Kiln

The problem

Cement makes 8% of the world's carbon emissions, and producers have no drop-in alternative that meets building standards.

The solution

Kiln replaces 60% of the clinker in cement with treated steel slag, cutting emissions in half with the strength that standards require.

Who it's for

Cement producers and large construction firms with carbon targets.

Market

Bottom-up: about 45,000 customers like this in Denmark and nearby, worth roughly $280 million a year at our prices.

Competition and edge

Headline metric

Pilot customers live

The team

Freja knows the customer and has sold to them before; Jonas has built this kind of system at scale. We have worked side by side since before Kiln had a name.

Worked together

More than 3 years

Hiring

A senior engineer and our first customer-success hire.

About the founder

Freja Nielsen

Founder & CEO · Copenhagen, Denmark · 10 years of experience

Freja holds a doctorate in materials chemistry and worked in a cement research lab. Started Kiln in 2025 and works on it full-time from Copenhagen.

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