Professional Engineering

Scotland has bold ambitions for its renewable energy sector. Last May, the country’s first minister, Alex Salmond, described his wish to make Scotland the green powerhouse of Europe, as he pledged that the country would generate 100% of its electricity from renewables by 2020, up from the 80% target set a year earlier and the 50% target set prior to that.

But as the target has crept up, so has the level of scrutiny. First, engineers started questioning whether enough power could be generated to keep the lights on, and how much it would cost. Hot on the engineers’ heels was the Scottish parliament itself, which launched an inquiry into the plan earlier this year.

One of the groups that gave evidence to the inquiry is Scottish Renewables, an organisation that represents 300 companies working in wind, marine and hydro. It believes that the target can be met. Rachelle Money, a director at Scottish Renewables, says: “The target is ambitious but achievable.” 

She says that Scotland has provisions to supply around 5GW of renewable energy, and an additional 23GW-worth of projects are at the scoping, planning, consent or construction phase – all of which could be generating by 2020. In a written contribution to the inquiry, Scottish Renewables says: “We need a third of these projects in operation by 2020 to hit the target.” 

Money adds: “Scotland had an interim target of 31% in 2011. We got the figures at the end of March that confirmed we exceeded the target – we met 35% of our electricity needs from renewables.”

But Stuart Cameron, vice-president of the Institution of Mechanical Engineers, believes the 100% by 2020 target is too ambitious. “The target for 2020 is very much based on a huge development in offshore windfarms.” More than 50% of Scotland’s electricity is due to come from wind power under the new plans, up from the 20% generated on a windy day in Scotland today. 

Cameron says there are several issues with relying on wind. Firstly, the turbines needed for offshore windfarms are far bigger than their land-based counterparts. Offshore wind turbine blades can be about 80m long and weigh several hundred tonnes. He adds that blades of this nature are not commercially available, and may not be until 2015. Not enough has been done to look strategically at where these will be manufactured, assembled and shipped. Once available, supplies of around one turbine a day would be needed to meet the 2020 target. As Scotland is not the only country going for windfarms, there could be supply and demand problems. Offshore turbines are two to three times more expensive than land-based ones. 

Installation is another concern. “Has anybody looked at the project of installing these?” asks Cameron. The process would require port and shipping facilities to get the turbines out to sea, as well as cranes to lift them onto the base. The logistics of maintenance could be problematic.  

In addition, the government may run into trouble finding places to put farms. “Suitable sites are becoming less and less available,” he says. The squeeze comes from local opposition to new windfarm developments and issues from the Ministry of Defence, as the turning blades can interfere with radar. 

Peter Hughes, chief executive of Scottish Engineering, says that the 100% target is “nonsense from cloud cuckoo land”. Wind turbines have an efficiency of around 25%, he says. “What are we going to do the other 75% of the time when the wind doesn’t blow? Are the lights going to go out?” The solution to securing the electricity supply could be having nuclear power plants to provide a baseline to top up energy levels when the wind is not blowing.

Scotland has two nuclear power stations that account for around 30% of the country’s electricity. Both of them are due to be decommissioned by 2020-25, and under the renewables commitment, nuclear is not part of the future energy mix. Hughes says it is silly for Scotland to turn its back on nuclear – it is the most efficient way of producing low-carbon energy.

But recent developments have seen politicians say that they would not stand in the way of extending the lifespans of nuclear plants, provided it was safe to do so. Without investing in new nuclear, the country could end up buying nuclear power from England or France in times of need. Hughes says: “It seems hypocritical. We’ll pretend that we are a non-nuclear nation, but we will use someone else’s nuclear-generated electricity.”