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 as an electron donor. Is not able to reduce the prenyl group of respiratory quinones. 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 Binds 1 FAD per subunit. Membrane lipid metabolism; glycerophospholipid metabolism. Reduction reaction proceeds via syn addition of hydrogen for double bonds. Belongs to the geranylgeranyl reductase family. DGGGPL reductase subfamily. Extended N-terminus.