Perhaps high speed rail is more suited to France?
High speed train manufacturers promote their products as having a low carbon footprint based largely on the TGV in France. There, only a small minority of their power is from fossil fuels, the majority being from nuclear, hence their claim.
TGVs pass through long distances of flat open country so typically they accelerate at full power then travel at least tens of miles, if not hundreds, at near full power without much fluctuation.
That sort of usage contrasts sharply with the energy demand predicted by Imperial College in its report on HS2 energy usage. Typically between London and Birmingham they predict about 20 changes in 50 minutes between near maximum power and near maximum regeneration, a range of about 40MW.
Is that compatible with nuclear or renewable energy? Clearly not. HS2 will add significantly to the variable profile of our national power demand all of whose variability is satisfied by fossil fuels. HS2 will not have a low carbon footprint here.
- Bryn Bird (M), Bryn.email@example.com
Severn Barrage: How much longer will it be?
It is difficult to know whether to laugh or cry about the goings on in regard to the Severn Barrage.
When I started work in the mid 1950s with the consultancy established by the late, great Sir Alexander Gibb, I was unaware – until much later – that some 30 years previously he had undertaken a detailed study via a plan and report on the Barrage which was submitted to government.
He had costed the electricity which would be generated at a halfpenny per unit!
Much later, when I was involved with the Central Electricity Generating Board I was made aware that the board was going ahead with the barrage project and was encouraging strong interest in other schemes around Britain’s coastline estuaries to take due advantage of varying tidal cycles.
Sadly, very sadly, all the board’s plans were scrapped by the crassly stupid decision of the Conservative government of the late 1980s to privatise the electricity supply industry.
This led to the wholly foreseeable and desperate crisis awaiting us all now. Nearly 90 years of talk and no action!
- Chris Joel (F), Keep Lodge, Sandy Lane, Ellesmere, Shropshire SY12 0RA
Oldies but goldies
Don Mudd (NCE 7 October) is quite right: there is a vast, untapped reservoir of knowledge and experience in the hands of retired/semi-retired professionals. All this is going to waste as we elderly engineers await the grim reaper.
The same applies in my opinion to all professions and my proposal to the Prime Minister for the government to utilise this resource as part of the “Big Society” ideal has yet to be adopted.
That is no reason why, in respect of civil engineering, the ICE should not take the initiative and organise a register of willing participants who as part of “active citizenship” would offer their skills to the industry as mentors, inspectors, value consultants and the like in return for modest fees or community merit points, where a lifetime of experience will not be totally wasted.
- Angus Marshall (M), Links House, Quebec Road, Dereham, Norfolk NR19 2DS
In the 1950s the Clyde Navigation Trust operated most of its cranes and capstans, and other equipment, by hydraulic power – the hydraulic power being stored in accumulators that were charged by steam driven pumps.
The accumulators were large diameter pistons in cylinders, the piston being weighted by cast iron ballast weights.
This principle could be adopted for tidal power, which although predictable as indicated in the article, “Electric Currents” (NCE 14 October) only produces energy for 33% of the time. Therefore, a storage system such as an accumulator or hydro storage, will allow power generation on demand.
To avoid generation of electricity under water with its associated costs, an alternative would be for the underwater turbines to pump seawater directly to an accumulator or hydro storage facility. This can be done better by adopting vertical axis turbines of the Savonius type driving the seawater pumps.
- Harry Osborn (M), 15 Cowal View, Gourock PA19 1EX
Debate storms over turbines
I am writing in response to DG Wardle’s ‘energy from storm water’ letter (Letters last week) on using turbines in the proposed Thames Tunnel drop shafts to recover energy.
Although not entirely discounted, this presents many technical and operational challenges for a relatively small return. CSO discharges are random events, with no dependability of when, how long and how much recovered energy will be available.
This limits the value of any energy recovered. One of tunnel project’s guiding principles is minimising the equipment installed at tunnel level for safety and maintenance reasons.
Installing low-level generators at our shaft sites, many in locations frequented by the public, conflicts with this. Also, under the current proposals, sewage spills will be unscreened, presenting a serious risk of damage to installed equipment. Fitting incoming-flow screens at CSOs would add to the environmental impacts and increase costs.
While we will continue to investigate these and other suggestions, the economic benefit of installed turbines in drop shafts does not at this stage appear to merit the investment and ongoing operational and safety.
- Malcolm Orford, Senior Project Manager, Thames Tunnel, Thames Water, Clearwater Court, Vastern Road, Reading, Berkshire RG1 8DB
Learning from ICE Conditions
The apparent groundswell of love for the ICE Conditions has come on the back of the decision by the ICE to no longer maintain and develop the ICE Conditions of Contract and an opportunity to further ride on the back of a rare case study.
It has allowed the anti-NEC brigade to rally around a single flag, and will do little to educate and further promote the NEC.
All contracts are an allocation of risk: fairly or not. The ICE Conditions made this allocation simple, if not fair, but understandable for most of the profession.
The NEC allows for different allocations of risk, which sadly and perhaps out of genuine ignorance of some clients has not been allocated fairly.
NEC projects require client contract administration in addition to that most recently applied to ICE Conditions projects.
This comes from familiarity with the latter and a drive from clients to cut down on supervision in the belief that contractors will do what they are contracted to do.
The debate at least will improve understanding. Although Will Gard’s reported quote (Letters last week) that “You have to define what you want up front and then manage it very carefully” should apply to all contracts and not as some kind of criticism of the NEC.
- Walter Scott (M), firstname.lastname@example.org
Letters to the editor
NCE welcomes letters from readers. We attempt to print as many as possible, which means letters longer than 200 words are likely to be condensed.