GHG emission reduction under RED II: thresholds, default values and calculations for biogas

Under the RED II directive, biogas and biomethane are recognised as a renewable fuel only if the greenhouse gas emission reduction over the whole life cycle is large enough compared with the fossil fuel. The threshold depends on the application and on the date the installation was commissioned: for biogas consumed in transport from installations commissioned from 1 January 2021 it is 65%, and for electricity and heat from biogas in new installations 70%, and 80% from 2026.

Who the thresholds apply to (status as of November 2020)

Directive 2018/2001 entered into force at the end of 2018, and Member States must implement it by 30 June 2021. The sustainability and emission-reduction criteria (Article 29) cover biofuels, biogas in transport, bioliquids and biomass fuels. In electricity and heat they do not apply to every installation: for gaseous biomass fuels, what counts is a total thermal capacity of the installation equal to or greater than 2 MW (for solid fuels – 20 MW). Member States may extend the criteria to smaller facilities. In transport the capacity threshold does not apply.

The date of commissioning is taken to be the start of physical production. In transport the reference is a fossil fuel emitting 94 g CO₂eq per MJ, so the 65% threshold means that the biogas emissions must not exceed about 32.9 g CO₂eq/MJ.

How the reduction is calculated

Article 31 allows four routes, and each is based on Annex V (biofuels, biogas in transport) or VI (biomass fuels in energy and heat):

1. Default value for the production pathway – permitted where one is given for the pathway concerned and the calculated emission from land-use change (e_l) is not positive.
2. Actual value – a full calculation according to the methodology in the annex.
3. Mixed – a sum of components, in which some components are taken from the tables of default values broken down by stage, and the rest are calculated on actual data.
4. Regional reports on emissions from cultivation, if the Member State adopts them.

The basic formula sums the emissions: cultivation (e_ec), land-use change (e_l), processing (e_p), transport and distribution (e_td) and fuel use (e_u), and subtracts the bonuses: soil carbon accumulation (e_sca), CO₂ capture and storage (e_ccs) and CO₂ replacement (e_ccr). The reduction is the difference between the emission of the fossil fuel and the emission of the biogas, divided by the emission of the fossil fuel.

Default values or your own calculation

The default values from the annexes are conservative by design – they are meant to be less favourable than a typical production run. For biogas from slurry or waste, with a closed digestate store and small methane leakage, your own calculation usually gives a clearly better result. For an installation with a large share of dedicated crops and an open digestate store the difference can be the opposite, and the margin to the threshold – small.

Waste and residues other than agricultural and forestry ones (for example post-production waste from the food industry) are subject only to the GHG reduction criterion. Animal excreta are an agricultural residue, so they additionally require soil quality and soil carbon plans. A broader discussion of the land criteria can be found in a separate entry on Article 29 of RED II.

What most often spoils the result

• An open digestate store – methane from it enters e_p; covering the tank and recovering the gas often decides whether the threshold is met.
• Methane leakage during upgrading and in the engine – the more modern the installation and the better the oxidation of the waste gas, the better.
• A high share of maize silage – raises the cultivation component; some of the emissions can be reduced by fertilisation and by deliveries from nearby.
• Lack of input data – an auditor will not accept estimates without documents: invoices, weighing records, delivery records, energy consumption.

What to do first

1. Determine whether the product will go to transport or to energy and heat – the threshold depends on this.
2. Check the date of commissioning of the installation and record it in the documents.
3. Choose the pathway from Annex V or VI that matches the technology (type of substrate, digestate store, upgrading).
4. Collect data from 12 months of operation: masses and origin of substrates, gas production, energy consumption, transport distances.
5. Calculate the result in both variants (default and actual) and compare with the threshold with a margin for variability.
6. Determine the certification scheme and the body that will verify the calculations within the mass balance.

An example of the reasoning (without numbers, which depend on the installation)

Imagine two installations of similar capacity. The first processes mainly slurry and post-production waste, has a closed digestate store and recovers gas from its cover. Its largest emission component will be the electricity consumed in the process and any methane leakage during upgrading; there is practically no cultivation, and the credit for slurry improves the result. The second is based on maize silage, has an open digestate tank and brings in substrate from a long distance. Here the result will be dominated by cultivation and methane from the store. The same threshold of 65% or 80% is achievable with a margin for the first installation, and for the second it is sometimes a target that requires technical changes. That is why a GHG analysis is worth doing at the concept stage, and not only before the audit.

The second pitfall is variability over time: calculations are based on actual operating data, so changes of recipe during the year (for example poorer availability of waste and more maize) can worsen the result below the threshold and require the documentation to be updated.

This text is for information only and does not constitute legal advice; before an investment or formal decision, check the current wording of the legislation and consult a lawyer or the relevant authority.