Abstract
On behalf of the Department for Business, Energy, and Industrial Strategy (BEIS) Offshore Energy's Strategic Environmental Assessment (OESEA) programme, Cefas have been commissioned to provide information on the use of chemicals in the construction, operation, and decommissioning of Offshore Wind Farms (OWFs). Development Consent Orders (DCO) for OWFs and other Marine Renewable Energy (MRE) developments all make provision for consideration of chemicals in some form. Whilst the Offshore Chemical Regulations (as amended) (OCR 2002) do not apply to OWF, marine licence conditions predominantly prescribe that all chemicals used for the construction, operation, and maintenance of MRE are notified to the national regulator.
The aim of the project is to provide information as part of an evidence base regarding chemical use in existing OWFs, and the likely future usage based on the projected scale of OWF developments around the UK.
This report is provided as a review of the consistency within marine licence conditions pertaining to chemical use in MRE and to what extent they have been applied. Development consent orders for all OWFs in England, Scotland and Wales were collated and the licence conditions pertaining to chemicals were extracted and categorised using expert judgment. Relevant documentation regarding the chemicals including developers reports and Cefas advice were interrogated using systematic search terms to generate a list of chemicals notified to the national regulator that are used within OWF construction, operation, and maintenance. This was done for both the generating (components of an energy development which generate the energy, e.g., wind turbine generators) and export (the components that export energy from the wind farm to the national grid e.g., cables) assets.
A list of the chemicals including their type of use, frequency, and quantity, where known were collated together with any risk assessments to determine their use in the marine environment for OWFs. These data were then compared to the types of chemicals used in the construction, operation, maintenance, and decommissioning of oil and gas platforms. The usage of chemicals, informed through available published data, was used to calculate potential quantities used for a generic OWF, with an average number of 50 monopiles. The usage was then compared to the quantities of chemicals used for an oil or gas platform using data from the annual status report (published from operator reports selected randomly in 2019).
A total of 316 Licence conditions were extracted from 49 DCOs and deemed to be relevant to the use of chemicals in OWFs. The most common licence condition (56 out of 316) stipulated that the chemicals used must be on the Offshore Chemical Notification Scheme (OCNS) Definitive Ranked list of registered chemicals (products), or that approval would be needed from the regulator prior to use. The second most common licence condition (33 out of 316) stipulated regulatory approval for use of non-water-based drilling muds. Whilst many licence conditions extracted perform similar functions, differences in wording have led to there being some variation in requirements for the use of chemicals in OWF construction and operation, and the reporting of their use.
From the anonymised chemical risk assessment (CRA), over 300 different chemicals were declared for use in the construction, operation, and maintenance of an OWF. The most used chemicals were grout and cementing chemicals, which aligned with the authors’ expectations before starting the project. For these types of chemicals, up to 70 tonnes of each per turbine were used to connect the base of the turbine to the transition piece that connects to the tower.
Chemicals were found to be used that were common to both the oil and gas sector and OWF sector, namely lubricant oil (needed to maintain low friction, efficient heat transfer and maintenance of hydraulics or moving mechanical parts), greasers (to prevent wear and tear used for bearings and gears), cement and grout, corrosion inhibitors, biocides, rigwash and dye.
Predominantly chemicals found to be used in very large quantities were found to be within ‘closed systems’, with no intentional discharge into the marine environment (e.g., transformer oil). However, for one installation, discharge of a chemical specified for use only in a closed system was seen to be captured routinely in a rainwater reservoir and discharged with the rainwater. Without description of the mechanism for use and top up requirements this was unlikely to have been captured, as for OCR any chemical described for use within closed systems are not assessed.
Although there is an identified difference between regulations/requirements for chemicals for use in OWFs, paints and coatings are exempt for notification to regulators for the oil and gas industry, whereas the OSPAR guidance (2008-3) states that for OWFs they are reported and their ecotoxicological properties are known. As there has been little research to date on chemicals that are routinely topped up and where they go (i.e., are they discharged?) for OWF, this could lead to inadvertent discharge of chemicals into the marine environment without adequate assessment of their impacts.
The usage data from the CRA for the generic OWF were scaled with both the type of foundation and likely number of turbines to provide an estimated annual tonnage, using an anonymised OWF as a basis. The use and discharge data from the annual returns statement from a random oil and gas operator was used as a comparison to those used for the generic OWF. The oil and gas operator declared 1834.15 tonnes of chemicals used in 2019 of which 165 tonnes were discharged by 12 assets. This equates to approximately 153 tonnes of chemicals used per asset and 14 tonnes discharged. By comparison, the generic 50 monopile foundation offshore wind farm was observed to use 709 tonnes of chemicals for construction and likely far less during operation and maintenance.
Gaps were identified in the supporting information and site-specific risk assessment of chemicals for environmental consideration supplied to regulators for the construction, operation and maintenance of OWFs.