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Why can't the different green energy camps get along?

Not such jolly green giants

The one thing that really annoys me about the various sectors involved in renewable energy production is the seemingly constant sniping at each other in some sort of trial of importance to prove who is the biggest and best big green giant.

The latest manifestation of this is 'More gas than wind' in Vol 3, #11 of E&T. William Knight quotes UK Department of Business, Enterprise and Regulatory Reform statistics for 2006 which show that landfill gas made up 33.1 per cent of renewable energy use, compared with wind at 8.2 per cent. He then proceeds to make a facetious remark about wind turbines.

If Mr Knight had read a little further in the same report he would have found the following statement, which clarifies the difference between use and electricity production. "Eighty-nine per cent of the renewable energy produced in 2006 was transformed into electricity. This is an increase from 87 per cent in 2005 and 82 per cent in 2004.

"While biofuels appear to dominate the picture when fuel inputs are being measured, hydro electricity is a larger contributor when the output of electricity is being measured…

"This is because on an energy supplied basis hydro (and also wind, wave and solar) inputs are assumed to be equal to the electricity produced. For landfill gas, sewage sludge, municipal solid waste and other renewables a substantial proportion of the energy content of the input is lost in the process of conversion to electricity."

This is accompanied by a chart showing the electricity generated from the various renewable sectors for 2006, which gives a much more balanced view as the various renewable sector inputs to the UK energy mix. Readers can check the report themselves at [new window].

I myself am involved in the hydro sector and it annoys me when large-scale hydro production is regularly excluded from renewable energy statistics, but I don't let this belittle the contributions of other renewable sectors.

Mr Knight's article is otherwise informative and useful. It is just spoiled by his over-egging the contribution made by landfill gas to the renewable mix.

Surely the various sectors in the renewable industry need to realise that they are all part of the same team and constant oneupship with each will only detracts from the positive story of more renewable energy production.

Sean Kelly MIET CEng, Kippen, Stirlingshire

The trouble with meat

'The Trouble with Meat' (Vol 3, #11) was interesting. The impact of meat production on the environment is an area worthy of examination in our modern society. I was, however, disappointed with the negative stance the article took on meat itself. It failed to mention that meat is a key ingredient in our diet, regardless of what vegans would have you believe.

It is a well-published fact that meat is the only available source of vitamin B12, key in the formation of blood and the operation of the nervous system.

While I would not condone the inhumane treatment of animals, it remains the case that, as with every other predatory organism on the planet, we need to harvest animals as part of our diet. Indeed, we at least have the courtesy to render unconscious and kill our animals prior to eating them, unlike the majority of other predators.

Arguing that we should reduce our meat intake on environmental grounds seems odd, considering that the most effective solution to reducting environmental impact is population control among humans. It seems many would prefer to focus on issues that already dominate the political landscape rather than looking at the root cause of the problem.

Jeff Hotchkiss, by email

'The Trouble with Meat' grossly simplifies a complex industry and could have been lifted directly from the propaganda output of a militant eco-vegetarian political organisation.

Meat from poultry and pigs that are largely grain fed is not differentiated from beef or lamb, much of whose diet is largely forage-based and where grain is used as an additive.

The propaganda says that the conversion ratio is 8:1. I would sack a farm manager who got results as poor as that. The conversion ratios of animals fed grain differs and can be as low as 2:1 for poultry. A high-yielding dairy cow might produce ten tonnes of milk per year from an input of 20 tonnes of grass and silage (which is mostly water) and three tonnes of cereal. Without the grain the output might reach six tonnes of milk. So the ratio is more like 4:3 but even that is misleading since the energy supplementation enables the cow to use the high protein in the grass.

Most of the UK is only suitable for growing grass. What are we supposed to do with this land other than keep cattle and sheep? And before anyone proposes all-grass systems, let it be stated that the supplementation by grain reduces the methane emission per kilo of milk and meat.

There are some serious flaws in the numbers thrown about without proper validation. In the 1990s, while trying to develop a cow breath sampling system, I identified that cows exhale dimethyl sulphide which is regarded as a counter to global warming, helping in cloud formation. Writing the report showed me the enormous leaps of faith on which climate models are based. No-one had previously identified this source, which could add 20 per cent to global emissions.

There are serious problems in livestock production, in animal welfare, in groundwater and atmospheric pollution. Many of the production issues can be ameliorated by engineering technology to improve management. It is axiomatic that pollution is a failure of efficiency of control. Unfortunately, the UK has systematically destroyed its research competence in this area and those of us left make a precarious existence as consultants.

Dr Toby Mottram CEng, Glasgow

It may be true that 8kg of grain is needed to produce 1kg of meat, but is that a good measure or a fair comparison? Meat has a much higher nutrient value than grain. One only has to consider the feeding habits of carnivorous and grazing animals. The thrust of the article is supported, but may I suggest a better comparison is the land area required to sustain one person given a various of dietary habits. I have little doubt meat will still be extravagant, but not by an 8:1 margin.

Alan Betts, by email

To click or not to click?

In 'Email's Worst Habits' (Vol 3, #9), Malcolm Etchells advises unsubscribing from unwanted newsletters and mailing lists. Other sources say you should never click on unsubscribe links because that will tell the sender that you actually exist. Who is correct?

Geoffrey Evans, Fellow, Digswell, Herts

Malcolm Etchells replies: "In terms of email management, my advice is to unsubscribe from email newsletters you don't want any more as long as you are 100 per cent certain that it is sent by a reputable company that will honour the unsubscribe request.

"The problem is where the user's email address may have been guessed or obtained by other means. In this case, I would recommend filtering the emails into the junk folder automatically. It is good practice to set up a free Web-based email account to use when an address is requested for subscription on Internet sites."

Maglev comes down to earth

In his enthusiastic support for Maglev, Dr Stephen Gergely (Vol 3, #10) suggests that such a system would offer immense advantages over the use of conventional steel wheel on rail by virtue of its inherent ability to control the horizontal forces on the maglev vehicle.

I am intrigued as to the means of securing such control following a catastrophic failure of the battery back-up power supply on the vehicle or of an uncontrolled de-levitation.

The prototype Maglev systems have landing skids to allow them to land safely in such an event. I assume that while the rate of deceleration achieved during such an emergency may be high in railway terms, it would not be so high as to be hazardous to standing passengers The implication of this being that the claimed advantage for the Maglev system may be somewhat less than expected, unless the approved safety case requires that all personnel on board be strapped in for the duration of the flight.

As the unfortunate events of 22 September 2006 proved, Maglev is not immune to unfortunate incidents, and how much worse would this have been if it had occurred on a developed system with many more vehicles on the guideway operating at the close headways propounded by Dr Gergely.

John Crickett MIET, Wells, Somerset

Happy birthday, Atomium

Pelle Neroth refers to the Brussels Atomium ('Food for Thought', Vol 3, #10) as "...the giant atom-shaped monument that defines the city". Define the city it may do: 'atom-shaped' it is not. The Atomium represents the body-centred-cubic (bcc) crystal lattice, something any student of metallurgy (such as myself) or crystallography would recognise.

The designer, André Waterkeyn, apparently based his design on the unit structure of iron which is a bcc lattice. The structure, built for Expo '58, the 1958 Brussels World Fair and, recently refurbished, celebrates its 50th birthday this year.

Tim Feest, Farnborough, Hants


The famous equation stated by Einstein that equates energy and mass, shows the two are interchangeable concepts, but not in the way Jack Donald seems to envisage in his letter about teleportation (Vol 3, #10). Mass does not have 'radiation elements', in the way that the signal representing a television picture has certain well-characterised frequency components, and so cannot be reduced to them.

Most importantly though, and key to any scheme of teleportation, is that the information in an object, not the actual 'material'. Teleportation has already been achieved, though admittedly on a rather small scale, by the use of quantum-entangled photons, but it is not the photon itself that is transported rather the information about it (implicit in the two being quantum entangled). It's the information in an object that tells you what you must re-build, not the material of which it is constructed. The transmission of this information is relatively simple in the case of a single photon but to do so for a macroscopic object might be a tad trickier!

Stephen P Holmes MIEE, MInstP, Laxfield, Suffolk

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