A cost comparison of metallic and earth return path for HVDC transmission System case study: connection Algeria-Europe

•In HVDC transmission field, the choice between metallic and earth return path is significant from economic points of view. However, the information about this choice is limited in literature.•The proposed method is generalised and allows making the choice for any case. Moreover, to have a general vision around the world, it gives the Break-Even Distance to pass from metallic to earth return according to metallic return, earth return and energy costs.•Regarding the calculation of energy losses in earth return paths, the contribution of the linear part of resistance, at the inter-electrode distance, on the total earth resistance present no more than 0.2% per 1000 km, so it is considered negligible.•For a given case, the choice depends on the energy source (Conventional or Photovoltaic) and on the mono-polar operation duration. The profitability of earth return is proportional to the energy cost and the mono-polar operation duration.•From the case study, the obtained curves of Break-Even Distances can be considered as an order of magnitude for general use.