The completion of a project to overhaul the power supply for a remote island in the South Atlantic Ocean will meet the needs of the community for years to come.

Before work began to improve the service which provided the 4,000 inhabitants of St Helena with an average hourly demand of 1MW, they were reliant on six aging diesel generators, supported by six wind turbines.

Unusually for a diesel-based power system, St Helena obtains a healthy proportion of its energy requirements from wind power and more recently has installed some small scale solar schemes. Energy is distributed to the island’s consumers via an 11kV distribution network over what can be steep and challenging terrain due to its volcanic origins.

Having been involved in developing the strategy, Senergy Econnect, which is part of global energy services group Senergy, was subcontracted by IMC Worldwide who are acting as Project Managers on behalf of the Government of St Helena, to produce tender specifications, issue, manage and evaluate the tender; and assist with contract negotiations.

Its team of engineers has previous experience of island power system design and operation and were able to specify a system suitable to meet the needs and challenges of the sovereign British territory.

The blueprint for the first major stage of the 20-year energy supply strategy for St Helena involved replacing four of the existing generators with larger and more modern units and an extensive control system upgrade.

The project also provided for replacement of the 11kV switchgear, installation of new fuel oil and lubrication oil tanks to improve oil storage and handling, and upgrading of the power station lighting, earthing and oily waste water disposal. The system improvements were also designed to harness a future expansion in the number of turbines at the existing wind farm on Deadwood Plain.  The power station lighting is fully dark skies compliant which is an important consideration as St Helena has some of the darkest skies in the world and offers a niche stargazing destination.

There was no possibility of travelling by air at the time (work began on an airport during 2012) and the island was only accessible by a two-day boat ride from Ascension Island or over five days from Cape Town, South Africa.

A team from the company, which is part of global energy services group Senergy, visited the island in 2010 to collect site data and carry out project planning. Transportation for the Newcastle-based team during this time was hampered however by the ash cloud caused following an eruption from an Icelandic volcano – the delay meant they missed the once-in-three weeks Cape Town sailing.

The project manager returned to the island in 2011 with the preferred tenderers, again in 2012 to supervise the installation and commissioning of the main plant by the main contractor, Barloworld Power, and finally during 2013 to supervise completion of the control system.

Project manager Ruth Kemsley said: “The remoteness of St Helena and the fact that we had to maintain the power supply during the installation meant we had to plan everything in detail and tried to make allowances for any possible contingencies. The limitations on the ship and the transport capacity of the island meant we couldn’t go for any plant equipment that would be too big.”

Source: Senergy