Letters: Lofty ideals for alternative heating
Of the many home improvements aimed at reducing overall energy consumption the provision of roof-mounted solar heating panels using dedicated solar collectors for domestic hot water appears to be among the least cost effective. Prices for such systems are quoted at up to £5000 with a saving of up to £95 per annum (Sunday Times 19/7/09). The cost of these systems appears to arise because they appear to have high installation costs combined with the requirement (in some) of a new hot water cylinder. I believe that there may be an alternative which overcomes some of the cost issues and I wonder whether this application should be considered by the heat pump manufacturing sector.
The basic principle proposed here replaces the need for solar panels on the roof and involves installing a suitably sized air-source heat pump in the roof space. The evaporator (low temperature) circuit is arranged to source the heat available from the warmed air in the roof space and the condenser (high temperature) circuit delivers its heat to the cold water storage cistern.
This system would have the following advantages;
Firstly - it uses the entire roof as a solar collector rather than dedicated panels.
There is no visual impact on the building and of course the cost of panels plus installation is eliminated. Although using the existing roof tiles to collect heat offers additional thermal resistance its advantage is that the collection area is much larger.
Secondly - the heat pump delivers the heat directly to the main cold water storage tank which feeds the (existing) hot water cylinder as normal and a new cylinder is not required. Delivery of heat directly to the hot water cylinder is via the feed water which would normally be cold but which (in this case) has its temperature raised. Of course the cold water tank would need to be insulated but in total the disruption to the domestic hot water supply system would be minimised which would save considerably on installation costs.
Some weeks ago a solar water heating system appeared in the press which used the novel feature of a coil installed directly into the hot water cylinder. Its main claimed advantage was its ease of installation.
The proposal described here goes further and links the two elements of heat collection and delivery using a self-contained heat pump situated in the roof space of the house.
The cost of the heat pump would be a high proportion of the total cost of the system but the design lends itself to minimum disruption and installation cost and perhaps should be considered by the energy saving industry for the future mass market.
Frederick T Murphy
Frodsham, Warrington
The government's refusal to create a Chief Engineer post in the civil service (PE, 8 July) should surely give us pause for thought as to how engineering is viewed generally. In England in the past a frankly snobbish attitude towards engineering, as compared with science, prevailed. This was typified by the absence of a chair of engineering at Oxford University until well into the twentieth century.
But what of today? I do not see the government's attitude as snobbish so much as ignorant and patronising. True, great engineers of the past are celebrated, although whether they are viewed as engineers or scientists or whatever is not clear.
What is clear is that technological innovation today is seen by the media as the preserve of scientists (when engineers are given credit, it is almost invariably the result of a foreign press release). I suspect that the public at large regards engineering as something outdated - steam engines and all that - having since been superseded by science. Perhaps a survey into such attitudes would be informative.
Meanwhile we have a job to do if the country is to get back on its feet, as your Editorial in the same issue makes clear. A vital part of that task is surely to persuade the public - and those in power - of the vital importance of engineering and the danger that allowing our engineering capability to decline poses.
Unfortunately, the heavyweight celebrity engineers who could facilitate this task are largely absent, but there are serious programmes like Panorama that could perhaps be prevailed upon to take up the cause.
Ian Berry
Enfield, Middlesex
I think our noble champion, Sir Robert Malpas, should add Alan Milburn to his list of correspondents. This well known former member of our government, in the guise of leader of a study team on education, has just declared that the social (financial) divide militates against the chances of the poorer gaining prominence in prestigious professions such as medicine and law. Medicine and law? Why does he not complete the insult to those of us who try (in my case, have tried) to keep the head of UK Ltd above water and include bankers, IT experts, politicians and members of the media.
Medicine can, of course, be seen as a special cause as we are all concerned for our health and grateful to those who try to preserve it; but just try a little analysis on even this relatively eligible case: the GP, who represents the bulk of the profession has become pretty much an anachronism, a rubber stamp, overtaken and overwhelmed by the variety and complexities of today’s available treatments and able to do little more than hopefully prescribe something to be taken or applied with little effect, or act as a clearing house for sending patients to hospital. He may still be a source of comfort but does this qualify him for reverence anymore than it does a trained nurse? At the other end of the range there are unquestionably men of great skill who specialise in and deal successfully with serious illnesses and are worthy of the greatest respect. However, His Lordship could point out to Mr. Milburn that these men have had their innate abilities greatly enhanced by the scientific discoveries that have been turned into medical tools by engineers. It is, of course, arguable that these men of special ability may be hidden in the ranks of those Mr. Milburn claims are deprived from entry to the profession but surely he is not suggesting that students embarking on it should be governed by considerations of prestige rather than service in the spirit of the Hippocratic Oath?
Turning now to law, I postulate that the prestige Mr. Milburn claims it enjoys is largely with lawyers amongst themselves, self perpetuating because laws are made by lawyers who have turned to politics and administered by lawyers who have not. The average person sees no prestige accruing to members of the profession, regrets being more or less forced to turn to them because of the way law is framed and fumes at the transmutation of the so called prestige into egregious financial reward for a non-productive, nay, counter-productive contribution to society. My own dealings with the legal profession have given insight into a world for which words such as ignorance, dilatoriness, incompetence spring to mind but, as we have seen of recent events involving those in the other categories of my opening paragraph, such adjectives are not a bar to conferring prestige as it is viewed from these heights where presumably it already is thought to exist, particularly in the context of translation into financial reward.
This expression of pique provoked by the utterances of a member of government is only a variation of what we write to each other regularly over the years without finding a route towards making an impact. Sadly, it would seem that prestige, whether intrinsic, or measured in terms of financial reward, has a proportionality factor related to the closeness of the practitioner to his client, a closeness that has declined progressively for engineers since the time of IKB.
John Gayfer
Alcester, Warwickshire
It is disappointing to find that there is still controversy about the efficacy of CHP in UK. A well ordered CHP plant can make use of more of the calorific value of fuel than any Rankine-limited conventional power plant that chucks its waste heat into the river or sea. Even Civil Engineers still do that much thermodynamics surely!
I lived for 9 years in Växjö, Sweden, population about 80,000, where the local power plant burned sawmill waste and prunings from parks, homes and forestry. The waste heat in the form of pressurised hot water was pumped to about half the local homes and all the public buildings to provide through separate supply heat exchangers our hot water and space heating. The insulation on these pipes was so good that they passed through a lake which froze each winter at the same time as all the other lakes in the area.
The remaining houses were all-electric, using heat pumps for space heating in the more modern ones.
The power company was able to balance the system properly because they decided whether each new estate would be water-heated or all-electric. There was no argument about this because a kWh cost the same (around 7pence in 2002) whether electric or thermal.
This system had been started in 1969.when the estate I lived on was built.
Incidentally, the meters were read centrally through the same cable that brought radio TV and internet to the home.
David Sherwin
Perth, Western Australia
3D is a great idea, but it allows some dubious short cuts. Let me give you two recent examples
1) A garden shredder. Looked good, good spec. Assembled from the box very easily. Wheeled 50 yards and both wheel fell off! Plastic ‘wheel holding’ widgets went into the bin. Back to the workshop, two holes, four washers and two spilt pins later it was fine.
2) A power planer with a red sprung widget on the sole plate that caught in everything and a power cord fed out of the back, nicely placed to be cut through on the second cut
I suspect that neither of these items had been built and tested but had gone from PC to production in one move. Last weekend we went for a tumble dryer (by the same group) – guess which brand we didn’t buy?
If this is being done by major groups then I have an uneasy feeling that it’s being done by a lot of others to cut costs.
Martin Akehurst
Henley-on-Thames, Oxfordshire
My local shopping area in a private road off the main road is too narrow to permit end-on or echelon parking. Consequently, most parking is done by parallel reversing into a space. Potholes in the reversing area are being constantly repaired but soon reappear.
I think they are caused by the surface shear of tyres when car wheels are turned on the tarmac whilst the vehicle is stationary. I feel that it would be better if the road had a concrete surface. I have surfed the internet trying to get data about the shear wear properties of tarmac and concrete surfaces, so far without success.
Can I ask through your letters if any engineer out there has any information which could further my enquiries?
Terence Bryant
Weaverham, Northwich
Mr. Spare (letters, 29 July) is unduly pessimistic regarding the ‘ruinous costs’ of renewable electricity. As natural gas (and petrol) becomes more scarce and expensive there must be a massive swing to electricity, from whatever sources, to make up the energy gap.
However, we are talking about a couple of decades down the road where 25kW of heating will only be needed if the house is large or very poorly insulated. Also pretty much everyone will have to have a version of the present ‘smart meters’ which will switch off the 25kW heating for the minute that it takes to boil the 3kW kettle.
Lawrie O’Connor
Ossett, West Yorkshire
Many people who support an Emission Trading Scheme (ETS) are often unaware of the severe harm it has caused in Europe and will in Australia if implemented.
However I have found that when they became aware of the harm it has caused, without providing any benefit or temperature reduction, they are pleased to drop their support for ETS.
Carbon dioxide (CO2) makes only one fortieth of 1% of the air, is a harmless and valuable fertiliser which has NEVER caused and cannot ever cause harmful global warming.
On the subject of Climate Change Europe has wasted about £50bn, USA $80bn and Australia has spent massive amounts of taxpayers funds without achieving any benefit.
In the future people are bound to wonder why we have become so stupid.
George Fox
Pymble, NSW
There have been several references recently to the possibilities of power from sewage plant as though this was a new idea. It is far from that, of course, and I have often wondered at the apparent lack of development. At 90 now I am inclined to undertake the research myself but feel that there must be a story there which you might think worth pursuing.
My own starting point would be Croydon, 1943 where I installed a Belliss & Morcom 6 stage vertical reciprocating compressor rated at 7500 psi. The design followed a series of similar machines which I had installed at Keith in Banffshire to compress hydrogen produced by electrolysis for supply to the wartime barrage balloons.
My memory for precise figures is now suspect but recollection is of three digestor tanks 30ft. dia, 60ft. deep supplying methane to an incinerator, a dual fuel engine driven generator and, via my compressor, to bulk storage cylinders for transfer to individual cylinders on vehicles. Because of the wartime fuel shortage it was intended to convert the corporation fleet and before I left enough of each type had been converted to demonstrate the feasibility and adequate supply of gas.
Why I wonder, did the idea not progress?
Victor L Holloway
Diptford, Totnes
There is a lot of unhappiness to read regarding the British approach to sustainability in the pages of PE almost every month. I would say however that there seems to be evidence for optimism that many more targets will be met that anticipated.
Here at work in Germany this week I received a new project to invest a 5 figure sum in "Energy Metering" -to be complete before the end of the year I might add. Off I go to my computer and research the topic and come up with the first three contenders.
I Email a company in Switzerland. They respond, deliver info per email & book an appointment inside 24 hrs.
In England I get through the switchboard in under 5 seconds..........to talk to an older voice at the end of the line who under great stress explains that the production unit was closed some years ago and sadly he wouldn't know anything about such products anyway.
I discuss the matter with my chief Electrician and find out that we have used a regional company from Munich 3 years ago for our (then) €36 Million newest production line. Odds on they will get the business - and complete it easily before the end of the year, we will get the best available technology, it will pay back easily in the 2 years (max) that are allowed and we will have achieved the efficiency gains that keep us ahead of the competition.
Chaps, I say that there is great cause for optimism in England because I cannot really see how you can expect to have a future economy comparable with today’s oil based system. This alone will surely reduce your carbon emissions and need for energy drastically.
There needs to be a re-assessment and an understanding that focuses on the technical strengths of the U.K. and where these fit best in the world market. When the majority focus on one area (example: Formula 1) you quickly achieve a critical mass which takes you beyond the sum of the individuals involved.
Find your strengths and use them (or loose them).
Lars Brookman
Augsburg, Germany
It never fails to amaze me that government departments get things so wrong. I wish to bring to the attention of your readers two prime examples. The first concerns electric battery driven vehicles.
In the early 1970s I and Prof John Sanger together with a final year Mechanical Engineering Student, at Salford University, put together a proposal for such a vehicle.
The design was based on a Ford Fiesta and incorporated a battery pack on a carriage which could be moved in and out of the vehicle thus precluding having to leave the vehicle on charge. I now see that such a scheme is being introduced in Hawaii and considered by other governments around the world. If my memory serves me rightly the vehicle was based on an electric motor driving hydraulic pump. This fed pump/motor units at the wheels which themselves were electrically controlled so that they incorporated regenerative braking, the whole system being designed so that optimised current drain would be achieved.
We tried in vain to obtain funds to continue the work and the final straw was a reply by the Civil Service that there was no future in such a scheme as there was a plentiful supply of cheap petroleum.
A few months later the first major oil crisis occurred. Did they change their opinions? No.
The second example concerns the Hawker P 1000. This was to be a supersonic transport several years ahead of Concorde.
My contribution was patented 4000 psi hydraulic system as I was then working at electro hydraulics who were the leading experts in designing equipment for use at that pressure.
The project was cancelled as a consequence of the then defence minister Duncan Sandys’ statement that the government saw no future for manned military aircraft. As the United States is still ordering aircraft for use into the 2050s the statement was a little premature.
It eventually led to the demise of EH Ltd and this country’s lead in this field. As I sit here in my retired state I wonder when and where the next fallacious decision will be made.
Now let us return to the need to go ‘green’ coupled with the finite sources of energy, why is so much money being pumped into trying to achieve nuclear fusion. The experts keep guessing how long it will be before they achieve a practical solution. This means they have no real idea and indeed it does raise the question of the feasibility of such a power source.
As there is so much thermal energy under our feet, it only being a short distance down to the molten core of the earth, why are we not devoting more energy to tunnelling down to tap into it. I believe at MIT they are going deeper than ever before and at least they are trying to tap into an almost infinite source of energy.
As mankind can build tunnels that are several miles long surely we have the ingenuity to go downwards. The heat available could then be used to produce all the power we need. Geothermal energy is a more realistic idea than giant mirrors in space etc.
William L Green
Whitefield, Manchester
A need for engineers in politics is debated, and so it should be. A Minister wants to cut emissions by 80% in 40 years, but another talks of our population exceeding 70 million and no limit.
Reducing our population from 60m to 12m would cut emissions by 80%, as would 60m and cutting fossil fuels by 80%, or some combination of the two; but where is the maths to calculate an emissions cut when the numbers of energy consumers can be 60, 80, 100m?
Politicians talk of nuclear, wind farms, etc. In 2007, nuclear electricity produced was 57250GWh and wind 5290GWh: the total UK energy consumption was 2.7million GWh. The problem of moving from fossil fuels is mathematically huge: have politicians understood that? They announce the world’s biggest offshore wind farm off the coast of Margate, but it would take 10 of these just to play catch up with a 70m population and that is before we move to electric cars.
Numbers of people is crucial in the maths of moving from fossil fuels, and it is not just technology, it is cost too. For example, solar panels and mirrors in a massive rented area of the Sahara might be technically feasible and possibly commercial too for local oil rich states, but for the UK?
Not all technology is affordable, particularly with our economy problems. GDP is still “the” measure of economic success but as it includes Government expenditure, the more MPs fiddled their expenses, the better the economy: another maths problem I think!
Politics does need the maths, logic, sceptical analysis, etc, of engineers but I doubt whether politicians will like it.
John Allison
Maidenhead, Berkshire
With reference to Paul Gillians' letter (PE 8 July). Whilst I cannot agree with the general gist of his contribution, I would say that there seems to be some perception that only high speed will do.
I suggest that in fact what is required is: reliability, frequency of service and sufficient number of connection stops between termini.
I regularly travel by public transport. I took the train on the Highland Line recently. In general I found it was a pleasant experience. It was fast enough, frequent enough, comfortable enough and with sufficient stops between termini. I would like to travel more on the West Highland Line but it runs less frequently and is slow - although the wonderful scenery makes up for the latter.
There are also other issues of importance to the comfort of passengers: working toilets, trolley service, and baggage facilities.
Speed is certainly important but it needs to be balanced against the other requirements and of course there needs to be a realistic fare structure.
Andrew C. Whyte
Milngavie, Glasgow
I refer to the item "Suppliers gear up for electrification" in PE 29 July and the sub-item "Electric trains cheaper to buy and run".
Now that the government appears to have been (re)converted to the merits of railway electrification - zero emissions at the point of use, lower emissions into the environment as a whole and significantly lower operating costs compared with diesel - one does wonder why similar thinking can not be applied to urban surface public transport.
Bus services in Britain's towns and cities could be worked by trolleybuses, for a similar life cycle costs to conventional diesel, if the collective will was there. Cities like Arnhem, Athens, Vancouver, Salzburg, Solingen and Moscow, where trolleybuses provide the backbones of the surface public transport systems, demonstrate this every day.
The modern trolleybus is established proven completely zero emission, not reduced emission technology like hybrids and available now. Traditional British objections to trolleybuses are surely out of date. With battery auxiliary power units, trolleybuses are no longer tied to the overhead line all the time and existing bus depots can be used without the expense of wiring them or the access to them.
Hopefully Leeds will pioneer the return of trolleybuses to British streets and set an example for other towns and cities to follow – but a push in the right direction from central government would be a big help.
Irvine Bell
Lytham St Annes, Lancashire
I read Ben Hargreaves article ‘Moonstruck’ with some interest because inevitably the fortieth anniversary of the moon landings has once again resurrected that old chestnut; did it happen or was it some great hoax?
There is no doubt that the US motivation to get a man on the moon in the 1960s as outlined by Dr Prince was very real but his technical assessment of the obstacles in the way of another moon mission does leave one wondering whether he really believes the first one happened.
He tells us that the lunar craft must have a lander with enough fuel for a carefully powered decent and the departure rocket must have enough power to break free from the moon’s gravitational pull, he also notes that NASA are now realizing what the problems are in coming up with the booster and spacecraft.
More importantly his greatest concern for a future mission is for the reliability of the engines used to power the craft during the lunar orbital part of the mission because the streams of hypergolic propellant and oxidant that will power the space craft have to be relied upon to burn in contact with each other in an environment where there are extremes of heat and cold.
I have no reason to challenge his conclusions but they do appear to be exactly the same obstacles that confronted the original moon-landing mission and if it has all been done before then getting back to the moon before 2020/2025 could be achieved by simply incorporating the latest technology into those original designs.
After all they went back to North America in a replica of the Matthew 500 years after Cabot made his trip.
Finally I must say that the picture accompanying the article did more for the doubters than it did for the believers; the astronaut’s shadow runs in a different direction to those of the moon rocks and the lunar buggy which with its four motorcycle mudguards suggests that the threat of rain was greater than the need to conserve weight!
Dennis G Roberts
Wells, Somerset
I read with some unease the article on organisational culture as a root cause of accidents ("Safety first", 8 July).
Does Mr Anderson, the HSE specialist inspector, really believe that " he could write a dozen reasons for an accident happening, seal them in an envelope, open it when the next major accident occurs in, say, 10 years, and the reasons would still apply"? If so, then why should any of us bother trying to make a difference?
Later on, Mr Anderson gives us the benefit of his experience by telling us that "If you can sleep at night and you are a refinery manager, there is probably something wrong"! Really? Well, that's just the type of comment that is going to attract bright engineers into responsible positions within industry, isn't it?
Such cynical and despairing attitudes are not helpful in trying to promote positive and responsible approaches to health and safety improvement in the workplace. Thankfully his opinions are not shared by those I come across within industry who show real leadership in striving to reduce the number of workplace accidents.
Let’s hope that Mr Anderson's approach is not symptomatic of a failing organisational culture within the HSE?
David Calder
Glasgow
The letter from Mr Davis in the last issue of PE reminded me that ideas often recur at intervals of thirty years or so. Recent interest in flywheel energy recovery seems to ignore what was done in the ‘seventies.
The most technically advanced and fully engineered high speed flywheel recovery system was that built by Garrett AirResearch. A train fitted with their equipment was run and thoroughly tested on the large test track at Pueblo in Colorado, where I saw it in 1976.
The problem with flywheel recovery is not the technology but the basic loss inevitable from a series of four electro/mechanical power transfers.
The energy in the train has to be converted into electrical energy by using the traction motors which is then converted into flywheel energy by another motor. This in turn is converted into electrical energy by the flywheel motor and this is finally converted to train energy by the traction motors.
The wide range of machine speeds and conditions necessarily involved prohibits their running at peak efficiency and an overall average of 80-85% each is a probable figure. Hence input from rail to flywheel would not exceed say 70% and from flywheel to rail another 70%, giving an overall recovery of only 50%.
There are other losses bringing the actual recovery even lower – in the complex control systems, in the flywheel itself and in the additional train weight. All at increased capital and maintenance cost.
Regenerative systems involve only two electro/mechanical transfers and offer a much higher percentage recovery and the technology is well established and widely used successfully.
Herbert Howard
Nantmor, Gwynedd
On reading Heath Reidy's article I was hoping for a balanced discussion on the pros and cons of using 3D CAD and what more needs to be done before 3D can truly replace 2D CAD. Unfortunately what I read seemed more like an advert by a 3D CAD supplier than a balanced view!
Let me make it clear from the outset that I believe that 3D is the future for CAD and I have witnessed many of the advantages mentioned in the article, however, 3D CAD is still a long way from being a fully developed tool. In particular, 3D CAD is most problematical for project based companies which design large and varied plant often with a significant bespoke design element.
In my opinion, there are three main issues which still need to be addressed before 3D CAD can take its rightful place as the tool of choice for engineers.
Firstly, workflow: Once models contain 1000s or 10,000s of parts, update times of hours or days are not uncommon. This is simply not practical in most design offices! In order to speed up workflow in large models parts have to be "simplified". Even with some packages offering "auto-simplification" this is not engineering work, but needless hours having to be spent to make the "tool" do its job properly.
Secondly, changes: Making changes in 3D CAD can be even more painful than in 2D! Because with 3D CAD it matters how a model is put together, any changes have to take this into account. Significant modifications which change the shapes of and links between several parts can be extremely complex to perform. I have lost count of the times engineers have said, "If you want that changed it will be quicker for me to model it again from scratch". This would simply never be the case with 2D CAD!
Thirdly, layouts: Ask an engineer to come up with a concept for a completely new part in 10 minutes and I almost guarantee you will be given a hand drawn sketch! Most 3D packages still acknowledge that "laying out" is easier in 2D by providing sketching functions. It should be possible to do better, quicker "sketches" in a 3D environment, but I've yet to see it done. Link this with my second point about changes and even if you do manage to produce a suitable concept sketch in 3D, the chances of being able to convert this into a usable product model are not good!
In the last couple of years, so called "Synchronous" models have reached the CAD market. This is where model creation history does not affect how changes must be made. Perhaps this will be the solution to my second and third points, but the technology is in its infancy at the moment.
So my answer to the question, "Why are so many companies slow to switch from 2D?" is "Because for many applications 3D software is simply not up to the job yet!"
Peter D Smith
Poole, Dorset
On the basis of the limited information following the recent crash of an Air France Airbus is now recommending the replacement of some A330/340 pitot tubes from Thales with similar sensors from the American Goodrich company, which are apparently not subject to the icing problem.
But I am prompted to wonder why, in this age of "high-tech" which allows an aircraft's position to be known almost to the nearest meter, courtesy of the now-ubiquitous GPS, all aircraft do not use a variant of the ultrasonic wind speed sensors produced by R-P-R.
These sensors - no doubt a "spin-off" from some type of military research - are "solid-state", with no little air-holes to get bunged up with ice or anything else, and could easily be maintained at a temperature sufficiently high to prevent surface icing which might affect the response.
In the interest of passenger safety, given that aircraft can at times suddenly find themselves running into unpredicted adverse weather, perhaps the aircraft industry should look into this alternative to a technology which is surely more than a century old.
Tony Marshallsay
Riyadh, Saudi Arabia
