Development of a Simplex Optimization Technique for Biogas Generation of Electrical Energy

Biogas energy production is a key technology in the development of sustainable energy supply systems aiming at covering the energy demand using renewable sources. The production can be achieved with anaerobic digestion.This paper developsa simplex optimization model for biogas energy generation. The bio-digester used to generate the biogas energy in this work is animal manure because of availability of the materials. The simplex optimization model was then developed by adding a slack variable to the biogas model in order to find a value of the decision variable for the model. This was done to find a value of the decision variable where all the constraints are fulfilled. When a feasible basic solution wasfound, the algorithm sought from new vertex to find the optimal solution. The next vertex was chosen such that the search direction was in the steepest feasible direction. The developed simplex optimization model was then used to optimize the full-scale of the biogas energy. A simplexoptimization model for biogas energy generation with a coefficient of -1.1733 and 20.639 (R square value of -0.073) was developed.The resultsshowed that the total biogas energy generated before optimization were 636.6MW and 889.49MW after optimization. The biogas energy generation was increasedby 252.89MW, which was 39.7% increase after optimization. The results showed the applicability of the optimization model which can be exploited using optimal control scheme. The outcome of the optimization result indicates that the developed model is a useful mechanism yielding an economical solution on one hand and increase in renewable energy contribution on the other. Keywords: Biogas Energy Production, Computer Simulation, Simplex Optimization, Renewable Energy, Anaerobic Digestion, Coefficient of Polynomial

A multiple system level modeling approach to coupled energy markets: Incentives for combined heat and power generation at the plant, city and regional energy system levels

The energy system can be subdivided into interconnected structural levels with differing boundary conditions and objectives. For heat and power generation, these levels may be the: electricity price area (regional); heat price area (city); and production site (power plant). This work presents a multi-system modeling approach for the analysis of investments and operation of combined heat and power (CHP) plants, as optimized on a regional, city, or production site energy system level. The modeling framework, comprising three energy system optimization models at the respective levels, is applied to a case study of Sweden, electricity price area SE3. The modeling levels are optimized separately but linked through electricity and heat prices. The results show that optimized CHP plant investments and operation on the three levels can both align and differ, depending on conditions. With a low biomass price and moderate congestion in transmission capacity into the city, the results from the three levels generally align. Differences arise if the biomass price is increased, which impacts the competitiveness of CHP plants in the region, while city-level CHP investments are mainly determined by the local heat demand and less-sensitive to external changes. The differences indicate a risk for diverging expectations between system levels

CFD Applications in Energy Engineering Research and Simulation: An Introduction to Published Reviews

Computational Fluid Dynamics (CFD) has been firmly established as a fundamental discipline to advancing research on energy engineering. The major progresses achieved during the last two decades both on software modelling capabilities and hardware computing power have resulted in considerable and widespread CFD interest among scientist and engineers. Numerical modelling and simulation developments are increasingly contributing to the current state of the art in many energy engineering aspects, such as power generation, combustion, wind energy, concentrated solar power, hydro power, gas and steam turbines, fuel cells, and many others. This review intends to provide an overview of the CFD applications in energy and thermal engineering, as a presentation and background for the Special Issue “CFD Applications in Energy Engineering Research and Simulation” published by Processes in 2020. A brief introduction to the most significant reviews that have been published on the particular topics is provided. The objective is to provide an overview of the CFD applications in energy and thermal engineering, highlighting the review papers published on the different topics, so that readers can refer to the different review papers for a thorough revision of the state of the art and contributions into the particular field of interest

Towards the synthesis of wastewater recovery facilities using enviroeconomic optimization

The wastewater treatment industry is undergoing a major shift towards a proactive interest in recovering materials and energy from wastewater streams, driven by both economic incentives and environmental sustainability. With the array of available treatment technologies and recovery options growing steadily, systematic approaches to determining the inherent trade-off between multiple economic and environmental objectives become necessary, namely enviroeconomic optimization. The main objective of this chapter is to present one such methodology based on superstructure modeling and multi-objective optimization, where the main environmental impacts are quantified using life cycle assessment (LCA). This methodology is illustrated with the case study of a municipal wastewater treatment facility. The results show that accounting for LCA considerations early on in the synthesis problem may lead to dramatic changes in the optimal process configuration, thereby supporting LCA integration into decision-making tools for wastewater treatment alongside economical selection criteria

Application of Biogas Installations as an Alternative Method to Receive Energy

The article proves that application of biogas installations as an alternative method to receive energy is efficient; it shows that there are certain difficulties in biogas production. The use of biogas installations in Russia is a quite new energy production method. Despite indisputable benefits of their application, there are also problems connected the half-baked process of their application, rather big investments and, as a result, not a short payback period. There are no federal methods of rate calculations for biogas energy. Besides the fact that electric power and heat received from biogas processing are very economical for enterprises, this production is ecologically friendly; it prevents methane emission in the atmosphere, which is an important thing. One more great benefit is the associated products received in the course waste conversion. The article also points out special features of biogas and biogas installations from the point of view of ecology and efficiency. We have described the project how to use a biogas installation, which characteristics considerably exceed its analogs

Simulation, optimization and instrumentation of agricultural biogas plants

During the last two decades, the production of renewable energy by anaerobic digestion (AD) in biogas plants has become increasingly popular due to its applicability to a great variety of organic material from energy crops and animal waste to the organic fraction of Municipal Solid Waste (MSW), and to the relative simplicity of AD plant designs. Thus, a whole new biogas market emerged in Europe, which is strongly supported by European and national funding and remuneration schemes. Nevertheless, stable and efficient operation and control of biogas plants can be challenging, due to the high complexity of the biochemical AD process, varying substrate quality and a lack of reliable online instrumentation. In addition, governmental support for biogas plants will decrease in the long run and the substrate market will become highly competitive. The principal aim of the research presented in this thesis is to achieve a substantial improvement in the operation of biogas plants. At first, a methodology for substrate inflow optimization of full-scale biogas plants is developed based on commonly measured process variables and using dynamic simulation models as well as computational intelligence (CI) methods. This methodology which is appliquable to a broad range of different biogas plants is then followed by an evaluation of existing online instrumentation for biogas plants and the development of a novel UV/vis spectroscopic online measurement system for volatile fatty acids. This new measurement system, which uses powerful machine learning techniques, provides a substantial improvement in online process monitoring for biogas plants. The methodologies developed and results achieved in the areas of simulation and optimization were validated at a full-scale agricultural biogas plant showing that global optimization of the substrate inflow based on dynamic simulation models is able to improve the yearly profit of a biogas plant by up to 70%. Furthermore, the validation of the newly developed online measurement for VFA concentration at an industrial biogas plant showed that a measurement accuracy of 88% is possible using UV/vis spectroscopic probes

Flexible operation of a combined cycle cogeneration plant - A techno-economic assessment

The need for flexibility in combined heat and power (CHP) plants is expected to increase due to the strong expansion of wind power in electricity systems. Cost-effective strategies to enhance the flexibility of CHP operation are therefore needed. This paper analyzes three types of flexibility measures for a combined cycle CHP plant and their relative impact on the plant operation and revenue. The types of flexibility are: operational flexibility of the fuel conversion system, product flexibility with variable plant product ratios (heat/electricity/primary frequency response), and thermal flexibility in a district heating network. A modeling framework consisting of steady-state and dynamic process simulation models and optimization model is developed to combine static, dynamic, technical and economic perspectives on flexibility. A reference plant serves as a basis for the process model development and validation, and an energy system model provides input profiles for future electricity price scenarios. The results indicate that product flexibility and thermal flexibility have the highest value for the cogeneration plant (up to 16.5\ua0M€ increased revenue for a 250 MWel plant), while operational flexibility (ramp rate) has a comparatively small impact (<1.4\ua0M€). A wide load span and plant versatility, e.g. electricity and heat generating potential between 0 and 139% of nominal capacity, is beneficial in future energy system contexts, but has a marginal value in the current system. Electricity price volatility is a main driver that increases the value of flexibility and promotes operating strategies that follow the electricity price profile rather than the heat demand

Composite Multi-Criteria Decision Analysis for Optimization of Hybrid Renewable Energy Systems for Geopolitical Zones in Nigeria

This paper presents eight hybrid renewable energy (RE) systems that are derived from solar, wind and biomass, with energy storage, to meet the energy demands of an average household in the six geopolitical zones of Nigeria. The resource assessments show that the solar insolation, wind speed (at 30 m hub height) and biomass in the country range, respectively, from 4.38–6.00 kWh/m2/day, 3.74 to 11.04 m/s and 5.709–15.80 kg/household/day. The HOMER software was used to obtain optimal configurations of the eight hybrid energy systems along the six geopolitical zones’ RE resources. The eight optimal systems were further subjected to a multi-criteria decision making (MCDM) analysis, which considers technical, economic, environmental and socio-cultural criteria. The TOPSIS-AHP composite procedure was adopted for the MCDM analysis in order to have more realistic criteria weighting factors. In all the eight techno-economic optimal system configurations considered, the biomass generator-solar PV-battery energy system (GPBES) was the best system for all the geopolitical zones. The best system has the potential of capturing carbon from the atmosphere, an attribute that is desirous for climate change mitigation. The cost of energy (COE) was seen to be within the range of 0.151–0.156 US$/kWh, which is competitive with the existing electricity cost from the national grid, average 0.131 US$/kWh. It is shown that the Federal Government of Nigeria favorable energy policy towards the adoption of biomass-to-electricity systems would make the proposed system very affordable to the rural households