▁pl asma ▁have ▁led ▁to ▁the ▁achiev ement ▁of ▁substantial ly ▁improved ▁energy ▁and ▁pressure ▁conf in ement , ▁which ▁reduces ▁the ▁project ed ▁cost ▁of ▁electric ity ▁from ▁such ▁react ors ▁by ▁a ▁factor ▁of ▁two ▁to ▁a ▁value ▁only ▁about ▁ 5 0 % ▁more ▁than ▁the ▁project ed ▁cost ▁of ▁electric ity ▁from ▁advanced ▁light - water ▁react ors . ▁In ▁addition , ▁progress ▁in ▁the ▁development ▁of ▁advanced , ▁low ▁activation ▁struct ural ▁materials ▁supports ▁the ▁promise ▁of ▁environment ally ▁ben ign ▁fusion ▁react ors ▁and ▁research ▁into ▁alternate ▁conf in ement ▁concepts ▁is ▁yield ing ▁the ▁promise ▁of ▁future ▁improvements ▁in ▁conf in ement . ▁Finally , ▁supp or ters ▁cont end ▁that ▁other ▁potential ▁rep lac ements ▁to ▁the ▁foss il ▁fu els ▁have ▁environmental ▁issues ▁of ▁their ▁own . ▁Sol ar , ▁wind , ▁and ▁hydro elect ric ▁power ▁all ▁have ▁a ▁relatively ▁low ▁power ▁output ▁per ▁square ▁kilometer ▁compared ▁to ▁I TER ' s ▁successor ▁DE MO ▁which , ▁at ▁ 2 , 0 0 0 ▁M W , ▁would ▁have ▁an ▁energy ▁density ▁that ▁exceed s ▁even ▁large ▁f ission ▁power ▁stations . ▁ ▁Similar ▁projects ▁P rec urs ors ▁to ▁I TER ▁were ▁E AST , ▁S ST - 1 , ▁K ST AR , ▁J ET , ▁and ▁T ore ▁Sup ra . ▁Similar ▁react ors ▁include ▁the ▁Wend el stein ▁ 7 - X . ▁Other ▁planned ▁and ▁proposed ▁fusion ▁react ors ▁include ▁DE MO , ▁ ▁N IF , ▁Hi