Hydrogen’s characteristic and sea water splitting device
Hydrogen is present in combination with other elements in our environment, but can be separated into its pure form. is a flammable element, and its combustion produces water.
It’s being hailed as a clean, green fossil fuel alternative, with a myriad of uses such as domestic fuel for heating, industry and fuel for the aerospace industry.
Splitting water with electricity has been experienced with for over 200 years and the reactions involved are well understood. At the cathode, H+ ions gain electrons to form hydrogen gas whilst OH- loses electrons at the anode to form oxygen.
Despite of the simplicity of the formula effective electrolysis is a particularly complicated process. Water splitting is thermodynamically unfavourable and requires both subtle designed catalytic electrodes and a specific input of energy to drive the reaction.
https://www.chemistryworld.com/news/water-splitting-device-solves
By a special process called electrolysis, it’s possible to split water into two separate elements, Hydrogen and Oxygen. This splitting of water is in actual fact a very easy process and it is already being done in sone sectors or science and industry using conventional water supplies.
With the abundant of sea water present on the earth, it could represent a significant step in clean, green hydrogen renewable energy sources. Affordability must be considered however, to ensure it can be produced cheaply enough and in significant quantities.
Chinese researchers’ new technique bypasses desalination
Chinese researchers from Shenzhen Uni and Nanjing Tech Uni are making claims that their new techniques bypasses desalination needs. With hydrogen having an image of being the miracle fuel fo the future, it would seem that its use is becoming more widespread.
Chinese researchers are making claims they have found a way to make hydrogen from seawater alone, without having to filter or purify it, a report in Chemistry World states.
Chloride ions in seawater are a particular issue and undergo competing oxidation at the anode to produce chloride. It causes reduce the electrochemical efficiency of the cell as well as it degrades the electrodes and inactivates the cell.
Another problem is the energy cost of desalination outweighs the value of hydrogen generated nu electrolysis. The two scientists solved this issue by harnessing the purifying power of evaporation.
Their purification system uses a liquid-gas-liquid phase transition to generate pure water from sea water directly within the electrochemical cell, a process driven by the subsequent electrolysis.
Professor Alex Cowan of Liverpool University has conducted cost benefit analysis of seawater electrolysis in the past. He said of the research: “What they’ve done is really perspective,” and that “This technology hits a potential niche market that hasn’t been addressed before.”
The challenge in using sea water to separate the two elements is the fact that such impurities like salt can have an adverse effect on the process, potentially destroying electrolysis equipment in the process.
Desalination of the water is a solution to this problem, but researchers state that this can cause extra production costs. A second solution is to make the electrolysis equipment more durable to such impurities, making them more. However this solution is viewed as being impractical.
Electrolyser using a waterproof breathable membrane that splits seawater
Heping Xie and Zongping Shao from Shenzhen Uni and Nanjing Tech Uni have discovered a potential workaround to the problem. Their theory was to protect the electrolyser by keeping the seawater separate from it using a waterproof, breathable membrane.
Only pure water vapour is allowed to enter the membrane by passing through the membrane itself. The scientists state this is a self sustaining system.
A porous PTFE-based membrane separates seawater from the inside of the cell, with the high density of fluorine atoms creating a hydrophobic barrier impervious to water and its impurities but permeable to water vapour.
On the other side, a concentrated potassium hydroxy solution surrounds the electrodes and provides the driving force for the water vapour migration. The potassium hydroxide electrolyte is at a higher concentration than the salt concentration in seawater.
Using a prototype they claim to have produced more than 1 million litres of hydrogen in 133 days with no reported electrolyser deterioration. Professor Cowan said that a new benchmark for stability had been set, as the team had run the equipment for more than 3,000 hours.
Potential applications can be applied to offshore wind farms that can be used to technology is already in use in the UK in the northeast around the Humber estuary where offshore wind is being used to power electrolysers to generate hydrogen for use at the local refinery there.
Currently Hydrogen only accounts for 2 percent of the energy market, and there is much hope that the new developments surrounding its production can bring about a akin to the developments recently in nuclear fusion.
Fusion energy doesn’t yet exist commercially however, and there is still more someway to go before it is. Hydrogen is already being used in places such as industry and commercial airlines, but in a dirtier form which involves the use if fossil fuels, and extraction from methane.
Scalability, production costs and reducing the carbon footprint are still hurdles that need to be overcome as time goes on. For now, the equipment efficiency is only on a megawatt level rather than gigawatt.
The UK hopes to double its target output to 10GW by 2030, as they pursue net zero. Attempts are being made in the US also to bring down the costs of such green hydrogen with the Hydrogen Shot Initiative. The target is to reduce it to $1 per kilogram within a decade.
The EU also has a plan to build hydrogen infrastructure over the course of 10 years. incorporating transport networks, and refuelling stations, and eventually hoping hydrogen will supercede natural gas in consumption heavy industries such as steel production.
Green energy still has an issue with potential affordability and production costs, but this is slowly falling to a more comfortable level, but much progress still needs to be achieved if we are to achieve a green, clean, hydrogen fuelled, carbon free future.
References: chemistryworld, H Xie et al, Nature, 2022, DOI: 10.1038/s41586-022-05379-5
