11-10-26 Valorising Waste Hydrogen

Valorising Waste Hydrogen

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26 Oct 2011PDF (543 kb)

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I read a lot of reports about the need for a hydrogen infrastructure, and the fact that all the industrial hydrogen currently produced already has a market, such as in the oil refining and chemical industries. Therefore to power the fuel cells of the future, new ways to produce hydrogen must be created. While this is true, surpluses of hydrogen occur in many industries worldwide, where it is typically burned to generate heat or energy; not maximising the potential value in the fuel.

The industrial production of chlorine and caustic soda (chlor-alkali process) is one such source of high purity waste hydrogen. The industry electrolyses brine (saltwater) on a massive scale, producing 12,544,000 tonnes of chlorine per year in Europe alone, according to eurochlor.org, and spends up to 70% of its variable costs on electricity. The requirement for electricity and the production of waste hydrogen make this industry an ideal candidate for fuel cells, and electricity cost savings of up to 20% can be achieved by diverting this waste hydrogen through fuel cells. The European chlor-alkali industry makes up only 23% of the world’s capacity, so a simple calculation reveals the industry as a whole has the potential to generate over 2.2 GW of power from its industrial by-products.

WasteH2Util

Waste hydrogen utilisation, source: www.eurochlor.org

Sustainability efforts underway in the chlor-alkali industry have seen the utilisation rate of waste hydrogen increase from 80% in 2001 up to 90% in 2010. The current utilisation target is 95% however, so there is still a considerable way to go. Currently the majority of hydrogen is mixed with natural gas and burned for heating or power generation, so further efficiency gains could easily be possible using fuel cells.

Two recent fuel cell projects are underway at chlor-alkali plants in Europe, seeking to address the issues of vented hydrogen and high electricity costs: a 50 kW AFC Energy alkaline fuel cell system at Akzo-Nobel in Germany and a 1 MW Nedstack PEM installation at Solvay in Antwerp.

Alkaline fuel cells are one of the oldest fuel cell technologies and AFC Energy is heavily focused on cost reduction, aiming to compete on cost with other power generation technologies such as turbines. It has a modular system, enabling stacks to be exchanged while the unit is in use without seriously affecting performance.

The PEM system at Solvay was designed by Nedstack and comprises 168 of its stacks in one containerised system. It was preceded by a 10 kW stack which was successfully tested at the same location.

Projects like these will prove fuel cell technology as a viable means of extracting value from waste hydrogen, and while the ultimate potential of this market is limited by the size of global chlor-alkali production, other sources of waste and by-product hydrogen can be found.

Bio-hydrogen is a subject attracting increased attention, which will undoubtedly grow, along with water electrolysis using renewables, but an area where I believe this technology could find a niche is in balancing the hydrogen supply and demand of chemical plants or refining processes operating with hydrogen pinch. The fine balance required to manage hydrogen production and consumption could be simplified using a fuel cell. The fuel cell could ramp up power production during times of surplus, and reduce it when other parts of the process flow require increased volumes. In addition to this, flared gases at refineries could also feed into this system, using the high efficiency of fuel cells to offset both power demand and emissions.

Dan Carter     Manager

dancarter@fuelcelltoday.com

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Dr Dan Carter
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