Evaluation of mobile storage systems for heat transport G. Storch, A. Hauer, A. Krönauer ZAE Bayern, Walther-Meißner-Str. 6, 85748 Garching, Germany
Outline Introduction Mobile Storage Units Case Studies: Setup Case Studies: Results
Motivation Obstacles : - temperature level - mismatch in availability - mismatch in place Cumulated waste heat in the Netherlands process industry. Source: P. Bach, Energy Research Centre of the Netherlands
Outline Introduction Mobile Storage Units Principle Energy Storage in Zeolites Other systems Case Studies: Setup Case Studies: Results
Concept Mobile storage units replace pipeline-bound system charging station Zeo Zeo Zeo User A truck + container Aluminium factory high uses initial public costs infrastructure Waste incineration right very plant of flexible way? inflexible higher running costs Zeo User B + User C, D,
Zeolite storage unit Modified freight container: zeolite volume 18,7 m³ zeolite mass 15 t bed height 0,8 m bed cross section 23,2 m² maximum airstream 20.000 m³/h sorbent sorbent Air Energy storage capacity Charging power discharging power max. 4.1 MWh max. 1 MW max. 750 kw
Principle of sorption heat storage adsorption desorption heat adsorbent area water molecules Sorption processes combine high thermal turnover (h ev,h2o =2440 kj/kg=0,68 kwh/kg) excellent repeatability low losses
Open sorption systems water vapour / zeolite atmospheric pressure zeolite pellets in fixed bed air as carrier gas for heat- and masstransfer Desorption charging discharging Adsorption air + vapour heat of condensation air + vapour heat of evaporation Zeolite air heat of desorption air heat of adsorption
Alternative: PCM-Technology Sodium acetate tri-hydrate, melting point 58 C PCM mass 22 t unit total mass 26 t PCM energy stored / unit thereof latent heat typical charging power (90/70 C) typical discharging power (38/48 C) typical discharging power (25/40 C) energy losses 2.4 MWh 1.6 MWh 250 kw 125 kw 220 kw ca. 10 kwh in 24h Heat carrier fluid Heat exchanger Other systems?
Outline Introduction Mobile Storage Units Case Studies: Setup Heat Sources Potential Users Parameters Case Studies: Results
Heat sources Aluminium factory Combustion of solvent-laden air 230 C Waste heat Only temporarily available Waste incineration Steam from extraction turbine 150 C reduces electricity generation Non-stop operation
Discharging III: drying applications auxiliary heating feed 20 C ϕ=60% AMB IN dryer OUT e.g. 60 C ϕ=55% 180 C ϕ=0.03% ADS zeolite
System boundary Mobile Storage charging system, container, truck, wages, fuel storage container hot, dry air warm water Energy costs (considered) Demand site docking station, heat exchanger, evaporative cooler Initial costs (not considered)
Reference System Utility electricity oil / gas / district heating Demand site heat exchanger, boiler, chiller, Energy costs (considered) Initial costs (not considered)
Parameter default values Parameter alu +zeo alu +PCM waste +zeo waste +PCM Availability (uptime) 4380 h/a 4380 h/a 8320 h/a 8320 h/a Internal heat costs 0 0 4.2 /MWh 4.2 /MWh Storage capacity / unit 4.1 MWh 2.4 MWh 3.4 MWh 2.4 MWh Charging time 5.5 h 9.3 h 5.8 h 9.3 h One-way distance 10 km 10 km 7 km 7 km Wages 40 /h 40 /h 28 /h 28 /h Transportation costs per 100km 55 55 55 55 Driving speed 25 km/h 25 km/h 25 km/h 25 km/h Auxiliary energy / unit 55 kwh 0 55 kwh 0
Outline Introduction Mobile Storage Units Case Studies: Setup Case Studies: Results
(Primary) Energy Flow Diagram Charging station COP > 9 in terms of auxiliary energy! waste heat 132% auxiliary energy, transport 10.5% Zeo useful energy 100% User Fuel 105%
Reduction of CO 2 emissions [t/a] 900 800 700 600 500 400 300 200 100 0 Zeolite Without mobile storage Gas boiler Auxiliary energy Transport
Cost distribution aluminium factory + sorption waste incineration + sorption internal heat costs 0% auxiliary energy 2% invest charging station 9% internal heat costs 14% auxiliary energy 2% invest charging station 11% labour 36% storage containers 27% storage containers 21% labour 28% variable costs transportation 8% maintenance 3% Sum: 114 000 /a fixed costs transportation 15% variable costs transportation 8% Sum: 146 000 /a maintenance 4% fixed costs transportation 12%
Parameter study: uptime 60 55 energy costs [ /MWh] 50 45 40 35 30 25 20 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500 uptime charging station [h/a] sorption PCM water oil natural gas
Summary Energy transportation via mobile storage systems is energetically sound Topics for ongoing research on zeolite systems: successful demonstration mechanical stability desorption with flue gases Economic performance depending on ratio wages / energy costs Ideal application: industrial drying
Acknowledgements We are grateful to BMWi for financial support our industry partners for fruitful cooperation Thank you for your kind attention! Questions?