Didcot Biomethane to Grid project Learning Points SGN and CNG Services Ltd (CSL)

BtG Plant Didcot designed as a pilot with IFI funding Important objective set by SGN to share learning SGN and CSL implemented a learning tracker reviewed monthly by Project Steering Group Allows future projects to benefit in all areas: Clean-up and upgrading plant specification and link to the injection plant Safety systems NEA specification Oxygen Siloxanes CV enrichment to FWACV Regulatory compliances Ofgem, HSE, EA System control and information flows RHI mechanism, metering

Principal Learning Points (1) Regulatory –Thermal Energy Regs, Direction and ‘normal’ monitoring lead to very high costs but have identified areas to reduce costs significantly –Direction of sites only allows one CV measurement device manufacturer and one company to package this device –End of Waste definition and resolution with EA Biomethane composition –Critical values only required - full Chromatography seeks components that are not present –O2 level is barrier for Biomethane, needs review in context of modern network conditions. Site specific dispensation time consuming and expensive –Measurement using “standard” instrument specification creates high costs Identified that there are cost reductions available with no adverse effects on Consumers or network integrity

Principal Learning Points (2) Oxygen Specification –GS(M)R O2 spec is 0.2% –Didcot biogas around % –So Didcot biomethane around 0.5 – 1% –At Didcot, no blending possible SGN commissioned report from GL which reviewed Oxygen –Identified no safety issues –Key issues possible higher rate of corrosion in wet gas areas –SGN surveyed grid and HSE agreed to give exemption to 2% –On going monitoring, feeds into wider review Oxygen specification an important hurdle to overcome

Principal Learning Points (3) Propane Enrichment to FWACV –At Didcot, no blending possible –Customers would be disadvantaged if propane was not added –Wobbe compliant gas at Didcot would have CV of around 37 MJ/M3 –Didcot area has FWACV of around 39.5 MJ/M3 (Milford Haven LNG) –Without enrichment local customers would be disadvantaged / FWACV Cap of 1 MJ/M3 exceeded System design –Each day a target CV to the site –The site computer then adds propane to met FWACV target –Propane energy has to be netted off the total energy for RHI Purposes In most cases, no alternative to addition of propane

Principal Learning Points (4) Safety and GS(M)R issues –Consideration of “whole” site plant to ensure correct operability, co-operation amongst various plant suppliers –Competency of host personnel before, during, after go-live –Engineering standards and procedures, interpretation for very low flows –On line vs Spot sampling for important gas constituents Network Capacity Modelling –Needs technique/design principles to model low flows, confirm firm capacity exists (or to quantify if not) NEA and Grid Entry contract –Needs version proportionate to flows and feasibility of Local Operating Procedures from unmanned sites –Reflect difference between bulk and small flow gas flows –Didcot was not a fully ‘commercial ‘ NEA’ – issues remain (capacity, liabilities etc) Quality and project management to address specifics

Conclusions Need a design for grid injection plant that is proportionate and affordable for Biomethane to Grid projects. –Need to avoid the snowball effect on costs and lower availability Significant cost savings available with –No reduction in safety management –No loss of protection to consumers or the existing gas network –No reduction in engineering standards –Continued regulatory compliances. Plant simplification would support many BtG projects where grid injection is the best option but economics are tight –Also higher avalability