Institute of Chemical Engineering, DIRECT ELECTRICITY PRODUCTION FROM HYDROGEN SULFIDE IN BLACK SEA WATER BY SULFIDE-DRIVEN FUEL CELL Prof. Venko Beschkov Institute of Chemical Engineering, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria

Problem: Greenhouse gas reduction?

Share of renewables, EU statistics 2016

Carbon-free energy/Renewable energy sources: Wind energy Solar energy Hydropower Biomass... What else?

Opportunity: the enormous amount of hydrogen sulfide in the Black Sea waters Tonnes of oil equivalent (toe) Electricity produced 4.587 Gt 2600 Mtoe (~1640 Mtoe EU total annual energy consumption, 2016) 31500 TWh (~ 3xEU annual production, 8780 TWh, 2016) Each year new 7,5 mln tons hydrogen sulfide are formed (54 TWh) BG annual electricity consumption – 34 TWh, 2018)

The beginning was a project for hydrogen production from hydrogen sulfide in the Black Sea water by electrolysis. However, the energy demand was higher than the one of the produced hydrogen.

Net reaction: S2- + 2O2 = SO42- +H, We propose: Direct energy production from hydrogen sulfide by new sulfide driven fuel cell (SDFC) 1 m3 water/sec yields 500 kWh energy total. The power consumption for pumping and operation is about 10% of the yield from SDFC. Anode: S2- + 4H2O - 8e- = SO42- + 8H+, Eo= 0.149 V Cathode:2O2 + 8H+ + 8e- = 4H2O, Eo=1.229 V EMF = 1,08 V Net reaction: S2- + 2O2 = SO42- +H, H = - 830 kJ/mol

Sulfide driven fuel cell Production steps Pumping from big depths (energy consumption); Energy production in sulfide driven fuel cell; DC/AC inversion,transformation and supply to the grid, and/or Splitting water by electrolysis and storage of the produced hydrogen for further processing (alternative applications). Simultaneous energy production and seawater remediation. To the grid Electricity Sea level Sulfide driven fuel cell Deep water Clean water

Customers/Market: Big companies with interests in energy production and distribution wherever this resource is available (Black Sea; Caspian Sea; Baltic Sea, mineral water springs,etc.); Governments of the coastal countries.

Competitors/opponents: Oil, gas and coal production and distribution companies; Power stations based on fossil fuels; Producers of energy based on solar and wind resources; Nuclear power stations.

Comparison of the energy potential of hydrogen sulfide with other energy sources Fuel Energy capacity, GJ/t Oil equivalent 41.86 Hydrogen 143.02 Methane 56.46 Ethanol 26.8 Methanol 19.9 Hydrogen sulfide 24.4 Equivalent to Tons of oil equivalent Electricity, TWh 4,6 billion tons H2S 2.6 billion 31000

SDFC and other fuels - comparison Energy source Features Fossil fuels (thermal power stations) (oil, gas, coal) Carbon emissions; expensive production; heavy operation; long switch on/off process; waste handling. SDFC Carbon free; less operational costs; easy switch-on/off; no waste. Nuclear fuel Expensive fuel production; heavy operation; long switch on/off process; hazardous operation and waste storage. Less operational costs; easy switch-on/off; no hazards, no waste. Wind Weather and season dependent; impact on environment (bird migration). Independent Solar Weather and season dependent; impact on soil and biodiversity Independent, environmental benefits

Costs for electricity yield Investment costs (€/kW ) Solar and wind parks, 500-5000 Nuclear power stations, 6000-8000 Sulfide power stations, 1000-2000 Operational costs (€/MWh ) Solar and wind parks, 10-20 Nuclear power stations, 40 Sulfide power stations, 10-20 Lifespan, years Solar and wind parks, 15 Nuclear power stations, 30 Sulfide power stations, 30

Implementation steps for a sulfide power plant Build pilot-scale prototype of 25 kW: € 150 000 Build full-size equipment of 10 MW: € 20 mln Full-size equipment of 240 MW on a rig: € 480 mln

Fuel cell lab-scale prototype- tested in situ on a ship in the Black Sea:

Off-shore expedition, July, 2014

Team: Research project HYSULFCEL sponsored by FP7, bs.era-net program Project team leader Business development Vladislav Hristov, PhD Roccon Research Center (Sofia, Bulgaria) Prof. Venko Beschkov, PhD, DSc (BAS, Sofia, Bulgaria) Technical team: Prof. N. Vaszilcsin, DSc (Polytechnical University, Timisoara, Romania) Prof. T. Marsagishvili, DSc (Tbilisi State University, Georgia) Assoc. Prof. E. Razkazova-Velkova, PhD (BAS, Sofia, Bulgaria) Assoc. Prof. M. Martinov, PhD (passed away)(BAS, Sofia, Bulgaria) Assoc. Prof. G. Shtereva, PhD (passed away) (BAS, Varna, Bulgaria) Research project HYSULFCEL sponsored by FP7, bs.era-net program

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