CERES :: Browsing by Author "Hanak, Dawid P."

Browsing by Author "Hanak, Dawid P."

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Open Access
Advanced power cycles for coal-fired power plants based on calcium looping combustion: a techno-economic feasibility assessment
(Elsevier, 2020-04-27) Michalski, Sebastian; Hanak, Dawid P.; Manovic, Vasilije
Carbon capture and storage is crucial to decarbonising the power sector, as no other technology can significantly reduce emissions from fossil fuel power generation systems. Yet, the mature CO2 capture technologies result in net efficiency penalties of at least 7% points. Emerging technologies, such as calcium looping combustion, can reduce the net efficiency penalty to 2.4% points. Further reductions can be achieved by replacing the conventional steam cycle with advanced power cycles. This study aimed to assess the techno-economic feasibility of the coal-fired power plant based on calcium looping combustion with different advanced Brayton cycles. These included single power cycles, such as recompression supercritical CO2, simple supercritical CO2 cycle, and xenon cycle, as well as combined power cycles based on helium, nitrogen and recompression supercritical CO2 cycles. The net efficiency and break-even electricity price, which was estimated using the net present value method, were used as the key techno-economic performance indicators. A parametric study was also conducted to assess the impact of the key thermodynamic parameters. This study showed that the case based on a single recompression supercritical CO2 cycle had the best overall techno-economic performance, while the recompression supercritical CO2 combined cycle case had the best techno-economic performance among combined cycle cases. The former was characterised with a net efficiency of 38.9%, which is higher than that of the reference coal-fired power plant without CO2 capture (38.0%). Such performance was achieved at a break-even electricity price of 71.2 €/MWel,neth, corresponding to a cost of CO2 avoided of 16.3 €/tCO2.
Open Access
Application of machine learning in assessment of combustion of liquified natural gas.
(Cranfield University, 2021-05) Alexandropoulos, Christos Dimosthenis; Hanak, Dawid P.; Longhurst, Philip
This work focuses on the implementation on carbon capture on ships which run on liquified natural gas (LNG). LNG ships present a real-world example of LNG as well as a study case for carbon capture on LNG combustion. There is also special interest for that as well, since the International Maritime Organization (IMO), imposed a limit of 0.5% wt. of sulphur content in ship fuel has been imposed from 2020 to reduce pollution emissions from global shipping activities. This initiative will lead to major changes since the previous limit was set at 3.5% wt., which broadened fuel options for ships. In addition, the IMO is developing a long-term plan to completely nullify shipping’s impact on CO₂ emissions by 2030. Consequently, stricter regulations will be imposed to marine activities worldwide. LNG fuel seems to be a promising solution. The sulphur emissions are lower, in compliance with the latest IMO regulations. Additionally, it has a greater energy density in comparison to traditional fuels, like heavy fuel oil (HFO). This paper aims to study the feasibility of a project, which equips an LNG fuelled ship with a carbon capture system. The study includes an examination of an on-board carbon capture system, by simulating the LNG engine as well as the carbon capture system in simulation software. The engine model chosen is the Wärtsilä 6L34DF. The results of these simulations are analysed to examine the correlation between the system’s variables and to evaluate the possibility of heat integration within the system. The economic feasibility of the project is then assessed, using economic data. The results show that heat integration is possible. For example, the heat provided from the flue gas is calculated at 1.323MW when the reboiler duty is 0.3353 MW. However, the project is not sustainable under current market conditions.
Open Access
Black liquor gasification with calcium looping for carbon-negative pulp and paper industry
(Elsevier, 2021-08-26) Santos, Mónica P. S.; Manovic, Vasilije; Hanak, Dawid P.
Although considered one of the major energy-intensive industries (EIIs), the pulp and paper industry has also the potential for energy production from an industrial waste, black liquor. This study proposes black liquor gasification (BLG) coupled with calcium looping (CaL) as a CO2 capture route for the pulp and paper industry. BLG with H2 production (BLG-CaL-H2), BLG with gas turbine combined cycle (BLG-CaL-GT) or with solid oxide fuel cell (BLG-CaL-SOFC) were considered. The dependence of carbon capture and storage (CCS) cost on the natural gas, limestone, electricity imported and H2 sale prices aside the expenditures related with BLG-CaL were evaluated. The CCS route, based on CaL retrofitted to the pulp and paper plant, was found to have a lower cost of CO2 avoided (39.0 €/tCO2) when compared with BLG-CaL (48.8–57.1 €/tCO2). Between the BLG-CaL scenarios, BLG-CaL-H2 presented the lowest cost of CO2 avoided (48.8 €/tCO2) but the highest energy penalty. Based on the thermodynamic performance, it was shown that CaL retrofit and BLG-CaL-SOFC presented the best overall performance, turning the electricity importer reference plant into electricity exporter. The economic sensitivity showed that the capital requirement of BLG-CaL has a strong effect on the cost of CO2 avoided for all alternatives. The H2 production is also strongly affected by the H2 sale price while BLG-CaL-SOFC and BLG-CaL-GT are strongly dependent on natural gas price.
Open Access
Calcium looping combustion for high-efficiency low-emission power generation
(Elsevier, 2017-05-19) Hanak, Dawid P.; Manovic, Vasilije
High-temperature solid looping technologies, such as calcium looping and chemical looping combustion are regarded as emerging CO2 capture technologies with potential to reduce the net efficiency penalties associated with CO2 separation. Importantly, high-temperature operation of these technologies allows utilisation of the high-grade heat for power generation. Building on these emerging technologies, this study intended to establish a new class of high-temperature solid looping combustion technologies for high-efficiency low-emission power generation called calcium looping combustion. Such combustion technology comprises a combustor, as a primary source of heat for indirect heating in a calciner, and a carbonator where CO2 is separated from flue gas leaving the combustor; hence high-grade heat, which can be used for power generation, and a concentrated CO2 stream, which can be either utilised or permanently stored, are generated. The techno-economic performance of calcium looping combustion was comparable to a conventional coal-fired power plant. Depending on whether the concentrated CO2 stream is utilised elsewhere or permanently stored, calcium looping combustion was characterised with a net efficiency gain of 0.7%HHV points or a net efficiency penalty of 2.4%HHV, respectively. Additionally, the cost of CO2 avoided for calcium looping combustion was estimated to be 10.0 €/tCO2 and 33.9 €/tCO2, respectively. Therefore, similarly to chemical looping combustion, calcium looping combustion introduced in this study is a viable high-efficiency low-emission power generation technology that produces a concentrated CO2 stream with no efficiency penalty associated with CO2 separation.
Open Access
Calcium looping with supercritical CO2 cycle for decarbonisation of coal-fired power plant
(Elsevier, 2016-03-11) Hanak, Dawid P.; Manovic, Vasilije
State-of-the-art integration scenarios of calcium looping (CaL), which is an emerging CO capture technology, assume that excess heat is used to raise steam for the steam cycle and result in a net efficiency penalty of 6.0-8.0% points. In this study, a concept using the supercritical CO cycle (s-CO) instead of the conventional steam cycle is proposed. Retrofit of CaL with recompression s-CO cycle to the 580 MW coal-fired power plant was found to result in a net efficiency penalty of 6.9% points. This is 1% point lower than that for the same system linked with the steam cycle having the same turbine inlet conditions (593.3 °C/242.3 bar). A further reduction of the net efficiency penalty to 5.8% points was achieved through considering a pump instead of a first CO compression stage and increasing the turbine inlet temperature to 620 °C and pressure to 300 bar. As the s-CO cycle's specific capital cost is up to 27% lower than that of the equivalent steam cycle, CaL with s-CO cycle is a viable option for the coal-fired power plant decarbonisation. Moreover, it can be expected that this cycle can be successfully implemented in other high-temperature looping cycles, such as chemical looping combustion.
Open Access
Carbon capture for decarbonisation of energy-intensive industries: a comparative review of techno-economic feasibility of solid looping cycles
(Springer, 2022-05-13) Santos, Mónica P. S.; Hanak, Dawid P.
Carbon capture and storage will play a crucial role in industrial decarbonisation. However, the current literature presents a large variability in the techno-economic feasibility of CO2 capture technologies. Consequently, reliable pathways for carbon capture deployment in energy-intensive industries are still missing. This work provides a comprehensive review of the state-of-the-art CO2 capture technologies for decarbonisation of the iron and steel, cement, petroleum refining, and pulp and paper industries. Amine scrubbing was shown to be the least feasible option, resulting in the average avoided CO2 cost of between 62.7C=⋅t−1CO2 for the pulp and paper and 104.6C=⋅t−1CO2 for the iron and steel industry. Its average equivalent energy requirement varied between 2.7 (iron and steel) and 5.1MJth⋅kg−1CO2 (cement). Retrofits of emerging calcium looping were shown to improve the overall viability of CO2 capture for industrial decarbonisation. Calcium looping was shown to result in the average avoided CO2 cost of between 32.7 (iron and steel) and 42.9C=⋅t−1CO2 (cement). Its average equivalent energy requirement varied between 2.0 (iron and steel) and 3.7MJth⋅kg−1CO2 (pulp and paper). Such performance demonstrated the superiority of calcium looping for industrial decarbonisation. Further work should focus on standardising the techno-economic assessment of technologies for industrial decarbonisation.
Open Access
Combined heat and power generation with lime production for direct air capture
(Elsevier, 2018-02-20) Hanak, Dawid P.; Manovic, Vasilije
Carbon capture and storage (CCS) has been shown to be the least cost-intensive option for decarbonisation of the power, heat, and industrial sectors. Importantly, negative-emission technologies, including direct air capture (DAC), may still be required after near-complete decarbonisation of the stationary emission sources. This study evaluates the feasibility of a novel polygeneration process for combined heat and power using a solid-oxide fuel cell, and lime production for DAC (CHP-DAC) that could contribute towards decarbonisation of the power, heat, and industrial sectors. Evaluation of the thermodynamic performance indicated that such process can achieve the total efficiency and effective electric efficiency of 65%LHV and 60%LHV, respectively, while removing CO2 from the air at a rate of 88.6 gCO2/kWchh. With the total expenditure spread over a number of revenue streams, the product prices required for the CHP-DAC process to break even were found to be competitive compared to figures for the existing standalone technologies, even if there was no revenue from CO2 capture from the air. Moreover, the considered process was shown to be economically feasible, even under uncertainty. Hence, it can be considered as the carbon–neutral polygeneration process for sustainable and affordable production of heat, power, and lime that is negative-emission ready.
Open Access
Conceptual energy and water recovery system for self-sustained nano membrane toilet
(Energy Conservation and Management, 2016-08-12) Hanak, Dawid P.; Kolios, Athanasios; Onabanjo, Tosin; Wagland, Stuart Thomas; Patchigolla, Kumar; Fidalgo Fernandez, Beatriz; Manovic, Vasilije; McAdam, Ewan J.; Parker, Alison; Williams, Leon; Tyrrell, Sean; Cartmell, Elise
With about 2.4 billion people worldwide without access to improved sanitation facilities, there is a strong incentive for development of novel sanitation systems to improve the quality of life and reduce mortality. The Nano Membrane Toilet is expected to provide a unique household-scale system that would produce electricity and recover water from human excrement and urine. This study was undertaken to evaluate the performance of the conceptual energy and water recovery system for the Nano Membrane Toilet designed for a household of ten people and to assess its self-sustainability. A process model of the entire system, including the thermochemical conversion island, a Stirling engine and a water recovery system was developed in Aspen Plus®. The energy and water recovery system for the Nano Membrane Toilet was characterised with the specific net power output of 23.1 Wh/kgsettledsolids and water recovery rate of 13.4 dm3/day in the nominal operating mode. Additionally, if no supernatant was processed, the specific net power output was increased to 69.2 Wh/kgsettledsolids. Such household-scale system would deliver the net power output (1.9–5.8 W). This was found to be enough to charge mobile phones or power clock radios, or provide light for the household using low-voltage LED bulbs.
Open Access
Design and planning of energy supply chain networks.
(Cranfield University, 2019-10) Murele, Oluwatosin Christiana; Hanak, Dawid P.; Hart, Phil
During a period of transformation towards decarbonised energy networks, maintenance of a reliable and secure energy supply whilst increasing efficiency and reducing cost will be key aims for all energy supply chain (ESC) networks. With the knowledge that about 80% of global energy is obtained from fossil fuels, appropriate design and planning of its supply chain networks is inevitable. Notwithstanding, renewable energy sources, such as biomass, solar, wind and geothermal, will also play important roles in the future ESCs as climate change mitigation becomes an increasingly important concern. To achieve this aim, energy systems optimization models were derived; (i) for the simultaneous planning of energy production and maintenance in combined heat and power (CHP) plants for overall cost reduction, with results obtained benchmarked against data from industry; (ii) for biomass integration into ESC networks for emissions reduction and benchmarking it against data from literature and the governing equations solved for optimality using the General Algebraic Modelling System (GAMS) software. Further, energy survey questionnaires were developed using the Qualtrics online survey tool and same disseminated to individuals in some counties of the United Kingdom (UK) with the aim of proposing strategies for improved renewable energy (RE) embracement in the UK energy mix. The case study of the coal-fired CHP plant predicted a 21% reduction in annual total cost in comparison to the implemented industrial solution that follows a predefined maintenance policy, thereby, enhancing the resource and energy efficiency of the plant. Additionally, the optimization model for integrating biomass into energy supply chain networks indicated that a reduction in the emissions level of up to 4.32% is achievable on integration of 5-8% of biomass in the ESC with a 4.57% increase in the total cost of the ESC network predicted at biomass fraction of 7.9% in the mixed fuel, indicating that the cost increment in a biomass and coal co-fired plant can be offset with the introduction of effective carbon pricing legislation.
Open Access
Direct air capture: process technology, techno-economic and socio-political challenges
(Royal Society of Chemistry, 2022-02-28) Erans, María; Sanz-Perez, Eloy S.; Hanak, Dawid P.; Clulow, Zeynep; Reiner, David M.; Mutch, Greg A.
Climate change mitigation scenarios that meet the Paris Agreement's objective of limiting global warming usually assume an important role for carbon dioxide removal and negative emissions technologies. Direct air capture (DAC) is a carbon dioxide removal technology which separates CO2 directly from the air using an engineered system. DAC can therefore be used alongside other negative emissions technologies, in principle, to mitigate CO2 emissions from a wide variety of sources, including those that are mobile and dispersed. The ultimate fate of the CO2, whether it is stored, reused, or utilised, along with choices related to the energy and materials inputs for a DAC process, dictates whether or not the overall process results in negative emissions. In recent years, DAC has undergone significant technical development, with commercial entities now operating in the market and prospects for significant upscale. Here we review the state-of-the-art to provide clear research challenges across the process technology, techno-economic and socio-political domains.
Open Access
Economic feasibility of calcium looping under uncertainty
(Elsevier, 2017-09-21) Hanak, Dawid P.; Manovic, Vasilije
An emerging calcium looping process has been shown to be a promising alternative to solvent scrubbing, which is regarded as the most mature CO2 capture technology. Its retrofits to coal-fired power plants have the potential to reduce both energy and economic penalties associated with the mature CO2 capture technologies. However, these conclusions have been made based on the deterministic outputs of the economic models that have not considered uncertainties in the model inputs. Therefore, this study incorporates a stochastic approach into the economic analysis of the retrofit of such emerging CO2 capture technology to the coal-fired power plant. The stochastic analysis revealed that levelised cost of electricity (LCOE) and specific total capital requirement were highly affected by the uncertainty in the input variables to the process and economic models. The most probable values for these key economic performance indicators were shown to fall between 75 and 115 €/MWelh, and 2100 and 2300 €/kWel,gross, respectively. Interestingly, the most probable LCOE values for the coal-fired power plant will fall between 50 and 150 €/MWelh. This indicated that the calcium looping retrofit scenario can become economically favoured, mainly due to the high economic penalties incurred by unabated coal-fired power plant associated with carbon tax. Importantly, the outputs of the stochastic economic assessment aligned well with the deterministic results reported in the literature. As the latter were generated using different sets of assumptions regarding the process and economic models, the stochastic approach to the economic assessment can minimise the impact of the model assumptions on estimates of the key economic parameters. Moreover, by indicating the probability of particular outputs, as well as ranking the model input variables according to their influence on the key economic performance, such analysis would allow making more insightful decisions regarding further funding and development of the calcium looping process. Finally, use of the stochastic approach in the economic feasibility assessment enables a more profound and reliable comparison of the different calcium looping retrofit configurations, as well as benchmarking different CO2 capture technologies.
Open Access
Effect of seawater, aluminate cement and alumina-rich spinel on pelletised CaO-based sorbents for calcium looping
(ACS, 2019-06-26) Morona, Lorena; Erans, María; Hanak, Dawid P.
Calcium looping (CaL) is considered as an emerging technology to reduce CO2 emissions in power generation systems and carbon-intensive industries. The main disadvantage of this technology is reactivity decay over carbonation/calcination cycles due to sintering. The main objective of this study was to evaluate the performance of novel sorbents for CaL. Three types of pelletized CaO-based sorbents for CO2 capture were developed by adding aluminate cement, aluminate cement with seawater, or alumina-rich spinel to calcined limestone. Different concentrations of seawater in deionized water solutions were tested: 1, 10, 25, and 50 vol %. All samples were tested in a thermogravimetric analyzer (TGA) under two different calcination conditions: mild (N2 atmosphere and 850 °C during calcination) and realistic (CO2 atmosphere and 950 °C during calcination). The samples were characterized using SEM and EDX. Aluminate cement CaO-based sorbents exhibited better performance in the TGA tests (25% conversion after 20 cycles achieved by limestone and 35% with aluminate cement CaO-based pellets, under mild conditions, and 11% conversion after 20 cycles with limestone compared to 15% utilizing aluminate cement CaO-based pellets, under realistic conditions). However, doping had a negative effect on the reactivity of the sorbent. Moreover, alumina rich spinel CaO-based sorbents showed the worst performance.
Open Access
Effect of uncertainty in sorbent characteristic on techno-economic feasibility of carbonate looping for decarbonisation of coal-fired power plant
(Wiley, 2022-07-19) Hanak, Dawid P.
Carbon capture, utilisation and storage (CCUS) technologies are forecasted to significantly contribute to the decarbonisation of the power sector. Chemical solvent scrubbing is now considered the most mature CCUS technology. Yet, its integration with fossil fuel power plants is forecasted to reduce the net efficiency of the entire process by at least 7% points, resulting in the avoided CO2 cost of 35 to 75 €/tCO2. Carbonate looping (CaL) has been demonstrated to be an emerging technology for decarbonisation of the power sector with lower efficiency (>5% points) and economic penalties (10-30 €/tCO2). The key challenge that may influence the viability of CaL is the decay in the sorbent CO2 uptake. Such a deterioration in sorbent performance is usually accounted for in the techno-economic assessments via semi-empirical correlations. Yet, such correlations include fitting parameters based on experimental data that is, in turn, associated with ±20% measurement error. This study employed a stochastic approach to quantify the impact of such uncertainty in the sorbent characteristics on the techno-economic performance of a 580 MWel coal-fired power plant with CaL retrofit. The stochastic assessment showed that the most likely figures for the efficiency penalty would fall between 7.7 and 8.7% points, with a median of 8.08% points. Such a figure was higher than the one determined using the deterministic approach (7.85% points). Moreover, the estimated CO2 avoided cost was between 29.74 and 46.50 €/tCO2, with a median of 35.94 €/tCO2. Such a figure was higher than that obtained in the deterministic assessment (32.40 €/tCO2). It implied that the economic assessment using the deterministic approach could underestimate the costs associated with the CaL retrofits. This study, therefore, revealed that the uncertainty in the sorbent characteristics would influence the techno-economic viability of the CaL retrofits.
Open Access
Efficient-and-Stable CH4 Reforming with Integrated CO2 Capture and Utilization using Li4SiO4 Sorbent
(Elsevier, 2021-08-16) Lv, Zongze; Qin, Changlei; Chen, Shuzhen; Hanak, Dawid P.; Wu, Chunfei
CO2 capture and utilization has been considered as an up-and-coming short- to mid-term approach to mitigate the excessive CO2 emission. Comparing to the conventional separate capture, transportation and conversion arrangement, the integrated CO2 capture and utilization (ICCU) could largely simplify the complex process and reduce the energy consumption. However, the poor stability of high-temperature CO2 sorption/desorption severely limit the potential of ICCU. Therefore, it is indispensable to develop a new sorbent/catalyst system ensuring the high-efficiency and long-term operation of the ICCU. In this paper, we propose and demonstrate the feasibility and performance of using K2CO3-doped Li4SiO4 as an efficient CO2 sorbent for ICCU operating at a relatively low temperature by dry reforming of methane. Results show that the ratio of H2/CO produced is stabilized at 1±0.05 in the pre-breakthrough stage, and the duration extends to be 1.6 times of the original value in the cyclic operations, displaying an excellent performance in reaction matching and process stability.
Open Access
Environmental life-cycle assessment of waste-coal pellets production
(Oxford University Press, 2021-12-20) Hanak, Dawid P.
Industrial decarbonization is crucial to keeping the global mean temperature <1.5°C above pre-industrial levels. Although unabated coal use needs to be phased out, coal is still expected to remain an important source of energy in power and energy-intensive industries until the 2030s. Decades of coal exploration, mining and processing have resulted in ~30 billion tonnes of waste-coal tailings being stored in coal impoundments, posing environmental risks. This study presents an environmental life-cycle assessment of a coal-processing technology to produce coal pellets from the waste coal stored in impoundments. It has been shown that the waste-coal pellets would result in the cradle-to-gate global warming of 1.68–3.50 kgCO2,eq/GJch, depending on the source of electricity used to drive the process. In contrast, the corresponding figure for the supply of conventional coal in the US was estimated to be 12.76 kgCO2,eq/GJch. Such a reduction in the global-warming impact confirms that waste-coal pellets can be a viable source of energy that will reduce the environmental impact of the power and energy-intensive industries in the short term. A considered case study showed that complete substitution of conventional coal with the waste-coal pellets in a steelmaking plant would reduce the greenhouse-gas emissions from 2649.80 to 2439.50 kgCO2,eq/tsteel. This, in turn, would reduce the life-cycle greenhouse-gas emissions of wind-turbine manufacturing by ≤8.6%. Overall, this study reveals that the use of waste-coal pellets can bring a meaningful reduction in industrial greenhouse-gas emissions, even before these processes are fully decarbonized.
Open Access
Evaluation of efficiency improvements and performance of coal-fired power plants with post-combustion CO2 capture
(Cranfield University, 2016-03) Hanak, Dawid P.; Manovic, Vasilije; Biliyok, Chechet
The power sector needs to be decarbonised by 2050 to meet the global target for greenhouse gas emission reduction and prevent climate change. With fossil fuels expected to play a vital role in the future energy portfolio and high efficiency penalties related to mature CO2 capture technologies, this research aimed at evaluating the efficiency improvements and alternate operating modes of the coal-fired power plants (CFPP) retrofitted with post-combustion CO2 capture. To meet this aim, process models of the CFPPs, chilled ammonia process (CAP) and calcium looping (CaL) were developed in Aspen Plus® and benchmarked against data available in the literature. Also, the process model of chemical solvent scrubbing using monoethanolamine (MEA) was adapted from previous studies. Base-load analysis of the 580 MWel CFPP retrofits revealed that if novel CAP retrofit configurations were employed, in which a new auxiliary steam turbine was coupled with the boiler feedwater pump for extracted steam pressure control, the net efficiency penalty was 8.7–8.8% points. This was close to the 9.5% points in the MEA retrofit scenario. Conversely, CaL retrofit resulted in a net efficiency penalty of 6.7–7.9% points, depending on the fuel used in the calciner. Importantly, when the optimised supercritical CO2 cycle was used instead of the steam cycle for heat recovery, this figure was reduced to 5.8% points. Considering part-load operation of the 660 MWel CFPP and uncertainty in the process model inputs, the most probable net efficiency penalties of the CaL and MEA retrofits were 9.5% and 11.5% points, respectively. Importantly, in the CaL retrofit scenarios, the net power output was found to be around 40% higher than that of the CFPP without CO2 capture and double than that for the MEA retrofit scenario. Such performance of the CaL retrofit scenario led to higher profit than that of the 660 MWel CFPP without CO2 capture, especially if its inherent energy storage capability was utilised. Hence, this study revealed that CaL has the potential to significantly reduce the efficiency and economic penalties associated with mature CO2 capture technologies.
Open Access
Evaluation of improvements on techno-economic performance of a supercritical oxy-fuel combustion power plant.
(Cranfield University, 2021-01) Wei, Xiaoyu; Hanak, Dawid P.; Manovic, Vasilije
To meet the global target for lowering greenhouse gas emissions and preventing climate change, the power sector has to be decarbonised by 2050. Since coal is projected to play a critical role in the future energy portfolio, carbon capture and storage (CCS) technology has taken on the role of decarbonisation. To find the ways potentially improve defects of the state-of-art oxy-fuel combustion power plant regarding worse techno-economic performance, the oxy-fuel combustion power plant coupling with recuperated supercritical carbon dioxide (sCO₂) cycle has the potential to surpass the state- of-art oxy-fuel combustion power plant. Its net electricity efficiency and levelised cost of electricity (LCOE) is 29.73% and 97.7 €/MWelh, respectively, at operating conditions of 593°C and 240 bar. Further study of chemical looping combustion (CLC) power plant with recompression sCO₂ power cycle achieved 35.49% of net electricity efficiency and 96.8 €/MWelh of LCOE for the manganese ore as the natural oxygen carrier. Conversely, an LCOE of 109.2 €/MWelh was obtained owing to selecting the manufactured oxygen carrier of nickel oxide. Particularly worth mentioning is the excellent decarbonisation ability by fuelling the biomass in the two processes with -1255 gCO₂/kWelh and - 1066 gCO₂/kWelh (Mn₃O₄ case) of specific carbon dioxide (CO₂) emission, respectively. However, it showed significantly higher LCOE with around 2.3%HHV and 3.8%HHV (Mn₃O₄ case) of net efficiency penalty, respectively, compared with the coal-fuelled cases. In the emission trading system with the uncertainty of carbon tax, the two processes fuelled by biomass have the potential to achieve lower costs than the coal-fuelled cases. Finally, the probability assessment is conducted in the proposed cases, showing a higher cumulative probability of LCOE in the coal-fuelled CLC case than in the oxy- coal case. Hence, this study revealed that technologies of CLC and the sCO₂ power cycle have the potential to improve the techno-economic performance of the state-of-art oxy-fuel combustion technology.
Open Access
An experimental investigation of the combustion performance of human faeces
(Elsevier, 2016-07-27) Onabanjo, Tosin; Kolios, Athanasios; Patchigolla, Kumar; Wagland, Stuart Thomas; Fidalgo Fernandez, Beatriz; Jurado Pontes, Nelia; Hanak, Dawid P.; Manovic, Vasilije; Parker, Alison; McAdam, Ewan J.; Williams, Leon; Tyrrel, Sean F.; Cartmell, Elise
Poor sanitation is one of the major hindrances to the global sustainable development goals. The Reinvent the Toilet Challenge of the Bill and Melinda Gates Foundation is set to develop affordable, next-generation sanitary systems that can ensure safe treatment and wide accessibility without compromise on sustainable use of natural resources and the environment. Energy recovery from human excreta is likely to be a cornerstone of future sustainable sanitary systems. Faeces combustion was investigated using a bench-scale downdraft combustor test rig, alongside with wood biomass and simulant faeces. Parameters such as air flow rate, fuel pellet size, bed height, and fuel ignition mode were varied to establish the combustion operating range of the test rig and the optimum conditions for converting the faecal biomass to energy. The experimental results show that the dry human faeces had a higher energy content (∼25 MJ/kg) than wood biomass. At equivalence ratio between 0.86 and 1.12, the combustion temperature and fuel burn rate ranged from 431 to 558 °C and 1.53 to 2.30 g/min respectively. Preliminary results for the simulant faeces show that a minimum combustion bed temperature of 600 ± 10 °C can handle faeces up to 60 wt.% moisture at optimum air-to-fuel ratio. Further investigation is required to establish the appropriate trade-off limits for drying and energy recovery, considering different stool types, moisture content and drying characteristics. This is important for the design and further development of a self-sustained energy conversion and recovery systems for the NMT and similar sanitary solutions.
Open Access
Feasibility of CaO/CuO/NiO sorption-enhanced steam methane reforming integrated with solid-oxide fuel cell for near-zero-CO2 emissions cogeneration system
(Elsevier, 2018-08-28) Diglio, Giuseppe; Bareschino, Piero; Mancusi, Erasmo; Pepe, Francesco; Montagnaro, Fabio; Hanak, Dawid P.; Manovic, Vasilije
In this article, a process for sorption-enhanced steam methane reforming in an adiabatic fixed-bed reactor coupled with a solid oxide fuel cell (SOFC) is evaluated using a 1D numerical reactor model combined with a simplified fuel cell simulation. A novel material comprising CaO/CuO/Al2O3(NiO) pellets is considered. Three operating stages are considered in the proposed system, namely (i) CaO carbonation/reforming, (ii) Cu and Ni oxidation, and (iii) CaCO3 calcination/CuO and NiO reduction. The operating conditions that enable cyclic operation of these stages and the strategy needed to switch between each stage are evaluated. Under the adopted control strategy, methane conversion was about 95%, whilst H2 yield and purity were around 3.2 molH2 molCH4−1 and 90%, respectively. Moreover, a concentrated CO2 stream ready for storage was obtained. By using a portion of the produced H2 to make the process self-sufficient from an energy standpoint, an equivalent H2 yield and a reforming efficiency of about 2.8 molH2 molCH4−1 and 84% were achieved, respectively. With respect to SOFC integration, net power and thermal energy generation of around 11 kW and 6 kW, respectively, can be achieved. With respect to the chemical energy of the inlet methane, the net electrical and thermal efficiencies of the considered process are 56% and 30%, respectively, i.e., the overall efficiency of the entire system is 86%. The proposed cogeneration system showed better thermodynamic, environmental and economic performances than those of conventional systems, with an investment pay-back period of 2.2 years in the worst-case scenario. The levelised cost of electricity, of heat and total power were about 0.096 € kW h−1, 0.19 € kW h−1, and 0.065 € kW h−1, respectively, while the CO2 emissions were avoided at no cost.
Open Access
From post-combustion carbon capture to sorption-enhanced hydrogen production: A state-of-the-art review of carbonate looping process feasibility
(Elsevier, 2018-10-04) Hanak, Dawid P.; Michalski, Sebastian; Manovic, Vasilije
Carbon capture and storage is expected to play a pivotal role in achieving the emission reduction targets established by the Paris Agreement. However, the most mature technologies have been shown to reduce the net efficiency of fossil fuel-fired power plants by at least 7% points, increasing the electricity cost. Carbonate looping is a technology that may reduce these efficiency and economic penalties. Its maturity has increased significantly over the past twenty years, mostly due to development of novel process configurations and sorbents for improved process performance. This review provides a comprehensive overview of the calcium looping concepts and statistically evaluates their techno-economic feasibility. It has been shown that the most commonly reported figures for the efficiency penalty associated with calcium looping retrofits were between 6 and 8% points. Furthermore, the calcium-looping-based coal-fired power plants and sorption-enhanced hydrogen production systems integrated with combined cycles and/or fuel cells have been shown to achieve net efficiencies as high as 40% and 50–60%, respectively. Importantly, the performance of both retrofit and greenfield scenarios can be further improved by increasing the degree of heat integration, as well as using advanced power cycles and enhanced sorbents. The assessment of the economic feasibility of calcium looping concepts has indicated that the cost of carbon dioxide avoided will be between 10 and 30 € per tonne of carbon dioxide and 10–50 € per tonne of carbon dioxide in the retrofit and greenfield scenarios, respectively. However, limited economic data have been presented in the current literature for the thermodynamic performance of calcium looping concepts.