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.

<p>The analyzed building in this project is located in Valbo, 9016 Stiftelsev 6. This house is a property of Gavlegårdarna, and it is being used as a house for disabled people. The building consists on five apartments, with one patient in each apartment. Some social workers help those patients in everything they need, making their living in the house as easy as possible.</p><p>The aim of this project is to find out the best option of reducing the energy consumption in this house. There are some alternatives to reduce the energy or the energy costs as; efficiency measures, load management and energy conversion.</p><p>This project is focused on the energy conversion for reducing the energy consumption. As it is the best option for obtaining a considerable reduction in the annual costs.</p><p>First of all the energy balance of the house is analyzed. By studying the energy balance it is possible to find out how the energy consumption of the house is divided. On one hand there is the heat supplied and on the other hand the heat losses.</p><p>As it was said before this project is focused in the reduction of the energy consumption by means of converting to another energy supplying method. Two alternatives have been studied: the installation of a heat pump and the connection to the district heating of Gävle.</p>

<p>Fuel availability and security of supply are two of the most important factors in the well functioning of a company like Gävle Energi. Another important factor is the price of the fuels used. The transportation cost plays also an important role when purchasing fuels from different sources. Currently the fuels used in Gävle Energi are mainly woody biofuels, but waste and peat could also be used in the future.</p><p>The aim of this thesis is to provide an overview of the different available biofuels in the region of Gävle. The fuels considered in the study are:</p><p>- Bark</p><p>- Forest Residues</p><p>- Wood waste</p><p>- Pellets and Briquettes</p><p>- Garbage/waste materials</p><p>- Peat</p><p>The research is focused on the physical properties of the fuels, their price and transportation cost, environmental and legislation issues and the availability in the region of Gävle. A 10-year perspective is defined for an estimated availability of the different fuels in te region.</p>

<p>The object of analysis in the present document is a residential house in Sätra. This building has a hydronic space heating system with radiators spread around the house and a heating recovery system ventilation which also use water for reheating. Water for space heating, ventilation and hot tap water is nowadays heated in an electric boiler.The aim of this project is to make a diagnosis of the current situation, evaluate different alternatives for supplying hot water to the house, and to study costs and possible savings by comparing the actual facilities with the proposals done.</p>

<p>Nowadays, reducing energy usage as well as reducing environmental impacts due to energy efficiency measurements is very common in the industrial sector. The objective of these measurements is to achieve better sustainable energy systems.</p><p>Sandvik Materials Technology (SMT) AB, one of the business areas of the enterprise Sandvik AB, is not an exception in that field.</p><p>The aim of this thesis project is to analyze how to use waste energy from the cooling of a steel plant for an internal district heating (DH) system within the industrial area of SMT AB located in Sandviken, Sweden. In order to reduce the energy use, the economic cost and the environmental impacts within the industrial area.</p><p>In order to achieve the aim has been studied the heat pump devices as the system to transfer the waste heat from the cooling of the steel plant to the DH system. Therefore, after the introduction to the project (part 1: Introduction) and the explanation of the aim</p><p>(part 2: Aim, methodology and delimitations), the basics of the heat pumps are studied and explained (part 3: Heat pumps theoretical study). After that, the knowledge acquired in part 3 is applied to define and calculate the heat pump system which fulfill the required</p><p>objectives achieving the greatest energy, economical and environmental impacts reductions (part 4: Heat pump practical study).</p><p>The achieved results show that there is a great opportunity to reduce the energy use within the industrial area (until 45300 MWh per year), the economical cost (until 2 millions euros per year) and the 2 CO emissions (until 2.3 millions of 2 CO kg per year1).</p><p>Therefore, the conclusion is that it must be taken into account to build the heat pump system and also that the effort of finding possible energy efficiency measurements within the industrial sector must be one priority for all the industrial companies, not only because the possible potential economical reductions, but also because of the potential environmental impacts reductions.</p>

The purpose with this report was to investigate the possibilities for smaller district heating plants to use recovered wood waste (RT-flis) as fuel. A smaller district heating plant in the north of Sweden (Sorsele värmeverk AB) was the main study object. To be able to incinerate this fuel there are a number of requirements that need to be fulfilled according to the law. In addition to these requirements, the incineration of this fuel also needs to be profitable. The results for this study were obtained through interviews, investigations of the incineration laws and the fuel supply, as well as an analysis of the opinions occurring within the personnel of the heating plants. The results show that the possibility to incinerate RT-flis depends on the appropriate technology; the possibility to fulfill the requirements of the law, as well as it has to be profitable. All these parameters are in close relation to each other. Whether it is technologically possible to use RT-flis largely depends on the construction and technology of the heater, which affects the possibility to fulfill the requirements on, for example, air emissions. Economically, main issues include investments into measuring equipment, but also the accessibility of fuel. The most important aspect is the quality of the fuel (e.g., contaminations).

A problem in the field of district heating is the oil burners needed to provide power when a peak load occurs. One possible way of reducing the needed amount of oil is to reduce the power demand for space heating in the district-heating substations when the need for district heating water exceeds a certain limit. This can be done by use of a locally working controller function. In this Thesis the options concerning load priority are evaluated. To evaluate the potential for using controller functions concerning peak load priority an experiment was brought out in a chosen district-heating substation. The impact on the indoor thermal comfort during a heat reduction was also taken into account. With simulations and mathematical models the building and the indoor air cool down was evaluated. Also a survey was given to the residents to validate how the indoor thermal climate was affected during the experiment. Possible savings by using these kinds of functions were also accounted for. The result demonstrates that a simple controller function provides a possible way of reducing the power demand, but is not sufficiently reliable. This is mainly due to the used regulating parameter. With modifications or by adding additional regulating parameters such as water flow into the controller, the functionality can be improved. The result from the survey shows that during the experimental period the residents experienced a minor impact on the thermal comfort. Parameters, such as ventilation and heat losses also have a major impact on the building´s thermal inertia, especially at the lowest occurring outdoor temperatures. The simulations confirm the theory regarding the building heat capacity to prevent a negative impact on indoor thermal comfort. In addition, the indoor air temperature can initially decrease faster than the building framework, especially under the influence of ventilation. This must be taken into account when applying functions for load priority. Calculations indicate that the economical benefits by adapting functions for load priority are primarily for the heat-producer, due to reduced oil dependence and also other system aspects. The current ownership structure in Uppsala provides for a possible obstacle when it comes to expanded use of load priority functions. More incentives for the consumer are needed to provide for an increased usage of load priority functions in their district-heating substations.

The analyzed building in this project is located in Valbo, 9016 Stiftelsev 6. This house is a property of Gavlegårdarna, and it is being used as a house for disabled people. The building consists on five apartments, with one patient in each apartment. Some social workers help those patients in everything they need, making their living in the house as easy as possible. The aim of this project is to find out the best option of reducing the energy consumption in this house. There are some alternatives to reduce the energy or the energy costs as; efficiency measures, load management and energy conversion. This project is focused on the energy conversion for reducing the energy consumption. As it is the best option for obtaining a considerable reduction in the annual costs. First of all the energy balance of the house is analyzed. By studying the energy balance it is possible to find out how the energy consumption of the house is divided. On one hand there is the heat supplied and on the other hand the heat losses. As it was said before this project is focused in the reduction of the energy consumption by means of converting to another energy supplying method. Two alternatives have been studied: the installation of a heat pump and the connection to the district heating of Gävle.

Fuel availability and security of supply are two of the most important factors in the well functioning of a company like Gävle Energi. Another important factor is the price of the fuels used. The transportation cost plays also an important role when purchasing fuels from different sources. Currently the fuels used in Gävle Energi are mainly woody biofuels, but waste and peat could also be used in the future. The aim of this thesis is to provide an overview of the different available biofuels in the region of Gävle. The fuels considered in the study are: - Bark - Forest Residues - Wood waste - Pellets and Briquettes - Garbage/waste materials - Peat The research is focused on the physical properties of the fuels, their price and transportation cost, environmental and legislation issues and the availability in the region of Gävle. A 10-year perspective is defined for an estimated availability of the different fuels in te region.

The object of analysis in the present document is a residential house in Sätra. This building has a hydronic space heating system with radiators spread around the house and a heating recovery system ventilation which also use water for reheating. Water for space heating, ventilation and hot tap water is nowadays heated in an electric boiler.The aim of this project is to make a diagnosis of the current situation, evaluate different alternatives for supplying hot water to the house, and to study costs and possible savings by comparing the actual facilities with the proposals done.