Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE credits
The feasibility of a Central solar heating plant with seasonal storage (CSHPSS) in a new district in Astana was evaluated. A total usable footprint of 481271 m2 of low energy (passivhaus standards) multi storey apartment blocks and single family houses (15000 expected inhabitants) was studied.
Astana is a very cold climate, with heating degree days (below 18 °C) of 5724 °C.day/year. However the solar radiation is higher than in northern Europe (where most CSHPSS are located). Space heating demand, using passivhaus standards, would be 7.2 GWh/y, DHW demand calculated was 11 GWh/y and transmission losses 2.41 GWh/y.
Astana’s DH network was studied in order to analyze the integration of this solar thermal system within the city network. Nevertheless due to its typology (open system) and its temperature regime a newly built DH within the existing network is chosen, a secondary 60/30 °C network is considered to be appropriate. Previous plants and technologies used in central plants were reviewed in order to select the most appropriate ones.
In the simulation, collector areas between 1.4 and 2.5 m2 per MWh heat demand and water storage volumes between 1.2 and 4.0 m3 per m2 collector area satisfy between 41 and 81 per cent of the total heat demand by solar thermal heat. Levelized cost of energy (LCOE) increases from 0.099 €/kWh to 0.107 €/KWh when increasing the solar fraction. Two systems were selected as optimum (from LCOE point of view) that gave solar fractions of at least 50 % and 80 %.
In order to calculate feed-in tariff, Net Present Value (NPV) and Payback Time (PBT), local economic figures were chosen considering different financial considerations resulting in a discount rate of 12% and inflation of 7%. Since the heat tariff for solar thermal is not defined by law, this tariff was calculated for an expected internal rate of return of 28%. For SF=50% the investment would have a feed-in tariff of 0.184 €/kWh, a PBT=8.2 years and NPV=9.92 M€. For SF=80% the investment would have a feed-in tariff of 0.191 €/kWh, a PBT=7.75 years and NPV=16.7 M€.
2015.