“Exciting!” When Gerrit Zijl­stra talks about the tiny house, he get’s excited. It is not even the cube’s modern cozi­ness, measuring 3.45 by 11.95 meters, that makes the physi­cist light up. In fact, the reason he is so excited cannot even be seen. Instead, it is some­thing that is felt: despite the Nether­lands’ winter winds, the tiny house has a cozy temper­a­ture and the water in the house heats up quickly, allowing for a pleasant hot shower to warm you up. This is a mile­stone for Zijl­stra and his employer, Dutch boiler manu­fac­turer Intergas, based in Coevorden. This is because their boiler in the tiny house provides hot water and warmth, heating entirely with hydrogen.

Hydrogen is both: storage and energy, which makes it an effec­tive solu­tion for the energy tran­si­tion. There­fore we are exploring this as a solu­tion.

Peter Cool, CTO Intergas

“For me, this is what is fasci­nating about the tiny house project: inte­grating new hydrogen tech­nology into a tried-and-tested product like a boiler and finding a solu­tion for sustain­able fuel. This enables us to reduce CO₂ emis­sions,” says Zijl­stra. Two years ago, Intergas embarked on this path. Because, as CTO Peter Cool says: “Hydrogen is both: storage and energy, which makes it an effec­tive solu­tion for the energy tran­si­tion. There­fore we explore this as a solu­tion.” Devel­oper Zijl­stra took on the H₂ capa­bility of Intergas’ prod­ucts as project manager for hydrogen. The first ques­tion to ask was, “How can we convert an existing boiler so that it can burn pure hydrogen?”

Photo: Miquel Gonzalez | Fotogloria

Tests in the hydrogen labo­ra­tory

The search for answers began in the company’s own hydrogen labo­ra­tory. First of all, that meant going back to the basic prin­ci­ples of combus­tion tech­nology. After all, hydrogen behaves completely differ­ently to natural gas, which is going to be replaced as part of the energy trans­for­ma­tion in the not-too-distant future. Zijl­stra explains, “With natural gas, we use its conduc­tivity to monitor the flame. In contrast, a hydrogen flame is not conduc­tive and is almost invis­ible. So first of all, we had to find a solu­tion to ensure flame moni­toring.”

The hydrogen boiler is the result of an inno­v­a­tive collab­o­ra­tion with a fantastic team of experts.

Gerrit Zijl­stra, devel­oper at Intergas

With a wide range of test setups and open burners, Zijl­stra got to work at the labo­ra­tory, with the major advan­tage that Intergas has short chains of command between the disci­plines required for an advanced boiler: “The hydrogen boiler is the result of an inno­v­a­tive collab­o­ra­tion with a fantastic team of special­ists who excel in elec­tronics, physics, embedded soft­ware, engi­neering, certi­fi­ca­tion, IT, product manage­ment, and marketing,” says Zijl­stra.

For Intergas devel­oper Gerrit Zijl­stra (left) and CTO Peter Cool, their hydrogen boiler is a mile­stone in the energy trans­for­ma­tion. (Photo: Miquel Gonzalez | Fotogloria)

Hydrogen behaves completely differ­ently to natural gas. There­fore, basic research on an open burner was neces­sary. (Photo: Miquel Gonzalez | Fotogloria)

Close links during the devel­op­ment

There are close links beyond the company and national borders too. “We brought ebm-papst on board at the start of our work on the H₂ boiler. After all, we suspected early on that the gas valve and the blower would play a crucial role. We already had very good contact with ebm-papst through Enno Vrolijk, the head of gas valve devel­op­ment.”

In Enno Vrolijk, Jürgen Schwalme, head of appli­ca­tion and certi­fi­ca­tion, the appli­cator Christoph Beck, and Ludwig Hirsch, head of the test work­shop, Intergas found contact persons who can provide both tech­nical support as well as help with all neces­sary formal­i­ties. “We had a lot of inter­esting discus­sions and iden­ti­fied poten­tial risks together. ebm-papst also provided us with proto­types that are tailored to the char­ac­ter­is­tics of hydrogen,” says Zijl­stra. These include, for example, a partic­u­larly tight gas blower and special hydrogen settings for gas valves. However, it also had to be ensured that no sparks from elec­tro­static charging occur inside the blower even if there’s a fault. The fact that ebm-papst has been dealing with the element H₂ for some time quickly paid off for Intergas.

In Enno Vroljik (left) and Jürgen Schwalme from ebm-papst, Intergas found contacts who have been working on hydrogen for a long time. (Photo: Miquel Gonzalez | Fotogloria)

From here to the energy revo­lu­tion: for two years, Intergas has been working on hydrogen for heating. (Photo: Miquel Gonzalez | Fotogloria)

Help with certi­fi­ca­tion

“As heating experts we are all about devel­op­ment, devel­op­ment, devel­op­ment,” says Zijl­stra. So when they got an exciting inqiry their moti­va­tion was boosted even further: various insti­tu­tions of the commu­nity of Hoogeveen had come together to build a small mobile house made entirely of sustain­able mate­rials, and oper­ated with green hydrogen. In September 2021, the “Water­stof Tiny House” was set to go on tour through the Dutch region of Drenthe as an ambas­sador for green living and to inspire the wider popu­la­tion, students, and those with a profes­sional interest. This was the ideal demon­stra­tion test for Intergas and its first H₂ boiler. However, by then, it was March already, so there was limited time.

A major chal­lenge for us was that the tech­nology is further along than the regu­la­tions.

Gerrit Zijl­stra, devel­oper at Intergas

“A major chal­lenge for us was that the tech­nology is further along than the regu­la­tions. We were unable to use certi­fied compo­nents because there simply weren’t any certi­fi­ca­tions,” says Zijl­stra. “But ebm-papst helped us in the certi­fi­ca­tion process that we had to undergo for the tiny house demon­stra­tion test.” Expert Jürgen Schwalme explains: “Even before the tiny house project, we had sat with different testing centers, such as DVGW-EBI, and worked with them to eval­uate risk analyses and to deter­mine and perform the neces­sary tests and inves­ti­ga­tions. We also partic­i­pated in the Euro­pean ‘Testing Hydrogen in Gas Appli­ances’ project, or THyGA for short, and were invited in the stan­dards consor­tium to partic­i­pate in drafting the Euro­pean guide­line for the use of 100 percent hydrogen for gas valves in heating tech­nology. Our network in Europe enabled us to provide Intergas with very quick support in the collab­o­ra­tion with Dutch testing center Kiwa.”

Hot water on the march with hydrogen: The Water­stof Tiny House was on tour through the Nether­lands as an ambas­sador for green heating. (Photo: Miquel Gonzalez | Fotogloria)

From tiny house to resi­den­tial area

Since then, the tiny house has completed its tour and has left a lot of lasting impres­sions. “The visi­tors were thor­oughly impressed, and the first thing many of them did was check whether warm water actu­ally comes out of the tap,” says Zijl­stra, who was there himself at some stops.

The tiny house is now at its final loca­tion in Hoogeveen, and Intergas is starting its next hydrogen project: a part of the village Wagen­borgen in Groningen, with houses from the 1970s, will be connected to a hydrogen network at the end of 2022. From that moment on the resi­dents of 33 houses will heat with a hybrid system — with hydrogen boilers and small heat pumps from Intergas.

With the 100 percent hydrogen boiler we are ready for a sustain­able future. This is pretty exciting for us.

Gerrit Zijl­stra, devel­oper at Intergas

However, with older houses, some of which are even listed as a histor­ical monu­ment, it is often not possible to install heat pumps for heating to bring them up to a level that is in line with the energy trans­for­ma­tion. “For these houses, hydrogen is a simple solu­tion that is also quick to install: based upon our expe­ri­ence with current gas boilers, an installer only requires a morning to install an H₂ boiler. With hydrogen tech­nology, we can accel­erate the trans­for­ma­tion,” says Gerrit Zijl­stra, adding: “With the 100 percent hydrogen boiler we are ready for a sustain­able future. This is pretty exciting for us.”