Powering trains with renewable energy

Sector convergence between transport providers and decentralised and decarbonised electricity suppliers at the grid edge is often assumed to involve big data, digital platforms and app-facilitated user-centricity. Such innovations, however, appear to be less significant for the electrification of railways. Despite over 100 years of experience, railway electrification remains difficult and costly, with few countries fully electrified and none fully decarbonised. Railway traction power currently relies on dispatchable (synchronous) energy resources. As these are mostly supplied by fossil fuels, such as gas and coal (but also biomass) or nuclear power, such electrification does not necessarily contribute to decarbonisation targets. This reflects the co-evolution of fossil energy systems and railways systems: Both national electricity grids and the railway shadow electricity grids tend to be dominated by AC (Alternating Current) and 25kV lines to maintain the same frequency. Both infrastructure systems support self-reinforcing carbon intensive practices which blind actors to innovations outside their siloes (Kuzemko et al. 2016). Breaking this path-dependency requires radical innovation. Digital connectivity, however, which is driving electrification and sector convergence between decentralised and decarbonised electricity supply and individual mobility demand, plays only a minor role in this process. Converging this supply with centralised mobility demand requires more conventional technological demonstration, regulatory compliance and de-risking procurement. Riding Sunbeams has technically proven that it is possible to match intermittent direct-wire solar energy (asynchronous) supply with the regular (synchronous) demand required for the reliable operation of railways (Nolden et al. 2020). Using the case study of Riding Sunbeams, this paper explores the changes to policy and regulation required to procure and value the multiple benefits of converging decentralised and decarbonised renewable energy supply with railway traction demand.