Is involved in the reduction of 2,3-digeranylgeranylglycerophospholipids (unsaturated archaeols) into 2,3-diphytanylglycerophospholipids (saturated archaeols) in the biosynthesis of archaeal membrane lipids. Can fully reduce the unsaturated isoprenoid side chains of membrane phospholipids and glycolipids. Is also able to reduce the omega-position isoprene of dolichol phosphate. a 2,3-bis-O-phytanyl-sn-glycerol 1-phospholipid + 8 oxidized 2[4Fe-4S]-[ferredoxin] = a 2,3-bis-O-(geranylgeranyl)-sn-glycerol 1-phospholipid + 16 H(+) + 8 reduced 2[4Fe-4S]-[ferredoxin] Binds 1 FAD per subunit. Membrane lipid metabolism; glycerophospholipid metabolism. Reduced pigmentation of cell colonies and lack of fully reduced isoprene chains of membrane phospholipids and glycolipids. Belongs to the geranylgeranyl reductase family. DGGGPL reductase subfamily.