“How to eliminate fossil fuel consumption in Uppsalas district heating system?” CW Energy systems engineering, Uppsala University Jakob Blücher, Per Ekström, Nathalie Fransson, Nils Jonsson Forsblad, Nils Norlander, Erik Wendin, Emma Wiesner

Uppsala District Heating System: Supports 250 000 inhabitants with heat and electricity Waste fired CHP Wood chips & peat fired CHP & HP 4 oil fired boilers á 80 MW Our thesis specifically looked at Uppsalas district heating system as a case study but the results from this study can be applied to any district heating system wanting to reduce or eliminate fossil fuels from the mix. Påminnelse till den som tar denna slide att läsa ut förkortningarna! CHP=combined heat and power production HP= heat production only

Background – how to make the system renewable? Vision: 100% Fossil free district heating system CO2-emissions 1990-2030 Plastic waste in fuel Fossil oil in peak load production Fossil oil in start burners Duration diagram Vision: 100% Four oil boilers used as reserve capacity for peak load production either when there is a sudden uptake on the demand side or for cold winter days when the temperature is below -10 degrees.

Studied alternatives: Conversion oil fired boilers to pine oil pitch Conversion oil fired boilers to wood pellets Construction of new boilers (biomass or electricity) Construction of hot water storage tank Energy storage in caverns Combinations of alternatives above Conversion of starting burners to pine oil pitch 5 minuter. Nils. Introducera vad vi tittat på i delrapporterna. -

Parameters to include: Challenges to solve: Important technical challenges: Oxidation of materials & corrosion Start-up times Parameters to include: Environmental impact (NOx,SOx, particles and CO2) Available fuels at plant Fuel prices Investment costs Payback times (Välja ut några pkt, typ start-up time och oxidation känns mer relevant än de andra så att man hinner säga något om dem.) For the start-up burners oxidation was considered a great challenge is a shift to pine oil was to be made. For the peak load production units the most important technical specification was start-up time. Parameters: Bio oils extracted from pine trees have slightly higher emissions of both SOx and NOx compared wood pellets, but both alternative renewable fuels have lower or the same emissions as the fossil alternative. The emission levels of particles stays within the same amount for all the alternatives.

Result: Meets technical demands Economically feasible One oil boiler should be converted to pine oil pitch (75 MW) One oil boiler to wood pellets (50 MW) Start burners converted to pine oil pitch Meets technical demands Economically feasible Environmental advantages NOx,SOx, particles & CO2 Sensitivity analysis (Behöver nog inte dra så mycket specifika siffror här, både för att det är svårt att förstå och för att de förmodligen är fel ;) )The total investment is €13 000 000 and the estimated savings by 20 years is €160 000 000 due to high fossil fuel prices and a large amount of available bio fuels. This solution means that the carbon dioxide emissions from the plants will be reduced by 18 240 tonnes/yr. Emissions of SOx will slightly increase with 1,9 tonnes/yr, NOx emission will decrease with 1,8 tonnes/yr and emissions of particles will be reduced by 76 kg/yr. Interestingly our sensitivity analysis showed that the price of oil would have to drop significantly for the business-as-usual option with fossil oil to be better from an economical stand-point. The analysis also showed that replacing fossil oil with two boilers to wood pellets or two boilers to pine oil are both equally good options meaning that the choice between wood pellets or pine oil in peak load production should be made based on the available knowledge and infrastructure at the specific plant.

Future fuels in a renewable heating system feasible. This provides a flexibility for other district heating systems or plants with oil boilers, looking to make a similar transformation away from fossil fuels to choose the fuel that better serves their plant with regards to logistics and available knowledge. Investments in renewable bio fuels in power plants is not only more sustainable and environmentally friendly but also technically possible, pays back its financial input, saves money and drives technical development.

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