INCREASED USE OF SOLAR ENERGY IN COMMERCIAL

Transcription

1 INCREASED USE OF SOLAR ENERGY IN COMMERCIAL BUILDINGS BY INTEGRATING ENERGY STORAGE Effsys Expand Conference maj 2016 Elsa Fahlén

2 Energy Performance of Buildings Directive Near zero energy buildings have very high energy performance. The low amount of energy that these buildings require comes mostly from renewable sources. All buildings by the end of 2020 All public buildings by the end of 2018

3 How large is the potential to reduce the specific energy use by installing photovoltaics on the rooftop? Solar power generation A previous study shows: Momentous use of electricity as operating electricity Max. installation on the rooftops of three different office buildings: 4-6 kwh/m 2, year The potential is larger assuming an alternative interpretation of the Swedish building standard Operating electricity

4 How can a PV plant be sized to maximise its profitability? A previous study shows: Easier to achieve profitable solutions for large PV systems In some cases, oversizing can be justified from an economical point of view

5 Aim Identify cost-effective system solutions which can increase the share of solar energy in commercial buildings by integrating energy storage technologies

6 Goals Identify system solutions which decrese surplus solar energy produced increase the share of solar energy in energy use increase the profitability of a solar energy plant A decision support for property owners, developers and contractors with consideration to technical, economic as well as management aspects

7 Limitations No environmental aspects Case studies of three office buildings Data availability of energy demand Only new solar energy plants Building-specific conditions with regards to design of the roof and facade are not considered

8 Participants

9 Four work packages 1. Mapping of energy storage technologies and identification of the most promising integrated system solutions with regards to maturity, energyand cost-efficiency 2. Collection of detailed measurements of the energy demand for three reference buildings 3. Techno-economic analysis of system solutions 4. Synthesis and dissemination

10 Mapping of energy storage technologies Thermal energy storage technologies have been mapped Sensible energy storage Latent energy storage Chemical energy storage Assessed with regards to maturity, costand energy effiency and potential application for office buildings

11 COMPARISON Pros Sensible Latent Chemical + Maturity + Cost Cons - Volume - Losses + Volume + Losses - Power - Cost + Volume + Losses - Cost - Maturity 70 m 3 16 m 3 7 m 3 Volume to store 6480 MJ (Passive house)

12 Mapping of integrated system solutions Heat Seasonal storage Cold Short term storage Electricity Short- or long-term

13 Identification of integrated system solutions 1. HEATING SYSTEM SOLUTION Solar thermal collectors, borehole storage, heat pump, water storage tank 2. COOLING SYSTEM SOLUTION Solar PV, chiller, water storage tank 3. POWER SYSTEM SOLUTION Solar PV and batteries

14 Data collection of reference buildings Building A Building B Building C City Malmö Stockholm Stockholm Tap warm water demand [MWh] Heating demand [MWh] Cooling demand [MWh] Property electricity [MWh] Temperated area [m 2 ] Specific energy demand [kwh/m 2 ] Roof area [m 2 ] Bedrock Limestone Granite Granite

15 Techno-economic analysis Choice and test of Polysun for simulation of thermal energy storage A model for a solar heating system combined with a borehole storage, heat pump and a tank A model for a solar cooling system based on photovoltaics combined with an electric chiller and a tank for storing cold water Limitations Only a general heat load profile based on geography Not designed for solar cooling on photovoltaics and an electriity-driven chiller (only based on solar thermal collectors and a heat-driven chiller) Scale of components not flexible (electricity driven chillers)

16 Design of a solar heat and borehole system Heat pump and borehole storage are dimensioned to meet 40, 50, 60, 70 or 100 % of the measured (peak) heat demand Solar collectors are dimensioned to balance the system in its 5 th year in operation Solar collector size fixed while the energy storage and heat pump sizes are varied

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18 Result parameters to be calculated Surplus generation Coverage rate Specific energy use Net present value Payback time

19 Example results - Savings in specific energy demand 35 kwh/m % 50% 100% Power coverage of storage Building A Building C Building A with weithing factor Building C with weithing factor 19/05/

20 Example results Net present value 2500 Net present value (Tkr) Building C 0 0% 50% 100% Power coverage of storage 19/05/

21 Preliminary conclusions so far Three interesting system solutions identified for further studies Preliminary results for solution 1 (solar collectors and borehole) show that there is potential for profitability and for savings in specific energy use The potential for profitability is dependent on a number of factors The potential savings in specific energy use is dependent on weigthing factors for electricity Optimal borehole storage depends on building-specific conditions, but often the results show profitability for a dimension around 50 % coverage of peak heat demand (for comfort heating and domestic hot water) More investigations are needed

22 Some critical aspects No available simulation program covers all needs Verification of the results in Polysun is needed due to limitations Assumption regarding ground water critical for borehole solutions

23 Next steps Mapping and assessment of technologies for storing electricity Data collection of cooling demand and electricity demand Modelling of solutions for meeting the cooling and electricity demand by solar energy Sensitivity analysis Workshop about different actors preconditions to implement and invest in energy storage technologies Conference Popular scientific paper

24 Thank you for your attention!