Abstract

The prospect of using biomass alone is broad, but there are a number of problems that make it difficult to achieve real profitability. In this paper, the thermal effects and reaction kinetics of cellulose and low-rank coal mixing at different mixing rates (25 wt%, 50 wt.% and 75 wt.%) and different heating rates (10 oC•min-1 , 20 oC•min-1 , 40 oC•min-1 ) were studied via thermogravimetric analyzer(TGA). The addition of low-rank coal can promote the formation of volatile substances in the copyrolysis process, and the degree of synergy is closely related to the heating rate and blending ratio. The kinetic results show that the average activation is 244.44 kJ•mol1 and 164.41 kJ•mol-1 when the low-rank coal blending ratio is 25% and 50%.

Abstract

In Niger, the majority of population today does not have access to electricity. This study analyzes how the electricity consumption could increase, and whether Niger’s supply plans are sufficient to meet the growing demand. With the current efforts of electrification, Niger will have supply capacity of 1,361 GWh by 2020 and 1,444 GWh by 2024. This accounts only for the national capacity expansion plans. If this proves true, the increase in generation capacity will be unable to maintain the country’s current electrification rate. This means, by 2021 there will be a supply deficit of 145 GWh, and it will reach to 783 GWh in 2030. In order to supply this deficit, e.g. with solar PV system, new installations ranging from 512 MW to 682 MW would be required by 2030.

Abstract

Sub-atmospheric pressure effects on pool fire behaviors using n-heptane with water mist based on the protection of the ozone layer in aircraft operation safety. Twin-fluid water mist has been evaluated as one of the most promising technologies to replace Halon fire suppressant for cargo fires. N-heptane pool fires with no water mist suppression activated and with water mist fire suppression system activated were tested and analyzed under standard pressure and different depressurization rates (91, 182, 328 Pa/s) in this work. The mass loss of fuel and chamber pressure history were measured. In addition, the suppression time for each test with water mist activated was also analyzed statistically. The test results under different depressurization rates demonstrated the effectiveness of the water mist system, and the average suppression time is less than 25 seconds. The different pressure ratios between water and nitrogen have also been compared and analyzed, and the results show that the suppression is more effective when the pressure of the water and nitrogen is 0.4 MPa and 0.48 MPa, respectively. The outcomes are of great significance for optimizing the design of fire extinguishing systems for aircraft.

Abstract

A new hybrid model of geothermal-solar power generation system has been investigated in this study with particular reference to the utilization of Hot Dry Rock (HDR) geothermal energy which usually associated with the application of enhanced geothermal system (EGS) technology. But long-term extraction of geofluid from the HDR could cause a considerable thermal energy depletion near the production zone, resulting in a decrease of the geofluid temperature. The hybrid system presented here is aimed at using solar energy to avoid continuously extracting too much geofluid in order to mitigate the thermal depletion circumstances. This hybrid system is designed as a power cycle with two interactive heat sources (geothermal and solar energy), which could generate the rated power of 1MW all the time by letting the two heat sources (two vaporizers) operation in different ways. The numerical simulation and optimization of different operation strategies under different solar conditions have been carried out. Organic Rankine cycle (ORC) is used for power generation. The total power output is controlled by adjusting the order in which the working fluid flows through the two vaporizers. The heating system in parallel mode as well as in series mode have been investigated. Results shows that, in the subcritical cycle scenario, the two vaporizers in series (with geothermal heating first) has a better performance. Whereas, in the transcritical cycle scenario, the two vaporizers in parallel has a better performance.

Abstract

The aim of this paper is to assess the impact of the energy transition on raw material demand and answer the question whether or not lithium, copper, cobalt and nickel might become critical due to their high content in low-carbon technologies of the power and transport sectors. Growing need for these ores and refined metals is expected along with the energy transition toward a low-carbon system due to the fact that all decarbonisation innovations are very raw materialintensive. To achieve this goal, we have developed the first detailed global bottom-up energy model, TIAMIFPEN (TIMES Integrated Assessment Model) with an endogenous representation of the lithium, copper, nickel and cobalt supply chain. Lot of the literature analysis have been focused on battery’s materials such as lithium, cobalt and at a lesser extent nickel but none has implemented raw material supply chain in longterm energy scenario in order to evaluate if the availability of these materials could impede the energy transition. This article would also like in addition to give more focus on structural materials such as copper. Indeed, the criticality of these structural materials have been neglected despite the continuing policy focus on raw material criticality and the many reports and books written on the topic. This model would clearly assess the dynamic criticality of these strategic materials according to the optimal technology paths with environmental and/or energy solicitations through different approaches: geological, geopolitical, and economic towards a sustainable development. Two climate scenarios (4°C and 2°C) have been conducted with two shapes of mobility each. The penetration of low-carbon technologies in the transport and power sectors (electric vehicles, low-carbon power generation technologies, etc.) should increase copper, lithium, cobalt and nickel demands drastically by 2050. However, this approach would also highlight the public policy drivers that can mitigate our results. Here, the case of public policy based on an integrated approach to urban land-use and transport planning has been implemented. The study of these particular strategic materials shows that the model could be a useful decision-making tool for assessing future raw material market stresses along with energy transition for more efficient regional and sectorial screening.

Abstract

Green infrastructure (GI) is identified as the critical technology to sustainable urban development in the United Nations New Urban Agenda. GI not only has the function of ecological services but also has the function of reducing carbon emissions, which is very important for building low-carbon cities. The carbon emission reduction effect of GI in Sponge City was analyzed by comparing the traditional drainage system (TDS) and the green drainage system (GDS). TDS also indicated combined sewer system (CSS), which undertakes a large amount of urban runoff and transfers it to wastewater treatment plant (WWTP). GDS mainly depends on rain gardens, grass planting ditches, etc., to purify and transfer rain-runoff, so the rain-runoff no longer enters into WWTP. TDS consumes much energy for pumping and wastewater treatment, which produces carbon emissions. GDS reduces the amount of water through the pumping station and sewage treatment plants resulting in a significant reduction in carbon emissions. In order to assess the carbon reduction effect of GDS, a new set of calculation has been proposed. Taking Dongying (Shandong province, China) as an example, the carbon-reduction benefit of the drainage system in Sponge City is calculated based on hydrological datasets and the carbon emission coefficients. The results show that the carbon emission is reduced by 54.3%, 43.3%, and 38.9%, for wet, normal and drought year, respectively.

Abstract

In view of the volatility of renewable energy and the randomness of load in the CCHP micro-grid, and considering that the shiftable loads model is an important means of demand side response, this paper studies the operation optimization of the system from the perspective of nonlinear modeling and load shifting. Firstly, the nonlinear model of the main equipment is established based on the nonlinear interpolation method. Then, the Shiftable loads model and the system optimization operation model with the objective functions of primary energy consumption (PEC), carbon dioxide emission (CDE) and daily operation cost (COST) are constructed. CPLEX is used to solve the above models. Finally, the effects of the nonlinear model and the linear model on the optimal operation of the system under the three objective functions before and after the load shifting are analyzed by numerical simulation. The results show that the nonlinear model can better respond to the load curve after translation than the linear model, so that the impact of load shifting on the optimal operation of the system is more obvious.

Abstract

Thermo-mechanical energy storage deployment in future energy grids presumes economic profitability is achieved through their operation. However, suitable technology design should not be pursued regardless of a technical evaluation of storage performance. In this paper, a combined economic and thermodynamic analysis is used to point out what are the guidelines for optimal size of a Liquid Air Energy Storage (LAES) system. Results show payback time around 25 years. They also suggest that, while financially a smaller liquefier should be preferable, this on the other hand implies higher thermodynamic inefficiencies.

Abstract

1D modelling for micro gas turbines (MGTs) is a major area of interest in the field of distributed multigeneration. In this paper a 1D simulation model for a commercialised MGT has been developed and validated against the manufacturer data using SimcenterAmesim. The developed model is a primarily tool to address the operational challenges of MGT, investigate future fuelling and investigate its integration with other energy storage / conversion systems. At this stage of research, the agility of the developed model is demonstrated by carrying out a parametric study to investigate the effect of varying the compressor inlet temperature on the overall system performance. Itwas revealed that the air mass flow rate was very sensitive to compressor inlet temperature change. Varying the compressor inlet temperature from 278K to 308K showed an increase of systemefficiency by 1.2%.

Abstract

Failure of the natural gas pipeline can have severe consequences to individuals, economy, environment and the public in term of consequential damage and property losses. There are various causes of natural gas pipeline failures among which third-party damage offers a high contribution. To minimize third-party damage of NGP contributing factors should be studied to establish viable solutions for risk mitigation. In this paper, factors contributing to third-party damage of NPG in Dar es Salaam region have been studied. A fault tree was constructed and by utilizing fuzzy logic and expert elicitation, the failure probabilities of the basic event were established. The prioritization of factors was performed by criticality measures. The results showed that lack of regulations awareness, unplanned settlements, encroachment and lack of HSE knowledge are among the high contributors of Third-party damage. Therefore, addressing these factors will help to mitigate NGP failures by third party damage.