As and Sb-bearing galena CO2 abatement cost CO2 emissions CO2-EGS Cornubian Batholith Death Valley EGS Enhanced Geothermal Systems (EGS) FWI LCOE LCOH MEET H2020 project Mohr diagrams NPV Noble Hills Noble Hills granite OVSP Owlshead Mountains granite Soultz-Sous-Forêts Soultz-sous-Forêts THM modeling United Downs Upper Rhine Graben Variscan fold-and-thrust belt Variscan rocks autoclave experiments blind geothermal system claystone clustering compositional anomalies