FR2851304A1 - Hydrogen and oxygen collector for water electrolysis unit uses energy of rising gas bubbles to drive belt connected to power generator - Google Patents

Abstract

Hydrogen and oxygen collector for water electrolysis unit consists of a series of divided chambers (5) attached to a vertical endless belt (6) that turns lower (7) and upper (8) shafts on a vertical supporting frame (10) mounted on a base (2). Hydrogen and oxygen collector for water electrolysis unit consists of a series of divided chambers (5) attached to a vertical endless belt (6) that turns lower (7) and upper (8) shafts on a vertical supporting frame (10) mounted on a base (2). The chambers on the rising side of the belt are located above electrodes (1) producing hydrogen (3) and oxygen (4) gas in the form of bubbles. The gases create buoyancy that lifts the chambers and turns the shafts, the upper one of which is connected to a power generator (9). When the chambers reach the top the hydrogen and oxygen are extracted from them by a suction system before they descend on the other side of the belt.

Description

The present invention relates to a process for extracting hydrogen by

water electrolysis.

  Before the world heats up, lights up or rolls properly with hydrogen, it is still necessary that this gas can be produced and transported at the lowest cost.

  Because if the democratization of the tandem fuel cell - hydrogen is already looming, a series of obstacles still stand in its way.

  The first is also the most decisive: o find the precious hydrogen? Well !, it must be extracted, since this element is only found on earth, associated with others, oxygen or carbon, for example. In fact, it is not a primary source of energy, like petroleum. However, the extraction of hydrogen is, apparently, nothing complicated.

  Each year, manufacturers extract more than 500 billion m3. And 95% of the hydrogen produced to date is produced by oil tankers! However, this hydrogen is not today intended to serve as an energy carrier: half of world production goes into the manufacture of ammonia fertilizers, the rest is used to develop fuels and to manufacture steels, glasses and ... margarine. Nevertheless: whatever the destination, the extraction process, called steam reforming, remains the same. It consists in reacting the methane of natural gas with water vapor on a nickel catalyst at high temperature (around 900 ° C) to release the hydrogen.

  The major drawback is the very use of natural gas: like petroleum, it is a hydrocarbon whose resources are not eternal! In addition, steam reforming releases CO2 which would have to be trapped at a great price (25% of the production cost), on pain of worsening the greenhouse effect.

  In addition to steam reforming, the production of hydrogen can take three forms: biomass, electrolysis and cracking. All three face real difficulties.

  Faced with steam reforming and the production of biomass, the electrolysis of water is a miracle solution: very simple to implement, the process rejects only hydrogen and oxygen! These two primary components of water are obtained by the passage of an electric current between two electrodes. But the energy efficiency of electrolysis is disastrous: if 5 kWh are required to produce 1 m3 of hydrogen, only 1.8 kWh of electricity is recovered from it in a fuel cell.

  This physical weakness does not totally condemn electrolysis from an economic point of view: it would eventually fulfill a backup mission, by storing the surplus electricity from the atom. Due to the inertia of their operation, nuclear power plants cannot instantly match demand fluctuations, which leads to inevitable overproduction.

  According to experts, (for whom the reforming of natural gas will constitute the main source of hydrogen in 2050), who are asked if electrolysis will one day come out of a surplus logic, the answer is: difficult, but not excluded.

  And it is precisely here that the objective of the present invention is situated.

  Technology progresses, on the way of the elevation of the pressures and the reactivity time of the electrolysers. New experimental routes at very high temperatures (8000C) are also explored, in tandem with a new type of nuclear reactor, the Very High Temperature Reactor (VTRH), the first prototype of which could see the light of day, around 2015.

  Studied as part of an international program called "Generation IV" in which ten countries 15 participate, including France.

  The final production chain currently under consideration is that of catalytic cracking. This process consists in "breaking" the molecular bonds of the water by heating it to 700 ° C, in the presence of a catalyst. However, catalytic cracking, like high temperature electrolysis, is still only a research hypothesis, and what is more, linked to the use of a new type of nuclear reactor.

  The present invention consists of an energy recovery device making it possible to improve the energy efficiency of water electrolysis, with a view to extracting hydrogen therefrom at a lower cost. It exploits the principle of Archimedes' thrust.

  The operation of the device is similar to that of a treadmill with buckets, the motor of which would be replaced by a current generator, and the buckets by receptacles intended to collect the gases. The assembly is immersed, and arranged vertically, so that the containers, covering the electrodes, recover the gases.

  When the current flows between the electrodes, gas is produced in the form of bubbles. The latter rise under the effect of Archimedes' push, and find themselves trapped in the container. The latter accumulates hydrogen and oxygen gases as well as the sum of their energy.

  Thus, the accumulation of energy, due to Archimedes' push, is transmitted mechanically by the container to the conveyor belt, then to the axis of the generator, which in turn transforms it into electrical energy, intended for the electrodes. The hydrogen and oxygen thus produced will be recovered at the top of the device before the full container enters the descending phase.

  The accompanying drawings illustrate the invention: Figure la shows in perspective, the device of the invention, Figure lb shows in perspective, the container in detail.

  The device is intended to operate in immersion in water constituting the electrolyte, such as for example in a marine environment in which salt water constitutes the electrolyte; or in any other sufficiently deep water tank. In the latter case, the addition of a chemical element such as salt and the like will make the water conductive.

  With reference to fig. la, the invention consists of a conveyor belt (6) on which are fixed the containers (5). The mat is stretched between two axes placed on bearings (11) and supported by the frame (10). The whole being arranged vertically. The axis (7) is free, while the axis (8) is connected to an electric generator (9). The assembly is fixed on the same base (2) as the electrodes (1), and in such a way that the containers, during their movement in ascending phase, circulate vertically above the electrodes.

  When supplied with direct current, the electrodes (1) produce gas evolution, in the form of bubbles of hydrogen (3) on the one hand, and of oxygen (4) on the other.

  The latter rise under the effect of Archimedes' push and are trapped in the container (5) covering the electrodes over their entire length.

  The gases accumulating in the container; the sum of the energies of each gas bubble is transmitted mechanically to the conveyor belt (6).

  The container above the electrodes fills with gas as it progresses, until the next one takes over.

  The energies thus stored in the ascending vessels give the structure its movement and transmit mechanical energy to the electric generator (9).

  The electrical energy thus recovered is intended to be added to the power source of the electrodes.

  With reference to FIG. 1b, the gases are accumulated separately due to the presence of a partition (12).

  The hydrogen and oxygen gases are recovered for storage purposes by a suction system before the full container enters the descending phase.

  Also, one could consider such a fully autonomous system (requiring an auxiliary source only to start it) if it is submerged to a sufficient depth, and equipped with ad hoc containers.

  Floats can be added above the structure, so as to make use of the mechanical energy of the waves present on the surface. This would be added directly to the axis of the generator. The structure already presenting the mechanical-electrical conversion system.

  Other renewable energies available on site: photovoltaic, wind, motor tide, ... may also be associated.

  We can notice the existence of dead times, due to the fact that the container gradually moves away from the electrodes. Indeed, when a bubble is produced, its energy is not recovered during the distance traveled before reaching the container. Also, a solution not shown here, consisting of a helical version of the device is being studied.

  1 5 The device according to the invention is particularly intended to produce at low cost hydrogen gas by electrolysis of water. 5

Claims (1)

CLAIM   1. Device intended to improve the efficiency of the electrolysis of water with the aim of extracting hydrogen therefrom, said device being composed on the one hand, of at least two electrodes immersed in electrically conductive water such as sea water, and supplied with electric current; on the other hand, a specific device for transforming mechanical energy into electrical energy consisting of a generator (9) responsible for transforming mechanical work into electrical energy, - a system for transmitting mechanical energy to the generator, 10 consisting of a conveyor belt (6) equipped with receptacles (5) and arranged vertically so that the ascending receptacles are found to be in an inverted position directly above the electrodes, the receptacles comprising a partition ( 12), so that the gases accumulate separately in their respective compartments, characterized in that the said receptacles are arranged above the said electrodes (1) so as to accumulate the gas bubbles and consequently the resulting mechanical energy of the Archimedes thrust exerted by the gases on the walls of said container, which container transmits, by means of said specific transmission system, ladi mechanical energy to the generator (9).