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An overview of carbon offset project types: biochar to reforestation to direct air capture
An overview of carbon offset project types: biochar to reforestation to direct air capture
From mineralisation to forest conservation to blue carbon, there are many different types of carbon offset projects – here’s an overview.
May 16, 2022

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In carbon offsetting we compensate for carbon emissions by financing projects that make an equivalent reduction in carbon emissions, either by avoiding emissions or by removing carbon from the atmosphere.

There are many ways of doing this, meaning that there are a lot of different types of carbon offset projects – so in this post we'll give an overview of of the most common types.

In this post we’ll be categorising projects based on two criteria – as per the advice of the Oxford Offsetting Principles:

  • If they are carbon removal or emissions avoidance projects
  • If they include carbon storage: a) no storage b) short-lived carbon storage c) long-lived carbon storage.

If you’re not sure what these terms mean, you can find out more in our blog on the difference between carbon removal and emissions avoidance in carbon offsetting.

NB: typical costs are accurate as of spring 2022 - the cost of carbon is changing regularly!

Biochar

Biochar is a carbon-rich material similar to charcoal, produced by heating biomass waste in a low oxygen environment. It is typically then applied to soil where it will remain as a permanent carbon store, whilst also improving the quality of the soil for plant growth.

  • Typical cost: £100-200/tCO2
  • Category: Carbon removal; Long-lived carbon storage; Oxford Offsetting Principles type 5
  • Example: The Future Forest Company

Blue carbon

Carbon is naturally sequestered in the world's ocean and coastal ecosystems, including in kelp, seaweed, salt marshes, mangroves, and more. Blue carbon projects enhance this sequestration process by preserving or restoring these ecosystems to increase the carbon removal potential.

  • Typical cost: £30-200/tCO2
  • Project type: Varies
  • Example: Seaweed sequestration at Running Tide (carbon removal; long-lived carbon storage, Oxford Offsetting Principles type 5) 

Direct air capture (DAC)

The process of capturing CO2 directly from the atmosphere. Chemicals are used which bind with the CO2 in the air, and the CO2 is then separated to produce a stream of concentrated CO2. This CO2 can then be stored or used in an end product (such as construction) – known as direct air capture and storage (DACS).

  • Typical cost: £300-500/tCO2
  • Project type: Carbon removal; Long-lived carbon storage; Oxford Offsetting Principles type 5
  • Example: Carbon Engineering

Forestry – carbon removal

Afforestation: planting a new forest

Reforestation: planting a forest where a forest was cut down in the past

Improved forest management: introducing better land management practices resulting in increased carbon storage within forests

Forestry – emissions avoidance

Forest conservation: protecting a forest from deforestation, typically through incentivising landowners via income from carbon credits

  • Typical cost: £10-30/tCO2
  • Project type: Emissions reduction; short-lived carbon storage; Oxford Offsetting Principles Type 1 or 2
  • Examples: Rimba Raya

Mineralisation

Mineralisation is a natural process that happens when CO2 in the air reacts with minerals to become a carbonate, permanently storing the CO2 in solid form. There are two main applications:

Enhanced weathering: the natural process of mineralisation is also known as rock weathering. Enhanced weathering speeds up the process by rocks being ground up into small particles, increasing surface area so that they remove CO2 from the atmosphere more quickly. The resulting material can be used in construction, or dumped in the sea. 

CO2 injection: captured CO2 can be injected into a material where it will be mineralised, turning it into solid form and permanently storing it. This is being done by concrete producers, known as concrete mineralisation. 

  • Typical cost: £150-250/tCO2
  • Project type: Emissions reduction; Long-lived carbon storage; Oxford Offsetting Principles Type 3
  • Example: GreenSand (enhanced weathering), CarbonCure (concrete mineralisation)

Renewables

Building wind or solar farms in areas where most energy comes from fossil fuel sources, to reduce future CO2 emissions. Renewable energy projects are typically the cheapest offsets, and are an avoidance project rather than permanent carbon removal.

  • Typical cost: £5-10/tCO2)
  • Project type: Emissions reduction; No storage, Oxford Offsetting Principles Type 1 or 2
  • Example: Larimar Wind Project
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