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 use of food crops, as opposed to food wastes represents an area fraught with challenges, which must be resolved on a case by case basis.
Biomass gasification is a widely used thermochemical process for obtaining products with more value and potential applications than the raw material itself. Cutting-edge, innovative and economical ...gasification techniques with high efficiencies are a prerequisite for the development of this technology. This paper delivers an assessment on the fundamentals such as feedstock types, the impact of different operating parameters, tar formation and cracking, and modelling approaches for biomass gasification. Furthermore, the authors comparatively discuss various conventional mechanisms for gasification as well as recent advances in biomass gasification. Unique gasifiers along with multi-generation strategies are discussed as a means to promote this technology into alternative applications, which require higher flexibility and greater efficiency. A strategy to improve the feasibility and sustainability of biomass gasification is
via
technological advancement and the minimization of socio-environmental effects. This paper sheds light on diverse areas of biomass gasification as a potentially sustainable and environmentally friendly technology.
The article reviews diverse areas of conventional and advanced biomass gasification discussing their feasibility and sustainability
vis-à-vis
technological and socio-environmental impacts.
Biomass is a promising renewable energy resource despite its low energy density, high moisture content and complex ash components. The use of biomass in energy production is considered to be ...approximately carbon neutral, and if it is combined with carbon capture technology, the overall energy conversion may even be negative in terms of net CO
2
emission, which is known as BECCS (bioenergy with carbon capture and storage). The initial development of BECCS technologies often proposes the installation of a CO
2
capture unit downstream of the conventional thermochemical conversion processes, which comprise combustion, pyrolysis or gasification. Although these approaches would benefit from the adaptation of already well developed energy conversion processes and CO
2
capture technologies, they are limited in terms of materials and energy integration as well as systems engineering, which could lead to truly disruptive technologies for BECCS. Recently, a new generation of transformative energy conversion technologies including chemical looping have been developed. In particular, chemical looping employs solid looping materials and it uniquely allows inherent capture of CO
2
during the conversion of fuels. In this review, the benefits, challenges, and prospects of biomass-based chemical looping technologies in various configurations have been discussed in-depth to provide important insight into the development of innovative BECCS technologies based on chemical looping.
This review article focuses on the challenges and opportunities of biomass-based chemical looping technologies and explores fundamentals, recent developments and future perspectives.
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.
Carbon capture and storage (CCS) is broadly recognised as having the potential to play a key role in meeting climate change targets, delivering low carbon heat and power, decarbonising industry and, ...more recently, its ability to facilitate the net removal of CO
2
from the atmosphere. However, despite this broad consensus and its technical maturity, CCS has not yet been deployed on a scale commensurate with the ambitions articulated a decade ago. Thus, in this paper we review the current state-of-the-art of CO
2
capture, transport, utilisation and storage from a multi-scale perspective, moving from the global to molecular scales. In light of the COP21 commitments to limit warming to less than 2 °C, we extend the remit of this study to include the key negative emissions technologies (NETs) of bioenergy with CCS (BECCS), and direct air capture (DAC). Cognisant of the non-technical barriers to deploying CCS, we reflect on recent experience from the UK's CCS commercialisation programme and consider the commercial and political barriers to the large-scale deployment of CCS. In all areas, we focus on identifying and clearly articulating the key research challenges that could usefully be addressed in the coming decade.
Carbon capture and storage (CCS) is vital to climate change mitigation, and has application across the economy, in addition to facilitating atmospheric carbon dioxide removal resulting in emissions offsets and net negative emissions. This contribution reviews the state-of-the-art and identifies key challenges which must be overcome in order to pave the way for its large-scale deployment.
Industrial processes such as Portland cement manufacture produce a large proportion of anthropogenic carbon dioxide and significantly reducing their emissions could be difficult or expensive without ...carbon capture and storage. This paper explores the idea of synchronising shutdowns for carbon capture and storage installation with major shutdowns required to refurbish major process units at industrial sites. It develops a detailed bottom-up model for the first time and applies it to the United Kingdom's cement industry. This research demonstrates that several policy and technology risks are not identified by the top-down models and it highlights the importance of reducing shut-down times for capture plant construction. Failure to do so could increase installation costs by around 10 per cent. This type of approach, which is complementary to top-down modelling, and the lessons learned from it can be applied to other capital- and energy-intensive industries such as primary steel production. It provides important information about what actions should be prioritised to ensure that carbon capture and storage can be applied without extra unnecessary shutdowns which would increase the overall cost of carbon dioxide mitigation and could delay action, increasing cumulative emissions as well.
•Bottom-up models provide new insight for CCS deployment in process industries.•Deep decarbonisation is achievable assuming a supportive policy environment.•Delayed capture plant deployment will cause additional costly plant shutdowns.•Some sectors require high capture rate CCS technologies to meet ambitious targets.•This bottom-up approach is complementary to top-down decarbonisation pathways.
Calcium looping is a high-temperature CO2 capture technology applicable to the postcombustion capture of CO2 from power station flue gas, or integrated with fuel conversion in precombustion CO2 ...capture schemes. The capture technology uses solid CaO sorbent derived from natural limestone and takes advantage of the reversible reaction between CaO and CO2 to form CaCO3; that is, to achieve the separation of CO2 from flue or fuel gas, and produce a pure stream of CO2 suitable for geological storage. An important characteristic of the sorbent, affecting the cost-efficiency of this technology, is the decay in reactivity of the sorbent over multiple CO2 capture-and-release cycles. This work reports on the influence of high-temperature steam, which will be present in flue (about 5–10%) and fuel (∼20%) gases, on the reactivity of CaO sorbent derived from four natural limestones. A significant increase in the reactivity of these sorbents was found for 30 cycles in the presence of steam (from 1–20%). Steam influences the sorbent reactivity in two ways. Steam present during calcination promotes sintering that produces a sorbent morphology with most of the pore volume associated with larger pores of ∼50 nm in diameter, and which appears to be relatively more stable than the pore structure that evolves when no steam is present. The presence of steam during carbonation reduces the diffusion resistance during carbonation. We observed a synergistic effect, i.e., the highest reactivity was observed when steam was present for both calcination and carbonation.
Carbon capture and storage update Boot-Handford, Matthew E; Abanades, Juan C; Anthony, Edward J ...
Energy & environmental science,
01/2014, Letnik:
7, Številka:
1
Journal Article
Recenzirano
In recent years, Carbon Capture and Storage (Sequestration) (CCS) has been proposed as a potential method to allow the continued use of fossil-fuelled power stations whilst preventing emissions of CO
...2
from reaching the atmosphere. Gas, coal (and biomass)-fired power stations can respond to changes in demand more readily than many other sources of electricity production, hence the importance of retaining them as an option in the energy mix. Here, we review the leading CO
2
capture technologies, available in the short and long term, and their technological maturity, before discussing CO
2
transport and storage. Current pilot plants and demonstrations are highlighted, as is the importance of optimising the CCS system as a whole. Other topics briefly discussed include the viability of both the capture of CO
2
from the air and CO
2
reutilisation as climate change mitigation strategies. Finally, we discuss the economic and legal aspects of CCS.
A comprehensive discussion of CCS technologies, deployment and prospects across the world.
•Steam hydration to increase reactivity of CaO for CO2 capture has been investigated.•The reactivity and friability of reactivated sorbent was investigated.•Carbonation extent was found to have a ...linear relationship with hydration extent.•Hydration was found to have a strong relationship with porosity/cycling history.•As a result, the optimal hydration frequency can be predicted.
The reversible reaction of CaO with CO2 can be used for post- and pre-combustion capture of CO2; however, the reactivity of CaO particles is found to reduce upon repeated use. Hydration has been shown to be an effective method of increasing the reactivity of (or reactivating) CaO to CO2 for CO2 capture. Here, a lab-scale fluidised bed reactor was used to investigate reactivation of sorbent using steam at two different hydration temperatures of 473 and 673K. Prior to hydration, the sorbent was cycled at three different calcination temperatures of 1123, 1173 and 1223K; the carbonation temperature was kept constant at 973K. Following hydration, the sorbent was either carbonated directly or carbonated indirectly via a CaO intermediate. The hydration extent was found to decrease with increasing calcination temperature before hydration and with increasing hydration temperature. The carbonation extent following hydration was found to increase linearly with hydration extent – depending on the method of carbonation – with direct carbonation resulting in higher conversions. Mass loss from the fluidised bed was found to be higher for lower hydration temperatures and increased calcination temperatures before cycling. The hydration behaviour of sorbent was subsequently investigated using a TGA at three different steam hydration temperatures of 483, 578 and 678K. Material for the TGA tests was prepared using the lab-scale fluidised bed reactor, with a calcination temperature of 1173K and a carbonation temperature of 973K. In this case, the number of cycles was varied from 0 to 13, in order to provide a wider range of sorbent properties. Data from the TGA were used to project subsequent carbonation conversions and relative increases in carrying capacity across hydration. The TGA hydration tests emphasise the importance of hydration temperature and prior cycling conditions and length on the increase in carrying capacity following hydration.
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