The EU-funded DualFlow project will introduce a new energy conversion and storage concept combining battery storage, hydrogen generation and production of useful chemicals into a single hybrid system using water-soluble redox mediators as energy transfer vectors. The system will be used for storing electricity or for converting renewable energy into hydrogen and value-added chemicals.
Current electrolyzer technologies are designed to be operated 8000 h per year. However, access to a continuous supply of green electricity will be unlikely given the recent trend in the increasing share of intermittent electricity being produced by solar and wind power. Therefore, systems able to flexibly utilize green electricity are a key to resolving this critical issue. Alkaline electrolysis has been optimized for efficient hydrogen production during the last 100 years, utilizing nickel-based catalysts and porous separators, and therefore it is exceedingly difficult to compete with it. Electrolysis produces oxygen, typically vented into the atmosphere, as a side-product and a way to bring down hydrogen cost is to produce added value chemicals instead of oxygen. As the scale of the hydrogen production is immense, the matching reaction on the positive side should also be suitable for large scale operation. DualFlow pursues a novel approach for solving the challenge, by producing hydrogen together with decarbonized chemicals. A hydrogen production unit will be incorporated as an additional part of a flow battery, only utilized when renewable energy is available in large quantities and the battery is fully charged. This means that the reactors where hydrogen production and the corresponding oxidation take place need to be simple and inexpensive, to justify additional costs of the unit that is used only when renewable energy production is high. Such a system will have lower efficiency than a commercial electrolyzer but will allow more flexible operation. Coupled together with production of chemicals, DualFlow will pave the way for a cost-competitive, sustainable, and flexible approach to energy storage and green hydrogen production.
The objectives of DualFlow are to:
1) Realize a proof-of-concept hybridized (alkaline) hydrogen production redox flow battery system. Specifically, DualFlow will demonstrate combined hydrogen production and electricity storage capability on a lab-scale by harnessing abundant and environmentally benign materials.
2) Develop processes to enable production of decarbonized chemicals. Specifically, we will demonstrate the continuous operation of an oxidation process in a biphasic system to produce thin poly(3,4-ethylenedioxythiophene) (PEDOT) films. The developed system will be adaptable to other reactions.
3) Realize a proof-of-concept production of chemicals. Specifically, we will demonstrate production of PEDOT, lidocaine and levetiracetam, and production of nanocellulose via mediated oxidation of cellulose.
