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Analysis of a hybrid energy system for a new neighbourhood

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.advisor Pitkälä, Riikka
dc.contributor.author Marongiu, Federica
dc.date.accessioned 2020-08-23T17:00:34Z
dc.date.available 2020-08-23T17:00:34Z
dc.date.issued 2020-08-17
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/45973
dc.description.abstract Building sector accounts globally for the 36% of energy consumption and is responsible for the 39% of CO2 emissions. Energy efficiency policies aim to lower the buildings’ energy demand, but the change towards more sustainable solutions must include also the energy sector. Finland is already taking action towards lowering the use of fossil fuels in the energy production. The main objective of this thesis is to analyse the feasibility of a local hybrid energy system. Geothermal energy is chosen as the main source for heating and cooling, while the additional energy is provided through district heating. As part of the system, a local low temperature network is used to supply the buildings. Research method is based mainly on simulations, through which energy demands, borehole field size and the local network performance are defined. Life cycle cost analysis and CO2 emissions estimation are also carried out. The best configuration for the borehole field resulted in a total of 154 wells, with a depth of 291 m. The proposed layout for the local plant would include three geothermal heat pumps, buffer tanks, district heating heat exchanger and free cooling equipment. With a heating output of 45◦C, heat pumps are able to cover up the 70% of the total heat demand. According to the study, the local network seems to be able to deliver enough heating energy to the buildings, with supply temperatures ranging from 65 to 61◦C. The investment cost for a geothermal system is significantly high, and borehole drilling cost covers the 72%. However, for a life cycle of 25 years, the Net Present Value is positive and a payback period of 9.7 years would suggest that the investment is profitable. Compared to a case where all heating is provided via district heating, the annual purchased energy costs can be lowered up to 68% and CO2 emissions would be reduced by 62%. It appears that such system can fulfil the needs of the new neighbourhood and to reduce the emissions. However, site-specific data need to be used in the borehole field sizing and more detailed analysis on the investment costs must be conducted in view of future development. en
dc.format.extent 75
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.title Analysis of a hybrid energy system for a new neighbourhood en
dc.type G2 Pro gradu, diplomityö fi
dc.contributor.school Insinööritieteiden korkeakoulu fi
dc.subject.keyword borehole thermal energy storage en
dc.subject.keyword geothermal heat pump en
dc.subject.keyword local network en
dc.subject.keyword renewable energy en
dc.identifier.urn URN:NBN:fi:aalto-202008234905
dc.programme.major fi
dc.programme.mcode fi
dc.type.ontasot Master's thesis en
dc.type.ontasot Diplomityö fi
dc.contributor.supervisor Virtanen, Markku J.
dc.programme Master's Programme in Building Technology (CIV) fi
local.aalto.electroniconly yes
local.aalto.openaccess yes

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