EN2.2
Anaerobic Digestion
Environment
- Waste Management
Anaerobic Digestion
Anaerobic digestion is a biological process in which microorganisms break down organic material (like food waste, animal manure, and sewage sludge) in the absence of oxygen. This process produces:
- Biogas (mainly methane and carbon dioxide), which can be used for electricity, heat, or as a vehicle fuel, and
- Digestate, a nutrient-rich residue that can be used as a fertiliser.
If users want to assess the emissions impact of their waste management practices, they can consult WRAP’s Carbon Waste and Resources Metric. However, it’s important to note that this metric is not designed for reporting Scope 3 emissions. For more information about principles for GHG accounting and reporting and three “scopes” of emissions, please visit EN1 Measuring Greenhouse Gas (GHG) Emissions.
Key Value
£16
The monetised environmental value of carbon savings per tonne of waste diverted by anaerobic digestion.
PLEASE NOTE: This value is not a “footprint” (i.e. carbon emissions) but a relative measure that can be used to quantify the carbon saving relative to any given treatment option for a given material / treatment combination.
The values are based on CarbonWARM2 which is the latest version of the Carbon Waste and Resources Metric developed by WRAP on behalf of Defra. This updated version provides conversion factors that enable organisations to assess the greenhouse gas (GHG) emissions associated with waste management practices, expressed in carbon dioxide equivalent (CO2e). It serves as an essential tool for evaluating and improving waste management strategies.
The metric values are shown below. The value represents a carbon emission, while negative values represent a carbon saving.
Table 1 Carbon WARM, unnormalised values (tonnes.CO2e/tonne)
| Material | tonnes.CO2e/tonne |
| Kitchen waste | -0.062 |
| Garden waste | -0.063 |
| Mixed organics | -0.063 |
| Average | -0.063 |
These numbers represent the amount of carbon dioxide equivalent (CO2e) emissions or savings associated with each material. The higher the value, the greater the environmental impact. The average carbon saving for anaerobic digestion is 63 kg.CO2e per tonne.
According to the 2021 carbon values from DESNZ/BEIS, Carbon values in 2020 prices per tonne of CO2: central series for 2023 is £252 or 25.2p per kgCO2e. For more information, please visit MeasureUp EN1 Measuring Greenhouse Gas (GHG) Emissions.
Average carbon emission per tonne of waste for anaerobic digestion is 63 kg.CO2e and Carbon values in £2020 prices per kg of CO2 is £0.252. Thus, the headline value is 63kg.CO2e*£0.252= £16 per tonne of waste for anaerobic digestion relative to landfill.
This value represents carbon savings for anaerobic digestion.
Local Needs Analysis Data Source
Before using this MeasureUp value, we encourage you to assess the local need in relation to the activity or outcome.
Here is the most useful initial data source for assessing local need in relation to this value.
To assess local needs related to the value EN2.2 ‘Anaerobic Digestion’, use the Household Recycling Rate from the Department for Environment, Food & Rural Affairs (DEFRA). This indicator reflects the percentage of household waste that is recycled instead of sent to landfill. It is updated annually and available at local authority and regional levels, helping to evaluate the effectiveness of local waste management and sustainability efforts.
Bronze
Effort
Accuracy
Monetised value:
The monetised environmental value of carbon savings per tonne of waste diverted by anaerobic digestion.
At the Bronze level, you should measure the amount of waste used in anaerobic digestion and use this to calculate the approximate carbon savings of your diverted waste.
Here’s an example
Assume as an organisation you use 100 tonne of waste for anaerobic digestion. If you don’t know the exact waste material , you can approximately calculate the monetised value of anaerobic digestion as (100tonne* 63 kg.CO2e) *£0.252= £1,600
This value represents carbon savings for anaerobic digestion.
Silver
Effort
Accuracy
Monetised value:
At the Silver level, you should measure the amount of waste used in anaerobic digestion by each type of material and use this to calculate the approximate carbon footprint of your diverted waste.
Table 1 Carbon WARM, unnormalised values (tonnes.CO2e/tonne)
| Material | tonnes.CO2e/tonne |
| Kitchen waste | -0.062 |
| Garden waste | -0.063 |
| Mixed organics | -0.063 |
| Average | -0.063 |
At Silver level you should calculate your approximate carbon footprint, by waste material type, as each material produces different levels of carbon emissions.
Here’s an example
Assume as an organisation you have 100 tonne of kitchen waste and 100 tonne of garden waste for anaerobic digestion. Thus, you can approximately calculate the monetised value of the anaerobic digestion as ((100tonne* 62kg.CO2e) +(100tonne* 63g.CO2e)) *£0.252=£3,150
This value represents carbon savings for anaerobic digestion.
Gold
Effort
Accuracy
At the Gold level, you would be expected to
- Measure more accurately using more specific data for you in-scope activities.
- Track the emissions or savings over time.
This will allow you to show your actual results over time against your estimates as outlined in Bronze and Silver. Think of this as assessing your forecast or budget against your actuals.
Here’s an example
A company is assessing the environmental impact of its annual carbon savings from anaerobic digestion different materials relative to landfill.
| Material | Tonnes2023 | Tonnes2024 | Monetised Value in 2023 | Monetised Value in 2024 |
| Kitchen waste | 50 | 75 | (50 × 62) × £0.252 = £781.20 | (75 × 62) × £0.252 = £1,171.80 |
| Garden waste | 100 | 120 | (100 × 63) × £0.252 = £1,587.60 | (120 × 63) × £0.252 = £1,905.12 |
| Mixed organics | 100 | 80 | (100 × 63) × £0.252 = £1,587.60 | (80 × 63) × £0.252 = £1,270.08 |
| Total | 250 | 275 | £3,956.40 | £4,347.00 |
The monetised value of avoided greenhouse gas emissions increased by £390.60 from 2023 to 2024, indicating improved environmental benefit due to higher levels of organic waste processed (especially kitchen and garden waste).
This value represents carbon savings for anaerobic digestion.
| Value Type: | Activity |
What's this?
This is the type of value. Some values are outcomes, which means many different interventions might lead to them, others are specific interventions that have a set value. |
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| UN SDG Categories: |
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What's this?
The UN Sustainable Development Goals are global goals adopted in 2015 for all signed up nations to achieve for us to have a sustainable global future by 2030. There are 17 Goals that address the global challenges we face, including those related to poverty, inequality, climate change, environmental degradation, peace and justice. The Goals are all interconnected, and in order to leave no one behind, it is important that we achieve them all by 2030. |
| 2020 Social Value Models: |
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What's this?
PPN 06/20 Taking account of social value in the award of central government contracts introduced the Central Government Social Value Model in 2020 which all Central Government contracting authorities must use in their in scope procurements. It consists of 5 themes, 8 policy outcomes, and 24 Model Award Criteria which outline key priority areas to achieve more social value. |
| 2025 Social Value Models: |
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What's this?
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Evidence
Measure Up focuses on empowering you to numerically measure the impact you’re having. We recommend that numeric reports are backed up with stories and other types of evidence to help illustrate, in human terms, the impact that’s being made on individuals.
We recommend seeking consent from participants in your intervention to collect and tell their story. This should include a little background on the participant, a summing up of life before the intervention, the human impact of the intervention, and the longer term (if known) impact on the person’s life outside of, and after, the intervention.
Providing photographs, audio recordings, video interviews or even artefacts from the intervention (for example, writing, paintings, music from creative interventions) can add more to the story, and convey the emotional impact of interventions more directly.
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