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

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.