Is involved in the reduction of 2,3-digeranylgeranylglycerophospholipids (unsaturated archaeols) into 2,3-diphytanylglycerophospholipids (saturated archaeols) in the biosynthesis of archaeal membrane lipids. Catalyzes the formation of archaetidic acid (2,3-di-O-phytanyl-sn-glyceryl phosphate) from 2,3-di-O-geranylgeranylglyceryl phosphate (DGGGP) via the hydrogenation of each double bond of the isoprenoid chains. Is not active with NADPH or NADH as an electron donor; the physiological reducing agent is unknown. Is also active on the more upstream precursors of membrane lipid biosynthesis, catalyzing the complete reduction of 3-O-geranylgeranylglyceryl phosphate (GGGP) to 3-O-phytanylglyceryl phosphate, and the partial reduction of geranylgeranyl diphosphate (GGPP) to phytyl diphosphate, thus reducing three of four GGPP double bonds and preserving the allylic double bond (at position 2). This reaction product is a reactive prenyl donor, which can be used as a substrate by archaeal prenyltransferases such as GGGP synthases. 8 A + a 2,3-bis-O-phytanyl-sn-glycerol 1-phospholipid = a 2,3-bis-O-(geranylgeranyl)-sn-glycerol 1-phospholipid + 8 AH2 2,3-bis-O-(phytanyl)-sn-glycerol 1-phosphate + 8 A = 2,3-bis-O-(geranylgeranyl)-sn-glycerol 1-phosphate + 8 AH2 4 A + sn-3-O-phytanylglycerol 1-phosphate = 4 AH2 + sn-3-O-(geranylgeranyl)glycerol 1-phosphate 3 A + phytyl diphosphate = (2E,6E,10E)-geranylgeranyl diphosphate + 3 AH2 Binds 1 FAD per subunit. kcat is 0.40 min(-1) for the reduction of GGPP to the hexahydro-product H(6)GGPP. Optimum pH is 5.5 for the reduction of GGPP to the hexahydro-product H(6)GGPP. Optimum temperature is 55 degrees Celsius for the reduction of GGPP to the hexahydro-product H(6)GGPP. Membrane lipid metabolism; glycerophospholipid metabolism. Monomer. Belongs to the geranylgeranyl reductase family.