Forward thinking as harbour construction project nears completion

An innovative new tidal power system is thought to be under

consideration to power the opening mechanism in the new lifting bridge shortly

to link to Poole Old Town to Hamworthy.

A PBO expert confirmed that the

mooted Hydrodynamic Stored Energy Lifting (HSEL) system is essentially a simple

concept that could save vast amounts of energy over the projected life of the

bridge.

Turbines at either side of the river would constantly convert the

considerable tidal flow between Poole Harbour and Holes Bay into rotational

energy, which would be imparted to two huge flywheels via a variable ratio

mechanical drive. When the bridge is required to lift, the drive would disengage

and a clutch transfer the energy to the bridge-lifting mechanism. As the bridge

closes again under gravity, much of the energy used would be returned to the

flywheels, leaving the tide simply to top up the remaining energy.

Many questions remain to be answered,

however, such as how the bridge-operating schedule (impacting traffic flow on

town roads as well as water traffic) would work with this lifting system – there is the

potential for more bridge openings during spring tides, owing to the extra

power available. However, this may mean too few during neaps, and it is unclear how this

possibly-erratic scheme would work with the existing bridge.

There are also concerns

about the turbines used to power the system, which may significantly narrow the

available shipping channel, and even suggestions that for one week in every

month access to Holes Bay (home of several marinas) could be restricted to

shoal-draught boats.

Nevertheless, such out-of-the-box thinking may well be an

indication of the radical new ideas necessary to conserve our dwindling power

reserves over the forthcoming years.