Decoded: How human poop became Microsoft's tool to fight climate change

To offset the impact of its AI data centres, Microsoft is investing in a method which involves buying human and farm waste and piping it thousands of feet underground through a pump

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Why’s a tech giant like Microsoft shopping for human poop? Well, it’s part of a serious climate play.

 

Microsoft has announced a 12-year deal with US startup Vaulted Deep to buy human excreta, manure, and agricultural waste to offset emissions from its energy-intensive data centres. The waste will be injected 5,000 feet underground, helping remove 4.9 million metric tonnes of carbon dioxide—cutting its data centre emissions. The partnership will extend over 12 years, until 2038.

 

How does Vaulted Deep offset carbon? 

A runner-up in Elon Musk’s Xprize Carbon Removal competition, Vaulted Deep uses human waste, animal manure, and paper sludge to create carbon-rich slurry, which is then injected deep into underground rock formations. Vaulted Deep’s key advantage lies in its ability to eliminate unusable waste and convert it into carbon credits.

 

What’s in it for Microsoft? 

The technology giant’s growing energy demands to support its artificial intelligence (AI) infrastructure have led to a rise in emissions. Since 2020, Microsoft’s carbon output has increased by nearly 25 per cent, undermining its 2020 pledge to remove more carbon from the atmosphere than it emits by 2030. By 2050, Microsoft aims to remove more greenhouse gases from the environment than it has released since its founding.

 

Burying bioslurry is one of several carbon offsetting strategies Microsoft is investing in, aiming to tackle climate change by preventing the release of carbon dioxide and methane into the atmosphere.

 

AI boom fuelling energy consumption 

AI-powered large language models such as ChatGPT rely on energy-intensive data centres. AI is expected to increase electricity demand from these centres by 50 per cent by 2027. The construction of data centres and upgrades to grid infrastructure further elevate energy consumption. Microsoft reported generating 14.9 million metric tonnes of greenhouse gas emissions—more than twice the level it aims to reach by 2030, when it plans to become carbon negative. The tech giant has expanded its investments in carbon removal technologies to meet this target.

 

How Vaulted Deep’s method works? 

Vaulted Deep collects what it refers to as ‘bioslurry’ – which includes human waste from municipal sewage systems, surplus manure from farms, and leftover sludge from paper mills. The material is ground into slurry and injected approximately 5,000 feet underground.

 

The slurry is sourced from municipal and industrial sites before being piped beneath natural rock layers. In the case of manure, deep underground storage halts decomposition, thereby preventing the release of greenhouse gases such as CO2 and methane into the atmosphere.

 

Vaulted Deep then sells carbon credits based on the amount of carbon successfully stored underground. These credits currently sell for around $350 per metric tonne. Vaulted Deep’s selling point is that it gets rid of waste that is unusable and turns it into carbon credits. To date, the startup has removed over 18,000 metric tonnes of carbon dioxide.

 

What are carbon credits and how do they help?

 

Carbon credits allow companies to offset their environmental impact by paying others to reduce emissions or capture carbon on their behalf. In more ambitious scenarios, firms use carbon credits to achieve carbon neutrality.

 

How do carbon credits work?

 

If a company cannot eliminate its CO2 emissions, it can pay another entity to reduce theirs, so that the total amount of carbon in the atmosphere declines—even if the original emitter continues its operations.

 

There are three categories of carbon credits:

Reduced emissions – typically through energy efficiency improvements

Removed emissions – including carbon capture and reforestation

Avoided emissions – for instance, choosing not to cut down rainforests