▁hydro gen , ▁a ▁pressure ▁of ▁ 1 4 5 0 0 ▁p si ▁( 1 0 0 0 bar ▁or ▁ 1 0 0 MP a ) ▁is ▁achieved . ▁A ▁pat ent ▁is ▁pending ▁claim ing ▁an ▁exer gy ▁efficiency ▁of ▁ 7 0 ▁to ▁ 8 0 % ▁for ▁press ures ▁up ▁to ▁ 1 0 , 0 0 0 ▁p si ▁or ▁ 7 0 0 ▁bars . ▁A ▁single ▁stage ▁electro chem ical ▁compression ▁to ▁ 8 0 0 ▁bar ▁was ▁reported ▁in ▁ 2 0 1 1 . ▁DO E ▁has ▁supported ▁develop ments ▁related ▁to ▁developing ▁low ▁cost ▁electro chem ical ▁hydro gen ▁compress ors ▁for ▁heat ▁p umps ▁with ▁X er gy ▁Inc .</ ref . > ▁ ▁H yd ride ▁compress or ▁ ▁In ▁a ▁hyd ride ▁compress or , ▁thermal ▁and ▁pressure ▁properties ▁of ▁a ▁hyd ride ▁are ▁used ▁to ▁abs orb ▁low - press ure ▁hydro gen ▁gas ▁at ▁ambient ▁temper atures ▁and ▁then ▁release ▁high - press ure ▁hydro gen ▁gas ▁at ▁higher ▁temper atures ; ▁the ▁bed ▁of ▁hyd ride ▁is ▁he ated ▁with ▁hot ▁water ▁or ▁an ▁electric ▁co il . ▁ ▁P ist on - met al ▁dia ph rag m ▁compress or ▁ ▁P ist on - met al ▁dia ph rag m ▁compress ors ▁are ▁station ary ▁high - press ure ▁compress ors , ▁four - st aged ▁water - co o led , ▁ 1 1 – 1 5   k W , ▁ 3