Abstract

Mixed CH4-THF hydrate formation has been investigated at ambient temperature (298 K) with focus on advancing the commercial feasibility of solidified natural gas (SNG) technology for natural gas storage. In addition to freshwater, direct use of seawater has also been studied for hydrate formation. There is quite a gulf between the two systems at the chosen experimental temperature of 298 K with final gas uptake for the freshwater system being more than double that of its seawater counterpart while the kinetics of hydrate formation also shows a marked difference, in favor of freshwater. To improve the kinetics of hydrate formation from seawater, possible use of two kinetic promoters, hydrophilic amino acid L-Arginine and hydrophobic amino acid L-Tryptophan has been proposed. Both kinetic promoters used enhance the kinetics of hydrate formation from seawater and while the final gas uptake is roughly equivalent for the systems without any promoter and with hydrophobic L-Tryptophan, presence of hydrophilic amino acid L-Arginine increases the final gas uptake obtained for seawater as well.

Abstract

CaO-based CO2 sorbents play a significant role in sorption enhanced methane steam reforming process for hydrogen production and CO2 emission reduction. In this work, pretreatment of CaO/Ca3Al2O6 sorbents in steam atmosphere at different temperatures was investigated for its influence on CO2 sorption capacity and cyclic stability. The sorbents were synthesized to contain a CaO to Al2O3 mass ratios of 9:1, and then subjected to cycling tests with repeated carbonation and calcination process. Results showed that the sorbents pretreated by steam at 250 °C obtained a minimum CaO grain size of 37.9 nm and a maximum surface area of 17.4 m2·g-1 . This resulted in an increase in CO2 sorption capacity, up to 8.53 mmol CO2·g-1 sorbent. After 50 cycles, the CO2 sorption capacity decreased, but still remained 10% above those for the original (no pretreatment) sample. The mechanism about the improved CO2 sorption performance of the pretreated sorbents was also postulated.

Abstract

As China delivering on the promise on energy transition, its photovoltaics(PV) market has become the biggest in the world, the total installed PV capacity has reached 180 GW. However, to meet the goal on 20% of total energy consumption from renewable sources, PV potential is appealing to continue release. Currently, PV deployment in China mainly focuses on residential rooftop PV systems and utility-scale PV plants, and is somehow stuck by curtailment. Distributed PV system for industrial users that has have many advantages is promising to achieve completely consumption onsite yet is still lack of investigation. Here, we present an assessment on the potential PV accommodation capacity in China’s power plants by using abundant real data from power plants and geographic information system(GIS). The results show the accommodation capability of PV is 31.30 GW in power generation sector, or 3.73×1010 kWh for auxiliary power demand and is able to reduce 5.81×107 tons of CO2 and 9.70×103 tons of PM2.5 annually.

Abstract

D-mannitol (DM) is a phase change material (PCM) for medium temperature thermal energy storage. In this paper the preparation of microencapsulated d-mannitol by a sol-gel process is reported. The microencapsulation of d-mannitol was confirmed by characterization using a scanning electronic microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR) analysis. The thermal properties of the microencapsules were measured by a differential scanning calorimeter (DSC) instrument. The thermal stability of the synthesized DM microencapsules was investigated by means of thermogravimetric analyzer (TGA). The results show that the microencapsulated d-mannitol have a high phase change latent heat of 220.3 J/g and improved thermal stability.

Abstract

The replacement of CH4 by injecting CO2 in methane hydrates is a promising method for simultaneously allowing geologic CO2 sequestration and CH4 recovery. However, the carbon dioxide hydrate layer formed on the MH surface acts as a barrier, which causes the slow diffusivity of CO2. Therefore, in this study, we proposed using an operation of multi-depressurization to increase the diffusivity of CO2 and enhance the CH4 recovery in the CH4/CO2 replacement processes. The results proved that both the value of the methane replacement rate and the carbon dioxide storage rate increase significantly.

Abstract

As a large energy prosumer in the urban energy systems, on the one hand, datacenters consume a large amount of electricity to ensure the IT facilities and ancillary power supply and cooling systems work properly; on the other hand, datacenters produce a large amount of waste heat due to the high heat dissipation rates of the IT facilities. To date, a systematic review of datacenters from the perspective of energy prosumers, which considers both integration of the upstream green energy supply and downstream waste heat reuse, is still lacking. This study fills in this gap and provides such a review. By providing a full picture of datacenters in the urban energy systems, this study aims to search new opportunities for improving datacenter overall energy efficiency and reducing carbon emissions

Abstract

Wind generators (WGs) may suffer from heavy imbalance costs caused by their uncertainty nature if they bid in electricity market independently. However, they can utilize demand response (DR) potential of flexible loads like air conditioners (ACs) to set off their power fluctuation. In this paper, WGs joint with ACs constitute a virtual power plant (VPP), and bid in the market as a whole. Transactive energy (TE) serves as the main approach to setting off power deviations of distributed energy resources (DERs) including WGs and ACs, through deviation energy trading among them. An optimal day-ahead strategy is proposed for VPP operator (VPPO) to select qualified trading partners for WGs based on their transaction demand. Then VPPO sets up realtime TE market inside the coalition and launches double auctions (DAs) in each time slot of the next day, inducing DERs to set off their power deviations through peer to peer (P2P) energy trading. Results of case study show that VPPO can select qualified trading partners for WGs efficiently, maximizing VPP’s prospective revenue as well as covering WGs’ transaction demand. Both DERs and VPPO can benefit from TE market without sacrificing AC consumers’ comfort.

Abstract

The paper outlines our ongoing efforts on building a framework for a flexible refined products supply chain. Current refined products supply chain faces the risks of supply and demand fluctuation, refineries and transport facilities (i.e. pipelines) disruption, and depots accidents. These risks will lead to the unmet demand of the sales market and affect social and economic developments. The framework integrates a basic mixed-integer linear programming model for current refined products supply chain simulation, a reliability assessment method, and an expanded model considering facilities expansion and multi-energy sources supplement. We introduce the concept and importance of refined products supply chain flexibility study, the conceptual framework and its integrated components. Finally, we summarize the current research challenges and give a conclusion.

Abstract

Powertrain control strategy is a key technology that determines the energy consumption of dual-motor electric vehicles. However, existing control strategies cannot meet the requirements of a new dual-motor powertrain configuration with a two-speed gearbox for one of the motors, which is likely to be the mainstream powertrain configuration of commercial vehicles in the future. In this paper, two control methods including dynamic programming and an offline global optimization method are conducted to optimize torque distribution strategy and gear shifting law. The performance of the proposed methods is reflected through simulations based on MATLAB/Simulink, the results show that the proposed methods present considerable promotion on energy consumption compared with that of the fixed proportional control method.

Abstract

CO2 conversion into the useful compound is gaining increasing interest in recent years but a huge amount of energy is required to activate CO2. Recently, plasma have been appearing as an attractive alternative for CO2 activation. Among plasma technologies, a low current plasma can be a competitive and valuable alternative because it is available at atmospheric pressure and room temperature and is easy to operate. In this study, the high efficiency of CO2 activation was demonstrated using a low current arc plasma. In addition, the effect of addition of γ-Al2O3 and CaO on the CO2 conversion and energy efficiency was investigated. The CO2 conversion and energy efficiency were 10.9% and 19% without catalyst. By adding CaO, they increased to 23.3% and 46%, respectively.