Capturing carbon dioxide as a polymer from natural gas

Limits to Paris compatibility of CO2 capture and utilization

Porous Metal-Organic Frameworks: Promising Materials for Methane Storage

Methane hydrate exists in huge amounts in certain locations, in sea sediments and the geological structures below them, at low temperature and high pressure. Production methods are in development to produce the methane to a floating platform. There it can be reformed to produce hydrogen and carbon dioxide, in an endothermic process. Some of the methane can be burned to provide heat energy to develop all needed power on the platform and to support the reforming process. After separation, the hydrogen is the valuable and transportable product. All carbon dioxide produced on the platform can be separated from other gases and then sequestered in the sea as carbon dioxide hydrate. In this way, hydrogen is made available without the release of carbon dioxide to the atmosphere, and the hydrogen could be an enabling step toward a world hydrogen economy.

Coal is the backbone of the Indian power sector with more than 60 % of the net installed electricity capacity being coal-based. Among other fossil fuels, natural gas also contributes significantly to the power sector in India. This contribution may increase in the future with exploration of new reserves of unconventional gases, more stringent climate norms and so on. Concurrently, the global climate change problem also becomes more enhanced if larger dependence on fossil fuels remains. In some scenarios, carbon dioxide (CO2) capture and storage (CCS) with natural gas combined cycle (NGCC) may be a feasible technological alternative. Such a scenario is manifested by some critical factors such as low natural gas prices and high carbon tax, among others. Nevertheless, several parameters remain highly uncertain if CCS is to be introduced in NGCC plants. As a result, modern computational techniques such as soft-computing approaches may be used to generate predictive models for cost and performance in such plants. This paper utilizes one such technique, multi-gene genetic programming (MGGP) to generate predictive models for cost of electricity (with coefficient of determination, R2 > 95 %), CO2 emission factor and net plant efficiency (R2 > 98 %). The sensitivity analysis carried out for these parameters show results which are expected in real situations. Subsequently, the calculation of the CO2 avoidance cost and energy penalty for a hypothetical case is demonstrated. The results show that MGGP can be successfully used in such applications.

Natural gas can be used to generate either blue or grey hydrogen depending on whether or not the carbon dioxide byproduct is captured and stored. When captured, the carbon dioxide (CO2) produced from a steam methane reforming (SMR) or partial oxidation (POX) process can be injected into the same natural gas reservoir for enhanced gas recovery (EGR) while simultaneously storing CO2. The objective of this work is the effective integration of these three major processes – blue hydrogen generation, carbon dioxide capture and storage, and enhanced natural gas production. Surface processes include separation of methane from CO2 and other inorganic and organic components in the produced natural gas. Produced CO2 will be injected back into the reservoir, and other components would be managed in ways standard to produced natural gas processing. An SMR or POX process followed by a shift reaction one will generate hydrogen and CO2 followed by separation of the hydrogen and CO2. To avoid a need for post combustion capture, continuous operation can use produced hydrogen to energize the SMR process. Integration of natural gas reservoir production, blue hydrogen generation, and CO2 injection back into the same reservoir leads to a process termed enhanced gas recovery and blue hydrogen (EGRBH). To optimize the reservoir management, analytical and numerical simulation models that address physical mechanisms such as CO2 diffusion, advection, and CO2 solubility in connate water provide guidelines on placement of injection and production wells, on their geometry (vertical or horizontal) and completion interval locations, and on well operating conditions. Displacing methane with CO2 is a miscible process with favorable mobility ratio, and simulations show that the methane recovery factor at CO2 breakthrough depends on both molecular diffusion and dispersivity related to reservoir heterogeneity. Continued production at constant methane rate enables additional blue hydrogen generation while increasing CO2 flow through the reservoir under declining average reservoir pressure. Injection of additional CO2 captured from other stationary point sources can achieve enhanced CO2 storage (ECS) up to a limit pressure less than the original reservoir pressure. The EGRBH process produces blue hydrogen at a price competitive with gasoline or diesel for transportation applications. When used for power generation, blue hydrogen decarbonizes natural gas fired generation at lower cost than can be achieved with post combustion capture from standard natural gas power plants. Blue hydrogen is also less than half the cost of so-called green hydrogen produced via electrolysis using electricity generated with renewable energy. This appears to be an ideal approach for developing and producing new natural gas discoveries.

Cryogenic carbon dioxide removal from natural gas requires accurate thermodynamic phase study of the natural gas mixture and individual components. Thermodynamic data generation of carbon dioxide‐methane mixture having 90 % carbon dioxide for cryogenic carbon dioxide capture from natural gas using Peng Robinson equation of state is discussed in this research work. Golden section search technique along with Eureqa optimizing tool is then used to optimize the pressure‐temperature conditions for the cryogenic carbon dioxide capture in the solid‐vapour two‐phase region. Cost optimization is done for the carbon dioxide capture system at atmospheric pressure and 20 bar. Temperature ranges for optimization were obtained from the predicted thermodynamic data for the mixture. The optimum temperatures obtained in this research work for the cryogenic carbon dioxide capture at atmospheric pressure and the 20 bar are −103.8 °C and −60.90 °C respectively. For atmospheric pressure at −103.8 °C the worth of methane, carbon dioxide, and energy is 114 $/h, 9 $/h, and 53 $/h respectively, while at 20 bar and −60.9 °C the worth of carbon dioxide, methane, and the energy are found to be 129 $/h, 46 $/h, 52 $/h, respectively.

Reducing the efficiency penalty of carbon dioxide capture and compression process in a natural gas combined cycle power plant by process modification and liquefied natural gas cold energy integration

Hydrogen is often viewed as an important energy carrier in a future decarbonized world. Currently, most hydrogen is produced by steam reforming of methane in natural gas (“gray hydrogen”), with high carbon dioxide emissions. Increasingly, many propose using carbon capture and storage to reduce these emissions, producing so‐called “blue hydrogen,” frequently promoted as low emissions. We undertake the first effort in a peer‐reviewed paper to examine the lifecycle greenhouse gas emissions of blue hydrogen accounting for emissions of both carbon dioxide and unburned fugitive methane. Far from being low carbon, greenhouse gas emissions from the production of blue hydrogen are quite high, particularly due to the release of fugitive methane. For our default assumptions (3.5% emission rate of methane from natural gas and a 20‐year global warming potential), total carbon dioxide equivalent emissions for blue hydrogen are only 9%‐12% less than for gray hydrogen. While carbon dioxide emissions are lower, fugitive methane emissions for blue hydrogen are higher than for gray hydrogen because of an increased use of natural gas to power the carbon capture. Perhaps surprisingly, the greenhouse gas footprint of blue hydrogen is more than 20% greater than burning natural gas or coal for heat and some 60% greater than burning diesel oil for heat, again with our default assumptions. In a sensitivity analysis in which the methane emission rate from natural gas is reduced to a low value of 1.54%, greenhouse gas emissions from blue hydrogen are still greater than from simply burning natural gas, and are only 18%‐25% less than for gray hydrogen. Our analysis assumes that captured carbon dioxide can be stored indefinitely, an optimistic and unproven assumption. Even if true though, the use of blue hydrogen appears difficult to justify on climate grounds.

Feasibility of combination of CO2 geological storage with geothermal-type water-soluble gas recovery in Yinggehai Basin, China

Introducing a hybrid oxy-fuel power generation and natural gas/ carbon dioxide liquefaction process with thermodynamic and economic analysis

In today’s world, owing to industrial expansion, urbanization, the rapid growth of the human population, and the high standard of living, the utilization of the most advanced technologies is unavoidable. The enhanced anthropogenic activities worldwide result in a continuous increase in global warming potential, thereby raising a global concern. The constant rise in global warming potential forces the world to mitigate greenhouse gases, particularly carbon dioxide. Carbon dioxide is considered as the primary contributor responsible for global warming and climatic changes. The global anthropogenic carbon dioxide emissions released into the atmosphere can eventually deteriorate the environment and endanger the ecosystem. Combating global warming is one of the main challenges in achieving sustainable development. Carbon capture and storage is a potential solution to mitigate carbon dioxide emissions. There are three main methods for carbon capture and storage: post-combustion, pre-combustion, and oxy-fuel combustion. Among them, post-combustion is used in thermal power plants and industrial sectors, all of which contribute a significant amount of carbon dioxide. Different techniques such as physical and chemical absorption, physical and chemical adsorption, membrane separation, and cryogenic distillation used for carbon capture are thoroughly discussed and presented. Currently, there are various materials including absorbents, adsorbents, and membranes used in carbon dioxide capture. Still, there is a search for new and novel materials and processes for separating and capturing carbon dioxide. This review article provides a comprehensive review of different methods, techniques, materials, and processes used for separating and capturing carbon dioxide from significant stationary point sources.

The major gaseous impurities in the subquality natural gas sources are acidic components, such as hydrogen sulfide and carbon dioxide. Considering that H2S easily dissociates into hydrogen and elemental sulfur, thermodynamic properties and specially phase equilibria of liquid and gaseous systems containing hydrogen, hydrogen sulfide, carbon dioxide, other acidic components, and light hydrocarbons are of much interest to the natural gas and gas condensate production industries. In this paper we report the development of a simple and accurate cubic equation of state for prediction of thermodynamic properties and phase behavior of sour natural gas and liquid mixtures. This cubic equation of state, which is based on statistical mechanical theoretical grounds, is applied to pure fluids as well as mixtures with quite accurate results. All the thermodynamic property relations of sour gaseous and liquid mixtures are derived and reported in this report. Parameters of this equation of state are derived for different components of sour natural gas systems. The resulting equation of state is tested for phase behavior and other thermodynamic properties of simulated and natural sour gas mixtures. It is shown that the present equation of state, even though it is simple, predicts the properties of interest with ease and accuracy.

Stringent environmental regulations and higher costs of effluent treatments in oil and gas process industries have necessitated research into ways to improve the operating procedures in effluent treatment plant. In Gas-to-liquid (GTL) plant, a significant quantity of reaction water is produced and various chemicals are used as intermediate treatment chemicals. The reaction water is contaminated by these chemicals which impair the pH and the related properties of the water. The pH has to be controlled before the water is re-used or released to the environment. A laboratory-scale effluent neutralization unit for pH control was designed and built to demonstrate the feasibility of utilising produced carbon dioxide (CO2) from reforming reactions in both the synthesis and hydrogen production units in GTL plant for insitu effluent treatment. At the end of the reaction, the total volume of carbon dioxide used was recorded. This paper presents experimental neutralisation characteristics for different operating conditions. The prime advantage of this process can be thought to be less expensive than other published carbon capture and storage (CCS) processes. Moreover the carbon dioxide does not require further compression, dehydration and storage facilities before usage. Pipeline transportation is also drastically reduced since the captured carbon dioxide is utilised within the plant. This study demonstrated that, the neutralisation time increased by 3.15 minutes with increase in effluent volume from 40 to 60 litres and by 10.4 minutes as the temperature increased from 20oC to 50oC. The increase in the flow rate of carbon dioxide from 15 litres/min to 35 litres/min decreased the neutralization time from 19.15 minutes to 13.32 minutes. Finally it was estimated that about 64% of the daily carbon dioxide production which would have otherwise been emitted to the atmosphere was used in the treatment process. Introduction The fact that the concentrations of carbon dioxide in the atmosphere are increasing is known to environmentalists, researchers and government agencies. The causes of global change lie in the industrial activities of human society and ultimately in the population growth and increase in resource use by man. Human activities have increased carbon dioxide concentrations from approximately 280 to 355ppm since 1800 (Vitousek, 1994). This increase is likely to have climatic consequences on biota in all earth's terrestrial ecosystems. The need to reduce global climate change due to emission of carbon dioxide (CO2) and other greenhouse gases has led to research in carbon capture and sequestration (CCS). Several relatively small-scale carbon capture and sequestration approaches are currently in development and demonstration stages as highlighted by Hoekman, 2010. Direct injection into the oceans has also been suggested but there are a number of uncertainties over the ecological impact and equilibrium of the gas with the atmosphere. In the medium term, depleted oil and gas reserves, unmineable coal seams, and deep saline formations are the best options for carbon dioxide storage. Deep saline formations appear to offer the potential to store several hundreds of years' worth of carbon dioxide emissions. This must be validated, and site selection criteria must be developed and shared internationally to identify the most appropriate storage sites. Wider international collaboration and consensus are critically needed to ensure the viability, availability and permanence of carbon dioxide storage. However carbon capture and sequestration faces both technical and economic challenges. Therefore, there is the need to explore other methods to deal with carbon dioxide emissions. Transformation to chemical feedstock like methanol is a commercially proven technology, however carbon dioxide captured from flue gas from furnaces will not be economical for this purpose because of its low pressure. Recompression is required before the carbon dioxide could be processed to methanol (Ritter et al, 2007). Another well-known process - the Sabatier reaction, converts carbon dioxide to methane as shown in Eq. (1).

Providing for increasing global energy needs while managing carbon dioxide emissions is the dual energy challenge the modern world faces. In order to meet this challenge, reliable and dispatchable low carbon energy sources are a likely component. For many scenarios, this suggests that cost effective carbon dioxide capture will be a key technology.[1] Carbon capture with carbonate fuel cells (CFCs) may be one such technology option.[2]Carbonate fuel cells concentrate carbon dioxide from the cathode to the anode as part of their normal operation, effectively doing both carbon capture and low carbon power generation in a single process. (see Figure 1) When generating power, typical carbon dioxide concentrations fed to the CFC cathode tend to be higher than carbon dioxide emissions of many industrial processes. This means that if we want to capture that carbon dioxide, we need the fuel cell to operate at lower carbon dioxide concentrations than it typically does. For carbon capture operations, cathode inlet carbon dioxide concentrations could be as low as 4%. Additionally, under typical power generation operations, CFCs only capture a fraction of the carbon dioxide (<50%) fed to the cathode, where for carbon capture rates may be as high as 90%. Together these two constraints (low initial concentration and higher capture) results in very low carbon dioxide concentrations in the cell, particularly at the cathode outlet. This may impact the fundamental chemistry of the process. Carbon dioxide capture at 4% and lower was tested in a fuel cell, specifically designed to minimize mass transport effects external to the active cell components. Carbon capture was demonstrated at a range of carbon dioxide concentrations ranging from standard operation for power generation (>10%) to <1%. Additionally, oxygen concentrations and current densities were varied over likely operational ranges. We demonstrate that under most circumstances, operations under carbon capture conditions proceed via a similar mechanism to those under power generation conditions. However, in harsh or extreme conditions, where carbon dioxide concentrations are low (<0.5%) and/or current densities high, alternative mechanisms appear. We demonstrate how the CFC performs when these alternative mechanisms are present. Additionally, our findings suggest that they appear to utilize water in place of carbon dioxide and allow the cell to operate at conditions beyond theoretical complete carbon capture. [1] IEA World Energy Outlook 2018; Bloomberg New Energy Finance, New Energy Outlook 2018 [2] Ghezel-Ayagh H., Jolly S., Patel D., Hunt J., Steen W., Richardson C., Marina O., (2013) A Novel System for Carbon Dioxide Capture Utilizing Electrochemical Membrane Technology ECS Transaction Vol 51 (1) 265-272 Figure 1

CACHET-II: Carbon capture and hydrogen production with membranes–A new in project in FP7-Energy