USING SOLAR ENERGY CONTINUOUSLY THROUGH DAY AND NIGHT FOR METHANE REFORMING – AN EXPERIMENTAL DEMONSTRATION J. L. Lapp, M. Lange, M. Roeb, C. Sattler ECCE10 –

CH 4 CO 2 CO H2H2 H2OH2O Background on Methane Reforming Primary source of industrial hydrogen Feedstock is typically natural gas Other possible feedstocks: biogas, refinery gas, coke oven gas Heat input needed at C Products (syngas) useful for synthesis of other fuels (Fischer-Tropsch) Catalyst required for kinetic reasons Steam Reforming: Dry Reforming: 2ECCE October 2015 Lapp et al.

Traditional Methane Reforming 800 °C 30% 800 °C 3ECCE October 2015 Lapp et al.

Solar Methane Reforming 800 °C 30% 42% increased output 4ECCE October 2015 Lapp et al.

Why use solar energy to produce chemical fuels? 1)Long term storage 2)Easy to transport 3)Compatible with current infrastructure 4)Uses in transportation 5ECCE October 2015 Lapp et al.

Solar Methane Reforming Background 6 Directly irradiated Indirectly heated Source: R. Tamme, 2002, SOLASYS – Final Report + High efficiency – High cost – Technically challenging + Consists of existing / simpler process units  Technically easy ? Efficiency potential unknown Concept first proposed in 1982 by Chubb of U.S. Naval Research Laboratory ECCE October 2015 Lapp et al.

Indirect Experimental Studies 7 ASTERIX (CIEMAT/DLR, 1991) 170 kW, 68-93% Conversion DCORE (CSIRO, 2009) 200 kW SCORE (CSIRO, 1999) 25 kW WIS, 2003, 480 kW Sodium Vapor HTF (WIS/SNL 1983) 20 kW ECCE October 2015 Lapp et al.

Direct Experimental Studies 8 INHA-DISH1, kW 60% conversion DIAPR (porcupine), WIS, % conversion Particle concept, WIS, 2009 SOLBIOPOLYSY, 2008, 250 kW, landfill gas ECCE October 2015 Lapp et al.

CAESAR – SNL/DLR 1987 – 100kW 9 Solar Power (kW) Receiver Efficiency (%) Chemical Efficiency (%) Methane Conversion (%) Radially Uniform Absorber Radially Non-Uniform Absorber ECCE October 2015 Lapp et al.

SOLASYS: DLR/WIS/Ormat, 220 kW, >90% conversion 10 Source: R. Tamme, 2002, SOLASYS – Final Report 4.9 bar7.5 bar Measured CH4 Conversion72.0%70.5% Calculated CH4 Conversion73.2%65.0% ECCE October 2015 Lapp et al.

SOLREF: DLR/WIS – 400 kW, 950 °C, 15 bar 11 Included novel catalytic system suitable for biogas, landfill gas, and high CO 2 natural gas 94.6% Conversion ECCE October 2015 Lapp et al.

Theoretical Efficiency Analysis ECCE October 2015 Lapp et al.12 Indirect Direct Energy balance (flow sheet) analysis Directly and indirectly heated receiver concepts (separate models) Annual efficiency calculated with hourly irradiation data

Direct and Indirect Concepts Directly Irradiated CatalystIndirectly Heated with Air HTF Technical DifficultiesWindow, Catalyst-AbsorberLow Heat Transfer Rate Dynamic BehaviorFastSlow Heat LossesModerateHigh Heat StorageDifficultEasy Hybridization (burners)DifficultEasy Coupling with CSP PlantDifficultEasy 13ECCE October 2015 Lapp et al.

Reactor: SiSiC - honeycomb structure with catalyst coating (Rh) Contisol Project CO + H 2 Hot air Cold air CH 4 + steam + CO 2 ECCE October 2015 Lapp et al.14

Contisol Project Thermal Storage Daytime Thermal Storage Nighttime Hot air to storage Hot air from storage ECCE October 2015 Lapp et al.15

Modeling Results 16 Concept 3D Computational Domain Applied Heat Flux Daytime Operation Nighttime Operation ECCE October 2015 Lapp et al.

Experimental Setup 17ECCE October 2015 Lapp et al.

Experimental Setup (simplified to thermal testing) 18ECCE October 2015 Lapp et al.

Experimental Preparation 19 Porous Silicon Carbide Monolith Infiltrated (dense) Monolith TC’s Mounted “Canning” Mounted Channels Closed Monolith Sealed and Mounted ECCE October 2015 Lapp et al.

Experiments 20 Gas coolersReactorAir PreheaterRadiation Shield Reactant Preheater Pressure Sensors ECCE October 2015 Lapp et al.

Experiments 21ECCE October 2015 Lapp et al.

Experimental Results 22ECCE October 2015 Lapp et al.

Experimental Investigation Used statistical design of experiments procedure (using Origin software) Identified key variables Gas flow rate (x2) Gas inlet temperature (x2) Monolith front temperature Even with 3 values of each variable, 243 runs needed to fully describe system (full factorial) Optimally distributed input parameter set over 23 runs Regression and co-variance analysis used to determine impact on efficiency of each varible Performance prediction of receiver fit by statistical model with R 2 > ECCE October 2015 Lapp et al.

Experimental Investigation Results (all CI 95%) 24ECCE October 2015 Lapp et al.

Experimental Investigation Results (all CI 95%) 25 Flow rates are less important at high monolith temperatures (re- radiation dominates) Flow rates are more important to the efficiency than inlet temperatures ECCE October 2015 Lapp et al.

Leakage Problem 26ECCE October 2015 Lapp et al.

Future Advancements 3-D printing of Inconel monolith 27 Test Sample, DLR, ECCE October 2015 Lapp et al.

Future Advancements 3-D printing of Inconel monolith Acid etching of surface required 28 Test Sample, DLR, Before Etching After Etching ECCE October 2015 Lapp et al.

Conclusions 41% upgrade of useful fuel energy with solar energy Indirect and direct concepts High conversion demonstrated, flexibility has not New concept (CONTISOL) has been modeled Thermal experiments begun Major challenge is leakage Will address in next steps 29 Thermal Storage ECCE October 2015 Lapp et al.