12th International Symposium on District Heating and Cooling

The <strong>12th</strong> <strong>International</strong> <strong>Symposium</strong> on District Heating and Cooling,September 5 th to September 7 th , 2010, Tallinn, Estoniaare analysed. The environmental benefits are analyzedwith a system perspective on greenhouse gases (GHG)emissions, taking into account both on and off siteconsequences of introduction of an energy combine;see Environmental evaluation below. Moreover, theresource efficiency in the form of CO 2 reduction perused quantity of biomass is evaluated for eachcombine.The economic benefits of the ―joint production‖ set upare analyzed through both a short and long-termcommercial lens. By using discounted cash flowtechniques as a base for this analysis, it is possible toaccount for both the yearly consequences as well aslong term economic value; see Economic evaluationbelow.Fit with existing business context is analysed withrespect to input/output markets, production and systemconfiguration and general business conditionsdominant in the host industry. The analysis focus onrestrictions for short term fit; see Business contextevaluation.Since the detailed characteristic of the district heatingsystem is paramount to the feasibility for integration ofbioenergy production, we base our investigation on fourreal district heating systems in Sweden with differentcompositions. The chosen systems are all of equal size(500-600 TWh of yearly heat deliveries) established intowns with 40 000 to 80 000 inhabitants. Thesesystems are in turn equipped with a bioenergyproduction unit that best suits ruling company strategyas well as operational characteristics and maximizesenergy efficiency. In order to capture the additionalvalues of these investments, evaluation of eachcombine configuration is made in relation to areference case consisting of the existing system(complemented with investments to maintain acomparable level of production quality). The referenceand combine cases are further described in theDescription of the cases below.Much effort was put into indentifying efficient technicalsolutions that best take advantage of the site-specificconditions in each system. This work includedeverything from choice of equipment, appropriate sizeof the integrated production unit and productionstrategies over the year regarding output of heat,electricity and other energy products. To identifyefficient technical solutions an integrative computerizedprocess was applied, including both the district heatingsimulation software MARTES [2], and detailed spreadsheet calculations. In order to guarantee high qualityinput data, representatives from these four companiesgave access to technical, environmental as well aseconomic data.Below follows a description of the environmental andeconomic evaluation procedure. It is important to stressthat the input data for these assessments only includethe change resulting from the integration of thebioenergy production. One implication of this approachis that the environmental benefit of the heat produced(for district heating) is not included, since one basecondition is that the heat deliveries are the same withand without bioenergy production. Another implicationis that production units in the district heating systemthat are not affected (e.g. base load and peak loadproduction units) are not included. This systemboundary is also pervading for the Description of thecases to follow.Description of the casesThe four district heating systems with reference andcombine cases, respectively, are presented in briefbelow. The four objects for the evaluation are alsosummarized in Table I. A more comprehensivedescription can be found in ref. [3].Table I. Overview of the reference and combine cases inthe four district heating systems. Economic and energydata are given for both the reference and combine case,separated with a slash (ref./combine).CONFIGURATIONHeat deliv.(TWh/y)1 2 3 4500 530 560 620Ref. inv. Bio CHP None Bio CHP Bio CHPCombinetechnologyPyrolysisEnzymatichydrolysisAcidhydrolysisGasificationProducts Bio oil Ethanol 1 Ethanol FTdiesel 2ECONOMIC DATA, reference/combine1 2 3 4Inv. (M€) 74/60 0/144 116/310 146/473O&M (M€/y) 2.3/2.8 0/8.8 3.6/15.8 6.1/11.1ENERGY CONSUMTION, (GWh/year), ref./combine1 2 3 4Biomass 397/244 730/1537 470/1271 362/2970Others 74/135 3 - - -ENERGY PRODUCTION (GWh/year), reference/combine1 2 3 4Electricity 125/0 218/209 145/55 99/78Biofuel 0/90 0/444 0/294 0/1336Others - - 0/384 4 -1 Besides ethanol also biogas and pellets is produced.2 Also kerosene and nafta is produced.3 Fuel oil (21/15) and industrial waste heat (53/120).4 Biogas (0/114) and Pellets (0/270)144