Electrolysis can be a viable choice to non-carbon hydrogen production from nuclear and renewable sources. Electrolysis is the method which involves with electricity to convert water into oxygen and hydrogen. The reaction occurs in an electrolyzer. Electrolyzers can range in size from small, appliance-size equipment that is well-suited for small-scale distributed hydrogen production to large-scale, central production facilities that could be tied directly to renewable or other non-greenhouse-gas-emitting forms of electricity production.
How Does it Work?
Similar to gasoline cells, the electrolyzers are made up of an anode and cathode, separated from an electrolyte. Different electrolyzers function in various ways, because of the various types of electrolyte materials used as well as the ionic substance it uses.
Polymer Electrolyte Membrane Electrolyzers
In a Polymer Electrolyte Membrane (PEM) electrolyzer the electrolyte is an extremely durable plastic material.
- The anode of water reacts with water to produce the oxygen and hydrogen positively charged Ions (protons).
- The electrons travel through a circuit external to hydrogen ions are able to move through the PEM towards the cathode.
- At the cathode, hydrogen ions mix with electrons in the external circuit and form hydrogen gas. Anode Reaction: 2H2O – O2 + 4H+ + 4e- Cathode Reaction: 4H+ + 4e- – 2H2
Alkaline Electrolyzers
Alkaline electrolyzers function by the transport of hydroxide-ion Ions (OH –) through the electrolyte from cathode and the anode. This is followed by hydrogen being created at the anode’s cathode. Electrolyzers with the liquid alkaline solution of potassium hydroxide or sodium as electrolytes are available commercially for several years. The latest methods together solid membranes for exchange of alkaline (AEM) as electrolytes are showing promise at the laboratory scale.
Solid Oxide Electrolyzers
Solid oxide electrolyzers make use of a solid ceramic as an electrolyte that conducts positively charged oxygen Ions (O 2-) at higher temperatures, which create hydrogen in a distinct method.
- The cathode’s steam combines with electrons in the circuit outside to create hydrogen gas as well as positively charged oxygen Ions.
- The oxygen ions move through the membrane of the solid ceramic and are able to react at the anode to create oxygen gas. They also generate electrons to power the external circuit.
Solid oxide electrolyzers need to function at temperatures that are high sufficient to allow those membranes made of solid oxide to work properly (about 700deg to 800degC, as opposed to PEM electrolyzers that run at 70deg-90degC and commercial electrolyzers made of alkaline, which generally operate at lower than 100 degC). Modern lab-scale solid oxide electrolyzers made of proton-conducting ceramic electrolytes have shown potential to reduce temperatures of operation to 500deg-600degC. Solid oxide electrolyzers are able to energetically utilize the heat generated at these temperatures (from diverse sources, such as the nuclear power) to reduce the amount of electricity required to create hydrogen using water.
Why is This Pathway being considered?
Electrolysis is a major method of producing hydrogen to actually achieve what is known as the Hydrogen Energy Earthshot target of reducing price of clean hydrogen by 80% and achieving $1 for every kilogram over one 10 years (“1 1”). Electrolysis-generated hydrogen could result in no greenhouse gas emissions dependent on the source of electricity utilized. The source of the required electricity–including its cost and efficiency, as well as emissions resulting from electricity generation–must be considered when evaluating the benefits and economic viability of hydrogen production via electrolysis. In many areas of the nation, the current power grid isn’t suitable to supply the power needed for electrolysis, due to the greenhouse gas emissions released and the amount of energy required due to the inefficiency of the process for producing electricity. Electrolysis-based hydrogen production is being investigated as a renewable (wind solar, wind geothermal) as well as nuclear energy alternatives. These hydrogen production methods yield virtually no greenhouse gas emissions and criteria pollutant emissions. However the cost of production has to be reduced substantially to compete with carbon-based alternatives that are more established like natural gas reforming.
Potential synergy potential in renewable power generation
Electrolysis-generated hydrogen production could provide synergies with intermittent and dynamic electricity generation. This is a characteristic of green energy sources. For instance, while the price of wind power is continuing to fall however, the inherent volatility of wind can be a barrier to the efficient utilization for wind energy. Hydrogen energy source and electric power generation could be combined at the wind farm, which would allow the flexibility to shift production to excellent meet resource availability requirements of the operation and market conditions. In addition, during times of excessive electricity generation generated by turbines, rather than cutting the power supply as it is usually done, it is feasible to utilize this surplus electricity to generate hydrogen by electrolysis.
It is crucial to keep in mind…
- The grid electricity we have today is not the best source of electricity to power electrolysis because the majority of electricity produced is created with processes that cause greenhouse gases and are energy heavy. The generation of electricity together nuclear or renewable energy technologies, whether separately from grid power or as a growing percentage from the grid mix could be an opportunity to overcome these constraints in the production of hydrogen through electrolysis.
- The U.S. Department of Energy and others are working to reduce the price of renewable electricity generation and also to create more efficient electricity generation from fossil fuels that utilizes the utilization of carbon, capture and storage. Production of wind-generated electricity for instance is increasing rapidly across the United States and globally.
Research is focused on solving problems
- Reaching the Hydrogen Shot Clean Hydrogen cost goal that is 1 / kg H 2. before 2030 (and an interim goal at $2 per kg H 2. in 2025) by gaining a better understanding of the performance, cost and durability trade-offs for electrolyzer systems in the future, based on predicted operational modes that are dynamic together CO 2.-free electricity.
- Lowering the capital cost of the electrolyzer unit, as well as the remainder in the overall system.
- Enhancing energy efficiency by converting hydrogen into electricity over an array of operating conditions.
- Understanding the electrolyzer cell and stack degradation processes, and formulating ways to mitigate the degradation process and boost the operational lifespan of.