Feedback: your letters

Energy packed but with zero calories - a true super-food for the brain. We open the floor and take a look at your letters.

Where would we put all the carbon?

'Carbon Consultant' (Vol 4 #10) makes interesting reading on plans to provide carbon capture and sequestration in sites under the North Sea. However, claims that significant greenhouse gas reductions could result from adopting this technology, assuming it works, are not reassuring.

The engineering techniques that underpin CCS have mainly been developed to improve oil and gas recovery from difficult wells by forcing carbon dioxide into them to expel the stubborn oil and gas residues. CCS produces extra oil and gas, which, when burnt, adds a considerable tonnage of carbon to the atmosphere, which would otherwise have been left safely below ground.

It takes a lot of energy to separate CO2 from the spent gases produced by the burning of coal, oil and gas in industrial plants and power stations, and to then compress and liquefy it. All this energy for CCS comes from burning fossil fuels thus adding a new source of greenhouse gases.

Moreover, CCS of very large volumes of CO2 for very long periods is an untried procedure. Some estimates say that it will not be possible to commission a fully-functioning CCS plant before 2025. In the meantime, new coal-fired power stations will be approved in anticipation of CCS becoming available, but will be built without it.

Statistical data on sequestration sites, when examined in conjunction with fossil fuel reserves, does not provide encouraging evidence for the effectiveness of this technology. Reports suggest that unused and 'sequestered' safely below ground there is currently 318 billion litres of oil, 6076 billion cubic feet of natural gas and 982 billion kilogrammes of coal.

Converting to a common dimension of cubic metres, we get 28 million for gas, 756 million for coal and 318 million for oil. If all of this fossil fuel store were to be burnt without CCS, as mankind seems determined to do, global warming will be so severe that, according to geophysiologist James Lovelock in his book 'The Vanishing Face of Gaia': "The Earth may be forced to move to a hot epoch where it can survive, although in a diminished and less habitable state. If, as is likely, this happens, we will have been the cause."

Could we avoid this fate by sequestering the released carbon? The collected and liquefied CO2 obtained from burning our remaining gas, oil and coal reserves would occupy 10.5 billion cubic metres. Evidence suggests that there are 2.2 billion cubic metres of potentially suitable well and aquifer sites available, which means that we can sequestrate only 20 per cent of the released carbon. There is really only one answer: we must move as rapidly as possible to a post-fossil fuel age.

Alan J Sangster CEng FIET, Edinburgh

The trouble with monorails

Yet another variation on the "not-exactly-a-railway" appears ('Wating for Nowait', Vol 4 #10). This time someone has re-invented the 'Neverstop' railway from the 1925 Wembley exhibition, expanded it, added a few gimmicks and called it 'Nowait'.

There is no way such a cumbersome thing could be economically built, maintained and operated, but maybe a small demonstration line will flower briefly then remain derelict for years like the Bennie Railplane and the Bertin Aerotrain.

The picture in the article shows a unidirectional single line. Twice that would be required to give an acceptable service. Later in the article it is alleged that monorails are less expensive than light railways. It depends on what you mean by 'monorails', a much abused word, and just how light the railways are, but generally no. Accepted experience is otherwise. The Shanghai maglev is an impressive thing, but too bulky to slot into the city centre, so can't take people where they need to go.

J R Batts, Banbury, Oxfordshire

Nuclear makes sense

MA Laughton (Letters, Vol 4 #9) rightly draws attention to the use made of the Chernobyl incident by anti-nuclear advocates in their quest to impede the use of nuclear energy.

The Chernobyl reactor design was rejected by the majority of designers because of its over-moderated and positive reactivity void coefficient characteristics, which largely contributed to its going promptly critical. Such a reactor design would not be licensed for construction, let alone operation, in most parts of the world.

Now add to this unstable design the operational transgressions, which would not be tolerated in the UK, USA etc. An unauthorised experiment that required operation of the reactor in a mode prohibited by the designers, who were aware of its unstable characteristics. The operators disabled several safety devices because they might interfere with the experiment. They also ignored dangerous condition warnings from the computer. It was disclosed later that some pensonnel had experience only on fossil-fuelled plants. It would be difficult to imagine a scenario more likely to produce disaster.

Hundreds of nuclear power plants around the world have operated for many years without significant incident. Now even safer designs are available, which can provide energy as cheaply as any other source. Solar and wind energy can make a useful contribution where they can be applied without adverse environmental impact and at reasonable cost. However, they can never reliably provide the sole supply source. They must be backed up by coal or nuclear.

Surely, based on these facts, there is only one choice.

J Fray CEng FIET, San Jose, California, USA

Up, up and away

'Transition into the Skies' (Vol 4 # 11) transported me back to the late 1940s and 1950s when I began an interest in aeronautics and started my career in aviation.

The concept of the 'flying car' was exercising various design teams, mainly in the US, who wanted to combine the advantages of the long range of the aircraft with the manoeuvrability of the car for city travel.

The first design of which I became aware was the Taylor Aerocar from the US in 1949. It was termed a 'roadable aircraft' with a pusher propeller that could achieve a road speed of 60mph and an airspeed of 110mph. It gained its airworthiness certificate in 1956. The second design I remember was the Aeroauto PL5C created in Italy in the 1950s. However, this was abandoned in 1953.

Historically speaking, the concept had been around for a considerable time. The story began with the roadable aircraft, pre-World War Two in the US, when Glenn Curtis designed a flying car in 1928. The vehicle was towed from Miami to New York but doesn't seem to have been flown.

The next attempt was in the US with the Waldo Waterman Aerobile of 1937 which was the first built in any number, six in total, and was developed from a tailless aircraft called the 'whatsit'.

In 1942, the Hafner Rotabuggy (formally the Malcolm Rotaplane) was a development of the Willys Jeep and an autogyro which was subsequently abandoned. Latter ML Aviation had a similar idea for a battlefield vehicle called the Rotatank but this never progressed to an end product. The Fulton Airphibian FA-2, another US project, was begun in 1946. The company was forced to sell up and the project was abandoned.

The last I remember was the US AVE Mizar between 1971 and 1973. It was a combination of a Cessna Skymaster and Ford Pinto - it did not go into production due to the prototype crashing during trials. Around this time reportage seemed to cease for the casual observer, however, background work was obviously in progress.

It is interesting to see the concept reappear. Possibly with new materials, powerplants, control systems and computer-aided design techniques it may finally come to fruition.

D Little MIET, By email

'Over-engineered' solar

The scope of Dan Lewis's article on solar grid parity in E&T Vol 4 #9 and the relevance of cost was brilliant, but it's only half the story. Global warming demands umpteen infallible 24/7 Terawatt green solutions.

The 'latest design' Sun farms are grossly over-engineered. Apart from a potentially flimsy unproven design, mirrors are still in the biplane era. Cheap, site-assembled stressed-skin mirrors measuring, say, 13ft x 29ft, are long overdue.

Solar is a field crop. Design and construction should be done by agricultural engineers. Starting from foldable, high-productivity lettuce-cauliflower-harvesting machines, I envisage a container-delivered, laser-guided machine that would enable one man to 'plant' the support pillars for the high-sunlight equivalent of 10MW per hour.

Every construction process can be revolutionised. Starting from 40ft containers of component parts, specialist teams of glass-house builders achieve a group construction rate of substantially over 1,000ft2 per man per eight-hour day. Two axis rotation, '100+ suns', mirrors, solar cells, cooling and wiring are not hard. Using cheap metal-bashed parts and assembly jigs, a few site engineers and 100 semi-skilled men might construct and wire the equivalent of one of Drax's 600MW generators within two months. Simultaneously, in two man weeks, factory-wired containers could convert and feed that energy to the supergrid.

Ultimately, it is grid parity that matters. After allowing 10 per cent of capital for maintenance redundancy, some technologies will create a 24/7 supply. I also believe that one of them will achieve true grid parity sooner than solar power, maybe within a dozen years - and start the decline of global warming within 20 years.

Francis Frampton, Bognor Regis

Just for the cars

Charles Dunn of Dublin, whose government has issued a target of 10 per cent of car sales to be electric vehicles (EV) by 2020, highlights the need for a purpose-designed connector for charging (Letters, Vol 4 #10).

He is correct in saying that the BS1362 and 4343 type pin and sleeve connectors were not designed for these applications. Marechal Electric has already designed and produced a connector specifically for EV charging. The inlet is standardised to offer up to 32A at single phase 230V AC or three phase 415V AC and 200A at 300V DC.

Other auxiliary contacts cater for the transfer of comms and data. This is acheived by using butt-contact technology, initially used in decontactor type sockets, a much more efficient way of transferring energy than pin and sleeve. An ergonomic design ensures strain-free usage by all users while a safety shutter closes when the coupler socket is removed from the inlet to shield the contacts.

Stephen Thackray, Marechal Electric, Chester

Don't forget Tesla

I am an investor in and have contributed at both a managerial and technical level to Tesla Motors, I also own and drive a Founders Series Tesla Roadster, so I admit to being a little biased, but to omit the market leading product and the technology leading company from your article 'Green Shoots From Tumbleweed' is notable to the point of raising the question why?

In 2002-2003, when Tesla Motors drove its first car out of its workshop, Lithium Ion was neither an obvious nor a recognised solution for powering an EV. Now in 2009 the debate is passed, EV development is rampant and Lithium Ion is the solution of choice.

There are over 500 Tesla Roadsters on the road and another 800 are due to be on the road by the end of this year. The company is making money at a time when the remainder of the automotive world is struggling, and cash from the Roadster supports the development of the newly released Model S, a seven-seater sedan.

A London dealership is opening in the next few weeks, an EV first for London and for Europe. In addition, Tesla has large UK engineering content through its UK subsidiary based onsite at its contract manufacturer Lotus Cars in Norfolk.

Those green shoots are more robust than you give them credit to be and they are coming at you. I recommend that in the spirit of the times you move past the potential future projects, get on down to the Tesla dealer and…burn rubber not gasoline.

Tim Watkins MIET, Managing Director, Valor Equity Partners, Chicago

Where's the robot now?

Does anyone know what happened to the robot at the Evoluon in Eindhoven? I think it was the mid-1970s and this bird-like creature would react to movement or noise from anyone in the room. The movements were quite simple, but it always felt rather life-like. In particular, if you kept doing the same thing it quickly got bored and went back to sleep or started looking at something new.

For its time it was very clever piece of computer art and I wonder if it has been preserved somewhere?

Arthur Moore, Antibes, France

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