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Abstract To address the problem of fossil fuel usage at the Missouri University of Science and Technology campus, using of alternative fuels and renewable energy sources can lower energy consumption and hydrogen use. Biogas, produced by anaerobic digestion of wastewater, organic waste, agricultural waste, industrial waste, and animal by-products is a potential source of renewable energy. In this work, we have discussed Hydrogen production and End-Uses from CHHP system for the campus using local resources. Following the resource assessment study, the team selects FuelCell Energy DFC1500™ unit as a molten carbonate fuel cell to study of combined heat, hydrogen and power (CHHP) system based on a molten carbonate fuel cell fed by biogas produced by anaerobic digestion. The CHHP system provides approximately 650 kg/day. The total hydrogen usage 123 kg/day on the university campus including personal transportation applications, backup power applications, portable power applications, and other mobility applications are 56, 16, 29, 17, and 5 respectively. The excess hydrogen could be sold to a gas retailer. In conclusion, the CHHP system will be able to reduce fossil fuel usage, greenhouse gas emissions and hydrogen generated is used to power different applications on the university campus.

Abstract A vapour absorption refrigeration system (VARS) in which a transfer tank replaces the conventional solution pump is analysed. Six fluid pairs with R22 as the refrigerant and different absorbents: DMA; DMF; DMETEG; DMETrEG; DMEDEG; and NMP are considered. Variations in COP, circulation ratio, percent mass of generated vapour utilised for transfer-tank operation, and minimum generator temperature are compared over a wide range of operating conditions. In general, R22-DMA, R22-DMF, and R22-DMETrEG are preferable for a transfer-tank operated VARS. At high generator temperatures or low condenser temperatures, R22-DMA gives the best overall performance. When the temperatures of the evaporator, absorber, and condenser are high, one may prefer R22-DMF as the working fluid.

Abstract A small reverse osmoisis (RO) plant supplied by a photovoltaic (PV) power supply has been installed at the island of Gran Canaria. On behalf of this system the feasibility of small PV-RO systems (1 m3/d) is investigated. The RO-plant is described in detail concerning its technical specifications, its operation constraints and its energy demand. Furthermore the photovoltaic power supply is described in detail. With simulations it is shown how the system is designed to guarantee a reliability of more than 96% in the water supply. A brief economic analysis shows that the water production costs are still high (about 16 $/m3) but can be lowered in future.

Abstract An indirect forced convection and desiccant integrated solar dryer is designed and fabricated to investigate its performance under the hot and humid climatic conditions of Chennai, India. The system consists of a flat plate solar air collector, drying chamber and a desiccant unit. The desiccant unit is designed to hold 75 kg of CaCl2-based solid desiccant consisting of 60% bentonite, 10% calcium chloride, 20% vermiculite and 10% cement. Drying experiments have been performed for green peas at different air flow rate. The equilibrium moisture content Me is reached in 14 h at an air flow rate of 0.03 kg/m2 s. The system pickup efficiency, specific moisture extraction rate, dimensionless mass loss, mass shrinkage ratio and drying rate are discussed in this paper.

Abstract To ensure techno-economically suitable installation of ground source heat pump (GSHP) systems, thermal and hydrogeological properties of the subsoil need to be investigated. In this paper, the geothermal potential for three types of GSHP installations in the urban area of Wuhan city is assessed based on preliminary geological investigations. The potential for shallow geothermal energy is evaluated for surface water heat pump systems (SWHP), groundwater heat pump systems (GWHP) and ground coupled heat exchanger heat pump systems (GCHP). The mapped shallow geothermal potentials provide essential information for the installation of GSHPs and for the management of geothermal resources of Wuhan city. Furthermore, the heat transfer rates for some typical configured borehole heat exchanger (BHE) are tested by field Thermal Response Tests (TRT). In order to understand the techno-economic feasibility of the GSHPs, different types of the installed systems are measured and analyzed.

Abstract The vertical pipe intake-outlet plays an important role in the pumped hydro energy storage (PHES), and its main parameters included the orifice height ratio (H∗), the diffuser short semi-axis ratio (a∗), the diffuser long semi-axis ratio (b∗) and the cover plate radius ratio (Rc∗). The aim of this study was to analyse effects of the parameters and obtain the optimal design. An integration method combining computational fluid dynamics (CFD), response surface methodology (RSM) and genetic algorithm was proposed. To evaluate grid independency, the grid converge index was introduced. Based on the validation for the baseline design (H∗ = 0.577, a∗ = 1.087, b∗ = 4.231 and Rc∗ = 1.635), a reliable CFD model was developed to obtain results of sample points. Then RSM models were constructed and assessed, and contribution and interactions of the parameters were analyzed. Finally, the optimal design (H∗ = 0.422, a∗ = 1.177, b∗ = 5.363 and Rc∗ = 2.115) was obtained. The CFD results show that the overall head loss coefficient, the inflow and the outflow velocity distribution coefficient are reduced by 4.687%, 11.765% and 38.596%, respectively. Especially, the negative velocity at the trashrack section in the pump mode is eliminated. The improvement demonstrates that the proposed method achieves significant superiority over the trial-and-error method traditionally adopted in the intake-outlet design.

Abstract Standardization of biogas technology is immensely important for the promotion of the biogas industry worldwide. China has built a complete biogas standard system, which is divided into common, household biogas, biogas engineering, biogas digester for domestic sewage treatment, output utilization, and service system standards. The problems and potential barriers for biogas standardization in China are analyzed and come down to sluggish standard, overlapped standard, government-dominated standard, and lagging international standard. Accordingly, all potential biogas standards should be evaluated and placed under the same department. China Biogas Society and China Association of Rural Energy Industry play leading roles in developing enterprise or group/association biogas standards and ISO biogas standards. The bio-natural gas standard system and experimental standardization should be developed as well to replenish biogas standard system. A paradigm shift in biogas standardization should be from government-dominated to market-oriented model. The lessons learned for other developing countries includes expanding standardization to multi-aspects to realize full lifecycle control and management, building rapid responding mechanism of standardization to adopt industry transformation, integrating outdated standards into new versions, and establishing market-based standard system.

Abstract It has been recognized that oils derived from microorganism and wastewater sludge are comparable replacements of traditional biodiesel production feedstock, which is energy intensive and costly. Energy balance and greenhouse gas (GHG) emissions are essential factors to assess the feasibility of the production. This study evaluated the energy balance and GHG emissions of biodiesel production from microbial and wastewater sludge oil. The results show that energy balance and GHG emissions of biodiesel produced from microbial oil are significantly impacted by the cultivation methods and carbon source. For phototrophic microorganism (microalgae), open pond system gives 3.6 GJ higher energy gain than photo bioreactor system in per tonne biodiesel produced. For heterotrophic microorganisms, the energy balance depends on the type of carbon source. Three carbon sources including starch, cellulose, and starch industry wastewater (SIW) used in this study showed that utilization of SIW as carbon source provided the most favorable energy balance. When oil extracted from municipal sludge is used for biodiesel production, the energy gain is up to 29.7 GJ per tonne biodiesel produced, which is higher than the energy gain per tonne of biodiesel produced from SIW cultivated microbes. GHG emissions study shows that biodiesel production from microbes or sludge oil is a net carbon dioxide capture process except when starch is used as raw material for microbial oil production, and the highest capture is around 40 tonnes carbon dioxide per tonne of biodiesel produced.

Abstract Thermal conductivity and thermal borehole resistance are basic parameters for the technical and sustainable design of closed ground source heat pump (GSHP) systems. One of the most common methods to determine these parameters is the thermal response test (TRT). The response data measured are typically evaluated by the Kelvin line source equation which does not consider all relevant processes of heat transfer in the subsurface. The approach only considers conductive heat transfer from the borehole heat exchanger (BHE) and all transport effects are combined in the parameters of effective thermal conductivity and thermal borehole resistance. In order to examine primary effects in more detail, a sensitivity study based on numerically generated TRT data sets is performed considering the effects of (1) the in-situ position of the U-shaped pipes of borehole heat exchangers (shank spacing), (2) a non-uniform initial thermal distribution (such as a geothermal gradient), and (3) thermal dispersivity. It will be demonstrated that the shank spacing and the non-uniform initial thermal distribution have minor effects (less than 10%) on the effective thermal conductivity and the determined borehole resistance. Constant groundwater velocity with varying thermal dispersivity values, however, has a significant influence on the thermal borehole resistance. These effects are even more pronounced for interpreted effective thermal conductivity which is overestimated by a factor of 1.2–2.9 compared to the real thermal conductivity of the saturated porous media.