On 4 September, the Swiss business news service punkt4 carried a short item that is easy to overlook: the methanol project run by the Umwelt Arena Schweiz and its partners is moving forward. The residential development in Bassersdorf (ZH) will spend another winter running its energy centre on purchased methanol, while the plant that is meant to make that methanol from Swiss solar power — at the waste-to-energy plant in Horgen — has received the permit for its building application, with the first assemblies already delivered on site.
It is not a headline-grabbing announcement. For anyone following seasonal storage in Switzerland, it is nonetheless more informative than most press releases ten times its length, because this is one of the very few places in the country where seasonal Power-to-X storage is being built and operated rather than modelled.
What the Bassersdorf system actually does
The building at Bahnhofstrasse 12 in Bassersdorf carries photovoltaic modules on both roof and façade. In summer it generates far more electricity than its residents use. Rather than pushing all of that surplus into an increasingly congested grid, the concept is to convert it into methanol — a liquid that can sit in a tank from July to January without losing a kilowatt-hour to self-discharge.
In winter the methanol feeds a Hybridbox®, a compact energy centre supplied by Hybridbox AG in Eschlikon (TG) that combines a combined heat and power unit with a heat pump. It was converted for methanol operation for the first time for this project; previously the same unit ran on renewable gas. It delivers heat and electricity precisely when both are scarce. And because the fuel is stored on site, the building can be kept running during a grid outage — a side benefit that tends to be worth more to a building owner than the energy arithmetic suggests.
What makes this unusual is the scale. Most Power-to-X projects live in refineries, chemical parks and airports. Bassersdorf puts the same chemistry in a basement, in a normal block of flats.
The honest number
Round-trip efficiency is where chemical seasonal storage always becomes uncomfortable, and the project team has not tried to hide it. Of 100 kWh of surplus electricity converted into methanol, roughly 20 kWh come back out as electricity, with an additional ≈34 to 40 kWh recoverable as usable heat along the way.
Measured against a lithium battery, that looks poor. Measured against the alternative it is actually competing with, it looks different. Swiss solar installations increasingly face feed-in restrictions at peak times and can be decoupled from the grid when the network cannot absorb their output. Curtailed electricity has a round-trip efficiency of zero. The relevant question is therefore not whether methanol beats a battery over a summer afternoon — it does not, and never will — but whether converting July surplus into a molecule beats discarding it in July and burning oil or gas in January. That is the comparison Bassersdorf is testing, and it is the comparison that matters for the winter gap. (By the way, this comparison also applies to eFuels for passenger cars. Here too it is not about eFuels vs. batteries but harvesting renewable energy vs. not harvesting it and burning fossil fuels.)
Horgen: where the fuel is supposed to come from
Until now the methanol burned in Bassersdorf has been bought in and imported. The second half of the project — and the half that decides whether any of this is a defossilisation story at all — is the production plant at the KVA Horgen, the waste-to-energy plant on Lake Zurich.
That plant is being built as a LivingLab inside «GreenHub», one of eight large-scale Flagship projects funded by Innosuisse. The consortium is led by OST – Ostschweizer Fachhochschule and brings together sixteen partners in all — seven research and nine implementation partners. On the research side these include EPFL, HEIG-VD, SUPSI, Hochschule Luzern, ZHAW and the University of Bern; on the implementation side Casale SA, SolydEra SA, Kanadevia Inova AG, Energie 360°, the municipality of Horgen and the Zweckverband Entsorgung Zimmerberg, operator of the KVA Horgen, which acts as the real-world laboratory. Several of them are SPIN members: OST, EPFL, HEIG-VD, SUPSI, ZHAW, Casale, Kanadevia Inova and IG Power-to-X. The stated ambition is blunt: to demonstrate, at regional scale, a route towards closing Switzerland’s seasonal energy gap of roughly 9 TWh.
A complementary project, «GreenHub Plus», supported by the Canton of Zürich and the Umwelt Arena Schweiz, examines how the methanol produced in Horgen is conditioned and used decentrally — including in the Hybridbox®.
The logic of siting it at a waste-to-energy plant is the same logic that makes industrial hosts attractive elsewhere in Power-to-X. A KVA offers, in one place, waste heat, a grid connection, an operator used to running process plant around the clock, and land that is already zoned for industry. Electrolysis on site turns surplus renewable electricity into hydrogen; the hydrogen is then synthesised into methanol with CO₂ delivered to the site in cylinders. The building permit now granted is the unglamorous milestone that turns that arrangement from a diagram into a construction site.
In parallel, the Umwelt Arena and its partners are running trials with the German firm IMT Industrie Motoren Technologie GmbH on the optimal conditioning of the methanol — the fuel quality question that decides whether an engine designed for one specification runs happily on another.
Which CO₂?
One condition remains non-negotiable from a Power-to-X perspective: e-methanol only makes climate sense when the carbon it contains is recycled CO₂ from biogenic, atmospheric or industrial sources, and when that recycling displaces fossil carbon instead of providing a reason to burn more of it.
In Horgen, the CO₂ for the synthesis is not captured from the plant’s own flue gas; it is delivered to the site in cylinders. Where that carbon comes from therefore remains one of the questions worth following as the project moves towards operation.
A waste-to-energy plant would in principle be an interesting host for the carbon as well. The carbon in Swiss municipal waste is part biogenic — paper, wood, food, textiles — and part fossil, principally plastics. Capturing it and putting it into a fuel that displaces heating oil would be recycling carbon that would otherwise have gone straight up the stack. What it must never become is an argument for keeping more fossil plastic in the waste stream because the CO₂ has found a buyer. The point of recycled carbon is to displace fossil carbon, not to give it a second business model.
The same principle applies to the industrial CO₂ sources that make Switzerland’s cement works and waste plants such obvious anchor sites for Power-to-X. The project team itself has pointed to cement plants as the natural next candidates once the Horgen concept is proven.
A two-tonne problem
One detail from the Bassersdorf build deserves to be quoted in every discussion about why Swiss Power-to-X moves slowly. Until autumn 2025, the threshold quantity for methanol under the Swiss Major Accidents Ordinance (Störfallverordnung) stood at 2 tonnes — a quantity that makes seasonal storage for a multi-family building arithmetically impossible. With effect from 1 October 2025, it was raised to 20 tonnes.
Nothing about the technology changed. What changed was a number in an ordinance that predated any thought of using methanol as a building’s winter energy store — and it changed because the industry was prepared to set out the state of safety engineering itself. SPIN developed consolidated safety standards for the production, storage and processing of methanol, together with its members, the Federal Office for the Environment (FOEN), the cantonal enforcement agencies and Powerloop, covering storage and handling, fire and explosion protection, training, protective equipment and emergency response. Those standards are the basis of the industry’s voluntary commitment to apply them, and that commitment is what allowed the threshold to be raised while clear safety requirements remain in place. They are published on the SPIN website (PDF, in German).
It is precisely the category of obstacle that SPIN’s position paper from July documents across 42 regulatory blockages: laws whose intent is sound, and ordinances underneath them that were written for a world in which nobody stored solar electricity as a liquid. Here the blockage was removed for everyone, not project by project — which is how it should work for the next twenty projects too.
Why the timing matters
Two days before the punkt4 item, the Federal Council adopted its report on synthetic energy carriers and seasonal storage, concluding that Power-to-X will play only a limited role in Swiss winter electricity supply. The conclusion may well turn out to be right for grid-scale supply. It is a poor guide, however, to what is happening at building and district scale, where the competing option is not a gas turbine but curtailment on one side and an oil boiler on the other.
Horgen and Bassersdorf will produce something a report cannot: measured numbers from a plant that actually runs. Together with the methanol-to-jet chain that PSI and Metafuels opened at Villigen in August — aerobrew — Switzerland is quietly assembling a methanol value chain: a molecule made from renewable hydrogen and CO₂ that can heat a building in winter or, further down the chain, become jet fuel.
Slowly, on purpose
The Umwelt Arena’s own framing of the delay is worth taking at face value. In its statement it notes that, as with many innovative technologies, new findings from research and development keep revealing scope for optimisation, and that individual development steps are therefore taken deliberately and in stages.
That is not a euphemism for trouble. It is what building a first-of-a-kind plant looks like when nobody is pretending otherwise. A second winter on imported methanol is not the announcement anyone wanted, but a permitted plant with assemblies arriving on site is a better position than a press release about an intention. The interesting reporting on this project will come in the winter of 2027/28, when the first molecules made from Swiss solar electricity reach a basement in Bassersdorf, and the round-trip efficiency stops being an estimate.
Sources: punkt4.info, 4 September 2026; Umwelt Arena Schweiz project page; Innosuisse Flagship GreenHub.
🤖 AI transparency: This text and its visual were created using AI, reviewed and approved by a human.
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