THE billionaire Collison brothers who control online payments company Stripe are spending a quarter of a million dollars to import special sand to a remote Caribbean beach.
But Patrick and John Collison are not creating a waterfront hideaway. Instead, Stripe is supporting a radical approach to fighting climate change.
The beach project - taking coarse-milled olivine to the water's edge so the waves can grind it up, allowing the ocean to absorb more carbon - is one of four investments in carbon removal by Stripe. Another technology deal will fund putting carbon into concrete to strengthen it. A third takes biomass that would decompose and spew carbon - such as almond shells - and produces bio-oil for burial underground.
Stripe is spending $1m (€920,000) all told, following CEO Patrick Collison's August pledge that instead of buying cheap carbon offsets, such as those from landowners who agree not to cut trees, the company would pay much more for innovative methods to get carbon dioxide out of the air.
Some studies have found that a majority of offsets used for regulatory compliance or tax breaks do not measurably and effectively improve the air, even if they let companies claim to be carbon neutral.
Instead of looking for the cheapest "negative ton" offsets for carbon emissions, which can cost as little as $10, Stripe will pay as much as $800 per ton for promising new approaches.
Project co-leaders Ryan Orbuch and Nan Ransohoff approached the task like venture capitalists. "We're looking for underfunded and under-invested-in areas, relative to their importance in fighting climate change," said Ms Ransohoff. "That's pushed us toward more early-stage stuff."
But the projects had to have a plausible path to neutralising large amounts of carbon at low cost, Mr Orbuch said.
Stripe is far from the first to sponsor carbon removal, which can take a multitude of forms from tree-planting to fans sucking carbon dioxide from smokestacks or the open air. But the collective scale of existing projects is orders of magnitude from where the experts say it needs be in 2050.
They say there is no way to limit temperature increases to those in the global Paris agreement without massive carbon removal on top of emission reduction.