A riverside office development being built and developed by Carillion in Durham has turned to a 2000-year-old technology to generate renewable electricity to supply 76% of the building’s energy needs – an Archimedes’ screw.
The £26m Freeman’s Reach development in Durham, due to be home to the state-owned National Savings & Investments bank and eventually a new branch of the Passport Office, is sited directly on the River Wear.
It has been awarded a BREEAM “excellent” rating, thanks in large part to the fact that three quarters of its energy needs are going to be met by hydro-electric power from an unusual water turbine designed to act as an Archimedes’ screw.
The turbine, which is 13m long and weighs 20 tonnes, was craned into its cofferdam by the Carillion team on Sunday morning. It has a predicted power output of 100kW, which will be generated 24 hours a day.
The screw design, used for more than 2,000 years to pump water from a lower to a higher level, usually for irrigation purposes, has only been used to generate hydroelectric power for the past 10 years.
The reason is that it is not as efficient as the more common Kaplan turbine, but unlike the Kaplan it is harmless to wildlife – and this was an important requirement on the Wear, with its population of salmon, otters, eels and invertebrates.
Project manager for the scheme is Ian Beaumont of IMB Management. He told CM: “There are strict environmental considerations. The Environment Agency and Natural England recognised that the ecology relating to the river was very sensitive. We put a ‘fish pass’ in that allows fish to filter through the turbine and as part of the environmental requirement we had to put a fish counter as well – that tells you how many fish pass through the turbine, and also reads their electrical signature to determine the species.”
Beaumont said that the factors behind the decision to install hydropower were fairly specific to this project. The weir was already present in the river, so there was a big enough “drop” between the level of the water entering and leaving the turbine to power it. “There was a weir already built, so we didn’t have the civils cost associated with that. The ideal site is where there has historically been some hydro power, and there was a turbine present from the thirties. Also, Durham County Council, the Homes and Communities Agency (HCA) and the NS&I were keen to see some sort of green use on the site and this particular form made sense.
"There was a weir already built, so we didn’t have the civils cost associated with that. The ideal site is where there has historically been some hydro power, and there was a turbine present from the thirties."
Ian Beaumont, IMB Management
“I’d love to see more [installations], but I think the combination of the client with a green agenda and these sites with a weir already in place are unusual. But if you’re next to the river there’s always a chance to look at a turbine,” he added.
The 1930s turbine mentioned by Beaumont was used to power an ice rink on the site, but it’s also thought that the history of hydropower at Freeman’s Reach dates back more than 800 years.
Beaumont said the combination of the civils work and remediation needed to create the site for the turbine, together with the procurement of the turbine itself, added up to about £1m, but he said he expected this to be paid back “relatively quickly”.
Work is now under way to install the rest of the generating equipment and undertake the civil engineering required in the intake channel. This is scheduled for completion in September, after which the turbine should be in operation.
The developer for the scheme was Maple Oak, a joint venture between Carillion, Arlington Real Estate and Richardson Capital. The client was Durham County Council and the HCA. The turbine was designed and manufactured by Spaans Babcock, the hydropower consultant was Renewables First and the engineer was WSP.
Neil McMillan, director of Carillion Developments, said: “We are pleased to have been able to continue a long tradition of energy generation at Freeman Reach, this 21st Century technology will harness the power of the River Wear for many years to come.”
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