Zug's buildings should become greener

There should be a regulation or a law to regulate the CO₂ balance: biochar should be added to road surfaces and to concrete for buildings.

A new asphalt mixture with biochar (see note below: ed.) is being used in the city of Basle. This means that CO₂ can be stored in road surfaces over the long term and the roads and streets can become greener. The canton of Basle-City (Basel-Stadt) publicised the use of the new surface at a media conference. The mixing of biochar into asphalt or concrete should now also be promoted in the canton.

Mitte (Central party) Cantonal Councillor (Kantonsrat) Patrick Röösli from Zug, who is an architect by profession, has submitted a postulate on the topic. In it, he invites the government council to “draft a law or regulation that defines the framework conditions under which biochar is to be financially supported and used in construction.”

Canton should set a good example
Specifically, Patrick Röösli is demanding that a law or regulation should regulate the following:

• The mixing of biochar into concrete for building and civil engineering.
• The canton should define the technical and normative framework for the financial support and use of building materials with biochar.
• The canton must define the framework conditions for higher material and construction costs in such a way that appropriate products are used. Market developments should be taken into account.

The Mitte party cantonal councillor justifies his request by saying that, although the canton of Zug prides itself as an innovative location in some areas such as finance, taxes and digitalisation, a lag in innovation can be observed in the canton's construction sector, writes Patrick Röösli. Due to the large amount of construction activity in the canton, it is therefore right for the canton to set a good example as a public builder and to open up to the use of new products.

The canton of Basle-City has extensively tested the asphalt with added biochar.    
In terms of colour, the CO₂-negative asphalt looks like conventional road surfaces               
Photos: zvg/Construction and Transport Department of the Canton of Basel-Stadt

According to the postulate, the addition of biochar “could permanently neutralise more than 200 kilograms of CO₂ per cubic meter of concrete.” And with an addition of 2% biochar, up to 6 kilograms of CO₂ could be stored per ton of asphalt.

Binding more CO₂ than is released during production
In fact, the CO₂-negative asphalt now being used in the city of Basle is considered to be a milestone in technology. As stated in a statement from the canton of Basel-Stadt, the technology could contribute to reducing CO₂ in the long term.

The figures expected in Basle are impressive. Even with a mixture that consists of 2% biochar and 50% recycled asphalt, the city could permanently store around 450 tons more CO₂ in the streets every year than is caused by CO₂ production.

From 2022, the civil engineering department of the canton of Basel-Stadt has been testing the surface in practice at a recycling building material transshipment point. A test area of 450 square metres was given a supporting asphalt layer made of 50% recycled asphalt and 2% biochar.

The results are very positive. “One ton of the new asphalt mixture permanently binds the equivalent of 50 kilograms of CO₂. In total, around one and a half tons more CO₂ was bound in the test area than was released during material extraction, production, transport and installation. The surface is therefore so-called 'CO₂ negative,” says the statement from the canton of Basel-Stadt.

Slightly higher costs
Although the production of green asphalt incurs additional costs of 10 to 15 % per ton, these are minor compared to the benefits it offers. The asphalt has good technical properties, is of high quality, meets all the requirements of the asphalt standards and is also long-lasting. In addition, the canton of Basel-Stadt produces the biochar itself. The resulting heat is fed into a district heating network.

For Zug Central party Canton Councillor (Kantonsrat) Patrick Röösli, any additional costs are only a temporary problem. If the canton uses these green building materials and mandates their use, demand will increase, which will trigger price competition. This will, in turn, make the new products more interesting in terms of price. And that’s why the canton should move forward “and include it in its construction projects.

Note:
Biochar is the lightweight black residue, consisting of carbon and ashes, that remains after the pyrolysis of biomass, and is a form of charcoal. Biochar is defined by the International Biochar Initiative as "the solid material obtained from the thermochemical conversion of biomass in an oxygen-limited environment". Biochar is a stable solid that is rich in pyrogenic carbon and can endure in soil for thousands of years.