New approach can expoit our raw resources, says Dr Alan Owen
SCOTLAND has far more than its fair share of renewable energy resources, from wind, hydro, wave and tidal, to geothermal, biomass and solar. It also (easily) has the indigenous technological capability to drive a new industry, capable of providing – with some caveats – all of Scotland’s energy needs, as well as exporting to UK and Europe. So, why doesn’t it have a more visible renewables industry?
Investor confidence is a major factor, as the small Scottish wind generator manufacturer Proven found to its cost in 2011 when a technically easy-to-resolve welding problem caused a nervous investor to withdraw support.
With yet another tidal energy resource assessment hitting the headlines recently, this time from Oxford University, the ongoing estimation of Scotland’s marine resources, specifically the Pentland Firth, continues unabated and a great deal of excitement is generated – even if the electricity isn’t.
Assessing the theoretical resource magnitude is not particularly difficult and the figures have varied widely over the years, but there needs to be a clear delineation between the different resource classifications, i.e. raw, technical and economic. Raw resource is the total energy passing through a particular cross-section; technical resource is that which can be harnessed using currently available technology; and economic resource is that which can be taken (and sold) at an economically viable rate.
Most raw resource models assume that the flow is well behaved, moving bi-directionally in orderly streams. However, data taken from tidal sites in Scottish (and Asian) waters, shows that the flow is often very turbulent and there are some occasions when the flow at five metres above the seabed is actually going in a different (sometimes opposite) direction from the flow at, for example, 20 metres above the seabed.
The resulting shear forces are proving difficult to manage at the turbine design stage and are one of the many issues leading to technical failure during at-sea testing. The hydrodynamics of tidal current sites are hugely challenging, but in the rush to develop to multi-megawatt scale the marine renewable research and development groups have forgotten an important component of industrial evolution – the Model T.
The Model T car, produced by Ford at the start of the 20th century, is widely acknowledged to be the first successfully mass produced automobile affordable to many Americans. It can be argued that the tidal energy industry has not yet built its Model T – a device that is so cheap, simple and reliable that it becomes boring, dull and highly profitable – and this is a vital missing step if Scotland is to properly harness its natural resources.
Arguably, the first modern tidal turbine was successfully tested in Loch Linnhe in 1992 and there have been many turbine proposals since then. The first 1-megawatt devices were being proposed less than 10 years later and now we have upwards of 2-megawatt devices being built, yet there isn’t one commercially viable device at sea, anywhere. This rush to gigantism was apparent in the 1980’s wind turbine industry, resulting in many failures and some reputational setback for the industry, which took many years to successfully deploy beyond 1-megawatt devices.
Similarly, the Osprey wave energy device made all the wrong headlines in 1995. The big difference between wind and marine is that the wind industry had spent many years successfully deploying commercially viable machines, learning their craft and building up their design knowledge.
It is the cheap, simple, reliable, boring and dull part which marine energy device manufacturers seem keen to not be associated with, whilst chasing the profitable part. However, any marine device that has a complex installation has an irretrievable cost problem before it is even in the water.
These installation costs are making investors shy of putting backing a major component of what should be Scotland’s biggest internal investment – a secure, reliable, indigenous energy generation system. Renewables are a vital long-term energy resource – possibly the only one – available to the human race, but we must get the engineering right and engineering failure is a necessary part of product development.
Manufacturers and developers of renewable energy systems must speed up development by pooling experience. Investors need to be convinced to commit to the industry by maths and physics built on real field experience.
• Dr Alan Owen is Director of the Centre for Understanding Sustainable Practice, Robert Gordon University www.rgu.ac.uk