Okofen heats with wood without emitting fine particles

The innovative technology of the European leader in pellet boilers remedies the main shortcoming of this mode of heating. But the equipment is still expensive, despite numerous aids.

Okofen heats with wood without emitting fine particles

After the stifling heat of summer nights, the cold suddenly set in when school started in France. Already, the first heating devices have been started, with, in the background, a growing concern about the delirious cost reached by energies.

And if, due to the crisis, electricity, gas and fuel oil hold the upper hand in the media, another source of energy is relatively discreet in the discourse: wood. However, of renewable origin and less expensive – 48 to 103 euros per MWh against 84 to 154 euros/MWh for gas or electric heating – it is used as fuel by around a quarter of the French population, i.e. some 7 million households. according to Ademe. An ideal solution at first sight.

But the weight of wood heating in France covers a very heterogeneous reality. Not much in common, in fact, between the fifty-year-old wood stove and the recent pellet boilers. Because the dilapidation of many devices in the fleet, as well as the variable quality of the fuel, is responsible for the main defect of this energy source: the emission of fine particles.

These are far from neutral. Figures from the government, which recently launched an action plan aimed at reducing these dust emissions by 50%, reveal that wood heating is the leading national emitter of these fine particles, which are dangerous to health. Several companies, including Okofen, want to develop solutions to restore this fuel to its natural virtue.

Okofen condensing boiler. Photo credit Andreas Balon

Excellent yield

Created a little over thirty years ago, this Austrian company was the first to approve a wood pellet boiler in 1997 – equipment not to be confused with smaller stoves that can run on the same fuel. These boilers are more massive equipment, which can be used for the central heating of a house or a building as well as for the production of hot water. With approximately 200 million euros in turnover achieved on the continent, including 80 million in France, Okofen is the European leader in the emerging sector of pellet boilers, which has experienced annual growth of 30 to 50% in recent years.

This equipment has a number of advantages listed by Thomas Perrissin, Managing Director of Okofen France: Compared to other means of wood heating, argument no. 1 is automation. Once the silo is filled with pellets, the boiler can have a year of autonomy, like fuel oil, without having to touch the fuel: there is therefore no need to reload several times a week as a stove requires. Next, pellet boilers have the best efficiency for wood heating, close to that of gas. This is due to the fuel, created from sawmill offcuts, which is drier, three times denser than a log, with a consistent caliber. The right quantity of wood and air is thus always brought in and the boiler operates in good conditions. »

But this sector, which has barely finished being structured, is still marginal. Thomas Perrissin estimates that of the 7 million wood-fired homes, only around 150,000 to 200,000 are equipped with pellet boilers. However, with 30 g of CO2 emitted per kWh, according to a study carried out by Ademe and Carbone 4, compared to 49 g for heat pumps, 147 g for electric heaters, 227 g for gas and 324 g for fuel oil, pellet boilers present the the most interesting environmental performances of the sector. Especially since Okofen seems close to solving the problem of particles.

Laurent Bestenti and Thomas Perissin, co-directors of Okofen. photo credit Okofen

No more filter neededs

We were interested in a technique already existing in high-power units, such as incinerators, which allows combustion gases to be reinjected into the flame to improve combustion and reduce particulate emissions. », explains Thomas Perrissin. After three years of in-house development, Okofen’s ZeroFlame technique is born.

By modifying the primary and secondary air circuits, adding a third inlet and improving the insulation of the hearth, the company has managed to drastically improve combustion, which no longer creates flames, and to limit particulate emissions at 2 milligrams per normal cubic meter versus 10 to 20 mg/Nm3 for conventional pellet boilers – 20 mg/Nm3 being the maximum emission authorized by equipment in areas particularly at risk for fine particle pollution, such as in certain metropolitan areas. The emissions of the ZeroFlame boiler are so low that they are even within the margin of error of the measuring devices, as the test of the device during the TUV certification in Austria showed.

This technology does not require any special maintenance, unlike electro-particle filtersassures Thomas Perrissin. In addition, its additional cost per boiler rises to 500 euros, against 2,500 euros for the filters. » Admittedly, the current pellet boilers reach even without this equipment the threshold of emissions authorized by law. But Okofen anticipates a tightening of the regulations, even new aid distributed according to the performance of the boilers, as is the case in Germany, Austria or Belgium.

Combustion of wood pellets, in the hearth of an Okofen boiler. Photo credit Laurent Cerino/REA

Up to 20,000 euros for installation

For the moment, this new technology only applies to Okofen’s high-end condensing boilers, whose energy efficiency exceeds 100%, compared to 85% for conventional boilers. The equipment cannot be installed on boilers that have already been commissioned. We are working to deploy this technology across our entire range over the next few years. », however assures Thomas Perrissin. For the moment, the company aims to deploy, in 2022, only 50 to 100 of these boilers out of 15,000 to 20,000 boiler rooms sold.

But if the ZeroFlame technology does not represent a substantial additional cost, the price of a pellet boiler room remains very high. It takes an average of 20,000 euros for the installation of Okofen’s complete top-of-the-range equipment, equipped with innovation. The price could come down, however, with the rollout of ZeroFlame on more basic boilers. Above all, the individual can count on generous aid from the State or communities, distributed subject to income, to install this virtuous equipment. MaPrimeRénov’ can thus provide up to 11,000 euros in subsidies, to which can be added 2,500 to 4,000 euros for the “heating boost”, as well as other local aid. Without mentioning aid of 1,000 euros to dismantle his old fuel tank, the heart of Okofen’s target.

So what should be done to further accelerate the deployment of pellet boilers, in order to gradually replace the 3 to 4 million oil-fired boilers that still equip the French? If Thomas Perrissin welcomes the generous aid from the State, he calls for “greater stability of these systems and of the regulations, to make the installations more fluid. There is also a paradox: the government has implemented a tariff shield on fossil fuels, but not on wood, whose prices are also extremely volatile due to the crisis. “. One more effort to be made, therefore, to meet the objectives of the Multiannual Energy Program which aims, by 2030, to equip 9.4 million homes with wood heating.

Leave a Comment