Hydraulic gas compressor

A hydraulic compressor system for compressing gas, comprising:

• at least one pump for pumping liquid;
• a gas reservoir for storing compressed gas;
• at least two compression tanks, each of said compression tanks comprises:
• an expandable bladder defining a bladder cavity, wherein the expandable bladder contains a liquid in the expandable bladder cavity and the expandable bladder is configured to expand when liquid is input into the expandable bladder cavity;
• a tank cavity outside of the expandable bladder, wherein the cavity comprises a compressible gas;
• wherein the expandable bladder and the tank cavity outside the expandable bladder form interdependent volumes of liquid and gas;
• a liquid line configured to fluidly couple the expandable bladder cavity with the at least one pumps such that the liquid is pumped into or out of the expandable bladder via the liquid line;
• a gas line configured to fluidly couple the gas reservoir with the tank cavity such that the gas flows into or out of the tank cavity via the gas line;
• wherein, during operation of the system, liquid is pumped by the at least one pump to the expandable bladder in a first compression tank and gas is expelled from the tank cavity of the first compression tank and directed to gas reservoir where it is compressed;
• characterized in that a volumetric ratio of the volume of the tank cavity at an end of a compression stroke to volume of the tank cavity at beginning of the compression stroke (Vc/Vo) is <=0.1.

A method for compressing gas, the method comprising:

• providing a first compressor tank comprising:
• an expandable bladder defining a bladder cavity, wherein the expandable bladder contains a liquid in the expandable bladder cavity;
• a tank cavity outside of the expandable bladder, wherein the cavity comprises a gas;
• a liquid input;
• and
• a gas port;
• connecting the gas port of the first compressor tank to a gas reservoir via a gas line;
• connecting the liquid input of the first compressor tank to a first liquid line;
• characterized in that,
• operating the first compression tank in either a compression stroke or a return stroke, wherein operating the first compression tank in the compression stroke comprises:
• compressing the gas in the tank cavity of the first compressor tank by pumping a liquid into the expandable bladder cavity of the first compressor tank via the first liquid line such that the expandable bladder of the first compressor tank expands into the tank cavity;
• displacing the gas out of the tank cavity of the first compressor tank, via the gas port, and collecting said gas in the gas reservoir;
• further compressing the gas in the gas reservoir;
• and
• wherein operating the first compression tank in the return stroke comprises:
• pumping a liquid out of the expandable bladder cavity of the first compressor tank via the first liquid line such that the expandable bladder of the first compressor tank contracts, which in turn increases a volume of the tank cavity of the first compressor tank;
• filling the tank cavity of the first compressor tank with gas from a low pressure gas source via the gas port.