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Generator

Requirements

Engine Requirements:
  1. Rotation - Must be able to convert up and down motion into rotation 
  2. Inertia - Use inertia to maximise turbine rotation with minimal energy
  3. Scalable - Must be easy to add more floats to the engine in order to increase its strength

Hydraulic Engine Design

The figure below shows a possible hydraulic configuration. The idea is to connect the cables to pistons. 
  • As the wave rises the piston is pulled up. This creates suction and pulls in fluid. As the fluid comes in it passes the turbine making it turn. 
  • As the wave lowers the weights on the piston (including the fluids weight) will force the fluid down again and keep the tension on the cable. This will force the fluid back down past the turbine helping it turn again. 
Figure 1: Hydraulic Engine Overview
Pros:
  • Scalable - More floats can easily be added to the engine.
  • Rotation inertia - By using turbines an inertia can be created which will help generate power
  • Simple design - This engine's construction is simple enough to be handled by most 3rd world countries
  • Higher power output - because of the inertia and the piston collaboration it is possible to get higher turbine speeds which will lead to higher outputs.
Cons:
  • This needs some expertise to construct. Rural communities might not be able to manage so this will need to be imported
  • In heavy storms the pressure in the system would need to be managed else the pipe might rupture

Piston Design

Figure 2: Piston Design Diagram
Design notes:
  • Safety Coil - The coil has a tension break build into it. If the tension on the cable gets too big it will release the coil onto the cable giving it slack and saving it from breaking.
  • Tension Spring - Due to the unpredictable nature of the waves a tension spring is needed to handle any unexpected up surges. By giving slack the cable and piston is spared any sudden change in pressure.
  • Downward Force Spring - Including a spring on the inside will add incremental downwards pressure in those cases where the piston weight gets too high in the shaft. Note that it is not attached to the weight. 

Simple Shaft Armature Design

This option concentrates on making the generator as simple as possible. Instead of converting the up and down motion of the waves into circular rotation the force is used directly. By simply lifting and dropping the magnets in the pipe electricity will be generated. Aka: Linear electric generator



Figure 3: Shaft design setup diagram

Pros:
  • Very simple - This design can be build from spare parts. All that's needed is copper wire and magnets making it idea for rural communities that would be making these for themselves. The components can be found in scrapyards.
Cons:
  • Less efficient - Because no inertia is retained this setup does not produce electricity at the top and the bottom.
  • Single generators - Each float will have to lift one coil. This concept can not work in series.
  • Lots of copper - Since the armature should cover the entire motion that the magnets can run (max wave height plus tides) a lot of copper winding will be needed. 
Ideas:
  • It is possible for bigger floats to lift multiple coils at the same time
  • Maybe move the earth magnets to the center and the coils on the outside. It depends on which option works out cheaper

Clutch Bearing Design

After doing the prototype the realization hit how easy it is to get one-way bearings in the form of bicycle sprockets. Not only that but the chains that go with it makes for a perfect grip so that minimal power is lost. The best part is that it's cheap. The generator in this case is a standard generator out of the box. I still want to see what type of performance I can get from a DIY generator setup. 

Figure 4: The side view of the sprocket setup

Figure 5: The top view of the sprocket setup working in parallel

Someone beat me to this concept but I must say it's a brilliant idea.
Pros:
  • Simple - The idea works like a bicycle which is easy to understand. 
  • Mass produced parts -  All the parts used are mass produced which will drive prices down. Second hand parts might also be obtained.
  • Grip - The sprocket and chain design allows for good grip on the rotor so that minimal energy is lost due to slippage. 
  • Scalable - It's easy to add more sprockets to the threaded steel rod as more floats are installed.
Cons:
  • Threaded rod - The rod that the sprockets connect to will need to have the same thread. This thread will need to be custom made
  •  Long chain - The bicycle chain will need to be able to handle the entire possible range of the wave as well as tidal differences.

Alternator

Building the alternator from scratch is essential for keeping the costs down. Luckily I've found this great site that shows step by step how to build a Alternator.

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