer comparable cycle efficiency with air- and oxy-combustion combined cycles. In regard to the design of biogas-based energy systems it is recommended to include (i) distributed production of biogas in order to avoid costs of long-distance transportation of high-moisture content biomass and (ii) centralised large-scale decarbonised biogas-to-electricity power plants since costs of pipeline transportation of gases are low but large-scale plants could benefit from increased energy and CCS efficiencies.     

The environmental impact and risk assessment of CO2 capture, transport and storage - An evaluation of the knowledge base

In this study, we identify and characterize known and new environmental consequences associated with CO₂ capture from power plants, transport by pipeline and storage in geological formations. We have reviewed (analogous) environmental impact assessment procedures and scientific literature on carbon capture and storage (CCS) options. Analogues include the construction of new power plants, transport of natural gas by pipelines, underground natural gas storage (UGS), natural gas production and enhanced oil recovery (EOR) projects. It is investigated whether crucial knowledge on environmental impacts is lacking that may postpone the implementation of CCS projects. This review shows that the capture of CO₂ from power plants results in a change in the environmental profile of the power plant. This change encompasses both increase and reduction of key atmospheric emissions, being: NO_x, SO₂, NH₃, particulate matter, Hg, HF and HCl. The largest trade-offs are found for the emission of NO_x and NH₃ when equipping power plants with post-combustion capture. Synergy is expected for SO₂ emissions, which are low for all power plants with CO₂ capture. An increase in water consumption ranging between 32% and 93% and an increase in waste and by-product creation with tens of kilotonnes annually is expected for a large-scale power plant (1 GW_e), but exact flows and composition are uncertain. The cross-media effects of CO₂ capture are found to be uncertain and to a large extent not quantified. For the assessment of the safety of CO₂ transport by pipeline at high pressure an important knowledge gap is the absence of validated release and dispersion models for CO₂ releases. We also highlight factors that result in some (not major) uncertainties when estimating the failure rates for CO₂ pipelines. Furthermore, uniform CO₂ exposure thresholds, detailed dose-response models and specific CO₂ pipeline regulation are absent. Most gaps in environmental information regarding the CCS chain are identified and characterized for the risk assessment of the underground, non-engineered, part of the storage activity. This uncertainty is considered to be larger for aquifers than for hydrocarbon reservoirs. Failure rates are found to be heavily based on expert opinions and the dose-response models for ecosystems or target species are not yet developed. Integration and validation of various sub-models describing fate and transport of CO₂ in various compartments of the geosphere is at an infant stage. In conclusion, it is not possible to execute a quantitative risk assessment for the non-engineered part of the storage activity with high confidence.     

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.     

Optimization of intercooling compression in CO2 capture systems

Compression of CO₂ is an essential process in the development of carbon capture and storage (CCS) technologies. In spite of power requirements for CO₂ compression could be as much as 100 kWe per tonne CO₂, the minimization of energy requirements has received little attention in the literature. Although intercooling compression reduces power requirements, it introduces important cooling necessities that could be minimized.The aim of this paper is the integration of intercooling compression into the low-pressure part of a steam cycle to take advantage of the intercooling heat and analyse the energetic and economical results under different assumptions. Simulation and optimization have been performed in order to evaluate the intercooling configuration, energy requirements and the most cost-effective integration. Results have shown reduction in compression power requirement around 40% and reduction of the incremental COE around 23%. Proposed integration could be used to increase the efficiency of CO₂ capture processes and, therefore, to reduce the CO₂ capture cost.     

Stakeholder perceptions of CO2 capture and storage in Europe: Results from a survey

During 2006, a survey was conducted of European energy stakeholders (industry, government, environmental non-governmental organizations (NGOs), researchers and academicians and parliamentarians). A total of 512 responses was received from 28 countries as follows: industry (28%), research (34%), government (13%), NGOs (5%) and parliamentarians (4%). Three-quarters of the sample thought that widespread use of CO₂ capture and storage (CCS) was ‘definitely’ or ‘probably necessary’ to achieve deep reductions in CO₂ emissions between now and 2050 in their own country. Only one in eight considered that CCS was ‘probably’ or ‘definitely not necessary’. For a range of 12 identified risks, 20–40% thought that they would be ‘moderate’ or ‘very serious’, whilst 60–80% thought that there would be no risks or that the risks would be ‘minimal’. A particular risk identified by nearly half the sample is the additional use of fossil fuels due to the ‘energy penalty’ incurred by CCS. Further concerns are that development of CCS would detract from investment in renewable energy technologies. Half of the respondents thought that incentives for CCS should be set either at the same level as those for renewables or at a higher level. Environmental NGOs were consistently less enthusiastic about CCS than the energy industry.     

Electricity consumption and CO2 capture potential in Spain

In this paper, different electricity demand scenarios for Spain are presented. Population, income per capita, energy intensity and the contribution of electricity to the total energy demand have been taken into account in the calculations. Technological role of different generation technologies, i.e. coal, nuclear, renewable, combined cycle (CC), combined heat and power (CHP) and carbon capture and storage (CCS), are examined in the form of scenarios up to 2050. Nine future scenarios corresponding to three electrical demands and three options for new capacity: minimum cost of electricity, minimum CO₂ emissions and a criterion with a compromise between CO₂ and cost (CO₂-cost criterion) have been proposed. Calculations show reduction in CO₂ emissions from 2020 to 2030, reaching a maximum CO₂ emission reduction of 90% in 2050 in an efficiency scenario with CCS and renewables. The contribution of CCS from 2030 is important with percentage values of electricity production around 22–28% in 2050. The cost of electricity (COE) increases up to 25% in 2030, and then this value remains approximately constant or decreases slightly.     

Potential for flexible operation of pulverised coal power plants with CO2 capture

Abstract

Fossil-fired plants play an important role in electricity networks as mid-merit plants that can respond relatively quickly to changes in supply and demand. As a consequence, they are required to operate over a wide output range and play an important role in maintaining the quality and security of electricity supply by providing response and reserve capacity. Carbon dioxide capture and storage (CCS) has been identified as a critical technology for future electricity generation from coal in the UK. Although the performance of CCS schemes where CO₂ capture plants are operated at full load has been considered in detail, part load performance is less well understood. Developing a better understanding of part load performance of plants operating with CO₂ capture is crucial in determining their suitability to operate as mid-merit plants. This paper presents an assessment of the potential impact of adding post-combustion CO₂ capture at pulverised-coal power plants. Estimated performance of steam cycles working with post-combustion CO₂ capture plant are presented at full and part load, leading to performance predictions for pulverised-coal power plants operated over a range of loads and with varying levels of CO₂ capture. By adjusting the operation of the capture plant, as well as the boiler/steam cycle, an extended range of operation can be achieved including lower minimum stable generation levels and additional 'pumped storage like' capacity for times of high demand. For example, plant operators can alter the energy penalty for the CO₂ capture plant with an associated change in plant output by reducing the level of CO₂ capture. This can allow extra electricity to be generated and sold when electricity prices are high. With solvent storage it should also be possible to increase power plant output for a number of hours, but without associated increases in CO₂ emissions.     

Barriers and incentives of CCS deployment in China: Results from semi-structured interviews

From March to July of 2008, we conducted semi-structured interviews with 31 experts from the Chinese government, scientific institutes and industrial sectors. This paper summarizes the experts’ opinions and draws conclusions about four crucial aspects that influence CO₂ capture and storage (CCS) deployment in China: technology research and experience accumulation, finance support, market development and policy and system. According to interviews result, technological improvement is necessary to cut down on CO₂ capture cost and decrease technological uncertainty. Then, to make some rational policies and systems, with elements such as a carbon tax and clean electricity pricing, to drive power plants to adopt CO₂ capture technology. Furthermore, financial incentive in both the long term and the short term, such as subsidies and CDM, will be important for CCS incentives, encouraging enterprises’ enthusiasm for CCS and their capacity to enact it. Lastly, CCS deployment should be conducted under a market-oriented framework in the long term, so a business model and niche market deployment should be considered in advance. Among these aspects, policy and system is more complex than other three aspects, to resolve this obstacle, the innovation on electricity market and government decision model for climate change is crucial.     

Carbon capture and storage: Fundamental thermodynamics and current technology

Carbon capture and storage (CCS) is considered a leading technology for reducing CO₂ emissions from fossil-fuelled electricity generation plants and could permit the continued use of coal and gas whilst meeting greenhouse gas targets. However considerable energy is required for the capture, compression, transport and storage steps involved. In this paper, energy penalty information in the literature is reviewed, and thermodynamically ideal and “real world” energy penalty values are calculated. For a sub-critical pulverized coal (PC) plant, the energy penalty values for 100% capture are 48.6% and 43.5% for liquefied CO₂, and for CO₂ compressed to 11 MPa, respectively. When assumptions for supercritical plants were incorporated, results were in broad agreement with published values arising from process modelling. However, we show that energy use in existing capture operations is considerably greater than indicated by most projections. Full CCS demonstration plants are now required to verify modelled energy penalty values. However, it appears unlikely that CCS will deliver significant CO₂ reductions in a timely fashion. In addition, many uncertainties remain over the permanence of CO₂ storage, either in geological formations, or beneath the ocean. We conclude that further investment in CCS should be seriously questioned by policy makers.     

Effects of technological learning on future cost and performance of power plants with CO2 capture

This paper demonstrates the concept of applying learning curves in a consistent manner to performance as well as cost variables in order to assess the future development of power plants with CO₂ capture. An existing model developed at Carnegie Mellon University, which had provided insight into the potential learning of cost variables in power plants with CO₂ capture, is extended with learning curves for several key performance variables, including the overall energy loss in power plants, the energy required for CO₂ capture, the CO₂ capture ratio (removal efficiency), and the power plant availability. Next, learning rates for both performance and cost parameters were combined with global capacity projections for fossil-fired power plants to estimate future cost and performance of these power plants with and without CO₂ capture. The results of global learning are explicitly reported, so that they can be used for other purposes such as in regional bottom-up models. Results of this study show that IGCC with CO₂ capture has the largest learning potential, with significant improvements in efficiency and reductions in cost between 2001 and 2050 under the condition that around 3100 GW of combined cycle capacity is installed worldwide. Furthermore, in a scenario with a strict climate policy, mitigation costs in 2030 are 26, 11, 19 €/t (excluding CO₂ transport and storage costs) for NGCC, IGCC, and PC power plants with CO₂ capture, respectively, compared to 42, 13, and 32 €/t in a scenario with a limited climate policy. Additional results are presented for IGCC, PC, and NGCC plants with and without CO₂ capture, and a sensitivity analysis is employed to show the impacts of alternative assumptions on projected learning rates of different systems.     

Performance and cost of wet and dry cooling systems for pulverized coal power plants with and without carbon capture and storage

Thermoelectric power plants require significant quantities of water, primarily for the purpose of cooling. Water also is becoming critically important for low-carbon power generation. To reduce greenhouse gas emissions from pulverized coal (PC) power plants, post-combustion carbon capture and storage (CCS) systems are receiving considerable attention. However, current CO₂ capture systems require a significant amount of cooling. This paper evaluates and quantifies the plant-level performance and cost of different cooling technologies for PC power plants with and without CO₂ capture. Included are recirculating systems with wet cooling towers and air-cooled condensers (ACCs) for dry cooling. We examine a range of key factors affecting cooling system performance, cost and plant water use, including the plant steam cycle design, coal type, carbon capture system design, and local ambient conditions. Options for reducing power plant water consumption also are presented.     

CO2 emissions and carbon capture and storage prospects in the electric power industry of Guangdong Province,China

The main objective of this study is to characterise the electric power industry's CO₂ emissions and to understand its carbon capture and storage (CCS) prospects in China's Guangdong Province. Coal-fired power plants in Guangdong are the major point sources, contributing to more than 90% of CO₂ emissions of the electric power industry. The fossil-fuelled power plants are mainly located in the Pearl River Delta (PRD), and the newly built and planned large plants are mainly located in coastal zones. More basic research and investigation are necessary in the coming years to develop CCS. In the medium term, the harbours of eastern cities can be the key areas for CCS demonstration projects. In the long term, the reduction effect can be more remarkable if the CO₂ capture and pipeline project could be constructed on a large scale within the densest CO₂ point source area in the PRD.     

Techno-economic and environmental evaluations of large scale gasification-based CCS project in Romania

Gasification is a promising technology in terms of reducing carbon capture energy and cost penalties as well as for multi-fuel multi-product operation capability. The paper evaluates two carbon capture options in terms of main techno-economic indicators. The first option involves pre-combustion capture, the syngas being catalytically shifted to convert carbon species into CO₂ and H₂. Gas–liquid absorption is used for separate H₂S and CO₂ capture, then clean gas is used for power generation. The second capture option is based on post-combustion capture using chemical absorption. The most promising gasifiers were evaluated in a CCS design.     

Capturing CO2 in flue gas from fossil fuel-fired power plants using dry regenerable alkali metal-based sorbent

CO₂ capture and storage (CCS) has received significant attention recently and is recognized as an important option for reducing CO₂ emissions from fossil fuel combustion. A particularly promising option involves the use of dry alkali metal-based sorbents to capture CO₂ from flue gas. Here, alkali metal carbonates are used to capture CO₂ in the presence of H₂O to form either sodium or potassium bicarbonate at temperatures below 100 °C. A moderate temperature swing of 120–200 °C then causes the bicarbonate to decompose and release a mixture of CO₂/H₂O that can be converted into a “sequestration-ready” CO₂ stream by condensing the steam. This process can be readily used for retrofitting existing facilities and easily integrated with new power generation facilities. It is ideally suited for coal-fired power plants incorporating wet flue gas desulfurization, due to the associated cooling and saturation of the flue gas. It is expected to be both cost effective and energy efficient.     

Efficiency enhancement of pressurized oxy‐coal power plant with heat integration

The oxy‐coal combustion with carbon dioxide capture and sequestration is among the promising clean coal technologies for reducing CO₂ emissions. Because most of oxy‐coal power plants need to cope with energy penalties from air separation and CO₂ compressor units, the pressurized combustion is added to reduce the electricity demand for the CCS system, and the waste heat of the pressurized flue gas is recovered by the heat integration technique to increase the power generation from steam turbines. Finally, the efficiency enhancement of a 100 MW_e‐scale power plant is successfully validated by Aspen Plus simulation. Copyright © 2014 John Wiley & Sons, Ltd.     

Pathways for the North European electricity supply

This paper investigates the development of the electricity-supply systems in Northern Europe (Germany, UK, Denmark, Finland, Sweden and Norway) until the year 2050. The focus is on the response to an assumed common stringent CO₂-reduction target and on the role of carbon capture and storage technologies (CCS). Special emphasis is put on turn-over in capital stock, timing of investments and the infrastructural implications of large-scale introduction of CCS. The analysis is carried out through scenario analysis with the aid of a techno-economic model, in which a case including CCS is compared to a case excluding this option. The phase out of the present capital stock (power plants) is included from the Chalmers energy infrastructure databases, which gives information on present and planned power plants down to block level for plants exceeding 10 MW net electric power. Assuming technical lifetimes for these plants yield residual capacities in each year, here referred to as the phase-out pattern. CCS technologies are assumed to become commercially available in 2020.     

Getting ready for carbon capture and storage through a ‘CCS (Carbon Capture and Storage) Ready Hub’: A case study of Shenzhen city in Guangdong province, China

China has been building approximately 1 GW of new coal-fired power plant per week since 2005. Power plants now in construction may continue to operate until 2040. “CCS (Carbon Capture and Storage) Ready” enables and eases the subsequent retrofitting of a plant to be able to capture carbon dioxide later in that plant’s lifetime. Building on the definitions of the IEA GHG (IEA Greenhouse Gas Programme) and GCCSI (Global Carbon Capture and Storage Institute), this study suggests a novel concept ‘CCS Ready Hub’ for implementing CCS Ready. A CCS Ready Hub not only includes a number of new coal-fired power plants but also integrates other existing stationary carbon dioxide emissions sources into the planning for potential infrastructure. We conducted a case study of Guangdong province in China with a detailed engineering and economic assessment in Shenzhen City. The study first reviewed the potential storage sites and analysed the existing stationary emissions sources in Guangdong using a GIS (Geographic Information System) approach. Thereafter, we focused on investigating the economic benefits of a ‘CCS Ready Hub’ at a potential 4 GW new USCPC (ultra-supercritical pulverised coal-fired) power plant in Shenzhen. Using the cost of carbon dioxide avoidance in 2020 as a criterion, we found that the concept of a CCS Ready Hub to finance CCS Ready at a regional planning level rather than at an individual plant is preferred since it significantly reduces the overall cost of building an integrated CCS system to reduce carbon emissions in the future.     

Carbon capture and storage

Carbon capture and storage (CCS) covers a broad range of technologies that are being developed to allow carbon dioxide (CO₂) emissions from fossil fuel use at large point sources to be transported to safe geological storage, rather than being emitted to the atmosphere. Some key enabling contributions from technology development that could help to facilitate the widespread commercial deployment of CCS are expected to include cost reductions for CO₂ capture technology and improved techniques for monitoring stored CO₂. It is important, however, to realise that CCS will always require additional energy compared to projects without CCS, so will not be used unless project operators see an appropriate value for reducing CO₂ emissions from their operations or legislation is introduced that requires CCS to be used. Possible key advances for CO₂ capture technology over the next 50 years, which are expected to arise from an eventual adoption of CCS as standard practice for all large stationary fossil fuel installations, are also identified. These include continued incremental improvements (e.g. many potential solvent developments) as well as possible step-changes, such as ion transfer membranes for oxygen production for integrated gasifier combined cycle and oxyfuel plants.     

The outlook for improved carbon capture technology

Carbon capture and storage (CCS) is widely seen as a critical technology for reducing atmospheric emissions of carbon dioxide (CO₂) from power plants and other large industrial facilities, which are major sources of greenhouse gas emissions linked to global climate change. However, the high cost and energy requirements of current CO₂ capture processes are major barriers to their use. This paper assesses the outlook for improved, lower-cost technologies for each of the three major approaches to CO₂ capture, namely, post-combustion, pre-combustion and oxy-combustion capture. The advantages and limitations of each of method are discussed, along with the current status of projects and processes at various stages in the development cycle. We then review a variety of “roadmaps” developed by governmental and private-sector organizations to project the commercial roll-out and deployment of advanced capture technologies. For perspective, we also review recent experience with R&D programs to develop lower-cost technologies for SO₂ and NO_x capture at coal-fired power plants. For perspective on projected cost reductions for CO₂ capture we further review past experience in cost trends for SO₂ and NO_x capture systems. The key insight for improved carbon capture technology is that achieving significant cost reductions will require not only a vigorous and sustained level of research and development (R&D), but also a substantial level of commercial deployment, which, in turn, requires a significant market for CO₂ capture technologies. At present such a market does not yet exist. While various incentive programs can accelerate the development and deployment of improved CO₂ capture systems, government actions that significantly limit CO₂ emissions to the atmosphere ultimately are needed to realize substantial and sustained reductions in the future cost of CO₂ capture.     

Carbon prices and CCS investment: A comparative study between the European Union and China

Carbon Capture and Storage is considered as a key option for climate change mitigation; policy makers and investors need to know when CCS becomes economically attractive. Integrating CCS in a power plant adds significant costs which can be offset by a sufficient CO₂ price. However, most markets have failed: currently, the weak carbon price threatens CCS deployment in the European Union (EU). In China, a carbon regulation is appearing and CCS encounters a rising interest. This study investigates two questions: how much is the extra-cost of a CCS plant in the EU in comparison with China? Second, what is the CO₂ price beyond which CCS plants become more profitable than reference plants in the EU and in China? To address these issues, I conducted a literature review on public studies about CCS costs. To objectively assess the profitability of CCS plants, I constructed a net present value model to calculate the Levelised Cost of Electricity and the breakeven CO₂ price. CCS plants become the most profitable plant type beyond 115 €/tCO₂ in the EU vs. 45 €/tCO₂ in China (offshore transport and storage costs). I advise on the optimal plant type choice depending on the CO₂ price in both countries.