Opinion - Your letters
The burning question
As a senior electrical engineer involved with two large UK waste projects it was no surprise to me to read in the 26 April 2008 issue of E&T that Switzerland is the best at recycling ('Not wasting waste'). First of all it's a very small country and second there is not much space for landfill, owing to the geology. Smaller countries have had to face the waste issue a lot earlier than most and are usually more innovative. But we can learn from this.
The UK is ceasing its landfill operations, but the knock-on impact of landfill areas is that the land is more often than not useless for anything else. Even when trying to build on it the cost to pile is prohibitive, plus the gas release has to be controlled. However, one of my projects does just that - building directly on top of landfill to create new recycling centres.
In the UK we have two options: separate and recycle with bio-waste used for combined heat and power schemes, or incinerate everything leaving a very small amount of ash for use in the building industry. To build such process plants is one of the most difficult businesses as it involves lots of money, good project management and a very active public.
I'm involved in both types of waste process and see the benefits of incineration - the separation of waste and recycling induces more vehicle use and more carbon dioxide, as some separated paper and plastic can travel 200 miles for recycling - and this is done on a daily basis.
With incineration comes heat and export power with 10MVA exported on my project; this is a sizeable load of 'green energy' for the network. The heat in the form of steam could be used to provide very low-cost heating.
The new recycling process will deal with 24 per cent plastic/sanitary waste and 25 per cent bio-waste with paper at 22 per cent and glass at 5 per cent, so just by recycling these we will already be over 75 per cent recycling rate, which would be a massive improvement. With the same products incinerated this would provide substantial export power from CHP.
I have no doubt that the UK will be at the front of recycling waste. There will be more and more waste projects coming on line soon as the penalties for not recycling at the EU's minimum rate will be financially crippling. So recycling is here to stay and will be very much an integral part of everyday life.
AP Rivans, Sale, Cheshire
PV outlook not so sunny?
Chris Goodall ('Living a low-carbon life', 12 April 2008) claims that a solar photovoltaic system with a 50 per cent grant and a net cost of £5,000 would generate a net income of about £216 and give a pay back period of about 25 years.
Unfortunately, he has neglected the cost of finance.
A building society mortgage for £5,000 would cost about £400 per year, giving an annual net loss of £184. Even financing the system from savings the loss of interest would exceed the income generated.
No mention was made of the effect on household carbon footprint. The electricity generated is carbon free, but the manufacture, installation, maintenance and eventual decommissioning are not; the manufacturing process of silicon solar cells is particularly energy intensive.
The UK Building Resarch Establishment has recently published the results of its study of the lifecycle of domestic wind turbine systems. This has shown that only in the most exposed windy positions do they generate enough energy to compensate for the carbon footprint of their manufacture and installation. It will be very interesting to see the results of a similar study of solar photovoltaics.
Chris Pryor MIET, Soham, Cambs
Bums on seats
Paul Curnick (Feedback, 12 April 2008) identifies the major problem he faces in moving from an engineering career in to teaching - free market economics just do not work in areas such as education and health. In essence, since the early 1980s, the main concern at all levels in education has been 'cost per bum on a seat'.
Physical sciences, craft skills and technology are very expensive - costly non-reusable materials, costly laboratories/workshops, costly equipment, half classes or double manned full classes for safety etc.
A major part of the cost is staff salaries, pension and national insurance overheads. Get rid of the techies with experience and replace them with cheap labour in the form of recent graduates is the way ahead so far as bursars and management accountants are concerned.
This aspect is graphically illustrated by an experience during my time in the education sector. We had a serious problem with the mathematical skills apparently required of students on a foundation GNVQ engineering course. I eventually got through to the BTEC person who was responsible for writing the unit - it turned out to be a young lady who had recently graduated in mathematics, had no teaching experience, no experience of engineering and no appreciation as to why a 16-year-old could not understand the mathematics of bending moments in beams.
The cost of a bum on seat does not just apply to teachers - it also applies to the examination bodies, employing staff who are just not up to the job. I have to admit I did leave that lady in tears - I have always regretted that, for my anger should have been directed at those who employed her but they were inaccessible.
Arthur M Wheeler, Alderney, Channel Islands
Stick with wheels
I'm intrigued by the interest in maglev for trains. Energy is needed to propel a train to overcome (crudely) four forces: gravity for the hills, inertia to provide kinetic energy, air resistance and rolling resistance in the wheels. Gravity and inertia are (ideally) a zero-sum game, at least with good regenerative braking. The power needed to overcome air resistance scales as speed cubed; the power to overcome rolling resistance scales linearly with speed.
Conclusion 1: at high speeds, air resistance will always dominate. So maglev, which allegedly gets rid of rolling resistance, is only useful for slow trains.
Now, how big is the effect that it allegedly removes? Rolling resistance for a steel wheel on steel track is around 8N per tonne. If we assume that every passenger needs half a tonne of train, we get a rolling resistance of 4N. At 100m/h (50m/s) the power needed to overcome rolling resistance is around 200W per passenger. Each passenger could make that by pedalling.
Conclusion 2: the wheel has served us well for 10,000 years. Maglev makes little difference.
Dr Chris Elliott FREng, Ewhurst, Surrey
I was perturbed to read the news story 'Client pressure puts squeeze on consultant fees' in the 26 April 2008 issue of E&T. What is manifestly apparent is the need for a change of mind-set on the part of consultants and, through them, changes to their clients' mind-sets. While Skillfair's Gill Hunt is correct in observing that many consultants find negotiating fee rates difficult, the key to solving this problem lies in three areas.
Never charge by the day or by the hour, charge by the project: charge what the client thinks it's worth to get their problem fixed, and never compromise on fees (although possibly be flexible on payment terms).
If consultants find these propositions painful, let me just ask: do 20 per cent of your clients take up 80 per cent of your energy for less than 20 per cent of your income? Being bold enough to cull this bottom 20 per cent is possibly the fourth element.
David Winch MIET, Ampthill, Bedfordshire
Through the mill
'When size matters' in the 12 April 2008 issue of E&T looks at how small hydropower could become an important part of the renewable energy mix. Some years ago a friend of mine bought up an old mill and installed a small water turbine. If memory serves, it was the Pelton type. The nominal output was 10kW, which he utilised for space heating. As it was an old mill site there was already a mill pond - essential for satisfactory operation.
Inevitably, the local water authority sent a bill for the use of the water. He replied that he would pay if the authority could prove the difference between the water that he returned to the stream and the water that arrived naturally at the same main stream point. In both cases the water flowed through the same head. As far as I know he never paid a bill.
ED Humphrey MIET, Colchester
Dickon Ross's editorial column on Arthur C Clarke in your 12 April 2008 issue reminded me of our first and last meetings with the writer. In the RAF in 1942, when he was briefly a CH/CHL technical assistant at Stoke Holy Cross & Hopton, Norfolk, he was so valuable that I and a senior officer put him up for a commission. There was a very long delay before he was successful. He told me that the mindset of the interview board, which included WWI airmen, made them hostile when he said that future interplanetary travel was a certainty.
Years later we met again when he travelled from Colombo to London to receive a prize. I pointed out that technology forecasting, which he had promoted so well, had made glaring errors and omissions. A 1937 study of prospects for 2000 completely missed out on computers, atomic energy, antibiotics, radar and jet propulsion,. He replied, "I will give you one forecast you won't be able to prove wrong. One day there will be more people living off the Earth than on it."
Sir Alcon Copisarow, London
Do audiophiles know best? The answer to this question, posed by a letter in the 12 April 2008 issue can be summarised as "objectively no, subjectively yes".
The ear is a poor transducer, but its shortcomings are brilliantly compensated for by the auditory cortex that it feeds. This even compensates for perceived defects in the source of the sound, so that, for instance, the fundamental frequencies of sounds emitted by the lowest strings of a concert grand piano are simulated, so as to produce a harmonious effect, although they were not really heard. These neural networks manage to give us what we would like to hear.
A dupe who has wasted thousands on his sound system wants it to sound better than a straightforward conventional system, so, to please him, it really does.
This explains why many musicians swear that their vinyl recordings sound better than CDs recorded in the concert hall. This conviction may be enhanced by association with reminiscences of the performer. Double-blind mass trials would give the same result.
Guy ff Bellairs, Funchal, Madeira
What they're talking about on the Internet
A contributor to the manufacturing sector discussion forum on the IET website asked: In my place of work it has become habitual to work within the safety cell with the safety door interlocks over-ridden whilst setting new teach points with the robot in creep mode. The system supplier informs me this is okay, but is it actually safe? Are there any guidelines/statutory laws for safety at work when dealing with robots and automated processes?
- Common sense would demand that you should always have someone outside the safety cell with a fist poised over the kill switch and that you should not be where the robot could pin you against a hard surface. Your company procedures should demand this as a minimum, and, in fact, there should be a risk analysis report signed off by a senior manager.
- Could you have a castell key on the doors such that when you are doing this work you put the key into a maintenance/teach mode? This could automatically switch the robot to creep but also allow the robot to run with the doors open. Part of the permit to work system could then be to obtain castell key from supervisor and ensure a safety man is posted outside of safety cell at all times.
- You need to read the HSE book HS(G)43 Robot Safety. Teaching is recognised as a necessary operation, but there need to be safety zones within the safety cage in which the teacher can sit.
- Whatever system you end up with, it would be better than overriding safety interlocks. The HSE would view that as possibly the worst offence. Some activities are inherently dangerous but as long as you try to reduce the risk and have procedures in place to cover areas that cannot be addressed you should be fine.
Join the debate, or start one of your own, at www.theiet.org/forums
|To start a discussion topic about this article, please log in or register.|
"Is augmented reality the next big thing or a marketing gimmick? Is it fundamental to the future or a fashion faux pas?"
- Fukushima Daiichi Unit 3 5th Floor Highly Radioactive Debris [03:09 pm 17/05/13]
- Cluster formation on cooja simulator [01:59 pm 17/05/13]
- DSLAM Power Consumption [01:58 pm 17/05/13]
- English is not my first language. [01:23 am 17/05/13]
- Transport 2020 [09:35 pm 16/05/13]
Tune into our latest podcast