Solar PV-powered SRM drive for EVs with flexible energy control functions

Electric vehicles (EVs) provide a feasible solution to reducing greenhouse gas emissions and thus become a hot topic for research and development. Switched reluctance motors (SRMs) are one of promised motors for EV applications. In order to extend the EVs’ driving miles, the use of photovoltaic (PV) panels on the vehicle helps decrease the reliance on vehicle batteries. Based on phase winding characteristics of SRMs, a tri-port converter is proposed in this paper to control the energy flow between the PV panel, battery and SRM. Six operating modes are presented, four of which are developed for driving and two for standstill on-board charging. In the driving modes, the energy decoupling control for maximum power point tracking (MPPT) of the PV panel and speed control of the SRM are realized. In the standstill charging modes, a grid-connected charging topology is developed without a need for external hardware. When the PV panel directly charges the battery, a multi-section charging control strategy is used to optimize energy utilization. Simulation results based on Matlab/Simulink and experiments prove the effectiveness of the proposed tri-port converter, which has potential economic implications to improve the market acceptance of EVs.

Solid biofuel production by mechanical pre-treatment of brewers' spent grain

The brewing industry produces large amounts of by-products and wastes like brewers' spent grain (BSG). In Germany, each year approximately 2.1 million tonnes of BSG are generated. During the last years conventional routes of BSG utilization face a remarkable change, such as the decline in the demand as animal feed. Due to its high content of organic matter energetic utilization may create an additional economic value for breweries. Furthermore, in the recent past breweries tend to shift their energy supply towards more sustainable concepts. Although, a decent number of research projects were carried out already, still no mature strategy is available. However, one possible solution can be the mechanical pretreatment of BSG. This step allows optimized energy utilization by the fractionation of BSG. Due to the transfer of digestible components, such as protein, to the liquid phase, the solid phase will largely consist of combustible components. That represents an opportunity to produce a solid biofuel with lower fuelnitrogen content compared to only thermal dried BSG. Therefore, two main purposes for the mechanical pre-treatment were determined, (1) to reduce the moisture content to at least 60 % (w/w) and (2) to diminish the protein content of the solid phase by 30 %. Moreover, the combustion trials should demonstrate whether stable processes and flue gas emissions within the legal limits in Germany are feasible. The results of the mechanical pre-treatment trials showed that a decrease of the moisture and protein content has been achieved. With regard to the combustion trials inconsistent outcomes were found. On the one hand a stable combustion was realized. On the other hand the legal emission levels of NOx (500 mgm -3) and dust (50 mgm-3) could not be kept during all trials. The further research steps will focus on the optimization of the air/fuel ratio by reducing the primary and secondary air conditions. Copyright © 2014,AIDIC Servizi S.r.l.

Short-term wind power forecasting using Gaussian processes

Since wind has an intrinsically complex and stochastic nature, accurate wind power forecasts are necessary for the safety and economics of wind energy utilization. In this paper, we investigate a combination of numeric and probabilistic models: one-day-ahead wind power forecasts were made with Gaussian Processes (GPs) applied to the outputs of a Numerical Weather Prediction (NWP) model. Firstly the wind speed data from NWP was corrected by a GP. Then, as there is always a defined limit on power generated in a wind turbine due the turbine controlling strategy, a Censored GP was used to model the relationship between the corrected wind speed and power output. To validate the proposed approach, two real world datasets were used for model construction and testing. The simulation results were compared with the persistence method and Artificial Neural Networks (ANNs); the proposed model achieves about 11% improvement in forecasting accuracy (Mean Absolute Error) compared to the ANN model on one dataset, and nearly 5% improvement on another.

Oil bearing seasonal crops in India:energy and phytoremediation potential

Purpose: A variety of biomass plantations are being raised for energy production. This case study is on energy production potential of seasonal oil bearing crops in India. These crops have the advantage of producing oil (liquid fuel) as well as biomass as agro residue (solid fuel). The purpose of the study is to estimate total energy yields of oil bearing crops and compare with other types of energy plantations. Also oil bearing crops bioaccumulate metals and thus phytoremediate soil. This provides scope for waste water irrigation. Design/methodology/approach: Relevant published papers on energy production by raising oil bearing crops have been analyzed. The effect of waste water irrigation and agronomic practices on increasing productivity is given special attention. Findings: It is shown that the seasonal oil bearing crops such as castor have a high potential to generate energy and this is comparable to energy produced by many perennial grasses. The energy yields of castor under irrigated condition was 196×103 MJ/ha and this is comparable to the reed canary grass which yields 195×103 MJ/ha. Some of the oil bearing crops are also super accumulators of certain toxic metals. Research limitations/implications: In this study, only all the accessible papers on the topic could be analyzed. Practical implications: This case study indicates that raising oil bearing crops such as castor using waste water has many advantages which include high energy yields, utilization of waste water for productive purpose and phytoremediation of soil. Originality/value: The comparison made between various types of energy crops for their energy generation is an original contribution. Findings of economic and environmental benefits by waste water irrigation are also of value. © Emerald Group Publishing Limited.

A micro industry with closed energy and water cycles for sustainable rural development

Sustainable development requires combining economic viability with energy and environment conservation and ensuring social benefits. It is conceptualized that for designing a micro industry for sustainable rural industrialization, all these aspects should be integrated right up front. The concept includes; (a) utilization of local produce for value addition in a cluster of villages and enhancing income of the target population; (b) use of renewable energy and total utilization of energy generated by co and trigeneration (combining electric power production with heat utilization for heating and cooling); (c) conservation of water and complete recycling of effluents; (d) total utilization of all wastes for achieving closure towards a zero waste system. Enhanced economic viability and sustainability is achieved by integration of appropriate technologies into the industrial complex. To prove the concept, a model Micro Industrial Complex (MIC) has been set up in a semi arid desert region in Rajasthan, India at village Malunga in Jodhpur district. A biomass powered boiler and steam turbine system is used to generate 100-200 KVA of electric power and high energy steam for heating and cooling processes downstream. The unique feature of the equipment is a 100-150 kW back-pressure steam turbine, utilizing 3-4 tph (tonnes per hour) steam, developed by M/s IB Turbo. The biomass boiler raises steam at about 20 barg 3 tph, which is passed through a turbine to yield about 150 kW of electrical power. The steam let out at a back pressure of 1-3 barg has high exergy and this is passed on as thermal energy (about 2 MW), for use in various applications depending on the local produce and resources. The biomass fuel requirement for the boiler is 0.5-0.75 tph depending on its calorific value. In the current model, the electricity produced is used for running an oil expeller to extract castor oil and the castor cake is used as fuel in the boiler. The steam is used in a Multi Effect Distillation (MED) unit for drinking water production and in a Vapour Absorption Machine (VAM) for cooling, for banana ripening application. Additional steam is available for extraction of herbs such as mint and processing local vegetables. In this paper, we discuss the financial and economic viability of the system and show how the energy, water and materials are completely recycled and how the benefits are directed to the weaker sections of the community.