An activatable pump is provided. The pump includes a piston in slideable
communication with an inner surface of a cylinder, which has a first end
and a second end. A first control valve and a second control valve are in
physical communication with the first end of the cylinder. The first
control valve and the second control valve are in fluid communication
with the piston. Either the first control valve or the second control
valve is not a check valve. A first check valve and a second check valve
are in physical communication with the second end of the cylinder. The
first check valve and the second check valve are in fluid communication
with the piston. A pressure controller communicates with the piston to
control an amount of force by or on the piston. A method and an energy
recovery apparatus are also provided.