The relatively recent introduction of battery electric vehicles (BEV) to the tunnelling and mining industries have shown there to be positive benefits in reducing embodied carbon through reduction of fossil fuel use, but also significant operational benefits of enhanced safety in operation, reduced whole life equipment cost of ownership, but also project costs. 
DC grid denotes DC transmission system of more than two terminals with at least one meshed DC line.  A DC microgrid is a localized power system that can run independent of the main power grid (AC) by generating and utilizing its own DC power. The most common ways of generating power for DC microgrids are with solar panels, fuel cells and wind turbines with any excess energy stored in battery solutions. 
One of the factors causing poor air quality and increased emissions is the higher number of heavy-duty construction vehicles caused by development of urban centres. One way to mitigate the air pollution and emissions is considered to be the electrification of construction vehicles
Transforming VSH to CO2 neutral infrastructure, means also integrating and showcasing novel, fossil free energy sources in the overall concept, e.g. by making use and showcasing the combination of viable technologies like using Solar power for Electricity, Heat and H2 Production or prototyping geothermal and wind energy options to ultimately produce more than needed energy to run the infrastructure and support the municipality.
Hydrogen storage is one of our main focuses at SubSpace Energy Hub, for which we are in the development phase with our partners. Currently, we are testing hydrogen storage in hard rock tunnels, as underground hydrogen storage is considered better in terms of safety, better land use, and less costly.
The development towards low carbon underground structures, particularly using sprayed concrete, is to address the design and construction in a holistic way, and not purely focused on cement reduction of the sprayed concrete itself. The SubSpace Energy Hub approach will drive the following approaches to each stage of a project to reduce carbon