Publications
185 results found
Hodgson P, Sceats M, Vincent A, et al., 2018, Direct Separation Calcination Technology for Carbon Capture: Demonstrating a Low Cost Solution for the Lime and Cement Industries in the LEILAC Project
The LEILAC (Low Emissions Intensity Lime And Cement) project will pilot a new breakthrough technology that would enable Europe’s cement and lime industries to capture their unavoidable process carbon dioxide (CO2) emissions for a minimal environmental or economic burden. This novel carbon capture technology does not involve any additional processes or chemicals. It is effectively a new calciner design that aims to separate the unavoidable CO2 released by the processing of cement meal for potentially comparable capital and operating costs to current conventional process equipment. 2018 has seen the construction of a pilot that will test the application of the technology in one of HeidelbergCement’s operational cement plants in Belgium. This pilot will be capable of processing 10 tonnes of raw cement meal per hour as a slipstream to the main plant. Operations will start in early 2019. This paper explains progress to date, and the growing case for Direct Separation in these industries.
Bond T, Tse Q, Chambon C, et al., 2018, The feasibility of char and bio-oil production from pyrolysis of pit latrine sludge, Environmental Science: Water Research and Technology, Vol: 4, Pages: 253-264, ISSN: 2053-1400
Sustainable methods are required in developing regions to treat and recover value from pit latrine sludge. One strategy is to pyrolyse pit latrine contents and generate char and bio-oil, which can then be used as a soil enhancer and fuel, respectively. Despite the many benefits associated with the process, there is very limited relevant literature available. This study examines its feasibility. Initially, the energy balance for the pyrolysis of sewage sludge was calculated using data from 14 literature studies. The average net energy recovery from pyrolysis of dewatered and dried sewage sludge followed by use of bio-oil as fuel was calculated as 4.95 ± 0.61 MJ kg−1. For dewatered sewage sludge, an average net energy input of 2.23 ± 0.31 MJ kg−1 was required. Parallel calculations were undertaken where pit latrine sludge with 0–100% water content was the hypothetical feedstock. On average, net energy recovery from produced bio-oil was achievable when pit latrine sludge with a water content of ≤∼55% was the feedstock. When both bio-oil and char were utilised, net energy recovery was feasible at a water content value of ≤∼65%. Char production is more favourable from stabilised pit latrine sludge with lower moisture and volatile solids content. Barriers to the pyrolysis of pit latrine sludge include its heterogeneous composition and the difficulty of collecting high-viscosity sludge. Overall, this study demonstrates the potential of pyrolysis as a disposal and value addition method for pit latrine sludge. Innovative methods for sludge drying and pit emptying will expedite the process becoming a reality.
Boot-Handford M, Virmond E, Florin N, et al., 2017, Simple pyrolysis experiments for the preliminary assessment of biomass feedstocks and low-cost tar cracking catalysts for downdraft gasification applications, Biomass and Bioenergy, Vol: 108, Pages: 398-414, ISSN: 0961-9534
The pyrolysis behaviour of beech wood, two rice husk variants from Brazil (BRH) and Thailand (TRH) and a solid waste water treatment residue from textile manufacture (TIR) were investigated using a lab-scale, 2-stage fixed-bed reactor at 773 K. Char yields increased and volatile yields decreased with increasing ash content. The TRH released 40% less tar than the BRH which was attributed to the substantially higher potassium content of the Thai species. The combustion reactivity of the TRH char in air at 773 K was similar to the BW char and almost double the reactivity of the BRH and TIR chars. The BW and TRH chars had a greater volume of macropores indicating that char combustion occurs predominantly through the growth and extension of the macroporous pore network. A different trend was observed for the char gasification reactivity with CO2 at 1173 K. The Ca and Mg content of the chars were found to have a more important catalytic role in the char gasification reactions with CO2.The effect of exposing volatile products from beech wood pyrolysis to elevated temperatures (973–1173 K) and sand beds containing calcined limestone or dolomite in a simulated downdraft gasification environment was also investigated. Tar yields decreased after exposure to elevated temperature and calcined limestone or dolomite. Tar cracking favoured the production of CO. CO yields were between 22 and 23 wt% at 1173 K. Calcined dolomite was slightly more effective at cracking tar than calcined limestone, eliminating 98 wt% of the tar at 1173 K.
Zhang Z, Yao JG, Boot-Handford M, et al., 2017, Pressurised chemical-looping combustion of an iron-based oxygen carrier: reduction kinetic measurements and modelling, Fuel Processing Technology, Vol: 171, Pages: 205-214, ISSN: 0378-3820
Chemical-looping combustion (CLC) is a novel combustion techology offering the potential to provide uninterrupted and reliable heat and power production from fossil or bio-derived fuels with integrated, intrinsic CO2 capture and minimal energy penalty. Operation of CLC at elevated pressures provides the potential for integration with a combined cycle, which makes the use of solid fuels significantly more feasible. To date, only a few experimental studies investigating CLC processes and oxygen carrier performance under pressurised conditions have been reported in the open literature. This article reports findings from investigations into the effect of pressure, temperature and CO concentration on the intrinsic reaction kinetics of an Al2O3-supported Fe-based oxygen carrier. Our study employed an innovative pressurised fluidised-bed reactor, designed for operation at temperatures up to 1273 K and pressures up to 20 bara, to simulate ex-situ gasification of solid fuels at elevated pressures. An intrinsic reaction model was developed and pseudo-intrinsic rate constants were derived. Differences in the activation energies and pre-exponential factors of the Al2O3-supported Fe2O3 and a pure Fe2O3 oxygen carriers were observed, indicating a change in reaction mechanism when Al2O3 was present. Subsequently, an adapted random pore model was developed to describe the variation of reaction rate with solid conversion. The good agreement between the adapted random pore model and empirical measurements indicated that the change in mechanism was due to a significantly higher product layer diffusivity for the Al2O3-supported Fe2O3 oxygen carrier compared with the pure Fe2O3 material. When pressurised, the observed reaction order with respect to CO was slightly lower than 1. The model developed using atmospheric pressure measurements was successfully applied to predict reaction kinetics at elevated pressures up to 5 bara providing further validation of the model.
Bond T, Tse Q, Chambon CL, et al., 2017, The feasibility of char and bio-oil production from pyrolysis of pit latrine sludge (Retraction of 10.1039/C7EW00132K, 2017), ENVIRONMENTAL SCIENCE-WATER RESEARCH & TECHNOLOGY, Vol: 3, Pages: 1171-1171, ISSN: 2053-1400
Fennell PS, yao JG, maitland GC, et al., 2017, Pressurized Calcium Looping in the Presence of Steam in a Spout-Fluidized-Bed Reactor with DFT Analysis, Fuel Processing Technology, Vol: 169, Pages: 24-41, ISSN: 0378-3820
Calcium looping is a high-temperature solid-looping process for CO2 capture, exploiting cyclical carbonation of CaO. Previous work investigating the effects of steam on the carbonation reaction has produced conflicting results, with the majority of work conducted using thermogravimetric analyzers (TGA). Here, pressurized carbonation kinetics in the presence of steam in a 3 kWe pressurized spout-fluidized bed reactor, gives a rigorous insight into the effects of steam. Pseudo-intrinsic kinetics were determined using an effectiveness factor model along with activation energies and kinetic expressions. The mechanism in which steam promotes CO2 adsorption on the surface of CaO was investigated using density functional theory (DFT). The molecular-scale changes on the CaO surface owing to the presence of steam compared to the base case of CO2 adsorption on a ‘clean’ (without steam) surface were simulated with the Cambridge Serial Total Energy Package (CASTEP) software. The results suggest that steam promotes CO2 adsorption via the formation of surface OH groups on the CaO surface.
Yao JG, fennell PS, Maitland GC, et al., 2017, Two-Phase Fluidized Bed Model for Pressurized Carbonation Kinetics of Calcium Oxide, Energy and Fuels, Vol: 31, Pages: 11181-11193, ISSN: 0887-0624
A two-phase reactor model has been developed using a system of ordinary differential equations in MATLAB to model the carbonation reaction and therefore determine the kinetics of calcium oxide in a pressurised fluidised bed reactor as part of the calcium looping cycle. The model assumes that the particulate and bubble phases are modelled as a CSTR and a PFR respectively. The random pore model developed by Bhatia and Perlmutter1 is incorporated into the system of equations to predict the rate of carbonation for pressures up to 5 bara total, and CO2 partial pressures up to 150 kPa. The surface rate constant and product layer diffusivity in the random pore model expression were obtained by fitting the model to experimental data for a range of pressures, CO2 concentrations and temperatures by minimization of the resid-ual sum of squares. The surface rate constants were found to be between 3.05 and 12.9 x 10-10 m4 mol-1 s-1 for a temper-ature range of 550 to 750 °C. The product layer diffusivities were found to be between 0.06 and 23.6 x 10-13 m2 s-1 for the same temperature range. The surface rate constant and product layer diffusivity activation energy were calculated using the Arrhenius e
Zhao X, Zhou H, Sikarwar VS, et al., 2017, Biomass-based chemical looping technologies: the good, the bad and the future, ENERGY & ENVIRONMENTAL SCIENCE, Vol: 10, Pages: 1885-1910, ISSN: 1754-5692
Leeson D, Fennell P, Shah N, et al., 2017, A Techno-economic analysis and systematic review of carbon capture and storage (CCS) applied to the iron and steel, cement, oil refining and pulp and paper industries., 13th International Conference on Greenhouse Gas Control Technologies (GHGT), Publisher: Elsevier, Pages: 6297-6302, ISSN: 1876-6102
A systematic review into the literature surrounding industrial carbon capture has been performed, with a particular focus on costs per tonne of CO2 avoided. The authors have reviewed 250 research articles in order to extract data regarding industrial CCS, focusing on four main carbon-emitting industries; the iron and steel industry, the refining industry, the pulp and paper industry and the cement industry. Only 25 costs were returned as part of the search, and across the four industries they suggested that the cost of carbon capture on industries after conversion to 2013 US Dollars is $20-140 per tonne of CO2 avoided. The highest costs were found using amine scrubbing, the most mature technology, with other less mature technologies reporting lower costs, for example, calcium looping applied to the cement industry was reported to have costs of in the range of $20-75 per tonne avoided, with the only lower costs reported being in the pulp and paper industry reported between $16 and $35. However, the paucity of costing data increases the uncertainty surrounding industrial CCS, meaning that more economic data are required before any conclusive decisions can be made.
Leeson D, Fennell P, Mac Dowell N, et al., 2017, Simultaneous design of separation sequences and whole process energy integration, CHEMICAL ENGINEERING RESEARCH & DESIGN, Vol: 125, Pages: 166-180, ISSN: 0263-8762
This paper presents a novel methodology for the optimisation of the preliminary design of heat-integrated multicomponent distillation sequences. This is achieved through use of a reduced process superstructure where the role of splitting each adjacent key component pair is assigned to an individual separation column, greatly reducing the size and complexity of the problem. This methodology uses information about other process streams on site with which heat can be exchanged within the initial design in order to find a plant-wide optimal separation configuration with the aim of reducing the cost of heating provided by utilities including those used for heating and cooling process streams. In order that this model can be formulated as a mixed-integer linear program, this model utilises a discretised temperature grid where stream temperatures are allowed to vary. This methodology was tested on an example of a mixed alkane feed stream, with the sequence changing dependent on the degree of process integration. The method was found to have the potential for significant cost reductions compared to a heuristic design, with the example exhibiting a cost saving of over 50% and a reduction in CO2 associated with process heating of almost 60%, though the magnitude of these savings is highly dependent on the specific example to which it is applied.
Bond T, Tse Q, Chambon CL, et al., 2017, The feasibility of char and bio-oil production from pyrolysis of pit latrine sludge, Environmental Science: Water Research and Technology, Vol: in press
Hills TP, Sceats M, Rennie D, et al., 2017, LEILAC: Low cost CO2 capture for the cement and lime industries, 13th International Conference on Greenhouse Gas Control Technologies (GHGT), Publisher: Elsevier, Pages: 6166-6170, ISSN: 1876-6102
The LEILAC project will apply a revolutionary carbon capture technology to the cement and lime industries. It aims to enable the capture of unavoidable process CO2 from limestone calcination for no energy cost and no extra capital cost (apart from compression). It is being developed by a consortium in a €21M five-year Horizon 2020 project. A 240 t/d pilot will be built atHeidelbergCement’s plant in Lixhe, Belgium, demonstrating that 95% of a plant’s process CO2 emissions could be captured (around 60% of a plant’s total direct CO2 emissions), and on-going R&D activities are reducing the uncertainties and risks involved.
Soltani SM, Fennell PS, Mac Dowell N, 2017, A parametric study of CO2 capture from gas-fired power plants using monoethanolamine (MEA), International Journal of Greenhouse Gas Control, Vol: 63, Pages: 321-328, ISSN: 1750-5836
The value of dispatchable, low carbon thermal power plants as a complement to intermittent renewable energy sources is becoming increasingly recognised. In this study, we evaluate the performance of post-combustion CO2 capture using monoethanolamine (MEA) retrofitted to a 600 MW CCGT, with and without exhaust gas recycle (EGR). Our results suggest that the EGR ratio plays a primary role in the regeneration energy penalty of the process. We contrast a gas-CCS process with its coal counterpart and show that whilst CCGTs have a greater energy penalty per tonne of CO2 captured than coal (i.e., GJtCO2Gas>GJtCO2Coal), owing to the high thermal efficiencies of CCGTs relative to coal-fired power plants, the energy penalty per MWh of low carbon energy generated is lower for gas than it is for coal (i.e., GJMWhGas<GJMWhCoal), making CCGT-CCS an attractive choice for low carbon electricity generation.
Patzschke CF, Zhang J, Fennell PS, et al., 2017, Density and Viscosity of Partially Carbonated Aqueous Solutions Containing a Tertiary Alkanolamine and Piperazine at Temperatures between 298.15 and 353.15 K, Journal of Chemical and Engineering Data, Vol: 62, Pages: 2075-2083, ISSN: 0021-9568
Measurements for the density and viscosity of partially carbonated solutions containing water, piperazine (PZ), and a tertiary amine, which was either dimethylaminoethanol (DMAE) or 2-diethylaminoethanol (DEAE), were conducted with total amine mass fractions of 30% and 40% over a temperature range from 298.15 to 353.15 K. Density and viscosity correlations of these mixtures were developed as functions of amine mass fraction, CO2 loading, and temperature. For both systems investigated, the average absolute relative deviations of the experimental data from these correlation are approximately 0.2% for density and 3% for viscosity. The correlations will be useful for thermodynamic analysis and computer simulations of carbon capture processes utilizing these promising blended amine systems.
Zeng D, Patzschke C, Fennell P, et al., 2017, Nanostructured Iron-based Mixed Metal Oxides for Efficient H2 Production via Thermochemical Water Splitting, 13th International Conference on Materials Chemistry (MC13)
Singh Sikarwar V, Zhao M, Fennell PS, et al., 2017, Progress in biofuel production from gasification, Progress in Energy and Combustion Science, Vol: 61, Pages: 189-248, ISSN: 1873-216X
Biofuels from biomass gasification are reviewed here, and demonstrated to be an attractive option. Recent progress in gasification techniques and key generation pathways for biofuels production, process design and integration and socio-environmental impacts of biofuel generation are discussed, with the goal of investigating gasification-to-biofuels’ credentials as a sustainable and eco-friendly technology. The synthesis of important biofuels such as bio-methanol, bio-ethanol and higher alcohols, bio-dimethyl ether, Fischer Tropsch fuels, bio-methane, bio-hydrogen and algae-based fuels is reviewed, together with recent technologies, catalysts and reactors. Significant thermodynamic studies for each biofuel are also examined. Syngas cleaning is demonstrated to be a critical issue for biofuel production, and innovative pathways such as those employed by Choren Industrietechnik, Germany, and BioMCN, the Netherlands, are shown to allow efficient methanol generation. The conversion of syngas to FT transportation fuels such as gasoline and diesel over Co or Fe catalysts is reviewed and demonstrated to be a promising option for the future of biofuels. Bio-methane has emerged as a lucrative alternative for conventional transportation fuel with all the advantages of natural gas including a dense distribution, trade and supply network. Routes to produce H2 are discussed, though critical issues such as storage, expensive production routes with low efficiencies remain. Algae-based fuels are in the research and development stage, but are shown to have immense potential to become commercially important because of their capability to fix large amounts of CO2, to rapidly grow in many environments and versatile end uses. However, suitable process configurations resulting in optimal plant designs are crucial, so detailed process integration is a powerful tool to optimize current and develop new processes. LCA and ethical issues are also discussed in brief. It is clear that the u
Fennell PS, hallett J, Brandt-Talbot A, et al., 2017, An economically viable ionic liquid for the fractionation of lignocellulosic biomass, RSC Green Chemistry, Vol: 19, Pages: 3078-3102, ISSN: 1757-7047
Cost-effective fractionation (pretreatment) of lignocellulosic biomass is necessary to enable its large-scale use as a source of liquid fuels, bio-based materials and bio-derived chemicals. While a number of ionic liquids (ILs) have proven capable of highly effective pretreatment, their high cost presents a barrier to commercial viability. In this study, we investigate in detail the application of the low-cost (ca. $1 kg−1) ionic liquid triethylammonium hydrogen sulfate for the fractionation of the grass Miscanthus x giganteus into a cellulose rich pulp, a lignin and a distillate. We found that up to 85% of the lignin and up to 100% of the hemicellulose were solubilized into the IL solution. The hemicellulose dissolved mainly in monomeric form, and pentoses were partially converted into furfural. Up to 77% of the glucose contained in the biomass could be released by enzymatic saccharification of the pulp. The IL was successfully recovered and reused four times. A 99% IL recovery was achieved each time. Effective lignin removal and high saccharification yields were maintained during recycling, representing the first demonstration that repeated IL use is feasible due to the self-cleaning properties of the non-distillable solvent. We further demonstrate that furfural and acetic acid can be separated quantitatively from the non-volatile IL by simple distillation, providing an easily recoverable, valuable co-product stream, while IL degradation products were not detected. We further include detailed mass balances for glucose, hemicellulose and lignin, and a preliminary techno-economic estimate for the fractionation process. This is the first demonstration of an efficient and repeated lignocellulose fractionation with a truly low-cost IL, and opens a path to an economically viable IL-based pretreatment process.
Leeson D, Mac Dowell N, Shah N, et al., 2017, A Techno-economic analysis and systematic review of carbon capture and storage (CCS) applied to the iron and steel, cement, oil refining and pulp and paper industries, as well as other high purity sources, International Journal of Greenhouse Gas Control, Vol: 61, Pages: 71-84, ISSN: 1750-5836
In order to meet the IPCC recommendation for an 80% cut in CO2 emissions by 2050, industries will be required to drastically reduce their emissions. To meet these targets, technologies such as carbon capture and storage (CCS) must be part of the economic set of decarbonisation options for industry. A systematic review of the literature has been carried out on four of the largest industrial sectors (the iron and steel industry, the cement industry, the petroleum refining industry and the pulp and paper industry) as well as selected high-purity sources of CO2 from other industries to assess the applicability of different CCS technologies. Costing data have been gathered, and for the cement, iron and steel and refining industries, these data are used in a model to project costs per tonne of CO2 avoided over the time period extending from first deployment until 2050. A sensitivity analysis was carried out on the model to assess which variables had the greatest impact on the overall cost of wide-scale CCS deployment for future better targeting of cost reduction measures. The factors found to have the greatest overall impact were the initial cost of CCS at the start of deployment and the start date at which large scale deployment is started, whilst a slower initial deployment rate after the start date also leads to significantly increased costs.
Brandl P, Soltani SM, Fennell PS, et al., 2017, Evaluation of cooling requirements of post-combustion CO2 capture applied to coal-fired power plants, Chemical Engineering Research and Design, Vol: 122, Pages: 1-10, ISSN: 1744-3598
Whilst CO2 capture and storage (CCS) technology is widely regarded as being an important tool in mitigating anthropogenic climate change, care must be taken that its extensive deployment does not substantially increase the water requirements of electricity generation. In this work, we present an evaluation of the cooling demand of an amine-based post-combustion CO2 capture process integrated with a coal-fired power plant. It is found that the addition of a capture unit translates into an increase in the total cooling duty of ≈47% (subcritical), ≈33% (supercritical) and ≈31% (ultra-supercritical) compared to a power plant without capture. However, as the temperature at which this cooling is required varies appreciably throughout the integrated power capture process, it is found that his increase in cooling duty (MW) does not necessarily lead to an increase in cooling water usage (kg/MW). Via a heat integration approach, we demonstrate how astute cascading of cooling water can enable a reduction of cooling water requirements of a decarbonised power plant relative to an unmitigated facility. This is in contrast to previous suggestions that the addition of CCS would double the water footprint.
Mac Dowell N, Fennell PS, Shah N, et al., 2017, The role of CO2 capture and utilization in mitigating climate change, Nature Climate Change, Vol: 7, Pages: 243-249, ISSN: 1758-678X
To offset the cost associated with CO2 capture and storage (CCS), there is growing interest in finding commercially viable end-use opportunities for the captured CO2. In this Perspective, we discuss the potential contribution of carbon capture and utilization (CCU). Owing to the scale and rate of CO2 production compared to that of utilization allowing long-term sequestration, it is highly improbable the chemical conversion of CO2 will account for more than 1% of the mitigation challenge, and even a scaled-up enhanced oil recovery (EOR)-CCS industry will likely only account for 4–8%. Therefore, whilst CO2-EOR may be an important economic incentive for some early CCS projects, CCU may prove to be a costly distraction, financially and politically, from the real task of mitigation.
Mechleri E, Fennell PS, Mac Dowell N, 2017, Optimisation and evaluation of flexible operation strategies for coal- and gas-CCS power stations with a multi-period design approach, INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL, Vol: 59, Pages: 24-39, ISSN: 1750-5836
Thermal power plants are increasingly required to balance power grids by compensating for the intermittent electricity supply from renewable energy resources. As CO2 capture and storage is integrated with both coal- and gas-fired power plants, it is vital that the emission mitigation technology does not compromise their ability to provide this high-value service. Therefore, developing optimal process operation strategies is vital to maximise both the value provided by and the profitability of these important assets. In this work, we present models of coal- and gas-fired power plants, integrated with a post-combustion CO2 capture process using a 30 wt% monoethanolamine (MEA) solvent. With the aim to decoupling the power and capture plants in order to facilitate profit maximising behaviour, a multi-period dynamic optimisation problem was formulated and solved using these models. Four distinct scenarios were evaluated: load following, solvent storage, exhaust gas by-pass and variable solvent regeneration (VSR). It was found that for both coal- and gas-fired power plants, the VSR strategy is consistently the most profitable option. The performance of the exhaust by-pass scenario is a strong function of the carbon prices and is only selected at very low carbon prices. The viability of the solvent storage strategy was found to be a strong function of the capital cost associated with the solvent storage infrastructure. When the cost of the solvent tanks has been paid off, then the solvent storage scenario is 3.3% and 8% more profitable than the baseline for the pulverised coal and gas-fired power plants, respectively. Sensitivity analyses showed that, for all strategies, the flexibility benefit declined with reduced carbon and fuel prices, while a “peakier” electricity market, characteristic of one with significant quantities of intermittent renewables deployment, more significantly rewarded flexible operation.
Mechleri E, Brown S, Fennell PS, et al., 2017, CO2 capture and storage (CCS) cost reduction via infrastructure right-sizing, CHEMICAL ENGINEERING RESEARCH & DESIGN, Vol: 119, Pages: 130-139, ISSN: 0263-8762
Bhave A, Taylor RHS, Fennell P, et al., 2017, Screening and techno-economic assessment of biomass-based power generation with CCS technologies to meet 2050 CO2 targets, APPLIED ENERGY, Vol: 190, Pages: 481-489, ISSN: 0306-2619
Biomass-based power generation combined with CO2 capture and storage (Biopower CCS) currently represents one of the few practical and economic means of removing large quantities of CO2 from the atmosphere, and the only approach that involves the generation of electricity at the same time. We present the results of the Techno-Economic Study of Biomass to Power with CO2capture (TESBiC) project, that entailed desk-based review and analysis, process engineering, optimisation as well as primary data collection from some of the leading pilot demonstration plants. From the perspective of being able to deploy Biopower CCS by 2050, twenty-eight Biopower CCS technology combinations involving combustion or gasification of biomass (either dedicated or co-fired with coal) together with pre-, oxy- or post-combustion CO2 capture were identified and assessed. In addition to the capital and operating costs, techno-economic characteristics such as electrical efficiencies (LHV% basis), Levelised Cost of Electricity (LCOE), costs of CO2 captured and CO2 avoided were modelled over time assuming technology improvements from today to 2050. Many of the Biopower CCS technologies gave relatively similar techno-economic results when analysed at the same scale, with the plant scale (MWe) observed to be the principal driver of CAPEX (£/MWe) and the cofiring % (i.e. the weighted feedstock cost) a key driver of LCOE. The data collected during the TESBiC project also highlighted the lack of financial incentives for generation of electricity with negative CO2 emissions.
Boot-Handford M, Florin N, Fennell PS, 2016, Investigations into the Effects of Volatile Biomass Tar on the Performance of Fe-Based CLC Oxygen Carrier Materials, Environmental Research Letters, Vol: 11, ISSN: 1748-9326
In this study we present findings from investigations into interactions between biomass tar and two iron based oxygen carrier materials (OCMs) designed for chemical-looping applications: a 100% Fe2O3 (100Fe) OCM and a 60 wt% Fe2O3/40 wt% Al2O3 (60Fe40Al) OCM. A novel 6 kWe two-stage, fixed-bed reactor was designed and constructed to simulate a chemical-looping combustion (CLC) process with ex situ gasification of biomass. Beech wood was pyrolysed in the first stage of the reactor at 773 K to produce a tar-containing fuel gas that was used to reduce the OCM loaded into the 2nd stage at 973 K. The presence of either OCM was found to significantly reduce the amount of biomass tars exiting the reactor by up to 71 wt% compared with analogous experiments in which the biomass tar compounds were exposed to an inert bed of sand. The tar cracking effect of the 60Fe40Al OCM was slightly greater than the 100Fe OCM although the reduction in the tar yield was roughly equivalent to the increase in carbon deposition observed for the 60Fe40Al OCM compared with the 100Fe OCM. In both cases, the tar cracking effect of the OCMs appeared to be independent of the oxidation state in which the OCM was exposed to the volatile biomass pyrolysis products (i.e. Fe2O3 or Fe3O4). Exposing the pyrolysis vapours to the OCMs in their oxidised (Fe2O3) form favoured the production of CO2. The production of CO was favoured when the OCMs were in their reduced (Fe3O4) form. Carbon deposition was removed in the subsequent oxidation phase with no obvious deleterious effects on the reactivity in subsequent CLC cycles with reduction by 3 mol% CO.
Smit B, Graham R, Styring P, et al., 2016, CCS - A technology for the future: general discussion, Faraday Discussions, Vol: 192, Pages: 303-335, ISSN: 1359-6640
Wilson G, Trusler M, Yao J, et al., 2016, End use and disposal of CO2 - storage or utilisation?: general discussion, Faraday Discussions, Vol: 192, Pages: 561-579, ISSN: 1359-6640
Lee JM, Rochelle G, Styring P, et al., 2016, CCS - A technology for now: general discussion., Faraday Discuss, Vol: 192, Pages: 125-151, ISSN: 1359-6640
Zheng L, Hills TP, Fennell P, 2016, Phase evolution, characterisation, and performance of cement prepared in an oxy-fuel atmosphere, Faraday Discussions, Vol: 192, Pages: 113-124, ISSN: 1364-5498
Cement manufacture is one of the major contributors (7-10%) to global anthropogenic CO2 emissions. Carbon capture and storage (CCS) has been identified as a vital technology for decarbonising the sector. Oxy-fuel combustion, involving burning fuel in a mixture of recycled CO2 and pure O2 instead of air, makes CO2 capture much easier. Since it combines a theoretically lower energy penalty with an increase in production, it is attractive as a CCS technology in cement plants. However, it is necessary to demonstrate that changes in the clinkering atmosphere do not reduce the quality of the clinker produced. Clinkers were successfully produced in an oxy-fuel atmosphere using only pure oxides as raw materials as well as a mixture of oxides and clay. Then, CEM I cements were prepared by the addition of 5 wt% gypsum to the clinkers. Quantitative XRD and XRF were used to obtain the phase and elemental compositions of the clinkers. The particle size distribution and compressive strength of the cements at 3, 7, 14, and 28 days' ages were tested, and the effect of the particle size distribution on the compressive strength was investigated. Additionally, the compressive strength of the cements produced in oxy-fuel atmospheres was compared with those of the cement produced in air and commercially available CEMEX CEM I. The results show that good-quality cement can be successfully produced in an oxy-fuel atmosphere and it has similar phase and chemical compositions to CEM I. Additionally, it has a comparable compressive strength to the cement produced in air and to commercially available CEMEX CEM I.
Smit B, Styring P, Wilson G, et al., 2016, Modelling - from molecules to megascale: general discussion, Faraday Discussions, Vol: 192, Pages: 493-509, ISSN: 1359-6640
Clough PT, Boot-Handford ME, Zhao M, et al., 2016, Degradation study of a novel polymorphic sorbent under realistic post-combustion conditions, Fuel, Vol: 186, Pages: 708-713, ISSN: 0016-2361
Calcium looping is a Carbon Capture and Storage (CCS) technology which has the potential to be applied to both power generation plants and some industrial emission sources. The main problem with the use of calcium oxide-based sorbents is their characteristic decay in carrying capacity. This is caused by sintering and is made worse during multiple cycles of CO2 absorption (carbonation) and release (calcination). This paper provides an investigation into the degradation of a novel type of sorbent that is able to regenerate porosity during the temperature cycling of calcium looping. The porosity regeneration of this sorbent is a result of a dicalcium silicate additive undergoing a reliable phase change (α′ ↔ β), which consequently has a useful volume change associated with it. The sorbent here, has been tested for the first time under reasonably realistic conditions within a TGA for multiple cycles. The results demonstrated that the sorbent displays the characteristic decline in carrying capacity when calcined in the presence of CO2, but not when calcined in the absence of CO2 in the fluidising gas. This paper also presents an improved method to conduct TGA carrying capacity measurements of CO2 sorbents which minimises the over carbonation between cycles.
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