District heating systems can contribute to reducing the UK's CO2 emissions. This thesis investigates the operational performance of current district heating (DH) systems with the existing and a possible future energy sector. The main contributions to knowledge are:  Operational, financial and exergy performance assessments of three functioning DH systems and one decentralised energy (DE) technology  A methodology to optimise a DH system in a resource efficient and cost effective way The aims of DH systems are to provide heat, reduce CO2 emissions, ensure energy security by operating in a resource efficient way and to tackle fuel poverty. However, the case studies in this project confirm that DH systems operate poorly in the UK. This is largely because of the heat losses from the DH network to the soil being high and the plant operation being suboptimal. Four case studies were analysed. The 785 room Strand Palace hotel has two 250 kWe combined heat and power (CHP) engines set to modulate following the hotel's electricity consumption and providing approximately 90% of this annual demand. It was found that the CHP engines never operate at full load throughout a full day, firstly because the plant cannot export electricity to the grid and secondly the system is not fitted with a thermal store. Financial analysis revealed that the hotel does not reduce its heating cost by operating the CHP engines, but that the energy service company (ESCo) makes £77,000 net operating income per year. Elmswell in Suffolk (UK) is a low heat density DH system that generates heat with a 2008 biomass boiler and pumps it to 26 terraced and semi-detached dwellings. It was found that 39% of its heat is lost to the soil and that the natural gas boiler generates 45% of the heating load and operates with a seasonal efficiency of 65%. The heat losses to the soil for this system were compared to a DH system of higher heat density, Loughborough University, with a lower heat loss of 22% to the soil. In August 2011, Loughborough University installed a 1.6 MWe CHP engine to operate with four 3 MWth natural gas boilers to supply heat to its DH network. A study undertaken demonstrated that by adding a 2 MWe CHP engine with a thermal storage instead of a 1.6 MWe CHP engine on its own could further increase the CO2 emissions savings from 8% to 12.4%. The energy centre at Pimlico District Heating Undertaking (PDHU) includes a gas fired cogeneration plant that supplies heat to 3 schools, 3,256 dwellings and 55 commercial units. It also benefits from a 2,500 m3 thermal store. Every component of PDHU was investigated in detail and its current operation was optimised and compared to a selection of new operating scenarios. It was found that: i) The thermal store operated with 93% thermal efficiency and was not used to reduce the energy consumption or to enable more cogeneration, ii) The CHP engines were undersized and generated only 18% of the required heat in 2012, iii) The boilers modulate and £ 70,000 could be saved per year by setting them to operate at full load by making use of the thermal store, iv) By installing an open-loop heat pump using the river Thames, PDHU could then guarantee to comply with current and likely future policies impacts by setting the energy plant to operate in CHP mode or as an electricity consumer at defined times to benefit from low energy utility costs and to minimise CO2 emissions. A comparison of selected performance metrics was then undertaken and it was found that none of the three DH systems operate in a resource efficient way and that the heating cost could be reduced further by optimising the operation of the systems. To do this, a new optimisation methodology is proposed by maximising their exergy efficiency in addition to maximising their overall energy efficiency and CO2 emissions reduction.

The objective of the study is to analyse the conditions for connection of residential buildings in heat sparse areas to district heating systems in order to increase electricity production in municipal combined heat and power plants. The European electricity market has been assumed to be fully deregulated. The relation between connection of heat sparse areas, increased electricity and heat production as well as electricity prices, fuel prices and emissions rights is investigated. The results of the study show that there is potential to expand the district heating market to areas with lower heat concentrations in the cities of Gavle, Sandviken and Borlange in Sweden, with both economic and environmental benefits. The expansion provides a substantial heat demand of approximately 181 GWh/year, which results in an electricity power production of approximately 43 GWh/year. Since the detached and stand-alone houses in the studied heat sparse areas have been heated either by oil boiler or by direct electricity, connection to district heating also provides a substantial reduction in emissions of CO2. The largest reductions in CO2 emissions are found to be 211 ktonnes/year assuming coal-fired condensing power as marginal electricity production. Connection of heat sparse areas to district heating decrease the system costs and provide a profitability by approximately 22 million EURO/year for the studied municipalities if the price of electricity is at a European level, i.e. 110 EURO/MWh. Sensitivity analysis shows, among other things, that a strong relation exists between the price of electricity and the profitability of connecting heat sparse areas to district heating systems. / Original Publication:Shahnaz Amiri and Bahram Moshfegh, Possibilities and consequences of deregulation of the European electricity market for connection of heat sparse areas to district heating systems, 2010, Applied Energy, (87), 7, 2401-2410.http://dx.doi.org/10.1016/j.apenergy.2010.02.002Copyright: Elsevier Science B.V., Amsterdam.http://www.elsevier.com/

Orientador: Caio Glauco Sanchez / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica. / Made available in DSpace on 2018-08-06T19:32:34Z (GMT). No. of bitstreams: 1 Muraro_Wilson_M.pdf: 1394873 bytes, checksum: fc32a4e69a7d3e841edaf12eb62d7411 (MD5) Previous issue date: 2006 / Resumo: Hoje no mundo há uma grande rejeição de matériais, resíduos e outros compostos orgânicos que podem ser aproveitados como fontes de energia. Exemplos podem ser observados em todo o mundo e principalmente em regiões onde a pobreza impera e que a energia elétrica pode ser de grande ajuda ou mesmo como um salva vidas. O emprego de pequenas centrais de geração de potencia integradas a um gaseificador comum motor de combustão interna (Integrated Gasefication Combustion EngineI GCE) do ciclo OTTO e adaptado para operar com gás de baixo poder calorífico, constitui uma alternativa interessante e economicamente viável,que possibilita a produção independente de energia elétrica e térmica (Marcelo,2004). Para o aproveitamento de resíduos de BIOMASSA,como a casca de arroz, utilizou-se um processo de gaseificação,que é uma técnica que possibilita o uso energético da biomassa através da obtenção de um gás de baixo poder calorífico (4a6 MJ/Nm33). Utilizou-se um gaseificador de leito fluidizado do Laboratório de combustão da FEM,onde foi instalado um motor de 5965 litros de cilindrada total e 6 cilindros, com taxa de compressão 12:1, do ciclo OTTO, que originalmente é utilizado em veículos movidos a gás natural comprimido. Obteve se os seguintes valores nos ensaios: Potência (kW)=40.7@ 1800 rpm, Avanço(Graus do virabrequim )=30;Temperatura de Escapamento (°C) =596; Lambda =1,12; Pressão Máxima de Combustão (PA) =4000000. Como funcionamento do motor, verificou se a necessidade de algumas alterações em seus componentes, como também mudanças nas regulagens de avanço. É necessário um sistema para aumentar a pressão do gás proveniente do gaseificador e um sistema de partida inicial. Dessa maneira teríamos um motor para operar como grupo gerador e fazer parte de uma planta piloto para geração de energia elétrica por gaseificação de biomassa / Abstract: Nowadays there is a great waste of organic matters, residues and other substances that could be used in a power plant. Examples can mainly be observed in the whole world and in regions where the poverty reigns and where the electric energy could be of great aid.The use of small power generation plants integrated to a gasification with an internal combustion engine (Integrated Gasification Combustion Engine-GCE) of cycle OTTO and adapted to operate with low power heat rate gas, consists an interesting and economical viable alternative, that makes possible the independent production of electric and thermal energy. For the exploitation of residues of BIOMASS, as the rice husk, we used a gasification process that is a form to increase the energy use of the biomass. The gasification can generate thermal energy and electric energy. It was used gasifier of fluidized bed from UNICAMP, where it was installed an engine with of 5,965 liters and 6 cylinders, with compression rate 12:1(cycle OTTO),which was originally used in vehicles powered by compressed natural gas, to running with the gas of low power heat rate (46 MJ/Nm3) produced by gasifier. Typical experimental result. Power (kW)=40,7@1800rpm; Advance (Degrees)=30; Exhaust gas temperature(°C)=596; Lambda=1,12; Maximum Combustion Pressure (PA)=4000000. During the running of the engine, the necessity of some alterations in some components was verified as well changes in the advance regulations. A system to increase the pressure of the gas proceeding from the gasifier and a system of start are necessary. In this way we would have an engine to operate as generating group and to be part of a pilot plant for generation of eletric energy for gasification of biomass in agricultural and interior cities / Mestrado / Termica e Fluidos / Mestre em Engenharia Mecânica