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Improving the performance of combined heat and power plants through integration with cellulosic ethanol production
Mälardalen University, School of Sustainable Development of Society and Technology. (MERO)
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Today’s biomass-fired combined heat and power (CHP) plants have surplus heat production capacity during warmer times of the year. In order to allow them to increase their electricity production, it is essential to find a use for the surplus heat.

Additionally, the transport sector is struggling with high fuel prices and the contribution of CO2 emissions to global warming. A promising way of reducing the negative effects caused by combustion of fossil fuels in the transport sector is to mix ethanol with gasoline, or to use pure ethanol in modified engines. Ethanol is produced by fermentation at low temperatures and the production process could be integrated with CHP plants.

The first generation of ethanol production as fuel has recently been criticized for competing with food crops and for its production chain being a larger polluter than was first thought. The second generation of ethanol production from lignocellulosic materials offers very promising results, but this process has several steps that are energy demanding.

This thesis presents the findings of research on the configuration of a CHP plant with an integrated second generation ethanol production process. It also presents the operational economics and optimal locations for such plants in Sweden. Two case studies were performed to compare different feedstocks for ethanol production.

The results show that when electricity prices are high, CHP plants benefit from heat consumption. Even with low yields in an ethanol production process, the integrated plant can be profitable. The plant must be located where there is sufficient heat demand. A cellulosic ethanol production process can work as a heat sink with profitable outcomes even with the current state of development of cellulosic ethanol technology.

Place, publisher, year, edition, pages
Västerås: Mälardalen University , 2011.
Series
Mälardalen University Press Licentiate Theses, ISSN 1651-9256 ; 130
Keyword [en]
Combined heat and power, Polygeneration, biofuel, bioenergy
National Category
Engineering and Technology
Research subject
Energy- and Environmental Engineering
Identifiers
URN: urn:nbn:se:mdh:diva-12070ISBN: 978-91-7485-009-3OAI: oai:DiVA.org:mdh-12070DiVA: diva2:408520
Presentation
2011-05-27, Kappa, Mälardalens högskola, Västerås, 09:10 (English)
Opponent
Supervisors
Available from: 2011-04-05 Created: 2011-04-05 Last updated: 2011-04-14Bibliographically approved
List of papers
1. Optimal location of lignocellulosic ethanol refineries with polygeneration in Sweden
Open this publication in new window or tab >>Optimal location of lignocellulosic ethanol refineries with polygeneration in Sweden
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2010 (English)In: Energy, ISSN 0360-5442, Vol. 35, no 6, 2709-2716 p.Article in journal (Refereed) Published
Abstract [en]

The integration of ethanol production with combined heat and power plants is considered in this paper. An energy balance process model has been used to generate data for the production of ethanol, electricity, heat and biogas. The geographical position of such plants becomes of importance when using local biomass and delivering transportation fuel and heat. An optimization model has thus been used to determine the optimal locations for such plants in Sweden. The entire energy supply and demand chain from biomass outtake to gas stations filling is included in the optimization. Input parameters have been studied for their influence on both the final ethanol cost and the optimal locations of the plants. The results show that the biomass cost, biomass availability and district heating price are crucial for the positioning of the plant and the ethanol to be competitive against imported ethanol. The optimal location to set up polygeneration plants is demonstrated to be in areas where the biomass cost is competitive and in the vicinity of small to medium size cities. Carbon tax does not influence the ethanol cost, but solicits the production of ethanol in Sweden, and changes thus the geography of the plant locations.

Identifiers
urn:nbn:se:mdh:diva-10358 (URN)10.1016/j.energy.2009.07.018 (DOI)000278506400040 ()2-s2.0-77953138345 (ScopusID)
Available from: 2010-10-04 Created: 2010-10-04 Last updated: 2015-07-06Bibliographically approved
2. Increased renewable electricity production in combined heat and power plants by introducing ethanol production
Open this publication in new window or tab >>Increased renewable electricity production in combined heat and power plants by introducing ethanol production
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2009 (English)Conference paper (Refereed)
Abstract [en]

The development towards high energy efficiency and low environmental impact by humaninteractions, has led to a change in many levels of society. Due to the introduction of penalties oncarbon dioxide emissions and other economic instruments, the energy industry is striving towardsenergy efficiency improvement and climate mitigation by switching from fossil to renewablefuels. Biomass-based combined heat and power (CHP) plants connected to district heatingnetworks have a need to find uses for excess heat to produce electricity during summer when theheat demand is low. On the other hand, the transport sector is contributing substantially to theincreased CO2 emissions, which have to be reduced. One promising alternative to address the twochallenging issues is the integration of vehicle fuel production with biomass based CHP plants. Inthis paper, the configuration and operation profits in terms of electricity, heat and ethanol fuelfrom cellulosic biomass are presented. A case study of a commercial small-scale CHP plant hasbeen carried out using simulation and modeling tools. The results clearly show that electricityproduction can be increased when CHP production is integrated with cellulosic ethanolproduction. The findings presented also show that the economical benefits of the energy systemcan be realized with near-term commercially available technology

National Category
Energy Engineering
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-7515 (URN)
Conference
International Conference of Applied Energy, Hong Kong, 5-7 January, 2009
Projects
Polygeneration
Available from: 2009-11-19 Created: 2009-11-19 Last updated: 2016-01-11Bibliographically approved
3. Performance evaluation of adding ethanol production into an existing combined heat and power plant
Open this publication in new window or tab >>Performance evaluation of adding ethanol production into an existing combined heat and power plant
2009 (English)In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 101, no 2, 613-618 p.Article in journal (Refereed) Published
Abstract [en]

In this paper, the configuration and performance of a polygeneration system are studied by modelling the integration of a lignocellulosic wood-to-ethanol process with an existing combined heat and power (CHP) plant. Data from actual plants are applied to validate the simulation models. The integrated polygeneration system reaches a total efficiency of 50%, meeting the heating load in the district heating system. Excess heat from the ethanol production plant supplies 7.9MWto the district heating system, accounting for 17.5% of the heat supply at full heating load. The simulation results show that the production of ethanol from woody biomass is more efficient when integrated with a CHP plant compared to a stand-alone production plant. The total biomass consumption is reduced by 13.9% while producing the same amounts of heat, electricity and ethanol fuel as in the stand-alone configurations. The results showed that another feature of the integrated polygeneration system is the longer annual operating period compared to existing cogeneration. Thus, the renewable electricity production is increased by 2.7% per year.

Keyword
Polygeneration, Combined heat and power, Bio-ethanol, Efficiency improvement, Bioenergy
National Category
Engineering and Technology
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-6828 (URN)10.1016/j.biortech.2009.07.087 (DOI)000271165700024 ()2-s2.0-70349417698 (ScopusID)
Projects
Polygeneration
Available from: 2009-09-16 Created: 2009-09-16 Last updated: 2015-07-06Bibliographically approved

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