Reduction of Greenhouse Gas Emissions from Gas,Oil, and Coal Power Plants in Pakistan by Carbon Capture and Storage (CCS): A Review

The production of energy in Pakistan as a developing country mainly depends on consumption of fossil fuels, which are the main sources of greenhouse gas (GHG) emissions. These emissions can be mitigated by implementing carbon capture and storage (CCS) in running plants. An overview of the current and future potentials of Pakistan for CCS is provided, indicating a great potential for this technology to capture CO₂ emissions. The amine CO₂ capture process as the most mature procedure is currently applied in many oil and gas companies in Pakistan, which can be employed to capture CO₂ from other industries as well. Pakistan has a great CO₂ storage potential in oil, gas, and coal fields and in saline aquifer as well as significant resources of Mg and Ca silicates suitable as feedstock in the carbon mineralization process. For further development and implementation of CCS technologies in Pakistan, economic and policy barriers as the main obstacles should be alleviated.     

Greenhouse gas emissions of bioenergy from agriculture compared to fossil energy for heat and electricity supply

Increasing the use of bioenergy is one promising option to reduce greenhouse gas emissions. Hence it is important to know the greenhouse gas emissions of bioenergy systems in comparison to fossil fuel systems. A life cycle analyses of biomass and fossil fuel energy systems is made to compare the overall greenhouse gas emission of both systems for heat and electricity supply. Different bioenergy systems to supply electricity and heat from agriculture are analysed for the Austrian situation in 2000. Total emissions of greenhouse gases (CO₂, N₂O, CH₄) along the fuel chain, including land use change and by-products, are calculated. The systems taken into consideration are different conversion technologies and different fuels from agriculture. The methodology was developed within the International Energy Agency (IEA) Bioenergy Task 25 on `Greenhouse Gas Balances of Bioenergy Systems'. In this paper the results of selected bioenergy systems for heat supply and combined supply of electricity and heat shown as emission of CO₂-equivalents per kWh for bioenergy systems in comparison to fossil fuel systems, and as a percentage of CO₂-equivalent reduction. The results demonstrate that some of the bioenergy systems reduce greenhouse gas emission already because of avoided emissions of the reference biomass use and/or because of certain substitution effects of by-products. In general the greenhouse gas emissions of bioenergy systems are lower compared to the fossil systems. Therefore a significant reduction of greenhouse gases is possible by replacing fossil energy systems with bioenergy systems. This comparison should help policy makers, utilities and industry to identify effective agricultural biomass options in order to reach emission reduction targets. This revised version was published online in August 2006 with corrections to the Cover Date.     

Canadian greenhouse gas mitigation options in agriculture

In 1991, on farm management practices contributed 57.6 Tg CO₂ equivalent in greenhouse gas emissions, that is, about 10% of the anthropogenic GHG emissions in Canada. Approximately 11% of these emissions were in the form of CO₂, 36% in the form of CH₄ and 53% in the form of N₂O. The CO₂ emissions were from soils; CH₄ emissions were from enteric fermentation and manure, and N₂O emissions were primarily a function of cropping practices and manure management. With the emissions from all other agricultural practices included, such as the emissions from fossil fuels used for transportation, manufacturing, food processing etc., the agricultural sector's contributions were about 15% of Canada's emissions. In this publication, several options are examined as to their potential for reducing greenhouse gas emissions. These involve soil and crop management, soil nutrient management, improved feeding strategies, and carbon storage in industrial by-products. The Canadian Economic Emissions Model for Agriculture (CEEMA) was used to predict the greenhouse gas emissions for the year 2010, as well as the impact of mitigation options on greenhouse gas emissions from the agricultural sector. This model incorporates the Canadian Regional Agricultural sub-Model (CRAM), which predicts the activities related to agriculture in Canada up to 2010, as well as a Greenhouse Gas Emissions sub-Model (GGEM), which estimates the greenhouse gas emissions associated with the various agricultural activities. The greenhouse gas emissions from all agricultural sources were 90.5 Tg CO₂ equivalent in 1991. Estimates based on CEEMA for the year 2010 indicate emissions are expected to be 98.0 Tg CO₂ equivalent under a business as usual scenario, which assumes that the present trends in management practices will continue. The agricultural sector will then need to reduce its emissions by about 12.9 Tg CO₂ equivalent below 2010 forecasted emissions, if it is to attain its part of the Canadian government commitment made in Kyoto. Technologies focusing on increasing the soil carbon sink, reducing greenhouse gas emissions and improving the overall farming efficiency, need to be refined and developed as best management practices. The soils carbon sink can be increased through reduced tillage, reduced summer fallowing, increased use of grasslands and forage crops, etc. Key areas for the possible reduction of greenhouse gas emissions are improved soil nutrient management, improved manure storage and handling, better livestock grazing and feeding strategies, etc. The overall impact of these options is dependent on the adoption rate. Agriculture's greenhouse gas reduction commitment could probably be met if soils are recognized as a carbon sink under the Kyoto Accord and if a wide range of management practices are adopted on a large scale. None of these options can currently be recommended as measures because their socio-economic aspects have not been fully evaluated and there are still too many uncertainties in the emission estimates. This revised version was published online in August 2006 with corrections to the Cover Date.     

Optimal European cooperative supply chains for carbon capture,transport, and sequestration with costs share policies

In the past decades, CO₂ constituted nearly the 80% of anthropogenic greenhouse gases emissions therefore, global actions are needed to tackle the increase of carbon concentration in the atmosphere. CO₂ (carbon) capture and storage has been highlighted among the most promising options to decarbonize the energy and industry sectors. Considering a large-scale infrastructure at European level, economic cooperation has been highlighted as a key requirement to relieve single countries from too high risk and commitment. This article proposes an economic optimization for cooperative supply chains for CO₂ capture and storage, by adopting policies that balance the spread of costs among countries, according to local characteristics in terms of population, CO₂ emissions, and macroeconomic outcome. Results show that the additional European investment for cooperation (max. +2.6% with respect to a noncooperative network) should not constitute a barrier toward the installation and operation of such more effective network designs.     

Assessment of Industrial Greenhouse Gas Reduction Strategies Within Consistent System Boundaries

With respect to the climate goals of the greenhouse gas (GHG) neutrality in 2050, different GHG reduction strategies are discussed for industrial processes. For a comparison of the strategies carbon direct avoidance (CDA), carbon capture and storage, and carbon capture and utilization (CCU), the method system expansion is applied. Exemplarily, the CO₂ reduction potential and the energy demand are determined. The Carbon2Chem® project is described as an example of CCU for the steel and chemical production. The direct reduction with H₂ represents the CDA strategy for the steel industry.     

A multi-scale framework for CO2 capture,utilization, and sequestration: CCUS and CCU

We present a multi-scale framework for the optimal design of CO₂ capture, utilization, and sequestration (CCUS) supply chain network to minimize the cost while reducing stationary CO₂ emissions in the United States. We also design a novel CO₂ capture and utilization (CCU) network for economic benefit through utilizing CO₂ for enhanced oil recovery. Both the designs of CCUS and CCU supply chain networks are multi-scale problems which require decision making at material, process and supply chain levels. We present a hierarchical and multi-scale framework to design CCUS and CCU supply chain networks with minimum investment, operating and material costs. While doing so, we take into consideration the selection of source plants, capture processes, capture materials, CO₂ pipelines, locations of utilization and sequestration sites, and amounts of CO₂ storage. Each CO₂ capture process is optimized, and the best materials are screened from large pool of candidate materials. Our optimized CCUS supply chain network can reduce 50% of the total stationary CO₂ emission in the U.S. at a cost of $35.63 per ton of CO₂ captured and managed. The optimum CCU supply chain network can capture and utilize CO₂ to make a total profit of more than 555 million dollars per year ($9.23 per ton). We have also shown that more than 3% of the total stationary CO₂ emissions in the United States can be eliminated through CCU networks at zero net cost. These results highlight both the environmental and economic benefits which can be gained through CCUS and CCU networks. We have designed the CCUS and CCU networks through (i) selecting novel materials and optimized process configurations for CO₂ capture, (ii) simultaneous selection of materials and capture technologies, (iii) CO₂ capture from diverse emission sources, and (iv) CO₂ utilization for enhanced oil recovery. While we demonstrate the CCUS and CCU networks to reduce stationary CO₂ emissions and generate profits in the United States, the proposed framework can be applied to other countries and regions as well.     

Potential of agroforestry for carbon sequestration and mitigation of greenhouse gas emissions from soils in the tropics

Losses of carbon (C) stocks in terrestrial ecosystems and increasing concentrations of greenhouse gases in the atmosphere are challenges that scientists and policy makers have been facing in the recent past. Intensified agricultural practices lead to a reduction in ecosystem carbon stocks, mainly due to removal of aboveground biomass as harvest and loss of carbon as CO₂ through burning and/or decomposition. Evidence is emerging that agroforestry systems are promising management practices to increase aboveground and soil C stocks and reduce soil degradation, as well as to mitigate greenhouse gas emissions. In the humid tropics, the potential of agroforestry (tree-based) systems to sequester C in vegetation can be over 70 Mg C ha^–1, and up to 25 Mg ha^–1 in the top 20 cm of soil. In degraded soils of the sub-humid tropics, improved fallow agroforestry practices have been found to increase top soil C stocks up to 1.6 Mg C ha^–1 y^–1 above continuous maize cropping. Soil C accretion is linked to the structural development of the soil, in particular to increasing C in water stable aggregates (WSA). A review of agroforestry practices in the humid tropics showed that these systems were able to mitigate N₂O and CO₂ emissions from soils and increase the CH₄ sink strength compared to cropping systems. The increase in N₂O and CO₂ emissions after addition of legume residues in improved fallow systems in the sub-humid tropics indicates the importance of using lower quality organic inputs and increasing nutrient use efficiency to derive more direct and indirect benefits from the system. In summary, these examples provide evidence of several pathways by which agroforestry systems can increase C sequestration and reduce greenhouse gas emissions.     

Engineering Solutions for Limiting the Increase of Atmospheric Carbon Dioxide

The article describes possible engineering solutions that can reduce the carbon dioxide (CO₂) content of the air. To demonstrate the point fossil fuel power plants will be taken as a model for the source of CO₂. The global mass balance shows that the oceans play a major role in storing CO₂. The hypothesis presented states that the real problem is not the absolute CO₂ content, rather its change. Consequently, present emissions should be stored for future release. Under the current worldwide measures to reduce power consumption CO₂ emissions are unlikely to decrease. A number of strategies for the maritime sequestration of CO₂ are reported in the contribution. One proposal for sequestration is the use of shallow waters which form a thermohaline current: the dissolved gas will travel for hundreds of years in deep sea currents. In the latter case, CO₂ injection is easily achieved. Several scenarios are considered for the fate of this CO₂‐enriched current. The environmental impact is briefly reported. The article will describe current research requirements, demonstrating that similar research in the US and Japan is presently more advanced in comparison to that in Europe. The sequestration of carbon dioxide on land will be the subject of a second publication. It is obvious that the sequestration of CO₂ is the method after all rational chances to save energy.     

Recent developments on carbon capture and storage: An overview

The Intergovernmental Panel on Climate Change assumes the warming of the climate system, associating the increase of global average temperature to the observed increase of the anthropogenic greenhouse gas (GHG) concentrations in the atmosphere. Carbon dioxide (CO₂) is considered the most important GHG, due to the dependence of world economies on fossil fuels, since their combustion processes are the most important sources of this gas. CO₂ concentrations are increasing in the last decades mainly due to the increase of anthropogenic emissions. The processes involving CO₂ capture and storage is gaining attention on the scientific community as an alternative for decreasing CO₂ emission, reducing its concentration in ambient air. However, several technological, economical and environmental issues as well as safety problems remain to be solved, such as the following needs: increase of CO₂ capture efficiency, reduction of process costs, and verification of environmental sustainability of CO₂ storage. This paper aims to review the recent developments (from 2006 until now) on the carbon capture and storage (CCS) methodologies. Special attention was focused on the basic findings achieved in CCS operational projects.     

Tendenzen der Energieversorgung im Hinblick auf die CO2-Diskussion

Energy supply trends with regard to carbon dioxide (CO₂). Carbon dioxide (CO₂) is regarded as the main cause of the ?greenhouse effect”? in the atmosphere. Although this problem is well known, the chances for a reduction of CO₂ emissions are limited. On the one hand there is no immediate need for action because for the time being the catastrophes are taking place on the computer only. On the other hand population figures and thirst for energy are steadily increasing. Moreover, the possible measures for a reduction of CO₂ are limited. Considering the FRG's share of the carbon dioxide concentration, the targeted 25% reduction of CO₂ emissions by the year 2005 could be achieved. A large potential of energy saving and CO₂ reduction are realized by industrial cogeneration. No further technical development in order to open up this potential is needed because the technically and economically optimal solution is already available with the combined gas turbine process. In order to make use of this potential, the hurdle in the licensing procedure for industrial power plants with an output of more than 10 MW must be removed. In addition, cooperation between the energy supply corporations and industry has to be improved.     

Interaction of Regulatory Aspects for Carbon Capture and Utilization Applications

Carbon capture and utilization (CCU) technologies can lead to a net reduction of CO₂ emissions but also to a transfer from emissions between different regulatory areas. This paper presents a tool to evaluate the impact of CCU technology within the European regulatory framework with respect to the accounting of carbon transferred between the CO₂ source and its subsequent application. Additional emissions caused by energy requirements of the capture or any conversion steps are not considered. The tool is applied to a variety of possible combinations and their respective impact evaluated.     

Burning and cultivation effects on greenhouse gas emissions and nutrients in wetland soils from Saskatchewan,Canada

Wetland fringe areas in prairie agricultural landscapes may be subjected to burning of vegetation in autumn followed by cultivation in spring. The objective of this study was to examine the greenhouse gas (CO₂, N₂O and CH₄) emissions and plant nutrient (NO₃, PO₄ and SO₄) supplies in wetland fringe soils as affected by simulated burning + cultivation, at field capacity and saturation moisture content. Using undisturbed soil cores collected from grassed wetland fringes at four sites in southern Saskatchewan, the impacts were examined over a 20-day period. The burning + cultivation treatment generally reduced CO₂ emissions, tended to increase NO₃–N availability, and had no consistent effect on N₂O emissions, or PO₄–P and SO₄–S supply. Production of CH₄ occurred only at one site, and only under saturated conditions. Compared to field capacity, saturation reduced CO₂ emissions and NO₃–N supply, tended to increase PO₄–P availability, and had no consistent effect on N₂O emissions and SO₄–S. The CO₂ emissions and SO₄–S were greater for soil cores with higher organic matter and salinity, respectively. The N₂O emissions were only occasionally related to soil NO₃–N supply rate.     

Adsorptive cyclic purification process for CO2 mixtures captured from coal power plants

CO₂ capture technology combined with bulk separation and purification processes has become an attractive alternative to reduce capture costs. Furthermore, the required purity in the application for CO₂ conversion and utilization is more stringent than that required from a captured CO₂ mixture for geological storage. In this study, an adsorptive cyclic purification process was developed to upgrade a CO₂/N₂ mixture captured from greenhouse gas emission plants as a feasibility study for a second capture unit or captured CO₂ purifier. To purify 90% CO₂ with balance N₂ as a captured gas mixture, two‐bed pressure swing adsorption and pressure vacuum swing adsorption (PVSA) processes using activated carbon were experimentally and theoretically studied at adsorption pressures of 250–650 kPa and a fixed vacuum pressure of 50 kPa. CO₂ with higher than 95% purity was produced with more than 89% recovery. However, a four‐bed PVSA process could successfully produce CO₂ with greater than 98% purity and 90% recovery. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1051–1063, 2017     

Assessment of chemical looping-based conceptual designs for high efficient hydrogen and power co-generation applied to gasification processes

Carbon capture and storage (CCS) technologies are expected to play a significant role in the coming decades for curbing the greenhouse gas emissions and to ensure a sustainable development of power generation and other energy-intensive industrial sectors. Chemical looping systems are very promising options for intrinsically capture CO₂ with lower cost and energy penalties. Gasification offers significant advantages compared with other technologies in term of lower energy and cost penalties for carbon capture, utilization of wide range of fuels, poly-generation capability, plant flexibility, lower environmental impact, etc.     

Critical review of strategies for CO2 delivery to large-scale microalgae cultures

Microalgae have great, yet relatively untapped potential as a highly productive crop for the production of animal and aquaculture feed, biofuels, and nutraceutical products. Compared to conventional terrestrial crops they have a very fast growth rate and can be produced on non-arable land. During microalgae cultivation, carbon dioxide (CO₂) is supplied as the carbon source for photosynthesising microalgae. There are a number of potential CO₂ supplies including air, flue gas and purified CO₂. In addition, several strategies have been applied to the delivery of CO₂ to microalgae production systems, including directly bubbling CO₂-rich gas, microbubbles, porous membrane spargers and non-porous membrane contactors. This article provides a comparative analysis of the different CO₂ supply and delivery strategies and how they relate to each other.     

Carbon capture from stationary power generation sources: A review of the current status of the technologies

The world will need greatly increased energy supply in the future for sustained economic growth, but the related CO₂ emissions and the resulting climate changes are becoming major concerns. CO₂ is one of the most important greenhouse gases that is said to be responsible for approximately 60% of the global warming. Along with improvement of energy efficiency and increased use of renewable energy sources, carbon capture and sequestration (CCS) is expected to play a major role in curbing the greenhouse gas emissions on a global scale. This article reviews the various options and technologies for CO₂ capture, specifically for stationary power generation sources. Many options exist for carbon dioxide capture from such sources, which vary with power plant types, and include post-combustion capture, pre-combustion capture, oxy fuel combustion capture, and chemical looping combustion capture. Various carbon dioxide separation technologies can be utilized with these options, such as chemical absorption, physical absorption, adsorption, and membrane separation. Most of these capture technologies are still at early stages of development. Recent progress and remaining challenges for the various CO₂ capture options and technologies are reviewed in terms of capacity, selectivity, stability, energy requirements, etc. Hybrid and modified systems hold huge future potentials, but significant progress is required in materials synthesis and stability, and implementations of these systems on demonstration plants are needed. Improvements and progress made through applications of process systems engineering concepts and tools are highlighted and current gaps in the knowledge are also mentioned. Finally, some recommendations are made for future research directions.     

Pilot plant study of post-combustion carbon dioxide capture by reactive absorption: Methodology, comparison of different structured packings, and comprehensive results for monoethanolamine

Post-combustion carbon capture (PCC) from fossil fuel power plants by reactive absorption can substantially contribute to reduce emissions of the greenhouse gas CO₂. To test new solvents for this purpose small pilot plants are used. The present paper describes results of comprehensive studies of the standard PCC solvent MEA (0.3 g/g monoethanolamine in water) in a pilot plant in which the closed cycle of absorption/desorption process is continuously operated (column diameters: 0.125 m, absorber/desorber packing height: 4.25/2.55 m, packing type: Sulzer BX 500, flue gas flow: 30-110 kg/h, CO₂ partial pressure: 35-135 mbar). The data establish a base line for comparisons with new solvents tested in the pilot plant and can be used for a validation of models of the PCC process with MEA. The ratio of the solvent to the flue gas mass flow is systematically varied at constant CO₂ removal rate, and CO₂ partial pressure in the flue gas. Optimal operating points are determined. In the present study the structured packing Sulzer BX 500 is used. The experiments with the removal rate variation are carried out so that the results can directly be compared to those from a previous study in the same plant that was carried out using Sulzer Mellapak 250.Y. A strategy for identifying the influence of absorption kinetics on the results is proposed, which is based on a variation of the gas load at a constant L/G ratio and provides valuable insight on the transferability of pilot plant results.     

Recent advances in polymeric membranes for CO2 capture

Membrane and membrane process have been considered as one of the most promising technologies for mitigating CO₂ emissions from the use of fossil fuels. In this paper, recent advances in polymeric membranes for CO₂ capture are reviewed in terms of material design and membrane formation. The selected polymeric materials are grouped based on their gas transport mechanisms, i.e., solution‐diffusion and facilitated transport. The discussion of solution‐diffusion membranes encompasses the recent efforts to shift the upper bound barrier, including the enhanced CO₂ solubility in several rubbery polymers and novel methods to construct shape-persisting macromolecules with unprecedented sieving ability. The carrier-bearing facilitated transport membranes are categorized based on the specific CO₂-carrier chemistry. Finally, opportunities and challenges in practical applications are also discussed, including post-combustion carbon capture (CO₂/N₂), hydrogen purification (CO₂/H₂), and natural gas sweetening (CO₂/CH₄).     

High Temperature Co-Electrolysis as a Key Technology for CO2 Emission Mitigation – A Model-Based Assessment of CDA and CCU

The mitigation of CO₂ emissions is a major challenge for modern society. While the mitigation of energy-related emissions can be achieved comparatively easy by switching to renewable energy sources, reduction of process-related industrial emissions is considerably more challenging. To reduce industrial CO₂ emissions, two basic routes are available: carbon direct avoidance (CDA) and carbon capture and utilization (CCU). It is shown that in terms of efficiency, CDA is to be favored when applicable. However, for applications where emissions cannot be avoided, CCU can be a viable approach allowing for emission mitigation.     

Biogenic versus abiogenic emissions from agriculture in the Netherlands and options for emission control in tomato cultivation

In this paper, present-day emissions of greenhouse gases and acidifying compounds from agriculture are analysed at the farm level. Quantitative estimates are given for these emissions from three nested systems in the Netherlands: the agricultural sector, greenhouse horticulture, and tomato cultivation under glass. Total emissions are subdivided into emissions from biogenic sources and abiogenic sources. We conclude that, although most of the emissions from the agricultural sector have biogenic sources, those from abiogenic sources should not be neglected. Abiogenic emissions are mainly from greenhouse horticulture. The cost-effectiveness of options to reduce carbon dioxide (CO₂) and nitrogen oxides (NO_x) emissions from on-farm combustion of natural gas in tomato cultivation under glass is analysed. An inventory is given of technical reduction options that are presently available in practice. Based on information about the costs and the reduction potential of each option, cost-efficiency curves are derived for both types of emissions. Relative to a situation where none of the described options were applied (early nineties), CO₂ and NO_x emissions from tomato cultivation can be reduced at most by about 70% and 75%, respectively, by combinations of technical options. This revised version was published online in August 2006 with corrections to the Cover Date.