The Dubai Metro has proved its green credentials with its design aspects and use of the latest technology helping cut energy consumption by 25 per cent, which translates into cash savings of Dh20 million per year in electricity costs besides also protecting the environment.

A recent study by the Dubai Roads and Transport Authority (RTA) has revealed the Metro project has successfully contributed to the RTA's energy conservation plans and helped achieve Dubai's strategic vision to "go green".

Dubai Metro's operational results showed that the specifications set by the RTA for the design of the Metro systems contributed to a 25 per cent reduction in power consumption, which is equivalent to Dh20 million per year. Reduced carbon dioxide emissions from power generation plants driving the Metro added more value to the cost savings.

The first is utilisation of the regenerative power released during braking. This power is used by trains during acceleration mode.

Each time the train brakes, power is generated and fed back through an electronic inverter and this regenerated power is utilised by other trains in a state of acceleration. Each train contains two inverters.

The second important factor contributing to energy saving is the use of a power network maintaining a higher voltage of 33 kilovolts (kV) instead of 11kV (locally used by Dubai Electricity and Water Authority). This network is the first to be installed in Dubai and cuts power losses during transmission through the cable by almost 90 per cent compared to normal 11kV networks. Additionally, the use of the 33kV grid helps to supply power over much longer distances. The 33kV grid can supply energy 40 kilometres away contrary to 11kV facilities which can only supply power over a few kilometres. This too results in savings by way of distribution costs.

The provision of air-conditioning at stations and depots using district cooling technology is yet another factor contributing to energy savings and protection of the environment.

Lower consumption

The district cooling systems used by the RTA helped cut power consumption by around 50 per cent.

The integrated energy control system installed in each station has also resulted in reducing power consumption between 10 and 20 per cent compared to conventional systems.

Also, the architectural design of stations has allowed more natural light into the station and as a result reduces the use of electricity.

The use of an Automatic Train Control system is another major element in reducing power consumption. It is estimated the regenerative braking power can save up to 25 to 30 per cent of what the rail system would normally need without this system.