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Going for hydro

I was disappointed by the arguments in the article ‘Does the UK need Norwegian hydropower?’ in the October issue of E&T. While the work at Leicester University on an app to identify and analyse hydropower sites in the UK sounds praiseworthy, it does nothing to undermine the case for importing clean, and no doubt cheaper, surplus hydropower from Norway.

The potential 2GW of UK capacity from small hydropower sources would be a useful addition to non-carbon generation, but will still be a minor contribution to substituting fossil-fuel generation. I would hope that the Norwegian green electricity would be seen as a useful addition to whatever we can generate in the UK from hydropower, which will take longer to come on stream than the six years for the link.

Of course there is the more important issue of why the government is happy for this investment to be made, while simultaneously eliminating the subsidies for UK wind and solar investments which are indigenous and provide thousands of UK jobs.

Solar electricity from PV will be viable without subsidy in a few years. To cut the feed-in tariff by 87 per cent in one fell swoop, rather than tapering it off over the next few years, will do untold damage to this important UK industry.

Ray Holland MIET
Plymouth

Amanda Saint’s article on the Norwegian interconnector appears to suggest that it’s not needed, as we could generate more from hydropower within the UK. Leaving aside the inevitable planning delays, battles and legal challenges that people in this country place in the way of almost any attempt to generate the electricity they wish to use, surely the answer is that we need both?

Demand for electricity continues to rise, coal-fired plant is vanishing rapidly, the price of gas is only temporarily stable and we are still arguing about the first new nuclear plant, let alone a fleet of them. Meanwhile, the plant margin gets ever thinner and a really sharp winter could put it into negative territory.

The development of a proper UK-wide energy policy is so long overdue that it will inevitably become driven by expedient and crisis.

EurIng Chris Thomas CEng FIET
By email

Two small hydropower projects are already up and running in the UK on the river Goyt, which is a tributary of the Mersey like the Tame. One is the Torrs Hydro at New Mills where an Archimedean screw has been generating power since 2008. It has produced an average of 140MWh per year. The other generator is Stockport Hydro at Compstall, which has been generating since 2012.

Both the Goyt and the Tame powered small textile mills in the 19th century and the modern hydropower schemes make use of weirs originally constructed for water wheels.

Rosemary Taylor MIET
Strines, Stockport

Nuclear shame

The proposal that design and installation of a new nuclear power plant in the UK should be carried out by a Chinese company in association with a French company is a sad indictment of the state of the country’s heavy engineering/nuclear engineering industry.

If we think back 60 years, Calder Hall nuclear plant was built by Taylor Woodrow construction, the turbines were supplied by CA Parsons, and the reactors designed and built by the UKAEA. The plant was connected to the national grid in 1956 and was the first in the world to produce electricity on an industrial scale from nuclear power.

It is a national shame that we no longer have the expertise to compete in this industry. It would appear that we are now going cap-in-hand asking others to build our energy infrastructure for us.

Barry Thorpe MIET
By email

Device oddities

Whether or not it is inevitable for progress in all areas of human activity to be marked by the occurrence of diversions and cul-de-sacs, it would seem to be so in the area of semiconductor device development and use.
In a career as a circuit designer, first in industry and then in academe, dating back to 1955, I can think of at least three blind alleys.

Following the advent of the tunnel diode, designs were proposed for its use in digital logic circuits. A former colleague experimented with the TD in digital storage, and Dr L Herbert employed a TD in the design of a fast pulse-height discriminator used in nuclear instrumentation. However, the lack of an independent control terminal and the coming of fast planar transistors contributed to the demise of the TD for circuit design purposes.

In 1963, at least one American semiconductor device manufacturer produced an integrated chopper transistor intended for the design of accurate analogue gate circuits. It was superseded when the metal oxide silicon field effect transistor came on the scene.

Later, I attended a lecture given by Mr C Southbank of the Standard Telecommunication Laboratories on the domain originated functional integrated circuit (DOFIC), a device, the precise function of which I cannot remember. Whatever happened to it?

Finally, at the risk of appearing overly immodest, I will mention a virtually unknown device oddity for which I was partially responsible. Towards the end of the 1960 a friend and former colleague, Dr RWJ Barker, and I developed a guarded-gate MOSFET intended to replace the conventional electrometer valve. It proved successful in tests and small quantities were made and marketed by what was, for a time, Marconi Microelectronics.

Alas, it subsequently sank without trace.

Dr Bryan Hart CEng MIET
Leigh-on-Sea, Essex

Sounds good to me...

Letters in the September issue of E&T comparing FM and DAB radio broadcasts highlight a very important issue for the engineering community. To compare complex systems based on a single operating parameter is not good enough. Audio compression techniques, cost and marginal area signal strength were individually used by the three correspondents to make their case. As professional engineers we must consider all factors in arriving at conclusions.

VHF/FM broadcasting has always been plagued by background noise, multi-path fading and adjacent channel related intermodulation distortion except under the most favourable reception conditions. VHF/FM is also relatively inefficient in terms of bandwidth for national broadcasting; 3 MHz for a single stereo audio channel is wasteful.

The innovative and smart combination of DAB carrier modulation (COFDM) with digital audio compression satisfactorily resolves all these issues and adds the capability for broadcasters to share a single national carrier frequency, adapting the compression levels to suit the broadcast material. About 2.3 Mbit/s is available to be split between an ensemble of broadcasters.

The real test is, what does it sound like, how much channel choice is available, is it easy to use and is it expensive. To my ears, from Radio 3 to local news, 190kbit/s joint stereo to 64kbit/s mono, the results are remarkable. Tens of channels are available while tuning is simply accomplished with stepped rotary control or push buttons. A price of £50-150 seems very reasonable for such sophisticated capabilities. I challenge anyone to convince me that the DAB experience is not outstanding - and why.

Technology evolves, and superior compression techniques (MP3 and MP4) will allow even greater channel choice with improved sound quality (DAB+). DRM will allow similar technologies to exploit lower frequency RF bands and there is no reason why DAB cannot provide traffic information rather better than that available over RDS. No doubt further investment will also resolve the marginal reception areas and make the batteries last longer.

Graham Knight CEng FIET
Saffron Walden, Essex

...But not to me

Why do we have a digital broadcasting system based on a very old compression system, obsolete when it was implemented, that loses a lot of detail? Agreed, the input power required at the transmitter is less, so it might be greener, but the receivers are more power hungry. The processing delay in different radios is not the same, so you cannot have two radios tuned to the same programme operating in the same house, something that is not unique to me as a radio listener.

The probable reason for jamming so much in a little bandwidth is so our government can sell off more and more of the radio spectrum to users who are prepared to pay a high price for something that is arguably a free resource (though international agreements and regulation are essential, or many popular sectors of the radio spectrum would end up unusable for much of the time). Broadcasters in general are not in a position to pay high prices for the bandwidth they need to operate so end up with a poor deal.

The British as a technically advanced rich nation deserve decent audio quality broadcasts as we have enjoyed ever since the VHF FM broadcast network was set up. If we must have a digital system, do not cram so much into a very limited bandwidth, and use the latest compression technology, if we need compression at all. Our aspiration should be digital radio as an all-round improvement. Other European countries do seem to take sound quality more seriously and do provide better quality.

There seems to be an acceptance that the lowest cost is always best regardless of the quality, the balance for digital broadcasting seems wrong, not something engineers should aspire to, and a terrible advert to the world of our attitude to quality of products and services.

Ian Coton MIET
By email

Will electric buses cause RF pollution?

I think I can claim to be reasonably enthusiastic about electric vehicles, having owned and driven an Ampera for almost a year. However, the article about inductively charging London’s buses (News, August/September 2015) fills me with misgivings.

Unless the all-electric buses are to carry around tons of iron in their induction loops, tens or perhaps hundreds of kilowatt-hours of energy will have to be transferred quickly to them via induction loops at radio frequencies. The process will not be 100 per cent efficient and there will be RF leakage, so we are going to have kilowatts of RF energy being sprayed about the streets of London from bus stops.

What is that going to do to the radio spectrum? I suggest it will cause widespread interference to many radio services. We shall be exchanging gaseous pollution for RF pollution. Is that really such a good idea?

Neil Gilchrist MIET
Ashtead, Surrey

Colour clash

The title of ‘The Future of Flight is Green’ (July 2015) reminded me of an incident with an English-language radio station I was helping in Laos some years ago. An NGO expert had written a piece entitled ‘The Future of Laos is Green’, but the producer was unhappy, stating that the future was red, i.e. communist.

When I argued the case for the original title, trying to explain the general significance of ‘green’ in energy terms, the producer still couldn’t understand, but, unwilling to offend me, suggested a compromise: “Suppose we call the article ‘The Future of Laos is Blue?’”

Fabian Acker MIET
By email

Routemaster

I greatly enjoyed Nick Smith’s excellent Classic Project article on the Routemaster bus in the October issue of E&T. Reading that “...the incorporation of aluminium in the bodywork, meaning that it resisted corrosion far better than modern steel buses”, reminded me that as an experiment, London Transport decided to leave a Routemaster unpainted (if my memory serves me right I believe it was RM664). I used to see it from time to time during the 1960s.

Gerry Bassingthwaighte MIET
By email

Is the term 'engineer' going down the crapper?  To the rescue

E&T readers may be interested in this photo of a weighing machine, taken in a Welwyn Garden City public convenience, which I offer with no further comment.

Geoffrey Evans FIET
Digswell

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