“Frontier has facilitated offtake agreements with CarbonRun, a Canadian company using a well-established method of river de-acidification called river liming for carbon removal. Frontier buyers will pay $25.4 million to permanently remove 55,442 tons of CO₂ between 2025 and 2029 at multiple sites, starting with deployments in Nova Scotia, Canada. This is the first carbon removal offtake via river liming.
River liming adds crushed up limestone (alkalinity) to acidified rivers to repair the damage caused by acid rain. It was successful in treating the acid rain problem in Scandinavia. Due to increased costs, the practice is in a state of decline, with many applicable regions having to cease or reduce river liming activities. CarbonRun discovered that adding limestone also boosts rivers’ natural ability to extract CO₂ from the air. The atmospheric and land-based carbon found in rivers combines with the limestone to produce bicarbonate. Bicarbonate in the river water makes its way to the open ocean for permanent storage.
The Frontier offtake focuses on rivers acidified by pollution and climate change, where river liming has both carbon removal and ecosystem benefits such as salmon and shellfish population restoration. Expanding river liming to pH-neutral rivers would give this approach the potential to reach gigaton scale.”
From Frontier.