Transporting electricity over long distances is an essential part of powering our modern world. In the Channel Islands we rely on three undersea cables between France and Jersey to bring the electricity we need. In other parts of the world, electricity is transported far greater distances to get from the place it is generated to the people who use it. Worldwide, most of us take it for granted that the electricity we use reliably and efficiently arrives in our homes and businesses.
But transporting electricity is a complicated process - and ever more so as power generation across the world becomes increasingly diverse, shifting from large power plants to more renewal energy as countries seek to reduce their carbon emissions. From offshore wind farms to desert solar farms, the electricity consumed across the world needs to travel greater distances than ever before. And there's a problem: some of it is getting lost.
In a country 2,680 miles wide by 1,582 miles high, transferring electricity has inherently been a challenge for US utility companies. Although the country's power network has been periodically upgraded, there are still issues with managing existing and new energy resources within the ageing infrastructure.
The move to increasingly diverse power generation has further increased stress to a system already experiencing blackouts more frequently than most developed countries. Quite simply, energy is getting lost from networks as it is transported over long distances.
Fortunately help is at hand, via a solution known as 'power superhighways'. For long-distance transmission, power superhighways may be less expensive and suffer lower electrical losses than traditional networks. So how do they work, and how can they help to improve a move towards more renewable energy by increasing efficiency and easing strain on current energy networks?
Wind farm in the midwestern state of Oklahoma, USA
AC / DC Highways
A Texas based company, Clean Line Energy Partners, working alongside General Electric (GE) have started work on new 'power superhighway' transmission lines, which convert the traditional alternating current (AC) into a form of direct-current called Highest-Voltage Direct-Current (HVDC).
Converting to DC conserves more energy across longer distance, making it more economical than AC. Using HVDC also provides greater control and coordination within the power flow, adjusting better to variations which are often seen in energy generated by wind and solar.
Clean Line Energy and GE's first collaborative project is expected to be completed by 2020, and will take electricity generated in the windy state of Oklahoma to the south-eastern states of Louisiana, Mississippi and Alabama - traveling over 720 miles.
Around 4,000 megawatts generated by wind farms will be sent to conversion stations where the AC to DC transfer takes place, before heading down HVDC superhighways to the south. At the other end, the DC is converted back to AC, preparing the energy to be transmitted on to homes and businesses.
The distance we transfer power from France to here in Jersey is so small and the quantities (up to 190MW) are such that our three undersea supply cables are AC lines.
Moving Energy Across Nations
Worldwide, HDVC projects are beginning to link large regions, counties and continents together to improve how power is manage globally.
In India, the world's second-fastest-growing economy, the need for supplying reliable electricity is fundamental to sustaining economic momentum. To help meet the country's ambition to deliver electricity to the 240 million Indians without power, GE have again embarked on helping build a 850 mile energy superhighway, carrying power from Chhattisgarh in east India to communities in the northern regions where it is needed.
China’s move towards constructing HVDC lines happened a few years before the US and India, with the need to transfer energy from the hydro, coal and wind-rich regions in the west to the industrial and large urban populations in the east. The latest HVDC line under construction is the Changji-Guquan link which will carry 12,000 megawatts (equivalent to around half the average power use of Spain) over 3,400km from Xinjiang to Anhui.
Europe has a series of HVDC lines which, although shorter than those being built in US and China, play a key role in managing power reliability and transferring electricity across energy markets. The UK already has fours lines, all of which are submerged - two to continental Europe and two to Ireland. Proposed lines to Norway and Iceland will further increase the High Voltage network across European nations.
Supporting The Move Low Carbon Energy
This requirement to connect markets is set to continue, as more countries and regions increase their low carbon energy quotas and need to address peaks and troughs within production from renewable sources. Through increasing the amount of HDVC power lines, maintaining energy across multiple sources such as wind, solar and hydro will become more efficient, helping the move towards low carbon energy with the ability to move surplus electricity between regions to balance supply and demand.