Techno-economic performance analysis of bio-oil based Fischer-Tropsch and CHP synthesis platform

The techno-economic potential of the UK poplar wood and imported oil palm empty fruit bunch derived bio-oil integrated gasification and Fischer-Tropsch (BOIG-FT) systems for the generation of transportation fuels and combined heat and power (CHP) was investigated. The bio-oil was represented in terms of main chemical constituents, i.e. acetic acid, acetol and guaiacol. The compositional model of bio-oil was validated based on its performance through a gasification process. Given the availability of large scale gasification and FT technologies and logistic constraints in transporting biomass in large quantities, distributed bio-oil generations using biomass pyrolysis and centralised bio-oil processing in BOIG-FT system are technically more feasible. Heat integration heuristics and composite curve analysis were employed for once-through and full conversion configurations, and for a range of economies of scale, 1 MW, 675 MW and 1350 MW LHV of bio-oil. The economic competitiveness increases with increasing scale. A cost of production of FT liquids of 78.7 Euro/MWh was obtained based on 80.12 Euro/MWh of electricity, 75 Euro/t of bio-oil and 116.3 million Euro/y of annualised capital cost.     

Aspen Plus simulation of biomass integrated gasification combined cycle systems at corn ethanol plants

Biomass integrated gasification combined cycle (BIGCC) systems and natural gas combined cycle (NGCC) systems are employed to provide heat and electricity to a 0.19 hm³ y⁻¹ (50 million gallon per year) corn ethanol plant using different fuels (syrup and corn stover, corn stover alone, and natural gas). Aspen Plus simulations of BIGCC/NGCC systems are performed to study effects of different fuels, gas turbine compression pressure, dryers (steam tube or superheated steam) for biomass fuels and ethanol co-products, and steam tube dryer exhaust treatment methods. The goal is to maximize electricity generation while meeting process heat needs of the plant. At fuel input rates of 110 MW, BIGCC systems with steam tube dryers provide 20–25 MW of power to the grid with system thermal efficiencies (net power generated plus process heat rate divided by fuel input rate) of 69–74%. NGCC systems with steam tube dryers provide 26–30 MW of power to the grid with system thermal efficiencies of 74–78%. BIGCC systems with superheated steam dryers provide 20–22 MW of power to the grid with system thermal efficiencies of 53–56%. The life-cycle greenhouse gas (GHG) emission reduction for conventional corn ethanol compared to gasoline is 39% for process heat with natural gas (grid electricity), 117% for BIGCC with syrup and corn stover fuel, 124% for BIGCC with corn stover fuel, and 93% for NGCC with natural gas fuel. These GHG emission estimates do not include indirect land use change effects.     

A new method for an economic assessment of heat and power plants using dimensionless numbers

A comparison of economic data for different technologies and fuels is difficult due to the number of parameters that can alter the profitability of heat and power production. In addition, the variation of currency exchange rates considerably reduces the possibility of comparing plants in different countries. In the present study, a new method based on dimensionless costs is proposed to overcome these difficulties. Dimensionless capital costs C (including maintenance) and dimensionless fuel costs F are introduced by dividing the costs by the price for heat or electricity. In a diagram of C versus F the economy of different technologies can be compared. The diagram is divided into a profitable and an unprofitable area. The orientation of the data from one specific plant shows immediately whether the plant can be operated economically or not. Furthermore it can be seen by which factor either the fuel costs have to be reduced, or the price for electricity or heat has to be increased, or the capital and maintenance costs have to be reduced to reach the profitable area. The dimensionless diagram is independent from currency exchange rates. To demonstrate the application of the method, data from an economic assessment study of power production plants from biomass using pyrolysis, gasification and combustion technologies are presented.     

On efficiency of plasma gasification of wood residues

High temperature plasma gasification of wood is evaluated for the production of a fuel gas (syngas) for combined heat and power production. The advantages of plasma by comparison with existing thermochemical processes are in the high heating value gases, process control and the lower energy consumption per unit of output. From one kilogram of 20% moisture wood it is possible to obtain 4.6-4.8 MJ of electricity (net of electricity input) and 9.1-9.3 MJ of thermal energy when using wood with average elemental composition and with a LHV energy content of 13.9 MJ, when using a combined Brayton and Steam cycle generating plant. Experimental data from an air plasma gasification plant using alternating current (AC) plasma torches was integrated with a thermodynamic model showing that the chemical energy in the produced syngas was 13.8-14.3 MJ kg⁻¹ with a power input of 2.2-3.3 MJ kg⁻¹.     

An update technology for integrated biomass gasification combined cycle power plant

A discussion is presented on the technical analysis of a 6.4 MW_e integrated biomass gasification combined cycle (IBGCC) plant. It features three numbers of downdraft biomass gasifier systems with suitable gas clean-up trains, three numbers of internal combustion (IC) producer gas engines for producing 5.85 MW electrical power in open cycle and 550 kW power in a bottoming cycle using waste heat. Comparing with IC gas engine single cycle systems, this technology route increases overall system efficiency of the power plant, which in turn improves plant economics. Estimated generation cost of electricity indicates that mega-watt scale IBGCC power plants can contribute to good economies of scale in India. This paper also highlight’s the possibility of activated carbon generation from the char, a byproduct of gasification process, and use of engine’s jacket water heat to generate chilled water through VAM for gas conditioning.     

Assessment of forest biomass for use as energy. GIS-based analysis of geographical availability and locations of wood-fired power plants in Portugal

Following the European Union strategy concerning renewable energy (RE), Portugal established in their national policy programmes that the production of electrical energy from RE should reach 45% of the total supply by 2010. Since Portugal has large forest biomass resources, a significant part of this energy will be obtained from this source. In addition to the two existing electric power plants, with 22 MW of power capacity, 13 new power plants having a total of 86.4 MW capacity are in construction. Together these could generate a combination of electrical and thermal energy, known as combined heat and power (CHP) production. As these power plants will significantly increase the exploitation of forests resources, this article evaluates the potential quantities of available forest biomass residue for that purpose. In addition to examining the feasibility of producing both types of energy, we also examine the potential for producing only electric energy. Results show that if only electricity is generated some regions will need to have alternative fuel sources to fulfil the demand. However, if cogeneration is implemented the wood fuel resource will be sufficient to fulfill the required capacity demand.     

Testing activity‐based costing to large‐scale combined heat and power plant using bioenergy

This paper deals with the energy production and economics of a large‐scale biomass‐based combined heat and power (CHP) plant. An activity‐based costing model was developed for estimating the production costs of the heat and power of the bio‐CHP. A 100 MW plant (58 MW heat, 29 MW electricity) was used as reference. The production process was divided into four stages: fuel handling, fluidized bed boiler, turbine plant, and flue gas cleaning. The boiler accounted for close to 50% of the production costs. The interest rates and the utilization rate of the CHP had a significant effect on the profitability. We found that below 4000–4500 h per year utilization, the electricity production turned unprofitable. However, the heat production remained profitable with high interest rate (10%) and a low utilization rate (4000 h). The profitability also depended on the type of biomass used. We found that, e.g. with moderate interest rates and high utilization rate of the plant, the bio‐CHP plant could afford wood and Reed canary grass as fuel sources. Copyright © 2013 John Wiley & Sons, Ltd.     

Process integration and economic analysis of bio-oil platform for the production of methanol and combined heat and power

Process to process material and heat integration strategies for bio-oil integrated gasification and methanol synthesis (BOIG-MeOH) systems were developed to assess their technological and economic feasibility. Distributed bio-oil generations and centralised processing enhance resource flexibility and technological feasibility. Economic performance depends on the integration of centralised BOIG-MeOH processes, investigated for cryogenic air separation unit (ASU) and water electrolyser configurations. Design and operating variables of gasification, heat recovery from gases, water and carbon dioxide removal units, water-gas shift and methanol synthesis reactors and CHP network were analysed to improve the overall efficiency and economics. The efficiency of BOIG-MeOH system using bio-oil from various feedstocks was investigated. The system efficiency primarily attributed by the moisture content of the raw material decreases from oilseed rape through miscanthus to poplar wood. Increasing capacity and recycle enhances feasibility, e.g.1350 MW BOIG-MeOH with ASU and 90% recycle configuration achieves an efficiency of 61.5% (methanol, low grade heat and electricity contributions by 89%, 7.9% and 3% respectively) based on poplar wood and the cost of production (COP) of methanol of 318.1 Euro/t for the prices of bio-oil of 75 Euro/t and electricity of 80.12 Euro/MWh, respectively. An additional transportation cost of 4.28-8.89 Euro/t based on 100 km distance between distributed and centralised plants reduces the netback of bio-oil to 40.9-36.3 Euro/t.     

Entrained flow gasification of straw- and wood-derived pyrolysis oil in a pressurized oxygen blown gasifier

Fast pyrolysis oil can be used as a feedstock for syngas production. This approach can have certain advantages over direct biomass gasification. Pilot scale tests were performed to investigate the route from biomass via fast pyrolysis and entrained flow gasification to syngas. Wheat straw and clean pine wood were used as feedstocks; both were converted into homogeneous pyrolysis oils with very similar properties using in-situ water removal. These pyrolysis oils were subsequently gasified in a pressurized, oxygen blown entrained flow gasifier using a thermal load of 0.4 MW. At a pressure of 0.4 MPa and a lambda value of 0.4, temperatures around 1250 °C were obtained. Syngas volume fractions of 46% CO, 30% H₂ and 23% CO₂ were obtained for both pyrolysis oils. 2% of CH₄ remained in the product gas, along with 0.1% of both C₂H₂ and C₂H₄. Minor quantities of H₂S (3 vs. 23) cm³ m⁻³, COS (22 vs. 94) cm³ m⁻³ and benzene (310 vs. 532) cm³ m⁻³ were measured for wood- and straw derived pyrolysis oils respectively. A continuous 2-day gasification run with wood derived pyrolysis oil demonstrated full steady state operation. The experimental results show that pyrolysis oils from different biomass feedstocks can be processed in the same gasifier, and issues with ash composition and melting behaviour of the feedstocks are avoided by applying fast pyrolysis pre-treatment.     

Techno-economic analysis of using corn stover to supply heat and power to a corn ethanol plant – Part 2: Cost of heat and power generation systems

This paper presents a techno-economic analysis of corn stover fired process heating (PH) and the combined heat and power (CHP) generation systems for a typical corn ethanol plant (ethanol production capacity of 170 dam³). Discounted cash flow method was used to estimate both the capital and operating costs of each system and compared with the existing natural gas fired heating system. Environmental impact assessment of using corn stover, coal and natural gas in the heat and/or power generation systems was also evaluated. Coal fired process heating (PH) system had the lowest annual operating cost due to the low fuel cost, but had the highest environmental and human toxicity impacts. The proposed combined heat and power (CHP) generation system required about 137 Gg of corn stover to generate 9.5 MW of electricity and 52.3 MW of process heat with an overall CHP efficiency of 83.3%. Stover fired CHP system would generate an annual savings of 3.6 M$ with an payback period of 6 y. Economics of the coal fired CHP system was very attractive compared to the stover fired CHP system due to lower fuel cost. But the greenhouse gas emissions per Mg of fuel for the coal fired CHP system was 32 times higher than that of stover fired CHP system. Corn stover fired heat and power generation system for a corn ethanol plant can improve the net energy balance and add environmental benefits to the corn to ethanol biorefinery.     

Assessment of the renewable energies potential for intensive electricity production in the province of Jaén,southern Spain

The foreseen depletion of the traditional fossil fuels for the forthcoming decades is forcing us to seek for new sustainable and non-pollutant energy sources. Renewable energies rely on a decentralized scheme strongly dependent on the local resources availability. In this work, we tackle the study of the renewable energies potential for an intensive electricity production in the province of Jaén (southern Spain) which has a pronounced unbalance between its inner electricity production and consumption. The potential of biomass from olive pruning residues, solar photovoltaics (PV) and wind power has been analyzed using Geographical Information System tools, and a proposal for a massive implementation of renewable energies has been arisen. In particular, we propose the installation of 5 biomass facilities, totaling 98 MW of power capacity, with an estimated annual production of 763 GWh, 12 PV facilities, totaling 420 MW of power capacity, with an estimated annual production of 656 GWh and 506 MW of wind power capacity in a number of wind farms, with an estimated annual production of 825 GWh. Overall, this production frame would meet roughly a 75% of the electricity demands in the province and thus would mitigate the current unbalance.     

Use of hydrogen produced by the air conversion of motor diesel fuel in an electrochemical generator

At present, the production of electric energy consumer remote from agro-based centralized networks is done using diesel-generator technology with limited service life of the engine and the extremely low efficiency in the use of expensive fuel. In this paper, is considered an innovative technology of combined production of electricity and heat using a preliminary conversion of diesel fuel in the synthesis gas and then serving it at high temperature electrochemical generator. Synthetic gas to operate the generator air conversion is made of an electrochemical engine diesel fuels in catalytic reactor-burner. On the basis of heat balances of the torch, battery power and boiler are calculated: battery electric efficiency SOFC, chemical efficiency burner, SOFC anode temperature, EMF Planar element, the proportion of hydrogen, oxidized anode SOFC, unit cost of diesel fuel for the production of electricity and thermal energy. Specific consumption of diesel fuel for the production of electrical energy 114 g/kWh (162 g. w. t./kWh), and thermal 31.7 kg/Gj (45.1 kg/GJ, w. t. 189 kg standard fuel/Gcal).     

Calculation of bright roof-tops for solar PV applications in Dhaka Megacity,Bangladesh

Bangladesh has already been known as the country of power crisis. Although the country's electricity generation capacity is 4275 MW, around 3000–3500 MW of electricity can be generated against the demand of more than 5000 MW. The country's power is being generated mostly with conventional fuel (82% indigenous natural gas, 9% imported oil, 5% coal) and renewable sources (4% hydropower and solar). But recently a remarkable decline of the indigenous gas takes place, which rapidly aggravates electricity generation. Dhaka, the capital as well as prime city of the country with its nearly 14 million populations faces the worst situation due to the shortfall of electricity. Around 1000–1200 MW of electricity is supplied to Dhaka Megacity, while the existing demand is nearly 2000 MW. As a result frequent load shedding takes place and most of the service sectors in the city are interrupted, which has recently created immense dissatisfaction among the city-dwellers. Given the city's power crisis and geophysical situations, applications of either stand-alone or grid connected PV systems would be very effective and pragmatic for power supplement. The conservative calculation of bright roof-tops from the Quickbird Scene 2006 of Dhaka city indicates that the city offers 10.554 km² of bright roof-tops within the Dhaka City Corporation (DCC) ward area (134.282 km²). The application of stand-alone PV systems with 75 Wp solar modules can generate nearly 1000 MW of electrical power, which can substantially meet the city's power demand.     

Multi-objective optimization of a clean combined system based gasifier-solid oxide fuel cell

Biomass can be used as fuel of fuel cells by conducting thermochemical process such as biomass gasification. In this study, the required fuel of a solid oxide fuel cell was supplied through pine gasification in a gasifier reactor. The purpose of this study was provided an appropriate configuration to a co-generation system produced heat and power and the state with maximum heat and power production and minimum carbon dioxide emission was obtained. The outputs were power, heat, and CO₂ emission investigated with respect to steam to biomass ratio of gasification and current density and fuel utilization factor of solid oxide fuel cell. The results indicated that fuel utilization factor contributed the most on power and hot water with shares of 73.64% and 47.27%, respectively. However, current density had the highest influence on carbon dioxide emission with a share of 83.41%. Parametric analysis illustrated that increasing fuel utilization factor remarkably enhanced the power production and mitigated hot water production. A considerable reduction was observed in carbon dioxide emission by increasing current density. Single-objective and multi-objective optimizations revealed that steam to biomass ratio of 2, 4600 A/m² of current density, 0.77 of utilization factor are the optimum states. Power production of 196.8 kW, hot water production of 1203 g/s, and carbon dioxide emission of 1261 kg/MW.h were the outputs of the optimum state.     

Integration of Kalina cycle in a combined heat and power plant,a case study

This paper presents the integration of the Kalina cycle process in a combined heat and power plant for improvement of efficiency. In combined heat and power plants, the heat of flue gases is often available at low temperatures. This low-grade waste heat cannot be used for steam production and therefore power generation by a conventional steam cycle. Moreover, the steam supply for the purpose of heating is mostly exhausted, and therefore the waste heat at a low-grade temperature is not usable for heating. If other measures to increase the efficiency of a power plant process, like feed-water heating or combustion air heating, have been exhausted, alternative ways to generate electricity like the Kalina cycle process offer an interesting option. This process maximizes the generated electricity with recovery of heat and without demand of additional fuels by integration in existing plants. The calculations show that the net efficiency of an integrated Kalina plant is between 12.3% and 17.1% depending on the cooling water temperature and the ammonia content in the basic solution. The gross electricity power is between 320 and 440 kW for 2.3 MW of heat input to the process. The gross efficiency is between 13.5% and 18.8%.     

Potential applications of high-temperature air/steam-blown gasification and pyrolysis systems

Several aspects of using the advanced, high-temperature air/steam-blown gasification and pyrolysis technologies for converting solid fuels into syngas are examined. The gasification/pyrolysis systems, known as Multi-staged Enthalpy Extraction Technology (MEET), employ high-temperature air and steam as oxidizer agents for converting the solid fuels into syngas and have many features that are advantageous for power generation. The low-cost gasifier/pyrolyzer is extremely compact and flexible, capable of operating efficiently on a wide range of low-caloric-value fuels. Potential uses of this technology range from large-scale integrated gasification power plants to small-scale waste-to-energy applications. Present R&D status of the MEET technology are summarized and its main components are described. Major fuel resources for the different markets are explored. The performance and feasibility of diverse power conversion systems to couple with MEET gasifier/pyrolyzer for combined heat and power applications are assessed.     

Analysis of MTH-System (Methylcyclohexane-Toluene-Hydrogen-System) for hydrogen production as fuel for power plants

The utilization of hydrogen (H₂) gas as green energy fuel in power plants is a great challenge due to its storage, deployment and transportation. Herein, we propose a simulation based study of H₂ fueled power plant by using Methylcyclohexane-Toluene-Hydrogen-System (MTH-System). A 266 MW gas turbine was selected and the performance of MTH-System for power plant was investigated. The process for methylcyclohexane (MCH) production was not discussed here. However, the conversion of MCH into gaseous H₂ for power generation was discussed in detail. A sustainable process flow diagram (PFD) was developed. The heat integration b/w power plant and dehydrogenation reactor reveal that, minimum 70% MCH conversion is required to accomplish the heat demand of whole system. The effect of addition of H₂ recycle stream to dehydrogenation reactor and combined cycle power plants was investigated. The sensitivity and economic analysis reveal 2291.4 $/kW capital cost based on dehydrogenation of MCH for power production and 0.186 $/kWh output electricity cost based on complete MTH-System.     

Design and analysis of an integrated concentrated solar and wind energy system with storage

This study analyzes a renewable energy‐driven innovative multigeneration system, in which wind and solar energy sources are utilized in an efficient way to generate several useful commodities such as hydrogen, oxygen, desalted water, space cooling, and space heating along with electricity. A 1‐km² heliostat field is considered to concentrate the solar light onto a spectrum splitter, where the light spectrum is separated into two portions as reflected and transmitted to be used as the energy source in the concentrated solar power (CSP) and concentrated photovoltaics (CPV) receivers, respectively. As such, CSP and CPV systems are integrated. Wind energy is proposed for generating electricity (146 MW) or thermal energy (138 MW) to compensate the energy need of the multigeneration system when there is insufficient solar energy. In addition, multiple commodities, 46 MW of electricity, 12 m³/h of desalted water, and 69 MW of cooling, are generated using the Rankine cycle and the rejected heat from its condenser. Further, the heat generated on CPV cells is recovered for efficient photovoltaic conversion and utilized in the space heating (34 MW) and proton exchange membrane (PEM) electrolyzer (239 kg/h) for hydrogen production. The energy and exergy efficiencies of the overall system are calculated as 61.3% and 47.8%, respectively. The exergy destruction rates of the main components are presented to identify the potential improvements of the system. Finally, parametric studies are performed to analyze the effect of changing parameters on the exergy destruction rates, production rates, and efficiencies.     

Exergetic analysis of solid oxide fuel cell and biomass gasification integration with heat pipes

This paper presents an exergetic analysis of a combined heat and power (CHP) system, integrating a near-atmospheric solid oxide fuel cell (SOFC) with an allothermal biomass fluidised bed steam gasification process. The gasification heat requirement is supplied to the fluidised bed from the SOFC stack through high-temperature sodium heat pipes. The CHP system was modelled in AspenPlus™ software including sub-models for the gasification, SOFC, gas cleaning and heat pipes. For an average current density of 3000 A m⁻² the proposed system would consume 90 kg h⁻¹ biomass producing 170 kW_e net power with a system exergetic efficiency of 36%, out of which 34% are electrical.     

Performance enhancement of conventional combined cycle power plant by inlet air cooling,inter-cooling and LNG cold energy utilization

This paper has proposed an integrated advanced thermal power system to improve the performance of the conventional combined cycle power plant. Both inlet air cooling and inter-cooling are utilized within the proposed system to limit the decrease of the air mass flow contained in the given volume flow as well as reduce the compression power required. The latent heat of spent steam from a steam turbine and the heat extracted from the air during the compression process are used to heat liquefied natural gas (LNG) and generate electrical energy. The conventional combined cycle and the proposed power system are simulated using the commercial process simulation package IPSEpro. A parametric analysis has been performed for the proposed power system to evaluate the effects of several key factors on the performance. The results show that the net electrical efficiency and the overall work output of the proposed combined cycle can be increased by 2.8% and 76.8 MW above those of the conventional combined cycle while delivering 75.8 kg s^?1 of natural gas and saving 0.9 MW of electrical power by removing the need for sea water pumps used hitherto. Compared with the conventional combined cycle, the proposed power system performance has little sensitivity to ambient temperature changes and shows good off-design performance.