Increased resource efficiency in an energy system could result in large economic and environmental benefits. Tekniska verken i Linköping AB (Tekniska verken) is responsible for the district heating network in Linköping. Their vision is to create the world’s most resource efficient region. An important step towards this vision is more efficient usage of produced heat, something which could be achieved through integration of a seasonal heat storage in the energy system. The purpose of the Master’s thesis is therefore to explore the economic and technical potential for a seasonal heat storage in Tekniska verken’s energy system. The investigated technology is borehole thermal energy storage using two different kinds of borehole heat exchangers; u-pipe and annular coaxial heat exchanger. To evaluate how Tekniska verken’s energy system changes through integration of a seasonal heat storage a calculation model has been developed in MATLAB. The heat from the seasonal storage needs to be upgraded in order to be used in the ordinary district heating network. Therefore two kinds of heat pumps have been evaluated in the model; absorption heat pumps and compression heat pumps. The main method used for calculations on the heat transfer processes in the storage is the finite difference method. During economic calculations, the economic potential of the investment is expressed solely in relation to the scenario that the storage is not built. Four different combinations of borehole heat exchangers and heat pumps have been simulated over a twenty year period. The simulated storages have a depth of 200-250 meters and a radius of approximately 100 meters which relates to1500 boreholes. The result shows small differences between the two types of heat exchangers. The choice of heat pump has though a crucial importance of the economic result. The systems with absorption heat pumps uses drive heat from existing steam production and can cover a major part of the peak load during winter. Meanwhile the compression heat pumps have a large cost for electricity. This causes a negative net present value according to the result, while the systems with absorption heat pumps have a discounted pay-back time of 12 years. Another positive effect of the systems with absorption heat pumps is the decrease in carbon dioxide emissions from the heat production. The result of the Master thesis shows that both economic advantages and increased resource efficiency can be achieved through integration of a borehole thermal energy storage with absorptions heat pumps.  To further investigate this potential seems therefore beneficial. / Att öka resurseffektiviteten i ett energisystem kan medföra stora ekonomiska och miljömässiga fördelar. Tekniska verken i Linköping AB (Tekniska verken) är ansvariga för Linköpings fjärrvärmeförsörjning. De har som vision att skapa världens mest resurseffektiva region. Ett viktigt steg på vägen för att nå detta är bättre utnyttjande av producerad värme, något som kan uppnås genom integrering av ett säsongsvärmelager i energisystemet. Syftet med detta examensarbete är därmed att utreda vilken ekonomisk och teknisk potential som finns för ett säsongsvärmelager i Tekniska verkens energisystem. Den lagerteknik som undersöks är borrhålslager med två typer av borrhålsvärmeväxlare; u-rör och ringformad koaxial borrhålsvärmeväxlare. För att utvärdera hur Tekniska verkens energisystem förändras vid integrering av ett säsongsvärmelager har en beräkningsmodell byggts upp i MATLAB. Två typer av värmepumpar har utvärderats i modellen; absorptionsvärmepumpar och kompressions­värmepumpar. Anledningen till detta är att den säsongslagrade värmen behöver uppgraderas för att kunna användas i ordinarie fjärrvärmenät. Den huvudsakliga metoden som använts vid beräkning av värmeöverföringsprocesser är finita differensmetoden. Vid ekonomiska beräkningar uttrycks investeringens ekonomiska potential enbart i relation till scenariot att lagret inte byggs. Fyra system med olika kombinationer av borrhålsvärmeväxlare och värmepumpar har simulerats över en tjugoårsperiod. De simulerade lagren har ett djup på 200-250 meter och en radie på cirka 100 meter vilket motsvarar ungefär 1500 borrhål. Resultatet påvisar små skillnader mellan de två typerna av borrhålsvärmeväxlare. Vilken typ av värmepump som används har dock en avgörande betydelse för det ekonomiska resultatet. Systemen med absorptionsvärmepumpar drivs av värme från befintlig ångproduktion och klarar av att täcka en större andel av topplasten vintertid. Samtidigt medför användning av kompressionsvärmepumpar en stor kostnad för drivel. Detta medför ett negativt nettonuvärde enligt examensarbetets resultat, medan systemen med absorptionsvärmepumpar har en diskonterad avbetalningstid på 12 år. Ytterligare en positiv effekt av systemen med absorptionsvärmepump är minskade utsläpp av koldioxid. Utifrån examensarbetets resultat framstår det som att genom integrering av ett borrhålslager med absorptionsvärmepumpar uppnås både ekonomiska vinster och en ökad resurseffektivitet i Tekniska verkens energisystem. Att fortsätta utreda denna potential framstår därmed som fördelaktigt.

<p>Despite big expansion of biogas plants in the world, does not have the levels in the Swedish market succeeded very good. Presently are not so many expanded biogas plants in Sweden. Especially biogas plants that are based on rest products from the industry. This study checks the possibility and takes up the profitability in producing biogas off spill products from rape oil production. The spill product that is interesting in this case is process water with high-energy contents that currently are given away to the local farmers for fertilization of farmland.</p><p> Results from the study show that the process water in itself is not appropriate substrate for digestion in a biogas plant. On the other hand if you use an involvement corresponding 20- 25% graft in the process water can the result become really good. But to use this biogas to heat power plant or upgrading to vehicle fuel can it be unsuitable on the basis of economic calculations. This entirely depends on that production of the process water is too little and that will give a result with smaller amount biogas production. This amount will not be neither enough to be sold to other companies for upgrading or other purposes.</p><p> This problem can be solved through cooperation with the municipality’s sewage treatment or local farmers that will supply their energy needs by themselves. If the cooperation takes in force can biogas plant becomes profitable irrespective of what the biogas will be used to.</p><p> Using biogas in heat power plant to force electricity and heat with minimum 200-kilowatt gas engine can investment be profitable, regardless of if the electricity will be sold on the market or it be used internal. It is also economic to upgrade biogas to vehicle fuel with a minimum prise of 7, 5 SEK/Nm³ biogas.   </p><p> Investment on biogas plant is depending on factors like interest rate, economic contribution, costs and political arrangements so. The results will be changed if the economic factors changed, for examples lower interest rate and higher economic contributions brings profitability in the investment. On the other hand higher raw materials or less economic contribution will make that the investment becomes uneconomical.</p>

Despite big expansion of biogas plants in the world, does not have the levels in the Swedish market succeeded very good. Presently are not so many expanded biogas plants in Sweden. Especially biogas plants that are based on rest products from the industry. This study checks the possibility and takes up the profitability in producing biogas off spill products from rape oil production. The spill product that is interesting in this case is process water with high-energy contents that currently are given away to the local farmers for fertilization of farmland.  Results from the study show that the process water in itself is not appropriate substrate for digestion in a biogas plant. On the other hand if you use an involvement corresponding 20- 25% graft in the process water can the result become really good. But to use this biogas to heat power plant or upgrading to vehicle fuel can it be unsuitable on the basis of economic calculations. This entirely depends on that production of the process water is too little and that will give a result with smaller amount biogas production. This amount will not be neither enough to be sold to other companies for upgrading or other purposes.  This problem can be solved through cooperation with the municipality’s sewage treatment or local farmers that will supply their energy needs by themselves. If the cooperation takes in force can biogas plant becomes profitable irrespective of what the biogas will be used to.  Using biogas in heat power plant to force electricity and heat with minimum 200-kilowatt gas engine can investment be profitable, regardless of if the electricity will be sold on the market or it be used internal. It is also economic to upgrade biogas to vehicle fuel with a minimum prise of 7, 5 SEK/Nm3 biogas.     Investment on biogas plant is depending on factors like interest rate, economic contribution, costs and political arrangements so. The results will be changed if the economic factors changed, for examples lower interest rate and higher economic contributions brings profitability in the investment. On the other hand higher raw materials or less economic contribution will make that the investment becomes uneconomical.

The global community is facing great challenges as the energy system is transforming towards more reliable, effective, clean and renewable production. Small-scale and micro networks will play an important role in this changeover. Its advantages over today’s large conventional energy systems are their reliability and stability. In small-scale and micro networks, there is usually a variety of production units such as photovoltaic, wind power and micro-combined heat and power (micro-CHP). In this study, a small-scale network with an application of two different types of biogas fueled micro-CHPs is analyzed. The units are a micro gas engine (MGM) and a micro gas turbine (MGT). The application of micro-CHP is validated using a reference facility connected to a small-scale district heating network. The reference facility is a heat production plant at a horse race track outside Eskilstuna, Sweden consisting of an oil boiler, a pellet boiler and a heat storage tank. The potential in replacing the oil boiler with renewable micro-CHP is investigated. A simulation model is built in the software GAMS, using Mixed Integer Linear Programming (MILP) and the solver CPLEX, and the model is simulated using the heat demand from the horse race track. Results from the model validation shows that it is possible for both the MGM or the MGT together with the pellet boiler and the heat storage tank to fulfill the heat demand of the facility. The horse race track handles 4 000 m3 of horse manure annually, which is transported 124 km to a compost treatment facility. Therefore, a general analysis of biogas production from horse manure is conducted in order to investigate the possibilities for better horse manure treatment on site. A calculation for a biogas reactor with a capacity for the maximum biogas requirement of the micro-CHP is implemented. Horse manure is suggested to be co-digested with food waste, in order to provide a higher biogas exchange. The result of a Life Cycle Cost (LCC) analysis indicates difficulties in justifying an investment of a micro-CHP together with a biogas plant at current prices for heat and electricity. The results show that the payback period for the MGM is 7 years which is 2 years shorter than its lifetime and the MGT payback period is 12 year which also is it lifetime. The MGM shows the largest investment potential since it has an investment cost approximately 860 kSEK lower than for the MGT. The MGM also has a slightly higher electrical efficiency which results in higher revenues from produced electricity. The chosen MGM in this study is slightly smaller than the MGT, resulting in a lower biogas demand and a lower investment cost for a biogas plant. A sensitivity analysis shows great impact of the electricity price on the payback period for both types of micro-CHP. The results show that with an electricity price of 280 SEK/MWh, both the MGM and the MGT repays within their lifetime. But since MGM has a higher net present value at all electric prices, is the MGM considered to be a more economical feasible investment. What the authors think should be highlighted is also the environmental benefits of more efficient treatment of horse manure at the horse race track together with the possibility of local production of fuel resulting in reduced CO2 emissions by 47 tons/year.

För att skapa ett hållbart och cirkulärt samhälle måste nödvändigt avfall börja ses som en värdefull resurs. Ett exempel på en sådan resurs är det slam som avskiljs vid rening av avloppsvatten. Genom att mikroorganismer bryter ner det organiska materialet i slammet bildas biogas som kan användas för att utvinna energi. Detta är ingen ny teknik utan har använts i 1000-tals år men processen för energiutbytet har effektiviserats och idag används ofta en syrefri och uppvärmd rötkammare för att påskynda nedbrytningen. Vid Horshaga avloppsreningsverk i Skara produceras biogas av slammet som utvinns vid reningen av vattnet. Biogasen används för intern uppvärmning av rötkammaren, vatten och lokaler. Ofta produceras det mer än vad verksamheten kan använda internt och biogasen eldas då istället upp i en gasfackla utan att energi tillvaratas. Syftet med studien är att kartlägga biogasproduktionen och energianvändning för att se om det går att nyttja överskottsbiogasen för kraftvärmeproduktion. I Studien har data samlats in från verksamhetens interna nätverk samt genom intervjustudie med anställda inom bolaget. Resultatet visade på att årsvis produceras det mer biogas än vad verksamhet kan använda, men under vintermånaderna råder ett underskott av biogas och då har fossilolja tillsatts för att täcka upp för värmebehovet. Största värmeförbrukning går åt till att värma upp rötkammaren. Vid kraftvärmeproduktion av överskottsbiogasen skulle intäkterna bli 267 576 kronor. Att öka kvalitén och minska den interna energianvändningen skulle bidra till mera tillgänglig biogas till kraftvärmeproduktion. Det kan också finnas andra värden än ekonomiska för egen elproduktion tillexempel ökad krisberedskap / To create a sustainable and circular society, waste must begin to be seen as a valuable resource. An example of such a resource is the sludge that occurs during wastewater treatment. When microorganisms break down the organic material in the sludge, biogas is formed that can be used to extract energy. This technology has been used for 1000s of years, but the process for energy exchange has been improved and today an oxygen-free and heated digester is often used to speed up the decomposition. At the Horshaga wastewater treatment plant in Skara, biogas is produced from the sludge extracted in the biological treatment of water. The biogas is used for internal heating of the digester, water and premises. Often more biogas is produced than the business can use internally and the biogas is the instead burned up without energy being utilized. The purpose of the study is to map biogas production and energy use to investigate possibility to use the surplus biogas for combined heat and power production. The study has been based on data from the company's internal network and a smaller interview study with employees within the company. The result showed that more biogas is produced annually than the business can use, but during the winter months there is a deficit of biogas, and fossil oil has been added there to cover the energy need. The largest heat consumption is used to heat up the digester. In the case of cogeneration production of the surplus biogas, the revenue would be SEK 267,576. Increasing the quality and reducing internal energy use would contribute to more available biogas for cogeneration production. There may also be values other than financial for own electricity production, for example increased crisis preparedness. / <p>2023-06-02</p>

Då det finns planer på att ersätta det befintliga reningsverket i Kalmar inom en överskådlig framtid och nya krav om nödförsörjning av el har kommit från MSB, undersöktes möjligheten att använda den biogas som skulle komma att produceras på det nya reningsverket inom den egna verksamheten, istället för att som i dagsläget säljas. I denna studie undersöktes lönsamheten i att antigen investera i en biogasdriven generator som i normalfall ger en besparing i el och fjärrvärme och kan leverera reservkraft vid spänningsbortfall på nätet, eller försäljning av biogasen och inköp av ett dieseldrivet reservkraftverk.  Kostnadsförslag för biogasdrivna generatorer och reservkraftverk togs in. I denna ingick även service och komponenter för att kunna använda biogasen som bränsle. Utav kostnadsförslagen gjordes en LCC. Besparing av el och fjärrvärme samt förtjänst av försäljning av biogasen ställdes i relation mot varandra. Arbetet konkluderar att, baserat på de uträkningar som gjordes, en ottomotor är det mest lönsamma för att generera el och värme för internt bruk. / Because of the plans to replace the old sewage treatment plant in Kalmar, which has come to the end of its life cycle, and due to new requirements of emergency supply from SCCA (Swedish Civil Contingencies Agency), the possibility of using the biogas on the plant itself was evaluated. In this study, the profitability of two alternatives was evaluated. To invest in a biogas powered generator to produce electric power and heat, which would create savings in purchased electricity and district heating and work as an emergency generator, or to continue selling the biogas and invest in a diesel-powered emergency generator. Cost estimates of biogas powered generators and the equipment needed for using the biogas as fuel was required from dealers and manufacturers. The cost estimates were then compiled in a LCC. The calculated savings and the income from selling the biogas was then added to the LCC, the alternatives was then compared to each other. The study concludes that the most profitable alternative, based on the calculations, is to invest in a biogas powered generator and use the electricity and waste heat on the sewage plant.

Energikontor Sydost har startat demonstrationsprojekt inom småskalig kraftvärme. Ronneby Miljö och Teknik AB driver en demonstrationsanläggning för småskalig elproduktion med ORC-turbin på värmeverk i Bräkne-Hoby. I samband med installation av ORC-turbin gjordes även ombyggnation av fjärrvärmeledning till närliggande sågverk. Detta examensarbete är en teknisk- och lönsamhetsanalys för utvärdering av investeringen. Elverkningsgrad uppgick för denna fjärrvärmesäsong till 2,23 %, alfa-värde till 2,3 %, systemverkningsgrad för ORC-system till 99,54 %. Ledningsförluster minskade från 19,7 till 17,25 % efter ombyggnation. Det visades även att sänkning av fjärrvärmereturtemperatur ökar elproduktionen. Investeringskalkyl visade en icke lönsam investering om el säljs externt. Att producera och använda el internt inom anläggningen visade sig lönsamt även utan investeringsstöd. Ombyggnation av fjärrvärmeledning visades även vara lönsamt. Tekniken är vid anslutning till värmeverk förnybar, lokal och har hög tillgänglighet vid högbelastningstider.