You and your colleagues recently updated the common methodology for calculating the carbon footprint of offshore wind farms through the Sustainability Joint Industry Program (SUSJIP). How was it calculated before that?
Before the SUSJIP methodology was developed, there was no sector specific guidance for calculating the carbon footprint of offshore wind farms. This is not to say there was not a lot of good work being done. There absolutely was. A lot of practitioners, from developers, academics, and consultants, were calculating carbon footprints of offshore wind farms. The problem was that there was no consistency in the methodology they used. This is because they were left to interpret cross-sector standards – standards that were not specifically written for renewable energy, let alone specifically written for offshore wind. It meant there was room for a lot of different interpretations of these standards. That led different practitioners to make different assumptions and apply different system boundaries, scopes and definitions. As a result, the calculations were inconsistent. It reduced their usefulness for decision-making and benchmarking across the offshore wind industry as a whole when everyone was using slightly different methodologies.
How did you update these calculations?
We published our revised methodology in March 2026, but we had actually published our first version in September 2024. The first phase was getting group consensus among offshore wind developers primarily on how they should perform these calculations – the assumptions, system boundaries, scopes, and definitions they should be using. We were trying to iron out some of those things that could lead to misinterpretation.
When we published the first version of the guidance, we knew it wasn’t perfect, but we also needed to get it out into the industry, and we needed it to be used. In this recent revision, we formed a working group of industry experts outside of the offshore wind developers themselves, which included industry academics and some other research organizations.
The second revision includes an updated reporting framework, updated templates for disclosing carbon footprints, and we’ve improved our guidance on data quality, sensitivity, and uncertainty. We’ve also provided a whole list of use cases demonstrating why you would want to use a carbon footprint calculation and why you would want to perform that assessment in the industry.
What is the ultimate goal of the SUSJIP?
The Sustainability Joint Industry Program (SUSJIP) is actually wider than this methodology document. The ultimate goal of SUSJIP is to accelerate decarbonization across the offshore wind industry. It’s important to remember that offshore wind, once up and running, is a form of clean-electricity generation. We know globally, the pipeline of offshore wind is expected to grow, and there are some emissions associated throughout the lifecycle of the wind farm. That’s mostly in the manufacturing process – everything that goes into all of the components – and through the transport and installation, there are big vessels transporting those components globally. There are several areas where we can look at decarbonizing across the offshore wind industry. However, it’s worth bearing in mind that the carbon emissions associated with offshore wind and renewable energy are much, much lower than traditional forms of electricity generation.
Alongside the harmonized carbon footprint methodology, we also have work streams focusing on data transparency and enabling consistent measurement of lifecycle carbon emissions. We are running a project that’s investigating how to incentivize lower emission steel in the industry, and in another one, we’re looking at improving circular principles through the refurbishment of minor turbine component parts. The SUSJIP consortium is made up of offshore wind developers. The benefit of bringing developers together is that they have a unified voice. Trying to understand their shared challenges and addressing these challenges together is more impactful than one developer alone.
You talked about harmony, in what ways does this update bring that harmony and transparency to carbon emissions measurement for the offshore sector?
We’re trying to establish that single agreed-upon approach for calculating offshore wind carbon footprints. We’re hoping that we’re reducing the variability caused by that different interpretation of standards. We want to ensure the methodologies used for those assessments are comparable across developers, across consultants, really across the industry.
We know the methodology has been adopted more widely than just our core group of developer partners, based on feedback we’ve received. Having one methodology will reduce some of the confusion in the industry. Ultimately, this will strengthen confidence in results and assessments as well through better treatment of data quality and uncertainty.
How can carbon footprint calculations be used across the offshore wind industry to provide insights into baseline data, emission hotspots, and these decarbonization opportunities?
By performing these assessments for offshore wind projects, we start to understand more about the baseline data in the industry.
The uncertainty of that baseline data is highly dependent on the data quality and availability. To reduce the uncertainty, we actually need primary, or supplier-specific, data. Ideally, developers want to understand supplier-specific emission data of all their components to get the most accurate carbon footprint assessments. If that data isn’t available, then the practitioner has to resort to an industry average carbon emission factor from a database. The industry baseline is actually only as good as the input data, and there is still inconsistency in the data availability and quality in the industry. This is a relatively newish practice that’s happening in the offshore wind industry and suppliers, and they don’t all have this data available. Wider adoption of carbon footprint assessments will naturally increase conversations between developers and suppliers, helping to improve the data quality and availability over time.
Once the lifecycle carbon footprint of the development is well understood, it’s possible to identify where the emission hotspots are and ultimately use that to determine key decision points such as design, procurement, or supply chain choices, based on the lifecycle emissions.
We largely know what these hotspots are. The most intensive areas are in manufacturing and the vessel fuels used in installation, operation, and maintenance activities. A lot of steel goes into offshore components, and steel is currently the biggest emission hotspot for offshore wind developments. Addressing challenges within those areas would make a substantial difference to the overall carbon emissions of the industry.
How does the adoption of SUSJIP lead to better carbon reporting, while making it more relevant for developers?
Our methodology takes into account international standards, including the ISO 14067 and the Greenhouse Gas Protocol Product Standard and a range of standards listed in our methodology. The outputs are directly relevant for offshore wind projects and could be used for decision making. We know developers have started to use this to assess their portfolios, which makes it easier to compare projects internally and understand what’s happening across their portfolio level.
Additionally, we know that carbon footprints are being considered in offshore wind auctions and tenders. If and when this is introduced, the important thing is to have harmonization, to reduce the administrative burden. If a lot of different markets use slightly different methodologies, then it becomes very complicated. The SUSJIP methodology provides this harmonized approach, which has already been adopted by our developers and more widely.
What are some real-world examples of how SUSJIP is being applied?
We have eight developer partners in Phase 2 of the program, and we know they are all aligned with the methodology internally. Alongside the mandated reporting requirements for carbon emissions, there are other reasons developers would want to understand their carbon emissions. We’ve published some examples of real-life case studies from three of our partners on our website:
ScottishPower Renewables, which is part of the Iberdrola Group, has produced a case study that highlights how they apply the methodology at their portfolio level. They’re looking at their key emission hotspots across their assets, which has strengthened supplier engagement and supported scenario modelling for lower-carbon design and procurement.
We have another one from RWE, detailing how they’ve used the methodology to calculate the carbon footprint of their Thor offshore wind farm in Denmark, which is one of their big flagship projects, and they have used the SUSJIP framework for that.
Ørsted’s case study shows how they’ve aligned their internal lifecycle assessment model, which includes other metrics outside of greenhouse gas emissions, with the SUSJIP methodology to ensure that consistency and identify emission hot spots.
Is there anything else you’d like to mention that we didn’t talk about?
We have a supplier specific annex for the methodology document that was scheduled to come out at the end of April. The methodology was written primarily for developers, calculating the lifecycle emissions of the offshore wind project from manufacturing all the way through to decommissioning. We know that’s not always tangible for a specific supplier or component, and understanding how you can apply the methodology is a little bit trickier. This supplier-specific annex will give more guidance on how to apply the methodology for a specific area or a specific part of the life cycle.
More info www.carbontrust.com/our-work-and-impact/impact-stories/offshore-wind-sustainability-jip-susjip
