CABLE INSTALLATION FEATURE JOINING UP
BACKGROUND HISTORY High voltage submarine cable interconnectors between adjacent countries have been around for over 50years. Traditionally, they have been relatively short and HVAC (HighVoltage Alternating Current) cables.
Due to high heat losses, they have been limited to cable lengths of typically 70km- 100km - depending on the amount of energy being carried. But in recent years, with improving technologies, there has been a shift to HVDC (High Voltage Direct Current) systems.
These transmit energy for far greater distances. For example, the BritNed interconnector recently commissioned between the UK and the Netherlands – is over 240km. Many more are underway.
GROWTH MARKET This growth in the interconnector market has many drivers...
• Achieving security of supply • Overcoming onerous onshore environmental constraints
• Advances in DC converter technology • EU directives
The latter requires 15 percent of energy to be from renewable sources by 2020. This means 30-35% of all electricity generated will be from renewable energy.
One consequence is that the countries of Western Europe will need to share renewable energy much more effectively through marine interconnectors; a major challenge given the timescales.
THE DOTS THE FUTURE OF THE GRID
A GREATER CHALLENGE However, a second consequence is even more challenging: how do we integrate the many offshore windfarms being built into a pan-European system?
THE ‘SUPERGRID’ An offshore grid, as envisioned by Eddie O’Connor of Mainstream, which would link farms and interconnectors, could be the answer.
HVDC technology accepts multiple connection nodes and could form the platform on which this Supergrid could be built. However, let’s not think that the infrastructure companies and investors have fully grasped this vision and will look to the construction of an offshore grid from the beginning.
This is not going to be the case. None of the projects mentioned here currently have ‘nodes’ planned to create an offshore network; they are point-to-point. But this is not surprising, as the investment needed and the commercial and supply chain challenges (restricted availability of materials and components, vessels and skilled staff are common to all offshore infrastructure projects) on such a large scale from the outset are prohibitive.
FUTURE SCENARIO – NODAL GRID? So what will happen in the future? Clearly, there is a firm commitment to interconnector development, and, interestingly, toes are being dipped into the water with respect to a nodal grid.
For example, the Dutch company, Tennet, is providing export cables for the German offshore wind market, which include the connection of projects under different ownership to a single export cable system.
Also, recent research, commissioned by the EU, suggests that a nodal, or hub, approach to interconnector and windfarm development may result in savings in the order of €20billion. Therefore, it is probably only a matter of time (if not already) before offshore generation and transmission developers in Western Europe engage in substantive discussions to develop the first node connections to interconnectors.
In the end, joining up the dots will give us the bigger picture.
James Hunt Intertek METOC
www.metoc.co.uk
74
www.windenergynetwork.co.uk
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