Sylfen: autonomy and long-term energy storage

Sylfen, a Grenoble start-up founded in 2015 has developed a hydrogen storage system for the construction sector. Its intelligent energy system (SHU) is capable of producing hydrogen, but also of being used as a fuel battery to restore electrical energy and heat to a building. Coupled with solar panels, this system significantly reduces the carbon footprint of a building, and fits perfectly into the many eco-neighborhood programs that are emerging! Ultimately, the company hopes to participate in the creation of cleaner and more autonomous cities, like smart cities.

Renewable products are on the rise and make it possible to democratize self-consumption, whether collective or individual. However, designing free-standing buildings is more complicated than it looks. To avoid making systematic use of the traditional energy network, it is indeed necessary to store the energy produced by the building in order to restore it later. Sylfen is developing a hybrid battery / hydrogen solution that allows short and long term storage.

Two subsets are used:

  • The first is a set of cabinets the size of a large fridge that can be integrated into spaces reserved for technical equipment. There are the batteries and the reversible R-Soc electrolyser, which functions as a fuel cell in the restitution phase.
  • The second is the hydrogen tank stored outside. It occupies the equivalent of one or two parking spaces depending on the power required.In terms of performance, we are on an efficiency of 90% for the batteries and 50% for our reversible electrolyser. This level of electrolyser efficiency is enabled by a new technology that we have developed. As a general rule, this type of equipment does not exceed 35% efficiency (70% for hydrogen production, 50% for energy release). The difference in efficiency between batteries and electrolysis is not a problem as the losses are mainly in the form of heat. We can therefore recover the latter for domestic hot water (DHW), exchangers, or for cold.

Another advantage of this technology is that if there is not enough hydrogen in stock, the battery can use methane. This makes it possible to use local biogas to limit the loss of autonomy of the building.

Finally, this solution is modular to adapt to the level of consumption required by each building. Sylfen thus developed a projection study service which makes it possible to calculate very simply the number of modules required according to the uses.

Sylfen’s activity is part of the sustainable development

The Sylfen’s ambition is to change the image we have of buildings. They want to turn them into producers and storers of energy. In their opinion, this is the missing brick for the ecological transition. A building will always be a consumer of energy, because it is a place of life, entertainment, etc. There is a lot of talk today about hydrogen in transport, which, along with the construction sector, is the main emitter of greenhouse gases. Why not transpose these technologies to construction? Depending on the energy mix of the countries, we can reduce greenhouse gas emissions by 25 to 75% by limiting the use of traditional energy networks as much as possible. It is necessary to decompartmentalise the world of construction. Energy must be included in the design of buildings and it is necessary to take into account that energy means both electricity and heat production.

In addition, the self-consumption aspect responds to another social debate: that of short circuits. By favoring self-consumption, access to energy is decentralised. It comes down to the local level to become closer to the users, the professionals who intervene, etc. This had not been the case since the beginning of the industrial revolution.

The batteries are recharging
The surplus is transformed into hydrogen and stored in a tank
Batteries provide electricity
Hydrogen is used to generate the missing electricity, as well as heat
When the stock of hydrogen is likely to be insufficient, methane can be used to produce electricity and heat. This high-efficiency cogeneration makes it possible to recover the biogas produced locally.
Alternatively, it is also possible to anticipate purchases of electricity on the network, in order to replenish reserves.

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