24th June 2019
Progress meeting. All agreed that overtopping device seems realisable. Dr Khairi requested to focus more on three devices which were overtopping device, wave attenuator and bulge wave device. For the three devices, find:
- existing product (device name, developer, location, etc.)
- construction of each device
- working principle (more details)
- specifications (how much power generated by each device, size, cost, etc.)
25th June 2019
Did some reading on the most popular overtopping device; Wave Dragon. Developed by Wave Dragon ApS in Denmark, it consists of a main body with a doubly curved ramp; a reinforced concrete and/or steel construction, two wave reflectors in steel and/or reinforced concrete mooring system, propeller turbines and permanent magnet generators.
The main body consists of one large floating reservoir. To reduce rolling and keep the platform stable; the Wave Dragon must be large and heavy. The device has two wave reflectors that direct the waves towards a ramp. Behind the ramp, a large reservoir collects the directed water, and temporarily stores the water. The reservoir is held above sea water level. Energy is extracted as the water leaves the reservoir through low-head hydro turbines and into the sea.
There are three models available with different number of turbines, different annual power production and different water depth. The annual power per unit is as in the table below.
26th June 2019
Studied on a bulge wave device called Anaconda. It was first invented by Rod Rainey and Francis Farley. I was later further developed by the licensed manufacturers Checkmate SeaEnergy Ltd. As the bulge waves travel down the tube and arrive at the stern, the pressure in the area ahead of the PTO cycles above and below the tube's rest pressure. During the high pressure part of the cycle, water passes through a set of non-return valves into an accumulator where pressure is allowed to build up. A smoothed flow of water then passes from the accumulator into a conventional hydraulic turbine which drives an electrical generator. Upon exiting the turbine, the water is accepted into a low pressure accumulator and is then drawn through another set of non-return valves back into the main tube during the low pressure part of the bulge wave cycle. A full scale design is about 150 meters long with a diameter of 7 meters was estimated to generate about 1MW of electricity.
27th June 2019
Studied on Pelamis, a type of wave attenuator. It was manufactures and operated by Pelamis Wave Power Ltd. (PWP) in1998. Pelamis is an offshore WEC, operating in water depths greater than 50 meters. It consists of a series of semi-submerged cylindrical sections linked by hinged joints.
The Pelamis is an attenuating WEC where it responds to the curvature of the waves (their shape) rather than the wave height. As waves can only reach a certain curvature before naturally breaking, this limits the range of motion through which the machine must move but maintains large motion at the joints in small waves.
Their first prototype, P1 was tested at European Marine Energy Centre's (EMEC) wave test site in Orkney, Scotland. The P1 has 4 sections which add up to a total length of 120m with 3.5m diameter. It produced 2.97 GWh annually. Their second prototype, the P2 has 5 sections. It was 180m long and 4m in diameter.
28th June 2019
Prepared PowerPoint presentation for next week's progress meeting.