Integrated Gasification Combined Cycle (IGCC) power plants have been considered as one of the best options for energy production in an environmental friendly manner. IGCC power plants are demonstrating better results, both in terms of plant performance and economics, when compared to a Pulverised Coal (PC) power plant with CO2 capture. The additional components required for an IGCC power plant when it is desired to operate in CO2 capture mode, give research potential with respect to an improved IGCC power plant performance. The IGCC power plant design framework studied and developed was based in DOE/NETL report and is presented. The conventional and CO2 capture IGCC power plants have been benchmarked in rigorous process flow diagrams developed using the commercial software Honeywell UniSim Design R400. As an essential part of the Innovative Gas Separations for Carbon Capture project (IGSCC EPSRC – EP/G062129/1) predictive simulation tools were produced to investigate the IGCC performance. The case studies considered include different gasification options for non-capture and carbon capture IGCCs, with a two stage Selexol process for the CO2 capture cases. Particular effort has been made to produce an accurate simulation component to describe the behaviour of the syngas in the Selexol solvent. The two stage Selexol configuration was investigated in detail and novel schemes are presented. No similar approaches have been reported in the literature, in terms of the proposed configuration and the capture efficiency. Moreover, innovative CO2 capture schemes incorporating combined units of physical absorption and membranes have been examined with respect to the power plant’s performance. In this thesis, contrary to other studies, all simulations cases have been conducted in unified flow diagrams. The results presented include overall investigations and can be a helpful tool for engineers and stakeholders in the decision making process.

Coal has been used as a fuel for electricity generation for centuries. Inexpensive electricity from coal has been a key component in building large industrial economies such as USA and China. But in recent decades the negative aspects of coal, mainly carbon dioxide emissions, has changed the view on the fuel. Carbon capture and storage (CCS) is a solution to be able to continue using coal as an energy source, while limiting carbon emissions. One of the drawbacks of CCS is the energy need associated with the capture process, the energy penalty. This study aims to gather and analyze the energy penalties for the most developed types of carbon capture technologies. It also aims to model how the implementation of CCS would affect the future coal consumption. The results show that the range of energy penalties for a given type of technology is wide. Despite obtaining the energy penalty with the same simulation software, the energy penalty for post- combustion with MEA can range between 10.7% and 39.1%. Comparing mean energy penalties show that pre-combustion capture is the most efficient capture method (18.4% ± 4.4%) followed by oxy- fuel (21.6% ± 5.5%) and post-combustion (24.7% ± 7.9%). Further on, CCS implementation scenarios were compared and used as a starting point for coal consumption calculations. Three pathways were constructed in order to investigate how different distributions of technologies would affect the amount of needed coal. The pathways describe a implementation with only the most efficient technology, the least efficient and a middle option. The results suggest that a large scale implementation of CCS on coal power plant will have a significant impact on the global coal consumption. Under certain assumptions it takes up to 35 % more coal to deliver the same amount electricity with CCS in comparison without CCS. It is also found that certain implementation scenarios will struggle to produce the amount of coal that is needed to power the plants. A sensitivity analysis was performed to examine the impact of assumptions made on for instance plant efficiencies. The analysis shows that optimistic assumptions on development in plant efficiency and deploying only the best technology, uses less coal than a development without CCS and with current plant efficiencies.

Fossil fuels constitute a significant fraction of the world’s energy demand. The burning of fossil fuels emits huge amounts of carbon dioxide into the atmosphere. Therefore, the limited availability of fossil fuel resources and the environmental impact of their use require a change to alternative energy sources or carriers (such as hydrogen) in the foreseeable future. The development of methods to mitigate carbon dioxide emission into the atmosphere is equally important. Hence, extensive research has been carried out on the development of cost-effective technologies for carbon dioxide capture and techniques to establish hydrogen economy. Hydrogen is a clean energy fuel with a very high specific energy content of about 120MJ/kg and an energy density of 10Wh/kg. However, its potential is limited by the lack of environment-friendly production methods and a suitable storage medium. Conventional hydrogen production methods such as Steam-methane-reformation and Coal-gasification were modified by the inclusion of NaOH. The modified methods are thermodynamically more favorable and can be regarded as near-zero emission production routes. Further, suitable catalysts were employed to accelerate the proposed NaOH-assisted reactions and a relation between reaction yield and catalyst size has been established. A 1:1:1 molar mixture of LiAlH4, NaNH2 and MgH2 were investigated as a potential hydrogen storage medium. The hydrogen desorption mechanism was explored using in-situ XRD and Raman Spectroscopy. Mesoporous metal oxides were assessed for CO2 capture at both power and non-power sectors. A 96.96% of mesoporous MgO (325 mesh size, surface area = 95.08 ± 1.5 m2/g) was converted to MgCO3 at 350°C and 10 bars CO2. But the absorption capacity of 1h ball milled zinc oxide was low, 0.198 gCO2 /gZnO at 75°C and 10 bars CO2. Interestingly, 57% mass conversion of Fe and Fe3O4 mixture to FeCO3 was observed at 200°C and 10 bars CO2. MgO, ZnO and Fe3O4 could be completely regenerated at 550°C, 250°C and 350°C respectively. Furthermore, the possible retrofit of MgO and a mixture of Fe and Fe3O4 to a 300 MWe coal-fired power plant and iron making industry were also evaluated.

Att koldioxidutsläppen neutraliseras är avgörande för att begränsa klimatförändringarna. Bioenergi i kombination med separation och lagring av koldioxid (BECCS) är en Teknik som kan generera negativa utsläpp. Det största hindret för dess storskaliga genomförande är de höga energikraven för processen. Detta projekt syftar till att kvantifiera energistraffen för lean solvent flash och modifikationer för multitrycksstrippning för att förbättra prestandan av koldioxidavskiljning (CC) i en kraftvärmeverksanläggning för förbränning av biomassa.  En jämviktsmodell utvecklades och validerades för att simulera en fullskalig CC genom kemisk absorption i Aspen Plus med kaliumkarbonat som lösningsmedel. Båda layoutändringarna resulterar i energipåföljder på 18-21 % för en kraftvärmeverk, medan energistraffet för baslinjeprocessen är 5 %. För ett kraftverk går straffen från 32 till 62 %. Detta visar hur en förbättring av processen kan minska kostnaderna för CCS, särskilt om värme anses vara en värdefull produkt. CCS i kraftvärmeverk har en mycket lägre energipåverkan än i kraftverk där värme inte återvinns. / Bio-energy with carbon capture and storage (BECCS) is a technology that can generate negative emissions. Hence it is recognized as a solution for becoming carbon neutral, which is essential for climate change mitigation. The main obstacle for its large scale implementation is the high energy requirements of the process. This thesis aims at quantifying the energy penalties for lean solvent flash and multi-pressure stripper layout modifications to improve the performance of carbon capture (CC) by means of absorption with a liquid solvent in a biomass-fired CHP plant. The work focuses on K2CO3 based solvents operated in a mixed temperature swing/pressure swing cycle witch is deemed advantageous for heat recovery.  An equilibrium model was developed and validated to simulate a full-scale CC by chemical absorption in Aspen Plus using potassium carbonate as solvent. Both layout modifications result in energy penalties of 18-21 % for a CHP plant, while the energy penalty for the baseline process is 28 %. For a power plant, the penalties go from 32 % to 62 % for the lean solvent flash and the multi-pressure stripper respectively. This shows how improving the process can reduce the costs of CCS, especially if heat is considered a valuable product. CCS in CHP plants has a much lower energy impact than in power plants where heat is not recovered.