Greening in construction with Hydrozine aggregates

Tech startup DENS, which emerged from the TU/e student team Fast, will be testing an emission-free generator on construction sites this year, together with several large construction companies. The generator runs on hydrozine, better known as formic acid. Max Aerts, CEO and co-founder of DENS, tells during the Energy Storage Event more about this innovative generator.

By: Dimitri Reijerman

Hydrozine can be an alternative to hydrogen as a sustainable energy carrier, Aerts explains: “If you look at the energy transition that has been initiated, we will have to store sustainably generated energy in order to be able to regenerate it elsewhere. Of course, this can be done with batteries, but they also have their well-known limitations. Then people quickly look at hydrogen under pressure, but hydrogen is quite difficult in large-scale storage and distribution. If you look at the current energy infrastructure, it is less well-equipped for hydrogen or batteries. Liquids, such as formic acid, fit in much better there, because we are already used to them, such as petrol and diesel. Liquid fuels are also easy to integrate into the infrastructure.”

In fact, formic acid is another carrier for sustainable energy, says Aerts, applied in this case in a generator: “Hydrozine is a liquid storage medium for hydrogen. So we have actually built a hydrogen generator. However, by packaging hydrogen as a liquid, you get the advantages that you also have with a diesel generator.”

Safer than hydrogen

In addition, formic acid is less dangerous than commonly used fossil fuels: “Its flash point is comparable to that of diesel and it is less explosive or highly flammable than hydrogen. That is why you can also store larger quantities of formic acid, for example on the construction site itself. The generator can easily be equipped with a month's supply tank of fuel.”

In the coming period, DENS will test its devices on a larger scale in practice with several partners: “We are going to deliver the first four generators within a few months. After that, we will start a series of pilots with a number of construction and rental companies. If everything goes according to plan, we can start serial production at the end of this year.”

The devices, as befits modern machines, provide the end user with real-time insight into performance: “Our hydrozine generators are full of sensors and we read this data continuously,” says Aerts. “This gives us insight into the CO2 savings and the emission of particulate matter compared to a diesel generator. And on the device you can already see via a touchscreen which savings have been achieved. No harmful emissions are released. After all, we bind a hydrogen molecule to a CO2 molecule. That process is CO2 neutral.”

Hydrozine production costs must be reduced

At the moment, diesel apparently still has a cost advantage over hydrozine. But according to Aerts, that is not a fair comparison, purely on the basis of cost price: “Looking at the kilowatt-hour price, you currently spend more on formic acid than on a classic diesel generator. But that does depend on the perspective you look through. If you look through the perspective of the government or society, the picture is different. Then you also take into account the costs of the emissions, for example the health effects of diesel emissions. Then a liter of diesel does not cost 1.30 euros but rather around 2.60 euros. In that perspective, formic acid is cheaper again.”

Currently, DENS is working with chemical giant BASF from Germany for formic acid. In the long term, the cost price should be able to decrease, the DENS CEO expects: “BASF can make formic acid based on biobased materials. With new techniques and economies of scale, the cost price per liter of hydrozine can still be significantly reduced. It is already a large existing market, because formic acid is an additive for food and animal feed.”

However, DENS is also looking at other possibilities than just developing green aggregates for construction, Aerts concludes optimistically: “In addition to stationary engines on formic acid, such as in aggregates, DENS is now also looking at other applications where diesel engines still dominate. We are currently working towards that in the first phase. Possibly something in the mobile or maritime sector, but it partly depends on whether certain pilot projects continue. We like to do that kind of thing together with partners.”

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