Bio-oil

From $750/tonne

Overview

Bio-oil has some similarities with biochar production. They both take waste or spare biomass and convert it to a highly stable form in a high temperature environment through pyrolysis process. The difference with bio-oil is that the result is liquid, and instead of being applied to soils, it is pumped in geological storage, where it’s highly likely going to stay permanently.

With a bit of help from plants (which to the removing from the atmosphere part) this process is therefore putting oil back into the ground.

The science

The feedstock biomass could vary from sawdust to agricultural residue, but the goal is to use biomass with no other use or value such as corn straw and leaves. The first step of the process is to pre-prepare the biomass and feed it to the fast pyrolyser consistently - which can be quite technologically challenging.

Bio-oil is produced by heating the biomass up to about 500°C in a few seconds without any oxygen. This process is called fast pyrolysis and results in liquid oil with high carbon content.

An advantage of the fast pyrolysis - it’s somewhat easier to make bio-oil than full gasify to biochar - is that the equipment needed is less complicated, smaller and can be made in modular, transportable units, reducing the need to transport bulkier biomass to it. This gives this technology and edge in terms of scalability.

Bio-oil is transported and injected into injection wells (disused oil wells), where the bio-oil sinks and solidifies in place for permanent storage. The bio-oil has much lower energy density than fossil oil as it’s heavily oxygenated, so the chance of it ever being pumped up again and used as fuel is really small.

Every carbon credit represents 1 tonne of net carbon removal. The actual carbon dioxide equivalents in the bio-oil sequestered are higher, typically 1.43 tonnes, to also compensate for things like the production of bio-oil (0.17 tonnes), transport of biomass feedstock and bio-oil to the injection site (0.20 tonnes) and the injection itself (0.06 tonnes).

There are a few environmental impacts that need to be considered, which are particulate and NOx emissions from pyrolysis and increased road traffic and the potential for seismic activity. Seismic activity could be increased by lubricating the interfaces between rock layers in the injection wells; not at current volumes but if this solution was to scale up massively. Geological sequestration capacity could become a constraint at larger scales. This is subject to ongoing research, and should not be seen as a dealbreaker in these early stages.

Research papers 2

Supercritical‘s view

It is interesting to compare bio-oil with bio-char. Both can use similar feedstocks, and the reliance on biomass feedstock is probably their main downside.

The big advantage bio-oil injected into geological storage has is that the carbon removal is truly permanent, whereas in the case of biochar proper application to soil, all carbon will be released again, although over very long timescales. Also, the bio-oil production generally scored better on additionality, as the suppliers are set up for one thing alone - carbon removal. Biochar on the other hand has the advantage of bringing additional co-benefits from soil improvement, but the existence of additional co-benefits also make the ‘additionality’ somewhat weaker.

Bio-oil really is about cleaning up the mess for good, and as such we believe it has a role to play in any carbon removal portfolio, and carbon removal in general.

Dr Mai Bui

Director of climate science

Our suppliers

Based in the US, Charm Industrial uses plants to capture CO₂ from the atmosphere. They then convert biomass to bio-oil via fast pyrolysis, prepare the bio-oil for injection, transport it to an injection well, and inject it deep underground.

California, USA
Colorado, USA

Verifications

Every project in the marketplace receives a score through our science-driven, commercially-focused vetting protocol.

Covering 100+ criteria across four key dimensions, this rigorous evaluation yields top-line scores, allowing you to compare projects and evaluate quality objectively. Dive deeper with our vetting explainer.

Climate science

Is the climate science that underpins the carbon credit rock solid?
- Remove carbon
- Have clear permanence
- Accurately issue credits
- Is additional
- Does not suffer leakage
- Strong MRV (Measured, Reported and Verified)
Environmental factors

Beyond the removal of CO2, does the project have a positive or negative impact on the local environment?
- Neutral or positive impact on biodiversity
- Neutral or positive impact on air quality
- Neutral or positive impact on soil health
- No negative effects on groundwater
Delivery risk

What is the risk of non-delivery of credits?
- Site development
- Site operational track record
- Team experience and capability
- Business plan and funding
- Levels of geopolitical risk
Social impact

Does the project have a positive or negative impact on local communities, per UN Sustainable Development Goals (SDGs)?
- Economic empowerment of local communities
- Integrates education and community engagement
- Better health outcomes

Browse our removal methods

Biochar

Biochar is charcoal-like material rich in stable carbon. It is produced by heating biomass in an oxygen-limited environment in a process called pyrolysis.

Permanence: MEDIUM From: $162/t
ARR

Afforestation and forest restoration, if done effectively, combat climate change by removing carbon dioxide and protecting biodiversity.

Permanence: LOW From: $58/t
Enhanced weathering

Enhanced rock weathering (ERW) takes natural weathering of silicate rocks that removes & mineralizes atmospheric CO₂ and speeds it up dramatically.

Permanence: HIGH From: $312/t
Direct air capture

Direct air capture (DAC) is a chemical process to capture ambient CO₂ from the atmosphere.

Permanence: HIGH From: $618/t
DAC with ocean storage

This employs seawater electrolysis to capture and convert atmospheric CO₂ into carbonate solids for construction and permanently stores dissolved bicarbonate ions in the ocean.

Permanence: HIGH From: $812/t
Woody biomass sinking

This is a method that sequesters carbon by submerging leftover woody materials in the oxygen-depleted layer of the Black Sea, which is approximately 2 kilometers deep.

Permanence: MEDIUM From: $375/t
Bio-oil

Bio-oil and biochar production both convert waste biomass through pyrolysis. Bio-oil is a liquid stored in geological repositories, while biochar is applied to soils.

Permanence: HIGH From: $750/t