Energy Bill 2015 Clean Growth Strategy CCUS Cost Challenge Taskforce CCS competition Industrial CCS North Sea infrastructure Cost Reduction energy intensive industries CCSA climate change CCS Costs regional growth UNFCCC SCCS CCUS fifth carbon budget Cost Challenge Taskforce Paris Agreement oil and gas energy demand £85/MWh CCS industrial strategy CO2MultiStore COP21 hydrogen CCS Strategy Oil and Gas Authority Spending Review 2015 CCS Lessons Learned CCS Clusters Delivering CCS CCS Technology CO2-EOR Joint Industry Project carbon cost-competitive CCS low-carbon heat Phase 2