Source of power in a hydrocarbon well facility

1. An apparatus for providing a source of power, the apparatus comprising:

a rotor having external blades for use in causing rotation of the rotor, and internal blades for use in propelling a fluid through the rotor during rotation of the rotor;

a fluid circuit coupled with the rotor, wherein rotation of the rotor propels fluid in the fluid circuit through the fluid circuit;

a power device configured to use the fluid propelled through the fluid circuit as a power source;

wherein the rotor is in a flow path for a second fluid, the rotor being rotatable by the flow of the second fluid through the path;

a stator in the rotor, such that the first fluid can be propelled between the rotor and the stator;

wherein the stator has a plurality of external blades interleaved with the internal blades of the rotor so that rotation of the rotor causes the fluid to be propelled between the internal and external blades;

wherein the volume between adjacent internal blades of the rotor and external blades of the stator decreases in the direction in which the fluid is propelled between the rotor and the stator; and

wherein the rotor is in a flow path for hydrocarbon fluid in a subsea hydrocarbon well facility, the power device using the fluid propelled through the circuit as a power source for the well facility.

2. The apparatus according to claim 1 , wherein the power device is configured to use the fluid propelled through the circuit as a power source to hydraulically operate at least one hydraulic device.

3. The apparatus according to claim 1 , wherein the power device configured to use the fluid propelled through the circuit as a power source generates electrical power from fluid propelled through the fluid circuit.

4. The apparatus of claim 1 , wherein a length of the internal blades of the rotor and the external blades of the stator decrease in the direction in which fluid is propelled between the rotor and the stator.

5. A method of propelling a first fluid, the method comprising:

providing a rotor having external blades and internal blades; and

coupling a fluid circuit with the rotor;

causing rotation of the rotor via the external blades to propel the first fluid through the rotor during rotation of the rotor;

causing further rotation of the rotor by a second fluid, wherein the rotor is in a flow path with the second fluid;

propelling the first fluid between the internal blades of the rotor and external blades of a stator, wherein the external blades of the stator comprise a plurality of external blades interleaved with the internal blades of the rotor;

wherein the volume between adjacent internal blades of the rotor and external blades of the stator decreases in the direction of the first fluid being propelled between the internal blades and external blades;

wherein the flow path is a flow path for hydrocarbon fluid in a subsea hydrocarbon well facility, the first fluid propelled through the circuit being used as a power source for the subsea hydrocarbon well facility.

6. The method according to claim 5 , wherein the propelled fluid is used for hydraulically operating at least one hydraulic device.

7. The method according to claim 5 , wherein the propelled fluid is used for generating electrical power.

8. The method claim 5 , wherein a length of the internal blade of the rotor and the external blades of the stator decrease in the direction in which fluid is propelled between the rotor and the stator.