Deliverables
Among other means of energy accumulation and reservation the particular significance is the possibility to set up of an electrolytic hydrogen and oxygen production directly from seawater, the electrical conductivity of which is due to soluble salts.
Seawater is the most widespread, cleanest and cheapest working medium, its resources are practically unlimited. In turn hydrogen is an ecologically pure fuel with the greatest specific heat of combustion. Seawater is a multicomponent natural electrolyte with sodium chloride as the main component.
Therefore the seawater electrolysis will be basically determined by the near-electrode processes, which are intrinsically for the sodium chloride solutions electrolysis. While electrochemical reaction at acceptable rates some amount of chlorine always evolves together with oxygen.
In view of chlorine being toxic, the problem of its utilization is to be solved. For example, utilization of chlorine can be achieved through absorbing of it by the aqueous solution of sodium hydroxide.
The reaction can proceed in directions resulting in hypochlorite or sodium chlorate formation. An anolyte formation of sulfuric acid is possible too.
Therefore apart from the essential electrolysis products - hydrogen and oxygen, in the course of seawater electrolysis one can produce sub-products, possessing self commercial values.
Elaboration of methodology of wave formation process analysis is dedicated to a hydro-meteorological grounding of wave energy resources estimation and exploitation opportunity.
On the base of data on waves and their characteristics, analysis methods were described of wind waves formation as well as evaluation of the wave energy resources. Contemporary methods of waves calculation in synoptic scale are based on hydrodynamic models, in climatic scale mainly on probability models. It was shown how the primary data about power of low amplitude regular sinusoidal waves can be generalized for irregular three-dimensional waves. Methods were examined to define a value of rough sea power on the basis of wave parameters in different time scales.
Also wave power resources evaluation was carried out for the nearshore area of the south east Euboea island (Greece). The area is characterized by relatively low seasonal and synoptical changeability of wave environment. The area appears to be suitable for wave converters testing, since it is easily assessable and the onshore infrastructure allows much room for assistance. This enables to regard this water area as a possible place for an experimental work provided the Marineco project will extend to the development stage of multimodule devices afterwards.
Float Wave Electric Power Station is a device destined for wave energy conversion to electricity. Since sea wave is characterized by spatially time variability of its properties, then the best facility for wave energy taking-off is oscillatory device matched with wave space. In accordance with the given rule, FWEPS employs the oscillatory drive.
The main elements of FWEPS module are: mechanical oscillatory drive, electric generator and auxiliary energy storage. They are maintained inside the sealed capsule-float of an axially symmetric streamline shape.
In addition to other wave energy converters advantages, FWEPS technically has several exceptional features owing to:
- Oscillatory property of the device when matched with outer wave space, thus giving the most effective mode for energy taking-off;
- Sustainable operation at varying lengths, velocities and intensities of waves and directions of their propagation, adapting to changeable external conditions;
- Reliability and long useful life because of sealed capsule-float protects elements of the device from corrosive attack of sea water and its vapour;
- Possibility of devices deployment directly in seas and oceans, in places unsuitable for human life or navigation as well as possibility of FWEPS location change in accordance with regional wave activity, seasonal or other reasons.
The formation of an adequate physical-mathematical model of sea water electrolysis requires basis in theory together with some experimental investigations. The experimental investigations of sea water electrolysis resulting in hydrogen as its main production target and some associated substances were carried out in a single-cell laboratory model of a flow-through, cation-exchange diaphragm type.
The study implemented enables to conclude the following:
- A sea water electrolysis procedure can be technically performed, rather effective and promising for the production of hydrogen as a target.
- Anode evolving chlorine can be utilized and returned into the environment as a clean product. The utilization of chlorine is reasonable to perform absorbing it by the solution of alkali or alkaline catholyte.
Apart from the essential electrolysis products (hydrogen and oxygen), in the course of sea water electrolysis one can produce, a diversity of sub-products such as hydroxides of alkali metals, in particular, a magnesium hydroxide from catholyte as well as sulfuric and hydrochloric acids from anolyte that is an additional advantage of the sea water electrolysis process.
The problems of wave energy conversion to electricity and hydrogen production, storage and use were surveyed and considered as concerned to the developing techniques. Wide encompassed reviews on wave power and hydrogen engineering current state and trends predict the much promising outlook for the developing techniques.
The main conclusions resulting from the consideration are as follows:
- The exploitation of ocean wave energy is prospective for massive power generation in the near future; some wave energy conversion technologies could meet the goal of electricity production at commercial scale by or before 2010;
- In the long term, hydrogen will be, along with electricity, one of the most important energy carriers and widely applicable;
- The hydrogen seawater electrolysis production and FWEPS are seemed to be intersupplemental technologies for supporting decentralised energy supply systems;
- Components of the power system under development are the promising candidates for the future power production-consumption market since for many regions the use of sea-wave energy is preferable and profitable for electricity generation, while hydrogen production by seawater electrolysis is superior to other means.
The technical and financial analysis shows that wave energy conversion by means of FWEPS is economically acceptable in electricity niche market and has good prospects of being competitive both commercially and ecologically. Design and economic calculation of powerful multimogule FWEPS project has been implemented.
The calculations made allow drawing the following conclusions:
- The economic analysis shows that after completion of the research and development phase of the multimode FWEPS, generating costs of 0.04 to 0.06kWh will be achieved. The device having been experimentally developed, the cost of power units will be about 1000 kW, depending on place and conditions of operation.
- The expenses for FWEPS production must be reimbursed during the operation period of two years at total equipment lifetime of some tens of years.
- The projected investment costs show the competitiveness of the FWEPS with other wave energy conversion systems. Evidence of the presented tendencies and circumstances, as well as the scaled, unoccupied and predisposed to intense development electricity market allows predicting bright outlook on the FWEPS project commercialization.
The computation and hydrodynamic development of a small-sized laboratory model of the FWEPS prototype were carried out for the subsequent physical modelling in the KSRIs seakeeping basin.
The computational scheme allows getting statistical characteristics of vertical and angular motions of a buoy with oscillation system inside. The test facilities includes seakeeping basin, wavemaker for generation of irregular waves, towing carriage with associated equipment, model restraining system in waves.
The objective of the study is to determine modelling parameters of the buoy motions as well as pendulum oscillations with respect to its body. The results of physical modelling irregular-sea behaviour of the FWEPS model at Sea States 4 - 5 numbers demonstrate that devices are basically serviceable in terms of relative vertical motions of the internal pendulum.
Analysis of the wave behaviour of FWEPS models indicate to a significant effect of the mean wave period and to a less pronounced dependence of buoy - pendulum relative motions on the Sea State within its investigated range.
The key assembly of the FWEPS is an arrangement transforming the oscillatory energy of capsule-float to rotational energy of electric generator. For experimental simulation of processes in the FWEPS dynamic system a small-scaled test bench with experimental model was designed.
The test bench is destined for the study of movement sustainability, power transmission, amplitude-frequency response, phase and other relationships at different values of weight mass, movement period, spring stiffness, damping factor, amplitude of exciting force and other parameters.
The study makes possible to search optimal conditions of an oscillatory system action and its optimal matching with the load as well as to estimate a practical efficiency of the converter.
The experimental study has shown that the mechanical actuator with an oscillatory system being one of its main parts can be used as a drive for an electric generator in the given type of energy converter.
As with any oscillatory process, the best facility for wave energy taking-off is oscillatory device matched with outer wave space. To this very day there are no devices in which a two degrees oscillating system can be used as an actuator for unwinding an electric generator. Likewise, there is no a physical-mathematical model describing adequately processes in such an actuator.
The dynamic processes proceeding in the system Earth - sea waves FWEPS as a heaving device are simulated adequately enough by a two-degrees-of-freedom oscillating model. The given job was devoted to the development of the calculation model, which enables to simulate processes in the oscillating system used as energy transmitting equipment for FWEPS.
As a result the consideration has been carried out of a physical-mathematical model of the processes in the oscillation mechanical system consisting of a capsule-float to the inner side of which an elastic pendulum with a large mass weight is suspended.The physical-mathematical simulation has been performed.
The analysis of current situation and trend motivation in power engineering distinctly show that, the artificial world energy production became already comparable with the capacities of natural energy fluxes in the Earths outskirts. This leads to the biosphere irreversible degradation. Before the environmental threat the most intelligent solution of problem of power production growth under protection of wilderness areas should be based on the use of renewable energy resources.
The especially attractive system among the first to meet these requirements is one based on the use of wave and aqueous resources of the World Ocean. The system comprises of a wave energy converter and installation for hydrogen production by means of seawater electrolysis.
Sea waves is a very promising energy carrier since they manifest the highest specific power among renewable sources.
In turn, seawater electrolysis is a very attractive hydrogen producing procedure, since seawater is the most widespread, cleanest and cheapest working medium; its resources are practically unlimited.
The system supplemented with accumulator and energy consumer presents an ecologically friendly power-industrial complex as if built into the environment, since the energy taken off and seawater after the working cycle are recycled so introducing no additional heat or whichever pollution.
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