Subsea systems probe the secrets of the deep
Technology for monitoring the oceans could help address some of mankind’s most pressing concerns.
On 11 June 1930, William Beebe and his companion Otis Barton crammed themselves into a 7ft hollow steel ball of questionable integrity to descend a quarter of a mile into the dark depths of the ocean.
Built on the basis of a napkin sketch by Theodore Roosevelt, the ’bathysphere’ was the first vehicle to give man a glimpse of what was previously thought to be a lifeless soup of dark water. The resulting account of a world of shifting light and bizarre sea creatures captured people’s imaginations and began an era of ocean exploration.
But despite the extensive advances in technology since the rudimentary two-tonne bathysphere, few locations on Earth remain as remote or mysterious. The continued lack of knowledge about the world’s watery depths has only increased people’s fascination, and unlocking the oceans’ secrets is regarded as an important step towards addressing major worldwide concerns over energy and climate change.
Dr Ralph Rayner, a research fellow at the London School of Economics (LSE), believes that a lack of understanding in ocean processes could undermine the validity of climate-change science. ’There are lots of areas of ocean processes that we don’t fully understand,’ he said. ’As you move through the chemistry to the biology, that becomes more and more the case. When you think that half the CO2 that doesn’t go into the atmosphere ends up in the ocean, monitoring these changes becomes vital.’
“Lack of understanding in ocean processes could undermine the validity of climate change science”
One technology that could help scientists fill in these blanks is the sub-sea ’glider’. These torpedo-shaped autonomous underwater vehicles (AUVs) are being developed to replace the thousands of profiling ’drifters’ currently used to collect data beneath the ocean surface. Unlike drifters, which are completely powerless, gliders can be programmed to move via satellite navigation to a specific location. Able to travel thousands of kilometres, gliders typically use buoyancy engines that expand and compress air, causing the craft to move forward as it rises and falls in the water.
The Leibniz Institute of Marine Sciences (IFM-GEOMAR) recently obtained the largest fleet of gliders in Europe. According to the group, the gliders, developed by US firm Teledyne Webb Research, will be able to explore the oceans at a depth of 1km while only consuming as much energy as a bicycle light. In the next few days, researchers at the institute will prepare the gliders for their first mission as a fleet, in the tropical Atlantic. Each glider will be equipped with sensors to measure the temperature, salinity, oxygen and chlorophyll content of the ocean.
’Gliders have gone from pretty much nothing to having a major impact, over the past four to five years,’ said Rayner. ’Many of the technical barriers for the gliders have been overcome. There are also lots of sensor technologies that can be fitted to these instruments, which are at the early stage of key capacity, particularly in the area of chemical measurements.’
Measuring the chemical make-up of the oceans has traditionally been carried out by ships taking regular samples. However, up until recently, instruments that could do this continuously were either too expensive or fragile. Sensors today are more robust, but their accuracy in the oceans’ high-pressure environment remains a challenge.
Over the past 20 years, the Global Ocean Observing System (GOOS) has worked with 12 regional alliances to overcome these difficulties and drive sensor technology forward. The group has launched 3,000 Argo profiling drifters - which record temperature and salinity in the upper ocean - and 1250 surface drifting buoys to monitor surface currents, temperature and atmospheric pressure. But while the current integrated global system of sensors is a step in the right direction, a detailed in-situ global monitoring system is still some years away. Instead, Thomas Gross, programme specialist at GOOS, believes the best opportunity for studying the oceans is provided by recent advances in space-based technology. According to Gross, recent collaborations with the Committee for Earth Observing Satellites and the European Space Agency have provided a tremendous opportunity to develop global ocean-monitoring capabilities. ’In the early days, satellite observation was associated with understanding the atmosphere,’ he said. ’Now we can continuously measure the sea surface temperature, changes in its wave height and circulation, from space.’
Last month, the European Organisation for the Exploitation of Meteorological Satellites approved the Jason-3 programme to build on the measurements made by the Jason-1 and -2 satellites on meteorology, operational oceanography and sea-level trends. Over 15 years, the Jason satellites have measured an average global annual sea level rise of 3.3mm.
These climate-change observations have caused the European Commission to commit to producing 20 per cent of its energy from renewable sources by 2020. With a recent study by the Geological Survey revealing a significant melting of the ice shelves along the Antarctic Peninsula, concern is mounting over the impact further melting will have on coastal areas.
But as well as being a potential cause of devastation, Rayner believes the ocean could also provide a solution to climate change and an impending peak-oil situation. ’The UK doesn’t have many resources left to exploit in terms of hydropower from rivers; it’s not a great place for solar; and there are lots of issues with onshore wind,’ he said. ’The decision to adopt offshore wind to hitting that target is a pretty sound one. But if you think about the scale of these things, each one is as big as the London Eye, so there are some big engineering challenges to delivering that.’
“A lot of companies involved in renewables tend to want to reinvent the wheel”
ROB LUIJNENBURG, FUGRO
Rayner claims that if Britain is to meet its 2020 target, a better balance needs to be struck between investment in finding the remaining oil reserves and developing offshore renewables. However, Rob Luijnenburg, Europe and Africa regional manager at geoconsulting firm Fugro, believes that some of the major renewables challenges could be solved using technology that the oil-and-gas industry is currently deploying in oceans.
’The same navigation technology and seismic technology we’ve used in the oil-and-gas industry can also be used in offshore renewables,’ explained Luijnenburg. ’Putting a huge wind turbine on the ocean floor is extremely difficult because you need to get the angle exactly right. This has to be done on a calm day and that is almost always impossible, as these things are placed in some of the windiest places in the world.’
Fugro recently integrated a range of ESA-developed satellite systems with Russian systems to provide a single global navigation system. During drilling-rig operations, the system lets engineers accurately position their equipment. The offshore renewables industry uses it to position sensors and wind turbines.
’The idea that you need to divert investment one way or the other is a non-issue because the same technologies are used in two different areas,’ said Luijnenburg. ’We’ve developed a “met” ocean buoy, which collects meteorological and oceanographic data for the oil-and-gas industry. We use the same in the renewables industry. In the same way cable installation is what we’ve done in offshore oil and gas, we use the same in renewables. It’s no different. A lot of companies involved in renewables have not been involved in oil and gas; they tend to want to reinvent the wheel. There needs to be better communication. The renewables industry can learn a lot from the oil-and-gas industry.’
An unmanned robotic glider crossed the Atlantic Ocean last year
In April last year, a group of students and scientists from Rutgers University launched an underwater robotic glider off the coast of New Jersey.
Eight months later, the 2m-long, 61kg glider became the first unmanned underwater robot to have successfully crossed the Atlantic Ocean. It made its formal entrance into the port of Baiona, Spain – the same place where Christopher Columbus announced his discovery of the New World in 1493.
The glider, nicknamed Scarlet Knight, transmitted data more than 1000 times via satellite during the mission, which was tracked online.
Researchers at Rutgers are now hoping to send another glider on an ambitious mission to circumnavigate the world.