Other enabling technologies
The range of sources of renewable energy requires a leap forward when it comes to innovation in energy storage and other enabling technologies that will help achieve the energy transition, including by balancing supply of and demand for power. These enabling technologies include electrolysis for the production of hydrogen, which can be used for chemical energy storage or as an alternative fuel itself, and carbon capture and storage technologies. Carbon dioxide can be captured by physical or chemical techniques and is then typically stored underground.
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- Electrolysers for hydrogen production
The 1.5°C Pathway report issued by the International Renewable Energy Agency (IRENA) predicts that hydrogen and derivatives will need to account for 12% of final energy use by 2050. Green hydrogen from water electrolysis using renewable energy is expected to be both a key strategic energy source and storage medium.
Several countries have already included targets for electrolyser capacity in national hydrogen strategies. Future electrolysers would ideally be built out of raw materials that are cheap and abundant, and use renewable electricity. According to a recent joint study published by the EPO and IRENA on innovation trends for electrolysers in hydrogen production, investment costs for electrolyser plants can be reduced by 40% in the short term and by 80% in the long term through improved design and construction, economies of scale, replacing scarce materials with abundant metals, and enhanced operational efficiency and flexibility. This would help increase global electrolyser capacity from today's 0.5 GW to the 5 000 GW by 2050 proposed in IRENA's 1.5°C Pathway report.
Five major groups of sub-technologies are important for reducing the cost of electrolysis[1] :
Cell operation conditions and structure
Operating electrolysis cells at a higher temperature and pressure increases the efficiency of electrolysis without compromising durability, while also reducing costs. The electrolysers must be designed to withstand these operating conditions.
High-temperature conditions in electrolysis cells - full result set
High-pressure conditions in electrolysis cells
A key element in optimising cell efficiency is the contact surface between the membrane and the electrode, reducing electrical resistance and heat generation:
Membrane electrode assemblies (MEA)
Electrocatalyst materials
The scarcity of materials, and of noble metals in particular, is a major barrier to reducing the costs of electrolysers and scaling up production. Alternatives are needed that make use of non-noble materials, for example. Developments include noble metals (including oxides), non-noble metals, alloys and ceramics, and organic, diamond and non-diamond materials.
The following search statements include electrodes that incorporate catalyst materials based on:
Non-noble metals and alloys
Ceramics (which do not contain any noble metals)
Organic compounds
Diamond-based catalysts - full result set
Stackability of electrolysers (stacks)
Electrodes, bipolar plates and porous transport layers can contribute significantly to the stack cost. Improvements in these components, including their manufacture, can help to reduce capital costs and increase scalability. While bipolar elements containing stacks remain the most important development area, the optimal combination of these with the membrane electrode assemblies is key:
Stacks comprising bipolar elements and membrane electrodes assemblies - full result set
Photoelectrolysis
Photoelectrolysis using photovoltaic cells as the energy source can integrate electricity and hydrogen production in a single element, potentially leading to higher efficiency. Although currently at a low technology maturity and process optimisation stage, promising developments for the future include:
Photoelectrodes with photoabsorber and photoelectrocatalyst - full result set
Photoelectrodes with single-layer photoelectrocatalyst - full result set
Co-electrolysis
The electrolysis of water alone produces hydrogen that is difficult to store. An emerging area of development is co-electrolysis, producing hydrogen in a more storable compound. Examples include nitrogen-containing compounds such as ammonia, presented below, and others such as syngas (CO/H2) and organic fuel production (methane, alcohols).
Co-electrolysis to produce ammonia - full result set
[1] IRENA (2020), Green Hydrogen Cost Reduction: Scaling up Electrolysers to Meet the 1.5⁰C Climate Goal, International Renewable Energy Agency, Abu Dhabi.
- Carbon capture and storage (CCS)
Although ideally all future energy should derive from renewable sources such as wind, solar or hydropower, a swift transition to such sources may not always be feasible. One solution to mitigate climate change in the meantime is to capture CO2 (carbon dioxide) from high-emitting processes (e.g. in fossil power plants and heavy industry) or even directly from the air (direct air capture), and then store it, normally underground or under the sea. This CO2 either remains there (physically trapped or chemically stored) or could eventually be used in certain industrial processes.
Carbon capture
There are several ways to capture CO2 from gases, based on its chemical or physical properties. Sorption techniques seem more appropriate for direct air capture (DAC). Due to the low concentration of CO2 in the air, very large volumes of air must be treated. Therefore, techniques that require low temperatures or high pressure are less suitable, as they also need larger amounts of energy. The following techniques are mostly used for carbon capture:
Absorption using liquid solvents
Adsorption on solid sorbents
Biological separation
Cryogenic separation
Membrane separation
Chemical separation / direct sequestration
Carbon storage
Once captured, the CO2 needs to be stored, typically in locations such as depleted oil or gas wells. Since these have already proven capable of holding oil or gas for eons, they are generally considered safe for current storage purposes. The infrastructure tends already to be in place for injecting the CO2 since gas is often used for keeping an oil well pressurised. Alternatively, CO2 can be made to react with certain mineral deposits to form carbonate minerals such as mafic or ultramafic rock (olivine, peridotite, etc.). In this dataset, we have tried to focus on applications that are not for pressurising wells, but rather for actual storage.
Subterranean or underwater CO2 storage
