The Catalyst Review June 2020 - 1

INDUSTRY PERSPECTIVES

The views expressed are those of the individual author and may not reflect those of The Catalyst Review or TCGR

Refuelling Alternative Fuel: Prospect of Formic Acid
By Joyanta Choudhury, PhD
Global energy demand is on the rise, with continued population expansion and volume of vehicles on the road, resulting in steady
increase in average energy consumption. According to the International Energy Agency (2015), carbon-based fossil fuels fulfil
over 81% of the total energy demand, globally. Burning of such a huge amount of carbon-intensive fuels over a long period has
led the current atmospheric CO2 concentration to an alarming level of >400 ppm as compared to the 280-ppm level during the
preindustrial time (Global Monitoring Laboratory 2020). Addressing the balance between the ever-increasing energy demand and
the environmental impact is imperative. Therefore, at this crucial stage, carbon-neutral energy production and carrier systems are
the viable options currently being seriously considered. A sustainable transition from fossil fuels to green energy is undoubtedly a
difficult challenge to the R&D sectors of all the stakeholders.
Molecular hydrogen (H2) is considered an attractive alternative to fossil fuels. Particularly in the mobility or transport sectors, it
will play a key role once the technological hurdles related to its production, storage and delivery are addressed. In fact, Japan and
Germany are the top two countries in the world to have the largest and the second largest hydrogen (re)fuelling station network,
respectively, for refuelling the hydrogen-driven fuel
cell vehicles (FCVs) (FuelCellsWorks 2020). However,
the present infrastructure of the hydrogen refuelling
stations is typically made suitable for using (a)
pressurized hydrogen (compressed gaseous hydrogen,
CGH2), or (b) liquid hydrogen (LH2) or (c) on-site
hydrogen produced via steam-reforming of methane
and water-electrolysis. These technologies, though
matured, have their own techno-economic problems
such as handling the gaseous H2 and liquefaction
or electrolysis energy demand. In this regard, a
naturally liquid organic hydrogen carrier (LOHC) can
become a promising choice as "alternative fuel." The
LOHCs can load H2 in the form of chemical bonds via
hydrogenation and can release the same for end-use
on-demand via a reverse dehydrogenation process.
Source: Global Monitoring Laboratory 2020.
Formic acid (FA) is a liquid and has low toxicity and
flammability at ambient conditions. It has a volumetric H2 capacity of 53 g H2/L which is equivalent to an energy density of 1.77
kW∙h/L, exceeding that of commercial state-of-the-art on-board 700 bar H2 pressure tanks providing an energy density of 1.4 kW∙h/L
in Toyota Mirai. Moreover, H2 can be released from FA at low temperature (< 80°C) and high pressure (> 600 bar). All of these
attractive properties can make FA a suitable candidate as a fuel for application in vehicles, as a long-term hydrogen storage system,
and as an effective liquid material for H2-transport and delivery at hydrogen refuelling stations. Finally, the released CO2 from FA
during H2-releasing step, can be recycled to FA via hydrogenation, thus making the whole technology a carbon neutral energy system
(Eppinger and Huang 2017).
Obviously, the next question that comes to mind is whether FA can be practically used as an LOHC fuel in commercial applications.
Indeed, FA (99.9 wt%) was used as an LOHC fuel to develop a 25-kW integrated FA-to-power converter system which was employed
in a full-scale hydrogen-powered city bus by the Team FAST/DENS start-up company in the Netherlands (Cursor 2020). The same
technology was also used as a standalone carbon-neutral electricity generator of 25 kW power capacity, for off-grid applications such
as charging electric equipment and vehicles, or powering illumination (DENS 2020). These early encouraging success stories might
pave the way toward many more mobile applications and developments of stationary power plants using FA as a prospective LOHC
fuel. Future applications may include FA-to-high pressure H2 release systems which can be used in H2 refuelling stations serving the
current FCVs, just after minimum infrastructural modification of the existing one, such as adding the FA tank and pump.
continue on page 6

The Catalyst Review

June 2020

The Catalyst Review June 2020

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