1,721,038 research outputs found
Research and Innovation Needs for the Waste-To-Energy Sector towards a Net-Zero Circular Economy
Full text linkThis perspective article aims to identify key research priorities to make the waste-to-energy sector compatible with the societal goals of circularity and carbon neutrality. These priorities range from fundamental research to process engineering innovations and socio-economic challenges. Three focus areas are highlighted: (i) the optimization of flue gas cleaning processes to minimize gaseous emissions and cross-media, (ii) the expansion of process control intelligence to meet targets for both material recovery and energy recovery, and (iii) climate neutrality, with the potential for negative emissions via the removal of atmospheric carbon dioxide across the full cycle of the waste resource. For each area, recent research trends and key aspects that are yet to be addressed are discussed
On the Integration of Sequential Supplementary Firing in Natural Gas Combined Cycle for CO 2-Enhanced Oil Recovery: A Techno-economic Analysis for Mexico
Full text linkA techno-economic analysis of a natural gas combined cycle (NGCC) integrated with MEA-based CO2 capture with an advanced configuration is carried out. Sequential supplementary firing in the Heat Recovery Steam Generator (HRSG) is combined with a supercritical combined cycle for the purpose of increasing CO2 production for Enhanced Oil Recovery (EOR) at a competitive levelised cost of electricity. Supercritical steam conditions with a double reheat in the steam cycle are used to largely improve performance and take full advantage of sequential supplementary firing in the HRSG. Sequential supplementary firing increases the flue gas temperature throughout the Heat Recovery Steam Generator (HRSG) by burning additional fuel at different stages to maximise the use of oxygen available in the flue gas exiting the gas turbine. The positive impact on the post combustion capture plant size and energy requirements for solvent regeneration are attractive for markets with cheap natural gas, and where the emphasis on capital cost reduction is important. This study then investigates the effect of fuel prices and capital costs for this configuration and compares it with a typical combined cycle integrated with MEA-based CO2 capture. A case study for Mexico is presented, at a range of gas prices where these modifications would be attractive, with a tentative target of $40/tCO2
A pilot-scale study of dynamic response scenarios for the flexible operation of post-combustion CO2 capture
Full text linkAbstractThe ability to operate flexibly is critical for the future implementation of carbon capture and storage (CCS) in thermal power plants. A dynamic test campaign examines the response of a CO2 absorption/desorption pilot-scale plant to realistic changes in flue gas flow rates and steam supply, representative of the operation of a Natural gas combined cycle (NGCC) plant fitted with post-combustion capture. Five scenarios, demonstrating the operational flexibility that is likely to be encountered in an energy market with significant penetration from intermittent renewables, are presented, with 30% monoethanolamine (MEA) as the absorbing solvent. It complements a wider effort on dynamic modelling of these systems where a lack of dynamic plant data has been reported.The campaign focuses on analysing critical plant parameters of the response of the pilot plant to a gas turbine shutdown, a gas turbine startup and three enhanced operational flexibility scenarios, including two for power output maximisation and one for frequency response with a rapid increase of steam supply to the reboiler. The campaign also demonstrates the use of continuous in situ solvent lean loading measurement with the use of a novel online continuous liquid sensor.It confirms that no significant barriers to flexible operation of amine post-combustion capture are found, although there remains scope for the improvement of plant response. Solvent inventory and circulation times are found to have a significant effect on capture rate during certain dynamic operations. A large solvent inventory increases total circulation times, which can result in additional time being required for the plant to return to steady state following a perturbation. The plant is forced to operate with a non-optimal capture rate while the solvent loading at the absorber inlet stabilises is identified as a potential impact.Use of interim solvent storage and continuous online measurement of solvent CO2 loading, combined with comprehensive knowledge of liquid circulation times and potential mixing effects, are suggested as methods for improving plant response to dynamic operation, thereby increasing CCS plant flexibility
Data set for " CNN-aided Flooding Prognostic in Packed Column using Electrical Capacitance Tomography."
No full textA dataset is presented for Flooding Prognostic in Packed Column using CNN-aided Electrical Capacitance Tomography (ECT). Numeric data containing measurement of ECT capacitance, pressure drop, liquid hold-up profiles. The ECT system used in this work includes sensors, data acquisition system and a computer with imaging software. The frame rate of the ECT system is up to 714 frames per second. The pressure inside the bed is recorded using pressure meters and data loggers, the pressure meters are placed on the capture column at the top and bottom of the column. The liquid hold-up inside the bed is derived from level meter measurements. We include data of ECT capacitance, pressure and liquid hold-up during the whole progress. The proposed CNN aided ECT accurately predicts the local liquid hold-up and enables the earliest detection of loading point at the bottom of the packed column and warning of flooding point at the top of the packed column, and therefore is highly suitable for flooding prognostic. This dataset could be used to accurate measurement of loading point and flooding point, and its application to flooding prognostic is significant to maximum the packed column mass transfer efficiency. Data supporting Chen et al (prepare to submission).Chen, Yuan; Liu, Chang; Jia, Jiabin; Lucquiaud, Mathieu; Yang, Yunjie. (2021). Data set for " CNN-aided Flooding Prognostic in Packed Column using Electrical Capacitance Tomography.", 2019-2021 [dataset]. University of Edinburgh. School of Engineering. Institute of Digital Communication. https://doi.org/10.7488/ds/3151
Managing incentives for greenhouse gas emission reduction
Full text linkThe Paris Agreement sets out the goal of limiting the increase in global average temperature to
within 2°C. Incentive mechanisms and low-carbon policies, such as emission trading schemes
(ETS), feed-in tariffs, carbon taxation, renewable obligation and emission performance
standards, are key instruments for achieving greenhouse gas emissions reduction. The cap-and-trade
ETS is one of the most popular policy instruments in controlling greenhouse gas
emissions. The carbon price quoted from the ETS allowances price is usually considered by
investors as the economic value of carbon emissions in formulating a long-term investment
decision. However, the allowances price is currently quite low across jurisdictions. Thus, in
order to incentivise large-scale and long-term low-carbon investment, a clear and strong carbon
pricing signal is essential.
There are divergent but increasingly prevalent views that additional policies may affect carbon
prices, as the emission reduction effect of parallel policies would reduce the demand for
allowances in the ETS, thus lower carbon prices could hamper the ETS’s capacity to promote
low-carbon technologies over the medium and long term. This PhD study investigates how
parallel energy and climate policies might affect carbon pricing in ETS and illustrates
stakeholders’ views on this impact. The study defines the ‘cross-over effect’ of parallel energy
and climate policies.
A two-stage survey, including a closed-form questionnaire followed by open interviews, was
conducted to elicit views and expectations of stakeholders on one of the carbon markets in
China, the Guangdong ETS pilot, with an emphasis on perspectives on how the ETS may
interact with other existing or proposed low-carbon and clean energy policies. Our survey
results show that academic stakeholders, more than stakeholders from other sectors, viewed
the policy interactions as a significant issue for developing a carbon market in China, and there
was a positive correlation between recognition of such policy interactions and the time spent
on energy saving and emission reduction policies. Relatively few respondents identified
correctly the fact that both increasing renewable targets and imposing a carbon tax in addition
to an existing ETS would be expected to depress prices in the ETS. Apart from government
respondents, all other key stakeholders generally lacked confidence in China’s carbon markets,
due to their lack of knowledge and information about the market and their concerns regarding
uncertainties and failures in government policy and regulation. Subsequently, an empirical study was conducted to probe the underlying rationality of pricing
behaviour and the effect of policy interaction with low-carbon policy in seven ETS pilots in
China using ordinary least square and event-based regression. The empirical results show that,
first, crude oil and domestic liquid natural gas are positively linked to the allowance price in
the Beijing, Shanghai and Guangdong pilots, while coal price lacks explanatory power. Second,
extreme weather is positively correlated with Shenzhen carbon prices. Third, in contrast to
existing studies, a positive correlation is found between renewable energy supply and carbon
prices in the Tianjin carbon market, and low-carbon policy that intends to promote renewable
energy would increase carbon prices in the Guangdong pilot. Finally, ETS regulatory events,
such as the announcement on surrender date (adjustment) and offset limitation, will increase
price variations in the Shenzhen and Tianjin pilots respectively. Overall, the empirical results
currently indicate that ETS pilots in China are segmented, but not as rational as previous studies
suggest.
Finally, the potential benefits of linking emissions markets across countries and regions are
well recognised. In theory, a global market provides more flexibility for parties to achieve
reductions in emissions at the lowest marginal cost across all covered sectors. Therefore,
quantifying the impact of emission trading market linkage would generate essential references
for the forming of a global market. Driven by the above motivation, the GTAP-Energy (GTAPE)
model was employed to assess the impact of carbon market linkage. Our results indicate
that, although the abatement costs increase in the Chinese carbon market after the linkage, the
strong and robust carbon price could give investors a correct signal on the value of carbon
emission. Furthermore, a linkage between the Chinese carbon market and the international
markets leads to a significantly smaller GDP reduction in China, 0.04% compared to the non-linkage
scenario (0.88%). In addition, allowing multilateral trading of emissions among these
countries shifts the burden of the reduction away from oil products in the relatively carbon-efficient
economies towards coal in the less carbon-efficient regions. This induces a substantial
reduction of the marginal abatement costs in the above economies.
In summary, this PhD research investigates stakeholders’ views on the Chinese carbon market
as well as interactions between energy and climate change policies; it also discovers the price
drivers for carbon prices in China’s pilot ETSs and assesses the impact of including Chinese
ETSs in a global emission trading system. Moving forward, as the results suggest that the
Chinese pilot ETSs may not be rational and most market participants are not fully aware of the function of the carbon market since they merely fulfil the need for government. The next step
would be to discover whether there is a media effect driving carbon prices
Variable capture levels of carbon dioxide from natural gas combined cycle power plant with integrated post-combustion capture in low carbon electricity markets
Full text linkThis work considers the value of flexible power provision from natural gas-fired
combined cycle (NGCC) power plants operating post-combustion carbon dioxide
(CO2) capture in low carbon electricity markets. Specifically, the work assesses the
value of the flexibility gained by varying CO2 capture levels, thus the specific energy
penalty of capture and the resultant power plant net electricity export. The potential
value of this flexible operation is quantified under different electricity market
scenarios, given the corresponding variations in electricity export and CO2 emissions.
A quantified assessment of natural gas-fired power plant integrated with amine-based
post-combustion capture and compression is attempted through the development of
an Aspen Plus simulation. To enable evaluation of flexible operation, the simulation
was developed with the facility to model off-design behaviour in the steam cycle,
amine capture unit and CO2 compression train. The simulation is ultimately used to
determine relationships between CO2 capture level and the total specific electricity
output penalty (EOP) of capture for different plant configurations. Based on this
relationship, a novel methodology for maximising net plant income by optimising the
operating capture level is proposed and evaluated. This methodology provides an
optimisation approach for power plant operators given electricity market stimuli,
namely electricity prices, fuel prices, and carbon reduction incentives.
The techno-economic implications of capture level optimisation are considered in
three different low carbon electricity market case studies; 1) a CO2 price operating in
parallel to wholesale electricity selling prices, 2) a proportional subsidy for low carbon
electricity considered to be the fraction of plant electrical output equal to the capture
level, and 3) a subsidy for low carbon electricity based upon a counterfactual for net
plant CO2 emissions (similar to typical approaches for implementing an Emissions
Performance Standard). The incentives for variable capture levels are assessed in
each market study, with the value of optimum capture level operation quantified for
both plant operators and to the wider electricity market. All market case studies
indicate that variable capture is likely to increase plant revenue throughout the range
of market prices considered. Different market approaches, however, lead to different
valuation of flexible power provision and therefore different operating outcomes
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The use of ultra-high temperature thermal energy storage for industrial decarbonisation
No full textSustainable energy solutions are crucial to mitigating global warming. The integration of Ultra-High Temperature Thermal Energy Storage (UHTS) into industrial processes and power generation stands out as a compelling strategy to decarbonise pre-existing infrastructure. This thesis introduces a novel approach to enhancing energy efficiency and reducing carbon emissions within the framework of existing thermal power cycles and industrial operations. Through an extensive review of current energy storage technologies, this study identifies UHTS as a critical technology capable of facilitating the transition to a low-carbon economy.
Employing computational methods, quantitative modelling techniques are used to explore the feasibility of UHTS deployment. The research examines the feasibility of retrofitting Rankine and Brayton cycles, specifically a gas turbine (GT) and a heat recovery steam generator (HRSG), with UHTS, assessing enhancements in operational efficiency and environmental performance.
This research also includes the development of a comprehensive mathematical model to simulate the optimal operational behaviour of a UHTS system integrated into GTs, HRSGs and Industrial Boilers (IBs) under two design conditions - arbitrage profitability and fuel displacement. This model allows for an evaluation of the impact on the cost-effectiveness of a UHTS system, and the resulting carbon footprint reduction across different industrial applications.
This study's findings emphasise the potential of UHTS to improve the flexibility and sustainability of thermal power generation and industrial heat processes. Integration into the combustion chamber of a GT for hybrid burning is shown to offer a fuel displacement of up to 88.9 %, facilitating a reduction in NOx of 93.8 %, CO of 98.6 %, and CO₂ of 86.6 %. Flow augmentation of the inlet of a HRSG is shown to be viable with minimal design alterations, providing additional heat in the manner of supplemental firing, without the use of additional fuel. The feasibility of fully replacing the inlet flow with a UHTS system has also been explored, outlining the requirement for flow stratification measured to make the retrofit route viable. The research also demonstrates that UHTS integration can provide an average monthly arbitrage profitability of up to £2,225,000, and carbon emission reductions of 33,900 tonnes.
The implementation of UHTS can significantly boost the viability of an increasingly renewable grid, by providing the ability to reliably dispatch stored renewable energy, thereby decreasing reliance on fossil fuels and curtailing industrial carbon emissions.
The results and conclusions presented in this thesis outlined a detailed investigation of UHTS technologies, encapsulating their operational, economic, and environmental benefits. The research offers valuable insights for design engineers, policymakers, and industrial investors. It outlines the benefits of further development and implementation of UHTS, based on its ability to drive an increase in the profitability of pre-existing systems, whilst aligning with decarbonisation goals
Steam cycle options for capture-ready power plants, retrofits and flexible operation with post-combustion CO2 capture
Full text linkThe energy penalty for post‐combustion carbon dioxide capture from fossil‐fired power plants can
be greatly reduced ‐ independently of the intrinsic heat of regeneration of the solvent used ‐ by
effective thermodynamic integration with the power cycle. Yet expected changes in electricity
generation mix and the current immaturity of post‐combustion capture technology are likely to
make effective thermodynamic integration throughout the operating life of such plants a challenging
objective to achieve because of a requirement for extensive part‐load operation and also for
matching to future technology improvements. Most previous published studies have, however,
focused on base‐load operation of the power cycle and the carbon dioxide capture plant and with
the assumption of a fixed technology.
For carbon dioxide capture‐ready plants the characteristics of the capture plant are also not known
when the plant is designed. The plant must operate initially without capture at a similar efficiency to
‘standard’ plants to be competitive. Capture‐ready plants then also need to be able to be retrofitted
with unknown improved solvents and to be capable of integration with a range of future solvents.
This study shows that future upgradability for post‐combustion capture systems can be facilitated by
appropriate steam turbine and steam cycle designs. In addition fossil‐fired power plants with postcombustion
capture may need to be able to operate throughout their load range with the capture
unit by‐passed, or with intermediate solvent storage to avoid the additional emissions occurring
when the absorption column is by‐passed. Steam cycles with flexible steam turbines can be
adequately designed to accommodate for part‐load operation with these novel operating conditions
and with rapid ramp rates.
Several approaches for effective capture‐ready pulverised coal and natural gas plants are also
described. These achieve identical performance before retrofit to a conventional plant with the
same steam conditions, but have the potential to perform well after capture retrofit with a wide
range of solvents, at the expense of only a small efficiency penalty compared to hypothetical plants
built with perfect foreknowledge of the solvent energy requirements. For existing plants that were
not made capture‐ready, and provided sufficient space is available and other physical limits are not
too constraining, ways to achieve effective thermodynamic integration are also discussed
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