Renewable energy, a more sustainable future

01 Apr 2015

A world-record wave in Scottish waters underlined the importance of the marine environment as a source of energy.

In February 2000, scientists from the National Oceanography Centre (NOC) sailed into the seas around Rockall, 175 miles west of the Scottish mainland, to carry out measurements related to global warming. The bad news is that they hit a storm. The good news is that they had wave-recording equipment on board.

The wind was blowing a severe gale, still some way short of the hurricane conditions associated with exceptionally high waves. Yet their ship, the RSS Discovery, was thrown around for five days by seas averaging over sixty feet in a terrifying ordeal that prevented them from running for cover. And one of the waves was recorded at over 95 feet from crest to trough, the height of a ten-storey building. It's a world record that still stands today.

World Record Wave

Higher waves have subsequently been estimated, during Hurricane Ivan for example, but not scientifically recorded. Where they are thought to have occurred, it has been caused by winds of hurricane force. Dr Naomi Holliday, who was one of the scientists on board the NOC boat, believes the cause of the Rockall waves was resonance, a harmony between wind and wave speed that feeds more and more energy into the waves.

Scotland is a small country with a lot of geography. Highland landscapes and mist-shrouded islands, celebrated in song and story, are part of the Scottish psyche. But there is pragmatism as well as romance there, and for a surprisingly long time the landscape has also been part of the Scottish energy supply. In fact, Scotland was pioneering renewable energy sources long before the current crisis-driven pursuit of green energy arose.

Water Power Pioneers

In 1890, monks at St Benedict's Abbey, Fort Augustus, built an 18kW water turbine to supply electricity to the town and the village. Around fifty years later, guided by the vision of Tom Johnston, ambitious engineering schemes brought hydro-electricity to the north. The world's first high-head reversible pumping station – a giant mechanical rechargeable battery – was built right inside Ben Cruachan, one of Scotland's famous Munros.

As long ago as the 1970s, Professor Stephen Salter of Edinburgh University was carrying out pioneering work on harnessing wave energy with his lines of nodding 'ducks'. And the first commercial wave generator in the world, the 'Limpet', was installed in 2000 off the coast of Islay. Developed and installed by Wavegen of Inverness, it uses oscillating columns of water to drive air through turbines and generate up to 500kW of electricity.

Scotland has a staggering amount of wave power to harness. A record-breaking amount, in fact.

The energy in the seas

The energy in the seas is now a major focus for Scots engineers and scientists researching alternative, sustainable ways of generating power. That research took a significant leap forward with the opening, in August 2004, of the European Marine Energy Centre (EMEC) at Stromness in Orkney.

EMEC harnesses the excellent local conditions around the Orkney Islands to provide unique testbed conditions for evaluating marine energy prototypes. The £5 million set up costs were met by a variety of agencies from the public sector demonstrating the widespread commitment to green energy.

The opportunities provided by EMEC are unique and far-sighted. Four berths for testing wave-power devices are based at Billia Croo on Mainland Orkney, where uninterrupted Atlantic waves of up to 15m in height are a regular feature. Waves here are reckoned to have some of the highest energy potentials in the world. There is a substation nearby, with switchgear to allow the devices under test to be connected to the National Grid (Orkney is the northernmost limit of the Grid network).

The pull of the tides

In August 2006 EMEC opened a second test site devoted to tidal energy. The location, off the south-west tip of the island of Eday between the Firths of Westray and Stronsay, was chosen for its powerful tidal streams – at up to four metres per second (around nine miles per hour) they are some of the fastest in Europe. The site incorporates five berths at depths between 25m and 50m, and again they all have facilities for connection to the National Grid.

Both test sites include sophisticated control and data acquisition systems with real-time technology and CCTV monitoring to the third EMEC site, the data handling and analysis centre and Head Office in Stromness. In parallel with recording the output from the test device, the prevailing weather and marine conditions are recorded so that efficiency and performance can be fully assessed.

Pelamis Wave Power (PWP) of Leith in Edinburgh, used the Billia Croo site to evaluate the . Like an enormous mechanical serpent the size of five train carriages, Pelamis lies along the surface of the water. As it turns to meet waves head-on, the movement of its articulated joints drives oil through a hydraulic generating system. A whole family of Pelamis "serpents", can be continually tuned to the prevailing conditions and send power back to the shore, via a single umbilical cable.

Following successful testing in Orkney, PWP won a major contract to install Pelamis in a commercial wave farm 5 km off the Portuguese coast. Since then they have secured the UK's first commercial supply contract in the marine energy sector with utility company E-on. In 2008 they secured a second with Scottish Power Renewables, for P2 machine which will launch in 2011.

The determination to pursue sustainable energy sources runs throughout the political spectrum with the Executive aiming to generate 40% of energy by 2020 through sustainable means. Ambitious? Yes, but achievable according to spokesmen.

The work of EMEC goes on. In Shetland, the Lerwick company Delta Marine and their Swedish-owned partners Seapower Scotland have been testing their EXIM tidal turbine in the Bluemill Sound. And, as if there weren't enough waves out there already, Edinburgh Designs Ltd are making more at their engineering base in the capital, they design and manufacture wave generators and control systems. Their software was integral to the Pelamis project.

Capturing Carbon

These companies, and many others in Scotland, are working to transform the energy of the water into consumable electricity. But underwater geology can also help us to use fossil fuels in less damaging ways. CO2 emissions are an inevitable product of petrochemical combustion. Their contribution to the greenhouse effect and global warming is critical. But, instead of being dispersed into the atmosphere, these gases can be collected at output and retained, in a process known as Carbon Capture and Storage (CCS). Where better to put them, for long-term high-volume safe keeping, than the geological formations from where the oil or gas they came from was extracted?

In fact, there's a double benefit as the pumping in of the CO2 can help to force out the remaining oil reserves. Scotland's oilfields have enormous potential for use in CCS, and they are close enough to shore to make the procedure economic. Power station could draw fuel from the ocean bed, sequester the CO2 and pump it back, creating a virtuous circle and a carbon-neutral electricity supply. Plans for a power station at Peterhead, utilising CCS technology, have already been proposed by BP plc and their partners.

The Marine Foresight Panel,, has calculated that if less than 0.1% of the ocean's renewable energy could be converted into electricity it would satisfy present demand more than five times over. Scotland, closer than most nations to the power of the seas, is leading the way in harnessing an invaluable natural resource.

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