History - Analysis of the existing wave power plants
ANALYSIS OF THE EXISTING WAVE POWER PLANTS
Nowadays wave power plants that transform wave energy are equipped with converters tracking the wave profile by oscillations of water column and underwater devices.
The type of converters tracking the wave profile first of all includes the development of S. Salter, professor of the University of Edinburgh, named after him – the Salter’s Duck ( Fig. 5). Technical name of the project is oscillating wing.
Fig.5 Salter’s Duck
The incoming waves make the Duck oscillate. Power is taken from the oscillation system axis. A string of twenty meter ducks with total weight of 16 tons was tested during four months under various wave conditions of the Loch Ness Lake and it showed the efficiency coefficient of 0.5 %.
Principal drawbacks are complicated manufacturing and installation and large load impact of the maximum waves.
Another type of this kind of wave energy converters is the Cockerell’s contouring raft (Fig. 6), that was tested in the Solent Channelnear the Southampton city.
Fig.6 Cockerell’s raft
WPP construction based on the concept of Cockerell’s raft is realized in the Wave Farm project by Pelamis Wave Power company, Scotland (former Ocean Power Delivery). Four pivotally connected sections bend under the wave influence and activate hydraulic cylinders that pump oil over to the generator drive hydraulic motors. The produced energy is transmitted to the coast over the bottomed cable. Three converters built on the Portugese seacoast are shown in the Fig. 7. Each converter (called Pelamis Wave Energy Converter) in terms of its length and cross section is comparable to a small railway vehicle with 120 m in length and 700 tons in weight.
The power of a single converter of this type is 700 kWt.
It is just the first stage of the project and it is planned to build 25 additional machines near the Agucadoura seacoast, that will result in total power of WPP rising up to 21 MWt.
Fig. 7. Pelamis Wave Energy Converters
This will suffice for 15 thousand houses, and it means that there will be 60 thousand tons annual reduction of carbon dioxide emissions from the heating stations.
Pelamis Wave Power is also planning to launch similar complexes near the Orkney Islands and at Cornwall seacoast, where they are going to build four and seven Pelamis converters correspondingly.
Principal shortcomings of such converters:
- high materials consumption;
- average annual capacity factor is not more than 0.4;
- high level of investment costs per unit, approximately $6000 per kWt;
There are also converters that use the energy of oscillating water column (Fig. 8). When the incoming wave attacks a partially submerged cavity that is opened under water, the water column in the cavity oscillates, causing pressure change in the gas over the water. The cavity is connected with atmosphere by a turbine. Flow can be regulated so that it goes through the turbine in one direction.
Fig. 8 Oscillating water column converters
This operation principle is also used in the converters called Masuda’s column (Japan) and Wells turbine (United Kingdom).
The shortcomings of such converters are low efficiency factor and high materials consumption.
4. WAVE POWER PLANT BY V. OVSYANKIN (TECHNICAL ASPECTS).
Specialists of scientific production company “Krok-1” (Kyiv, Ukraine) under the guidance of V.Ovsyankin have created the design of the brand new wave power plant converting sea wave energy under high sea conditions into electric power and having a series of fundamental distinctions from all the existing WPPs.
First of all, distinction of WPP by Ovsyankin design is that its operating parts (energy-absorbing cells) are a part of water environment they occupy. Relative movements of separate water volumes that arise under the incoming waves influence are received by the WPP operating parts by means of hydrodynamic thrust, creating torsion moment on working shafts. This moment is converted and transmitted to the generator shaft.
WPP design is patented in Ukraine (patent ¹56481) and has good prospects for patenting of various design updates in other countries.
WPP has modular assembly; standard module is shown in Fig. 9.
One kilometre of wave front can be equipped with up to 24 modules. They can be combined both into a single WPP and, for example, into 6 WPPs each consisting of 4 modules. Reasonability of a certain solution is determined while developing the construction project and taking into consideration all the relevant factors.
For the high seas and oceans the designed modules have power of 1 and 2 MWt, for enclosed seas it is up to 0.5 MWt.
Recommended module power and its dimensions for the WPP are calculated in terms of the exploited water area energy potential.
WPP is connected to the coastal substation by electric cable.
WPP reliable performance in the sea storm is provided by its design features, such as wave transmittivity and ability to submerge into the area where the waves of rated parameters operate.
Water area there WPP is supposed to be built must be absolutely open to the waves, be at least 25 m in depth and have a location as close to the power consumer object as possible.
While considering the water area, it is preferable to choose sea areas with high energy potential and long seasonal duration of average heaving.
WPP by Ovsyankin has the following advantages:
- flexible energy-absorbing system that constantly changes its parameters under the influence of incoming waves having wide range of lengths and amplitudes, providing high efficiency of the WPP;
- low level of investment costs per unit – $3500-$4000 per kWt;
- low cost of produced electric energy - $0,05-$0,08 per 1 kilowatt-hour;
- low materials consumption – up to 150kg per kWt;
- high reliability in the sea storm;
- power plant is portable and can be towed away to any part of the water area.
Fig. 9. Standard WPP module
Energy characteristic of 2 MWt WPP operation is represented in the Fig. 10.
Fig. 10 Energy characteristic of 2MWt wave power plant.
SPC “Krok-1” has carried out works on creation of wave power plant for over 20 years. During this period 8-stages testing of power plant model and its 10 kWt prototype (WPP-10) was held.
Model testing was held in the wave basin of the Institute of Hydromechanics of NAS of Ukraine, as well as in the natural environment of the Kyiv water storage. The results of the tests proved the functionality of power plant models and gave the basic data for the design of the power plant prototype.
The obtained results enabled the National Aviation University (Kyiv, Ukraine) to develop a methodology of energy-absorbing cell parameters calculation;
Fig.11 shows the testing of wave power plant models in the wave basin.
Fig. 11. Testing of models in the water basin
WPP-10 prototype was assembled in 2006 by the Kyiv Shipyard. Testing of the prototype was held in spring 2007 on the basis of Scientific Research Centre of Ukrainian Armed Forces “State Oceanarium” (Sevastopol, Ukraine).
Fig. 12 shows WPP-10 prototype on the pier before the submergence.
After the launch, WPP-10 was towed 60 m away from the pier. Control and monitoring station was on the pier in the GAZ-66 automobile shown in the Fig. 13. It was connected with the power plant by the power cable and control cable that were bottomed in the water area. The load was simulated by rheostats.
In the course of the tests video recordings of all the key moments were made.
Fig. 12. WPP-10 prototype on the pier before the launch
Fig. 13 Control and monitoring station of the WPP-10
Tests were carried out in March-April 2007.
WPP-10 plant is designed for the waves of 0.3- 1.0 m, that is why the Kozatska Bay was chosen to be the tests site, as it is protected from the waves of the high sea.
Depth in the place of installation was 8 metres.
During the test in the water area waves up to 2 metres and periods of dead calm were observed.
Under the influence of waves having 0.3-0.4 m in height, rotation of the working shaft of 4-5 revolutions per min was observed that corresponded to the indications of the tachometer on the generator shaft – 400-500 rpm.
Operation of WPP-10 was the most effective under the influence of short waves having 0.6-0.7 m height and 2.0-2.2 m length, when the working shaft revolutions value was within the limits of 12 to15 rpm and the power produced by generator made up 2-3 kWt.
Test results provided reasons for the following conclusions:
1. WPP-10 prototype demonstrated its functionality within the range of rated values of waves height and stood the test.
2. For the designed wave power plants, the energy-absorbing cell length must make up about 1 to 2 maximum wavelengths of the rated range for the specified water area regardless of the WPP power. Thus, for Black Sea water areas the length of the energy absorbing cell must be 40-50 metres.
ÒMoreover, according to the WPP-10 tests results the engineering specifications were worked out for the standard project development of the wave power plant module with the power of 200 kWt for the Black Sea water area. This project was developed by the National Shipbuilding University (Mykolaiiv, Ukraine).
For the purpose of building a wave power plant with the power of 2000 kWt in the Black Sea water area there is a need of $8 mln investment.
As a result of project realization, the water area observation will be carried out, its energy potential will be evaluated, construction project will be developed, underwater and coastal facilities will be built, the corresponding standard WPP project will be developed, a 2000kWt wave power plant will be produced, installation and commissioning will be carried out, testing and startup will be performed.
Project implementation time is 2.0 – 2.5 years.
Wave energy use will provide the required conditions for the development of Zmiiny Island multi-faceted infrastructure, the objects of continental shelf and in the coastal area, allowing to save the unique natural environment of the Black Sea..
In December 2008 the project on WPP construction was considered and approved by the academic council of the State scientific and research project designing institute of the power engineering and energy saving innovation technologies.
COMPANY PROFILE
Scientific and Production Company “Krok-1” was founded in 1990.
Since the day of the creation and up to present V. Ovsyankin has been the founder and its managing director.
SPC specializes in the work package performance of scientific research in the field of high technologies, developing of new specimens of equipment and machinery; conducting engineering development and its launch into production.
SPC has the license for carrying out the design work, building and construction work.
On the basis of unique technologies of metal and alloy working developed by the company, 12 production companies were created in Ukraine, Russia, and Lithuania. These manufacturers are conducting cylinder barrel hardening and recovery of marine, tank and auto engines.
At present, SPC is an official corporate supplier of maintenance service of manufacturing equipment for all nuclear power plants of Ukraine. In particular, modernization and maintenance service of cupola manipulators for nuclear power plants reactors, hydraulic equipment maintenance, restoration of twenty 1000 ton jacks have been conducted.
For more than 20 years SPC has been working on developing of effective and reliable WPP. National Aviation University, National Shipbuilding University, Institute of Hydromechanics of NAS of Ukraine, Kyiv Shipyard and others participated in these activities.
Currently, the memorandum of agreement on participation in the WPP construction project has been signed with Bosh Rexroth Corporation.
The author and WPP patent owner is V. Ovsyankin.
Contact Details
• Scientific and Production Company “Krok-1”
• Ukraine
• Kyiv, 5A Anri Barbusa Street
• Tel/fax +38 044 287-44-48
• E-mail: • E-mail: krok-1@meta.ua
BUSINESS MATTERS
Optimal capacity of one WPP for the Black Sea water area is 2 MWt, it consists of 4 modules each having the capacity of 500 kW .
Economic indexes of wave plant with the capacity of 2 MWt in the Black Sea water area are shown in the Table1.
Table 1
|
Characteristics |
WPP |
|
Designed capacity, ÌWt |
2,0 |
|
Capacity factor |
0,5 |
|
Average annual efficiency, ÌWth |
1,0 |
|
Electric power production per year, ÌWth |
8760 |
|
Cost of one kWh of electricity produced by the diesel generator, $ |
0,4 |
|
Investment costs per unit, $/kWt |
4000
|
|
Total investments, mln. $ |
8,0 |
|
Payback period, years |
2,6 |
|
Cost price 1 kWth, $ |
0,05 |
|
Annual profit, mln. $ |
3,1 |
Optimal capacity of one WPP for the high seas and oceans is 10 MWt, it consists of 5 modules that have the capacity of 2 MWt each.
Comparative economic indexes of wind and wave power plants per one kilometer of wind (water) front for 2 MWt module are given in the Table 2 and the comparative indexes with Palamis wave power plant are shown in the Table 3.
Table 2
|
Characteristics |
Wind power plant |
Wave power plant |
|
Designed capacity, ÌWt |
0,5 |
2,0 |
|
Number of modules per one kilometer, pcs |
10 |
20 |
|
Total designed capacity, ÌWt |
5 |
40 |
|
Capacity factor |
0,2 |
0,6 |
|
Average annual efficiency, ÌWth |
1,0 |
24,0 |
|
Electric power consumption per year, ÌWth |
8760 |
210240 |
|
Green power rate, $ |
0,4 |
0,4 |
|
Annual electricity selling profit, mln. $ |
3,50 |
84,10 |
|
Investment cost per unit, $/kWt |
3500 |
3800
|
|
Total investments, mln. $ |
17,5 |
152,0 |
|
Plottage, m2 |
200.000 |
100 |
|
Face value 1 m2, $ |
10 |
10 |
|
Land allocation cost, $ |
2.000.000 |
1000 |
|
Payback period, years |
7,2 |
1,8 |
|
Cost price 1 kWth, $ |
0,09 |
0,05 |
|
Annual profit, mln. $ |
2,7 |
83,0 |
The realization of the WPP construction programme involves signing a contract between the Customer and SPC “Krok-1” as the general contractor. SPC “Krok-1” signs the contract with subcontractors on special work execution.
Separate parts of works and WPP construction in whole are carried out as provided by normative documents of the corresponding products.
All the warranty liabilities will be represented in the concluded contracts.
All the rates are specified for the particular water area and consumption object.
Table 3
|
Characteristics |
Palamis |
WPP (Ovsyankin) |
|
Designeg capacity, ÌWt |
0,7 |
2,0 |
|
Number of modules per one kilometer, pcs |
20 |
20 |
|
Total designed capacity, ÌW |
14 |
40 |
|
Capacity factor |
0,4 |
0,6 |
|
Average annual efficiency, ÌWth |
5,6 |
24,0 |
|
Electric power production per year, ÌWt/h |
49056 |
210240 |
|
Green power rate, $ |
0,4 |
0,4 |
|
Annual electricity selling profit, mln. $an> |
19,62 |
84,10 |
|
Investment cost per unit, $/kWt |
4800
|
3800
|
|
Total investments, mln. $ |
67,2 |
152,0 |
|
Payback period, years |
5,5 |
1,8 |
|
Cost price 1 kWth, $ |
0,15 |
0,05 |
|
Annual profit, mln. $ |
12,27 |
83,0 |