Wave energy converter (WEC)

A wave energy converter (WEC) comprising:

• a shell mounted about a piston forming a combination which when placed in a body of water is responsive to waves in the body of water for producing relative motion between the shell and the piston;
• a mechanical motion to electrical energy converter, including an electric generator, responsive to the relative motion between the shell and the piston for producing electrical power at an output of the electric generator;
• means coupling a load to the output of the electric generator, said load having an impedance whose value is a function of the period of the waves and of the mass of the water in the shell;
• and
• wherein the shell has a length, L, and wherein the electric power produced at the output of the electric generator is a function of the length of the shell.

A wave energy converter (WEC) comprising:

• a shell mounted about a piston forming a combination which when placed in a body of water is responsive to waves in the body of water for producing relative motion between the shell and the piston;
• a mechanical motion to electrical energy converter, including an electric generator, responsive to the relative motion between the shell and the piston for producing electrical power at an output of the electric generator;
• means coupling a load to the output of the electric generator;
• and wherein when the body of water has a depth, Dw, and the wavelength, λ, of the waves may be expressed as λ=(gT2/2π) tan(2πDW/λ), and where Dw/λ is greater than 1/3, then the length of the shell is made equal to Kλ;
• where K is a constant less than 1.

A method for selecting the length of a tubular shell of a wave energy converter (WEC) to be used in a system, where the tubular shell is mounted about a piston and forms a combination therewith which when placed in a body of water is responsive to waves in the body of water for producing relative motion between the tubular shell and the piston and where the WEC includes a mechanical motion to electrical energy converter, including an electric generator, responsive to the relative motion between the shell and the piston for producing electrical power at an output of the electric generator, comprising the steps of:

• (a) determining the values of power output for
• P=ρg2H2TA δ2/(32πL) as a function of L, where L is the length of the tubular shell, and
• Where:
• ρ=is the density of the mass within the shell of the buoy;
• g=gravity;
• H=to the wave height peak to trough;
• T=period of wave;
• A=the area of the buoy normal to the surface of the water;
• and
• δ=1−cos h(2πL/λ)+tan h(2πDW/λ)sin h(2πL/λ).
• (b) selecting the value of L providing the best results in view of the power generated and cost of the system.

A method for selecting the length of a tubular shell of a wave energy converter (WEC) to be used in a system, where the tubular shell is mounted about a piston and forms a combination therewith which when placed in a body of water is responsive to waves in the body of water for producing relative motion between the tubular shell and the piston and where the WEC includes a mechanical motion to electrical energy converter, including an electric generator, responsive to the relative motion between the shell and the piston for producing electrical power at an output of the electric generator, comprising the steps of:

• (a) calculating the different values of L as a function of λ and Dw, where
• 5 L = 1 - cos ⁢ ⁢ h ⁡ ( 2 ⁢ π ⁢ ⁢ L / λ ) + tan ⁢ ⁢ h ⁡ ( 2 ⁢ π ⁢ ⁢ D w / λ ) ⁢ sin ⁢ ⁢ h ⁡ ( 2 ⁢ π ⁢ ⁢ L / λ ) ( 4 ⁢ π / λ ) ⁢ sin ⁢ ⁢ h ⁡ ( 2 ⁢ π ⁢ ⁢ L / λ ) + ( 4 ⁢ π / λ ) ⁢ tan ⁢ ⁢ h ⁡ ( 2 ⁢ π ⁢ ⁢ D w / λ ) ⁢ cos ⁢ ⁢ h ⁡ ( 2 ⁢ π ⁢ ⁢ L / λ )
• and where:
• DW=water depth;
• and
• λ is a solution to the equation λ=(gT2/2π) tan(2πDW/λ).