Electrification of steam methane reforming is an interesting approach towards the EU carbon neutrality target. This paper presents a dynamic continuous-stirred-tank-reactors (CSTRs) model for simulating an electrically heated washcoat tube that represents a steam methane reforming reactor. Results from the engineering model are presented, such as temperature, gas molar fraction, CH4 conversion, and effects of dynamic operation. The model is validated by a previously published CFD model, which has been validated by experimental data. The engineering model provides much faster results than the CFD model and can accurately re-produce the CH4 conversion and the temperature profile in the reactor.
Nowadays, global carbon dioxide emissions into the atmosphere have reached a historically high level due to carbon dioxide emissions. The current effort to change the alternative energy source of LNG fuel was found to be one of the cleanest fossil fuels due to lower carbon emissions to ease the rapid growth of carbon emissions.
LNG marine industry forecasts that the increasing demand for FLNG vessels will accelerate the development of gas resources, research work on the system process analysis and optimisation of the Liquefaction system. The rapid growth in equipment and processes of FLNG development is the response to the challenges due to weight and space limits.
One of the critical objectives onboard FLNG is to build the combined plant models of clean energy. The research boundary covers processes of LNG liquefaction, nitrogen separation and boil-off gas handling. BOG re-liquefaction will be used as a fuel gas supply system. BOG will also be converted to clean energy fuel such as hydrogen or ammonia for the main and auxiliary engines onboard.
A small-scale liquefaction process with a refrigerant cycle is proposed in this study to meet these FLNG challenges. The Brayton refrigeration (BR) cycle is found to be most suitable for FLNG vessels, among other refrigerant cycles. The BR cycle using nitrogen as a refrigerant and a single expander is the focus of this study .
Accurate capacity estimation is crucial to ensure operational safety of Li-ion battery. In this paper, a novel capacity estimation approach is proposed for Li-ion battery cell. Two voltage-related features on probability density function based incremental capacity curve and average temperature are extracted as healthy indicators. Regression between healthy indicators and capacity is constructed using random forests. Results show that the capacity estimation error could be controlled within 2.5% throughout the whole lifecycle of the battery.
The objective of this work is to study heat and mass transfer processes in a single biomass particle before its thermal degradation (< 200 °C) under high intense acoustic fields. For that, was developed a numerical code for Biot number higher that one, i.e., non-isothermal particles. The hypothesis is that an acoustic field alters the interaction between the gas and particles, proving drying. Acoustic fields can be obtained by using a loudspeaker inside a reactor. The proposed model predicts moisture mass transfer completion for different particle sizes and oscillating frequencies. The obtained data are relevant for plant conversion capacity and reactor's preliminary design.
The sizing of long duration storage is one of the main challenges in the study of the feasibility of low-carbon power systems. In reviewing the literature, we identify that the consideration of technical and environmental constraints as well as uncertainty in production and consumption impact its sizing. We then determine that, with a classical unit commitment optimization, the choice of the simulation horizon, as well as the length of that horizon and the combination of years on which the study is carried out have a significant impact on the sizing of long duration storage. The reasons for this are the different long duration storage (LDS) discharge need profiles in different years and the sizing method used. We also found that the sequence of meteorological events significantly impacts the LDS sizing. Hence, our need for LDS considerably increases compared to the results proposed by the literature which in most cases doesn’t consider those methodological aspects. This finding calls for the development of more robust methods for sizing long duration storage as well as further research on the LDS role in high penetration variable renewable energy (VRE) power systems.
A methane (CH4) slip is normally un-avoided during biogas upgrading, and water scrubbing is the most widely adopted upgrading technology. As CH4 is also a key greenhouse gas, such a slip can damage the carbon neutrality of bioenergy and result in a positive emission. In order to eliminate the negative influence, a post treatment to handle the released CH4 is essential. Regenerative thermal oxidation (RTO) is a commercially available air pollution control technology, and it can be used for the post treatment. This paper aims to analyze the technical and environmental performance of RTO for removing CH4 from the waste gas of biogas upgrading by water scrubbing. A three-dimensional numerical model was developed for the thermal flow-reversal reactor (TFRR). CH4 content in waste gas is investigated as the key factor, and the energy consumption, the amount of CH4 elimination and associated CO2 equivalent avoidance are estimated as key performance. It was found that the higher CH4 content benefits maintaining the operation of RTO. With the increase of CH4 content, the energy consumption of CH4 removal decreases. For example, it decreases from 8.05kWh/kg to 1.22kWh/kg when CH4% rises from 0.28% to 0.42%. The case study on a real biogas plant that produces 3909ton biogas per year shows that removing CH4 corresponds to a CO2 equivalent avoidance of 231.38ton/year.
To achieve net-zero emissions by 2045 in Sweden, bioenergy with carbon capture and storage (BECCS) has been identified as a key technology. Biomass fired combined heat and power plants (bioCHPs) constitute the second largest CO2 emission source after paper and pulp plants. Therefore, integrating BECCS in bioCHPs will contribute significantly to achieve Sweden’s climate goal. In the prerequisite of maintained heat generation for district heating (DH) sectors, this paper aims to estimate the aggregated negative emissions when integrating CO2 capture into existing 110 bioCHPs, in which the boiler load can be increased to the maximum capacity. A physical model was developed for bioCHP, and the operation of an example bioCHP can be determined by the objective function of maximizing the heat for CO2 capture. Based on results of example plant, the artificial neural network models were further established to predict the capture performance from other plants. Not only the amount of captured CO2, but also the amount of avoided CO2 was examined for a better understanding of the contribution of negative emissions. It is estimated that the heat generation used for DH is 33925.83 GWh/year. The aggregated amount of captured CO2 is estimated of 23.11 Mton/year; the aggregated amount of avoided CO2 is estimated of 20.22 Mton/year. The electricity generation is found to be decreased by 8810.82 GWh/year (63.6%) when BECCS is included.
Using transcritical CO2 air source heat pump for space heating is a clean and environmentally friendly solution. Based on the concept of the Lorenz cycle and CO2 heat pump system with traditional dedicated mechanical subcooling (DMS), CO2 system with DMS employing zeotropic mixture as working fluid for subcooling is proposed. Its life cycle economic performance is assessed. The results indicate that the energy performance of zeotropic working fluid with high-temperature glide is higher than that of the pure working fluid. The capital cost and fuel cost are obviously reduced by using high-temperature glide zeotropic mixtures for subcooling. The levelized total annual cost is saved by 5.70, and 19.12% compared with that using pure refrigerant, and baseline CO2 system. The mixture with high-temperature glide is recommended.
In the modern energy sector, energy flexibility is highly essential. Participation in demand response programs is open to different power customers, with the greatest potential for some high-consumption industrial firms. This paper proposes a novel optimization model to maximize the profit obtained by marketing energy flexibility in a generic manner which is applicable for different industries. Two particular strengths of this model are its inclusion of dependencies between loads and load aggregation. We investigate the model’s performance in two use cases: one with dependent loads and another with aggregated loads. Results demonstrate that the proposed model can achieve its objectives in different use cases, giving exceptional usage for industrial flexibility cases.
Access to timely, affordable, and good quality food is a sine qua non for human existence. Unfortunately, huge volumes of edible foods are wasted or lost along the food value chain thereby impacting food security. Recycling and conversion of food waste ensure the appropriate utilization of the untapped resources in food waste. The current study reviews the biological (landfill, composting, anaerobic digestion, and fermentation) and thermochemical (incineration, pyrolysis, gasification, and hydrothermal carbonization) technologies for the conversion of food waste into clean energy, chemicals, and other utilizable products. The process, products, benefits, and drawbacks of these conversion technologies are also discussed. Commissioning of multidisciplinary and collaborative research is recommended to garner expert perspectives towards achieving cost-effective, ecofriendly, sustainable, and practicable food waste conversion technologies.