What Is Green Diesel?
Green diesel is the common name for marked gas oil (MGO) in Ireland. It is chemically very similar to ordinary road diesel but is dyed green (and in some cases red, in Northern Ireland) to identify it as a tax-reduced fuel intended for off-road use. Because it attracts a lower rate of mineral oil tax than road diesel, it is substantially cheaper per litre at the point of sale.
The colour marking exists precisely so that Revenue (in the Republic) and HMRC (in Northern Ireland) can detect misuse: a roadside fuel check involves a test strip that reacts to the dye. Using green diesel in a road vehicle is a serious offence carrying significant fines and potential seizure of the vehicle.
Green diesel may only be used for the purposes permitted by the Revenue Commissioners (Republic of Ireland) or HMRC (Northern Ireland). Using it in a road vehicle, or in any application outside the permitted categories, is an offence. Always confirm your intended use is covered before purchasing.
Who Uses Green Diesel?
The permitted uses of marked gas oil in the Republic of Ireland cover a range of agricultural, marine, and industrial applications.
In Northern Ireland the rules are broadly equivalent and are administered by HMRC. Certain heating applications (particularly for commercial or industrial premises not served by the gas network) may also be permissible. Check the relevant authority guidance for your specific use case, as the permitted categories have changed over time and can vary between ROI and NI.
Why Is Green Diesel Cheaper Than Road Diesel?
The price difference between green diesel and road diesel comes almost entirely from the excise duty differential. Road diesel carries a full rate of mineral oil tax, which contributes a large portion of the pump price. Green diesel is taxed at a substantially lower rate because its intended uses are treated as economically essential activities (farming, fishing, energy production) or activities that do not burden public roads in the same way as private motoring.
The underlying crude-oil and refinery cost is similar for both products. So when you see green diesel prices, the difference from road diesel reflects tax relief, not a different product. Both fuels move up and down in line with global oil markets.
Bulk purchasing and storage
Unlike road diesel, which farmers and marine operators typically collect in smaller volumes at a forecourt, green diesel is often purchased in bulk and stored on-site in licensed above-ground tanks. Large farms and fishing fleets may keep a tank of several thousand litres and fill it periodically from a specialist depot. The price per litre generally improves with larger order volumes, similar to the pricing structure for home heating oil.
If your farm or operation runs its own bulk tank, compare at least two or three depots before each fill. Green diesel depots are less common than petrol forecourts and geographic variation in price can be more pronounced. FuelWatch's Green Diesel layer shows depot locations with community-reported prices.
The FuelWatch Green Diesel Layer
FuelWatch includes a dedicated Green Diesel map layer alongside Car Fuel and Home Oil. To use it, open the FuelWatch app or web app at app.fuelwatch.ie and tap the Green Diesel pill at the top of the map screen.
The layer switches the map to show agricultural and marine fuel depot locations across the Republic of Ireland and Northern Ireland. Pin taps reveal the most recently community-reported price for marked gas oil at that depot.
How prices are reported
Prices on the Green Diesel layer are crowd-sourced from FuelWatch users. Farmers, contractors, and marine operators who have just received a delivery can open the app, find the depot, and report the price they paid. The FuelWatch integrity system checks the report against the current median for nearby depots and, if it is plausible, updates the displayed price.
The agricultural and marine community tends to be spread across rural areas where comparison information is harder to come by. Every depot price you contribute helps other operators in your area make better-informed buying decisions.
Green Diesel Versus Other Fuels
Several fuels are used across Irish agriculture and marine operations. Here is how green diesel relates to the others commonly found on the FuelWatch platform:
- Green diesel vs. road diesel: The same base product, but road diesel is fully taxed and green diesel is not. Road diesel can legally be used in any application; green diesel can only be used in the permitted off-road categories.
- Green diesel vs. kerosene (home heating oil): Kerosene is lighter and designed for domestic oil boilers and range cookers. Kerosene is not suitable for diesel engines. Green diesel is not suitable for domestic heating appliances. See our Home Heating Oil page for kerosene pricing.
- Green diesel vs. AdBlue: AdBlue is a diesel exhaust fluid added to the separate AdBlue tank on modern diesel vehicles with SCR emissions systems. It is not a fuel. Many modern tractors and agricultural machines require both green diesel and AdBlue.
- Green diesel vs. biofuels: Some fuel merchants offer a proportion of hydrotreated vegetable oil (HVO) blended into marked gas oil. If you are considering a high-blend biofuel, confirm your machinery is rated for it before filling.
Compliance and Record-Keeping
If your business purchases green diesel in bulk, maintaining accurate records of purchases and consumption is important for Revenue compliance. Licences for on-farm storage tanks may also be required depending on tank capacity. Consult the Revenue Commissioners website or your fuel merchant for guidance on the licensing and record-keeping obligations specific to your situation.
Frequently Asked Questions
What is green diesel in Ireland?
Green diesel in Ireland is marked gas oil (MGO), also called agricultural diesel or agri diesel. It is chemically very similar to road diesel but is dyed green and carries a lower excise duty because it is intended for off-road use: farming, marine, and certain industrial applications. It is illegal to use in a road vehicle.
Who is legally permitted to use green diesel in Ireland?
In the Republic of Ireland, permitted uses include agricultural tractors and machinery, fishing vessels, inland navigation, and certain industrial plant and heating applications. In Northern Ireland, rules are set by HMRC and broadly cover the same categories. Always check the Revenue Commissioners (ROI) or HMRC (NI) guidance for your specific use case.
Why is green diesel cheaper than road diesel?
Green diesel attracts a significantly lower rate of mineral oil tax than road diesel because it is designated for off-road use. The fuel itself is chemically similar to road diesel, but the tax differential means it can be substantially cheaper per litre at the point of sale.
How does FuelWatch show green diesel prices?
FuelWatch has a dedicated Green Diesel map layer. Open the app or web app and tap the Green Diesel pill to switch the map to agricultural and marine fuel depot locations across Ireland. Each depot pin shows community-reported prices for marked gas oil.
Can I use green diesel in a domestic oil boiler?
No. Domestic boilers and ranges are designed for kerosene (28-second oil), not marked gas oil. Green diesel has a heavier viscosity and burns differently. Using it in a domestic boiler can cause damage, produce excessive soot, and may void the appliance warranty. Use kerosene for home heating.
Check green diesel depot prices on the FuelWatch map