Anaerobic digestion (AD) is at the heart of Pretoria Energy’s mission to create cleaner, greener, and truly sustainable energy. As one of Europe’s largest vertically integrated biogas producers, generating 125 million m³ of biogas per year, Pretoria Energy has perfected an innovative system that turns crops and organic material into renewable fuel – all while capturing carbon and supporting the UK’s growing demand for low‑emission energy.
What is anaerobic digestion?
Anaerobic digestion is a natural, biological process where microorganisms break down organic material in oxygen‑free conditions. This produces biogas – a blend of methane and carbon dioxide – along with nutrient‑rich digestate that can be repurposed in agriculture.
Pretoria Energy uses a highly efficient version of this process, capable of handling multiple feedstocks sourced directly from its own sustainable farming operations. Their AD systems are described as “highly advanced, efficient and adaptable” to different crop types.
Step 1: Sustainable feedstock production
Pretoria Energy manages over 10,000 hectares of arable land every year, producing crops such as maize, sugar beet, triticale, wheat, grass and straw specifically for use in its AD plants. This vertically integrated model means the company controls every stage – from sowing and harvesting to processing – ensuring reliable, traceable and local feedstock.
This localised loop also reduces transport emissions and supports regional farming partnerships across the East of England.
Step 2: Feeding the anaerobic digesters
Once harvested, feedstocks are delivered to Pretoria Energy’s AD facilities, including major sites such as Chittering and Mepal. Here, the organic material enters sealed, oxygen‑free tanks where naturally occurring microorganisms begin breaking it down.
The tanks maintain optimal temperatures and mixing conditions, allowing microbes to work efficiently and continuously. This breakdown process releases biogas, which is captured for further refinement.
Step 3:Biogas upgrading – producing Bio‑LNG
The raw biogas undergoes an advanced refining process that separates methane from other gases. Pretoria Energy produces 100% biogenic Bio‑LNG, a high‑purity fuel recognised as carbon‑negative due to the company’s integrated carbon‑capture systems.
Because this Bio‑LNG is produced entirely from renewable feedstock grown on local land, it offers fleet operators a reliable and traceable alternative to conventional fossil fuels.
Pretoria Energy’s commitment to scaling up waste‑based biomethane is further demonstrated through its partnership with Roadgas, supporting the decarbonisation of over 2,500 gas‑fuelled trucks annually within five years.
Step 4:Capturing biogenic CO2
A significant advantage of Pretoria Energy’s system is that it doesn’t just make clean fuel – it also captures food‑ and beverage‑grade Bio‑CO2, produced as a natural by‑product of anaerobic digestion.
Unlike CO2 derived from fossil fuels or industrial combustion, Pretoria’s CO2 is biogenic, renewable, and carbon‑negative, as their closed‑loop production captures more carbon than it emits.
Step 5: Returning nutrients to the land
Nothing is wasted. The remaining digestate becomes organic fertiliser, marketed through the Natura Grow range. This nutrient‑rich material improves soil structure, boosts fertility, and supports regenerative farming — completing the natural cycle.
A closed‑loop system creating real climate impact
Pretoria Energy’s anaerobic digestion process goes far beyond traditional biogas production. By integrating sustainable crop growth, advanced AD technology, on‑site biogas upgrading, and carbon capture, the company delivers energy solutions that are local, traceable, and truly carbon‑negative.
With every stage designed to maximise efficiency and minimise environmental impact, Pretoria Energy is leading the UK’s transition to cleaner fuel — proving that the future of industry is, indeed, green.