Good article. I've been threatening to write about this for a while now but I kep getting distracted.

Local microgeneration of DC power is the only way to go. Wind/water/solar/tidal generators on massive scale combined with a lower usage, decommisioning of all existing powerplants. This is due to both power line loss, the waste and atmospheric pollution and climate change this causes, and the resultant illnesses caused by electromagnetic radiation. Tesla was wrong, Edison was right, DC power doesn't produce any magentic fields. It is corporate bullshit to suggest this couldn't be achieved in the next year if people genuinely prioritised future generations over their own personal comforts and profits. Atomkraft nein danke.

Secondly, lots of people complain about the 'blight on the landscape' overhead pylons and demand underground cables. From what I've been reading underground cables are even more dangerous than overhead cables for a simple reason - they tend to be closer to you. This has been known since the 60's and publicised since the 70's and yet things just keep getting worse. It is almost the definition of capitalism, short term profit over long term survival.

'DC power doesn't produce any magentic fields'.

The magnetic field around a wire is directly proportional to the current through it, irrespective of the voltage.

And DC is not the way to go. DC voltages are fixed and difficult to change. AC voltages can be converted to any other voltage very easily.

Nor is microgeneration the way to go. Large power stations are intrisincally more efficient, which is why they were built in the first place.

And to webber: 'To generate the higher voltages requires more fuel.' Not true. I think you are confusing voltage and power. You don't generate particualrly high voltages, you step up or down existing voltages using transformers.

Fine generatoring your power if you have a stream nearby. And if you don't?

the amount of steam pressure required to turn a turbine at the revolutions needed to generate x amount of voltage is proportional to the fuel.If you use your argument then transformermational is microgenerational.

"The magnetic field around a wire is directly proportional to the current through it, irrespective of the voltage."

Doh. Static elector-magnetic fields aren't harmful to life any more than magnets are. The fields that 50-60hz AC electricity gives off are.

"And DC is not the way to go. DC voltages are fixed and difficult to change. "

That is meaningless. You haven't heard of DC to DC Coverters ? You give me any DC input voltage I've give you a simple circuit for any output votlage you wish. Physicist my arse - I learned more than you by the time I was in third year at school.

"AC voltages can be converted to any other voltage very easily."
See previous answer.

"Nor is microgeneration the way to go. Large power stations are intrisincally more efficient, which is why they were built in the first place."

Bullshit detector goes off the scale and damn, you broke my bullshit detector. The article above quotes powerline loss at 20% due to the inefficency of the powerlines as conductors ( you know what a conductor right ? you have heard of impedance yeah ? ). I'd go for a more conservative 8-12% but the point is the same - a large percentage of the power you generate in a distant powerstation is thrown away before it even gets to your town. The closer to home you produce the power the lower the losses. And look at my comment - was I suggesting we all have mini-nuclear power stations or coal-fired turbines in our homes ? You are not comparing like with like. And even comparing like with like, it obviously makes more sense to have a wind-generator ( or whatever ) closer to the load.

"Fine generatoring your power if you have a stream nearby. And if you don't?"
Each house having it's own wood-burning stove, ground source heat pump, solar panels, etc backed up by a communal sytem of renewable generators backed up by a much didminished national grid. This is perfectly feasible and only an expensive solution because too few of these devices are made currently because most of industry is building 'necessities'

steam pressure is irrelevant - mass of steam required is the important factor.

you can, of course, increase the thermodymanic efficiency by using steam at a higher temperature and pressure, which means bigger boilers, hence more efficient on a large scale.

voltage again is irrelevent, and pressure x voltage is quite meaningless.

still co-efficents to fuel.you do not get something for nothing.MI5 should employ the educated.Oh the educated would not work for them.

dc to dc converters are hideously inefficient [they work by making a form of ac, tranforming it, then rectifying it]. transformers are not.

proof that 50Hz magnetic fields are dangerous? that's why all the birds that sit on power lines drop dead, is it?

wood burning stoves - really useful in high rise blocks of flats. ditto ground source heat pump. solar cells - just the thing in the uk in winter.

>dc to dc converters are hideously inefficient [they work by making a form of ac, tranforming it, then rectifying it]. transformers are not.

Yeah, I used to design them for Burr-Brown you patronising idiot, and that isn't necessarily true. Anyway you don't need DC-DC convertors. You can have multiple DC generators. You can design most devices that are currently used to run off a standard 12 V DC. Now if we could only harness the amount of hot air you produce we'd be self-sufficent already.

>proof that 50Hz magnetic fields are dangerous? that's why all the birds that sit on power lines drop dead, is it?

You know I lived in Skye, in a wonderful house that generated it's own DC electricity by the way, and I volunteered for the RSPB. We found one eagle, two buzzards and a few other 'less important' birds in a single day, dead under power-lines with no sign of burns. You can laugh but that is because your knowledge and experience are laughable. When did childhood leukemia begin ? What coincided with that ?

>wood burning stoves - really useful in high rise blocks of flats. ditto ground source heat pump. solar cells - just the thing in the uk in winter.

A wood-burning stove can heat an entire block of flats. They do in Finland.

A ground-source heat pump can heat an entire block of flats. They do in many countries.

Solar cells still produce power in winter.

You claim to be a physicist but you don't have even the basic understanding of the subjects you calim to be an expert in. Can I ask what level of qualification you have in what subject, and what experience you have ? Because a 'fizzy cyst' seems to be closer to the mark.

[ http://www.guardian.co.uk/medicine/story/0,,2067556,00.html'
Ban on homes close to pylons would cut child leukaemia says report'
Saturday April 28, 2007 The Guardian]

I'm not massively following who's right or wrong in the discussion above, perhaps it's due to the various pseudonyms.

For anyone interested in microgeneration I've been working on a wind turbine project for the last year following in the footsteps of Hugh Piggott of Scoraig Wind. Well worth a look - www.scoraigwind.co.uk

Now, just being a mere ex-electronic tech, and not an esteemed 'physicist', I am curious as to how someone so self-promoting and 'scientific' could call a DC-DC convertor, with a ineffeciency of less than 5% 'hideously inefficient' could defend a AC power system with power line losses of over 7% ( and from my personal work experience that is a big underestimate).

The main technical point is you don't need DC-DC convertors at all if you design the load equipment to run on a standard voltage voltage as happens just now with '240V' kit, but even if you do then it is still more efficent.

The main health point is DC EMF doesn't kill kids ( and birds etc) , AC EMF does.

The main anarchist point is when ever someone who knows squat but claims to be an expert and starts patronising you, you should rub their nose in their own shit so that they don't do it again.

So come on Physicist, take offence, state your qualifications and experience, explain your previous basic blunders in argument. Or to put it politely, let us have a technical discussion. Cos you are faking it and it showed from your first post. Now I apologise if you are a thirteen year old child who is looking for some free education. That certainly seems likely. But kid, you shouldn't really call yourself 'physicist' until you actaully pass a physics exam, and even then, wait until you have a bit of real life experience. And if you ever want to patronise someone again, try and read up on the subject first eh ?


"Physicist" "Architect" "Scientist" - aye, right, and I'm the King of France.




 http://www.maxim-ic.com/appnotes.cfm/appnote_number/3166

DC-DC converters, common in battery-driven, portable, and other high-efficiency systems, can deliver efficiencies greater than 95% while boosting, reducing, or inverting supply voltages. Resistance in the power source is one of the most important factors that can limit efficiency.


 http://en.wikipedia.org/wiki/Electric_power_transmission

Losses

Transmitting electricity at high voltage reduces the fraction of energy lost to Joule heating. For a given amount of power, a higher voltage reduces the current and thus the resistive losses in the conductor. Long distance transmission is typically done with overhead lines at voltages of 110 to 1200 kV. However, at extremely high voltages, more than 2000 kV between conductor and ground, corona discharge losses are so large that they can offset the lower resistance loss in the line conductors.

Transmission and distribution losses in the USA were estimated at 7.2% in 1995 [2], and in the UK at 7.4% in 1998. [3]

In an alternating current transmission line, the inductance and capacitance of the line conductors can be significant. The currents that flow in these components of transmission line impedance constitute reactive power, which transmits no energy to the load. Reactive current flow causes extra losses in the transmission circuit. The ratio of real power (transmitted to the load) to apparent power is the power factor. As reactive current increases, the reactive power increases and the power factor decreases. For systems with low power factors, losses are higher than for systems with high power factors. Utilities add capacitor banks and other components throughout the system—such as phase-shifting transformers, static VAr compensators, and flexible AC transmission systems (FACTS)—to control reactive power flow for reduction of losses and stabilization of system voltage.

Electrical power is always partially lost by transmission. This applies to short distances such as between components on a printed circuit board as well as to cross country high voltage lines. Power lost is proportional to the resistance of the wire and the square of the current.

Ploss = RI2

For a system which delivers a certain amount of power, P, over a particular voltage, V, the current flowing through the cables is given by I = \frac{P}{V}. Thus, the power lost in the lines, P_{loss} = R I^2 = R (\frac{P}{V})^2 = \frac{R P^2}{V^2}.

Therefore, the power lost is proportional to the resistance and inversely proportional to the square of the voltage. A higher transmission voltage reduces the current and thus the power lost during transmission.


Health concerns

There are a number of health concerns that are implicated with proximity to Powerlines, or, more accurately, exposure to elevated levels of ELF magnetic fields. These include, but are not limited to, Childhood Leukemia, Adult Leukemia, Amyotrophic Lateral Sclerosis, Miscarriage, and Clinical Depression.

[edit] Leukemia and Cancer

In 2001, Ahlbom et al conducted a review into EMFs and Health, and found that there was a doubling in Childhood Leukemia for magnetic fields of over 0.4 µT, though importantly summarised that "This is difficult to interpret in the absence of a known mechanism or reproducible experimental support".[3] In 2007, the UK Health Protection Agency produced a paper showing that 43% of homes with magnetic fields of over 0.4 µT are associated with overground or underground circuits of 132 kV and above.[4]

Ahlbom's findings were echoed by Draper et al in 2005 when a 70% increase was found in Childhood Leukaemia for those living within 200m of an overhead transmission line, and a 23% increase for those living between 200 and 600m. Both of these results were statistically significant.[5] The authors considered it unlikely that the increase between 200m and 600m is related to magnetic fields as they are well below 0.4 µT at this distance. Bristol University (UK) has published work on a theory that could account for this increase, and would also provide a potential mechanism.[6] [7]

The World Health Organisation factsheet on ELF (Extremely low frequency) EMFs and cancer concludes that they are "possibly carcinogenic", based primarily on IARC's similar evaluation with respect to childhood leukemia. It also stated that there was "insufficient" data to draw any conclusions on other cancers.[8] It is important to note that this factsheet was written in October 2001, and is now largely out of date due to the increase in the scientific literature since then.

[edit] Other Health Concerns

The California Department of Health produced a report in 2002 from their California EMF program, set up to review the health effects from electric and magnetic fields from powerlines, wiring, and appliances. They concluded that EMFs were responsible for an increase in Childhood Leukemia, Adult Brain Cancer, Lou Gehrig's Disease, and miscarriage.[9] This is in disagreement with a review by the International Agency for Research on Cancer in 2001, and the NRPB (National Radiological Protection Board, now part of the UK Health Protection Agency) review in the same year. The reasoning given was that "there were reasons why animal and test tube experiments might have failed to pick up a mechanism or a health problem; hence, the absence of much support from such animal and test tube studies did not reduce their confidence much or lead them to strongly distrust epidemiological evidence from statistical studies in human populations. They therefore had more faith in the quality of the epidemiological studies in human populations and hence gave more credence to them."

However, the California report concluded that they did not find there was a strong enough association between EMFs and birth defects and low birth weight, and were divided on the evidence for suicide and adult leukemia.

[edit] UK SAGE Report

The Stakeholder Advisory Group on ELF EMFs (SAGE) has been set up by the UK Department of Health to explore the implications and to make practical recommendations for a precautionary approach to power frequency electric and magnetic fields as a result of the HPA recommendations in March 2004.

The first interim assessment of this group was released in April 2007, and found that the link between proximity to powerlines and Childhood Leukemia was sufficient to involve a precautionary recommendation, including an option to underground new build powerlines where possible and to prevent the building of new residential buildings within 60m of existing powerlines.

It is important to note that the latter of these options was not an official recommendation to government as the cost-benefit analysis based on the increased risk for childhood leukemia alone was considered insufficient to warrant it. The option was considered necessary for inclusion as, if found to be real, the weaker association with other health effects would make it worth implementing.[10]

All power to you, if you forgive the pun. My last comment was posted before I had read yours. I've twice been invited to Scoraig and still haven't yet made the trek/pilgramage. It sounds the most amazing place, and a lot of good innovations get posted from there.

On a personal note, did you meet the nice French couple, Mathiew and Talita who visited last year ? They loved it there.

A quote from your reference:

'DC-DC converters are most efficient when the input voltage is closest to the output voltage.'

which, sadly, is not the case for power lines. There you want the current as low as possible [I^2R] and thus the voltage as high as possible.

12V for the home? For heaters? For kettles? For the TV? Any device rated more than 120W is going to struggle - it would need 10A current supply. Even a desktop computer would be drawing more than 10A at 12V.

Qualifications? Oh, teaching physics and chemistry to A level for 35 years.

"which, sadly, is not the case for power lines. There you want the current as low as possible [I^2R] and thus the voltage as high as possible."

Thus local micro-generation obviating the need for power lines.

>12V for the home? For heaters? For kettles? For the TV? Any device rated more than 120W is going to struggle - it would need 10A current supply. Even a desktop computer would be drawing more than 10A at 12V.

Again, you might notice I was recommending a combination of generators to reduce the amount for large distant powerstations. The ground heat extractor and the wood burner are capable of heating an entire street as in the Finnish example I gave where people pay a flat rate for their hot water and central heating. And yes, 12v wind and solar micro-generators are more than capable of supply lighting and TV and PC usage when these devices are properly designed to do so.

>Qualifications? Oh, teaching physics and chemistry to A level for 35 years.
That explains why you talk to us as if we were uneducated children. Don't you think 'Physicist' is a bit grand a pseudomyn for a school teacher with no practical or inductrial experience in the subject - not exactly an Einstein are you ? Admit it, you were thinking of linear regulators when you came out with your 'hideously inefficent' statement weren't you ? With patronising and uneducated people like you in schools, no wonder the sciences have been in decline in the UK for the past 30 years.

you seem to ignore the basics.

Wood burning in Finland - jolly good. Now let's see - look at all the forests round Manchester, just ready and waiting to be cut down and fed into those furnaces ... perhaps a bit of education might have done you some good.

The type of appliance that can be run from 12V probably represent about 1% of the total energy use of any house. And forget houses - you're going to run office blocks off wood burning furnaces and solar panels? Factories? The amount of sunlight received in Glasgow in December is probably less than your IQ. Ah, wind generators - and then we get a nice anticyclone - frost at night and no energy. Any other 'renewables' you have in mind?

work together on this.

Why don’t we use 110 volts in our homes instead of 240?

Assuming that's a serious comment, then:

It's helpful to keep current in wires as small as possible, else the wires need to be much thicker. For a given amount of power, you can have a high voltage and low current, or vice versa. The drawback to a high voltage is safety: if by any chance you touch a live wire, you will get a shock, and the higher the voltage, the greater the chance of being killed.

240V is reckoned to be safe, although the US uses 110V. this means that electric kettles, for example, either have to be lower powered or use a much bigger current. The UK uses cabling which is reckoned to be safe up to 13A, a kettle might use 8-10A. An equivalent kettle in the US would then need around 20A.

Another issue is flex. Solid wires are better for high currents, but wires of that thickness do not easily bend [and once bent, will tend to stay bent]. UK mains leads are made of many separate strands and so are flexible [are for safety reasons, are double insulated - i.e., have one insulation layer round each conductor, then a second insulation layer around the three conductors].

"Come on lads work together on this."

I presume you are talking to me and the 'phyicist' teacher ( obviously English wasn't one of his subjects) . I am unsure how to 'work together' with someone so arrogant and yet ignorant. Do you want me to continue to teach him elementary electronics that he clearly doesn't understand but claims to be an expert in ? Have you never heard the quote “Never try to teach a pig to sing; it wastes your time and it annoys the pig.” I have one annoyed pig on my hands now and better things to do with my time. After 35 years misteaching children he is bound to be about retired so there is very damage he can still do. He isn't just arguing - without any technical experience or understanding, without any serious educational qualification, and most seriously without any workplace experience against the feasibility of proven and unavoidable renewable technologies, he is talking down to someone who does have these things. He has been conditioned into talking down to children as inferiors and now he has been exposed as fraud talking down to someone who knows far more than he ever will in his chosen speciality. Miseducation, miseducation, miseducation.

So I'm not going to try to teach that pig to sing. I have the greatest respect for the man from Scoraig, because I know Scoraig isn't connected to the grid, I know they have innovators there. Maybe the man from Scoraig would be happy and forgiving enough to educate our uneducated pensioner-teacher with delusions of competence, but me, nah. I would like to point out he sounds just like the faker who used to post as 'scientist'. Oh, and he sounds just like the Chemistry teacher at my school who killed his wife by mis-wiring their house.

Now if anyone here who has any experience in power theory or electonics or emf health risks or renewables or global warming want to dicuss somtehing with me, then fair enough. And if I ever want any advice how to control an unruly class of teenagers, I'll submit to the resident expert on that.

the danny dost protest too much

"Me thinks the danny dost protest too much"

Should read "The lady doth protest too much, methinks." Doth, not dost. Might've been 'dost' if you hadn't added the 'the' to Danny. Shakespeares Hamlet - I wonder when they stopped teaching that in English schools ? Truth is I probably don't protest enough since I am stuck here giving lessons in Electronics and now Shakepearean Grammar to 6th formers pretending to be teachers pretending to be activists.

Your profound pretention is dangerous in one so ignorant. I guess at your age and 'social-status' you can't bear to be corrected on the basic facts, but that doesn't change the basic facts.

Not only is Danny an expert on physics, electronics, and Shakespearean quotations, he's even able to detect the age and qualifications of posters of Indymedia. Such skill! Such talent!

They're winding you up and your biting.

"They're winding you up and your biting."
Yeah, I guess 35 years talking to children must make 'physicist' close to his second childhood by now, I should humour him rather than scold him. Still, it has distracted somewhat from your sound main point "that the local generation of power is economical and is not subject to power loss." I would only add that is also an inevitablity if we wish to survive as a species.

"Nor is microgeneration the way to go. Large power stations are intrisincally more efficient, which is why they were built in the first place." - Physics Teacher.

The utility of large centralised power stations is that they have high security, not high efficiency. There is a distribution cost from generation source to consumption sink. This is not negotiated away by selecting AC or DC, it is the nature of "moving stuff" whether that stuff happens to be surly youths or "particles in a sub hadron space" (the most evocative definition of electricity I have ever heard). Consequently distributed generation is a trade off between security and distribution cost. That is where the economy of scale comes from.

If you regard security as irrelevant - and I suspect a lot of Anarchists would nod - you are left with the substitute concept of safety. Distributed Systems can have increased intrinsic, passive safety. A distributed system does not have a single point of failure - thereby localising hazards and increasing the overall system safety at the expense of localised risk. In short, it really does not matter if you generate AC or DC, if you do it locally then the aggregate system safety is increased. Security becomes lessened and the entire Energy strategy becomes less "militarised".

To illustrate the effectiveness of such a system look at the Internet and the structure it has taken. It is a distributed system with no single central server. True there are a limited number of "whole Internet" Name Servers but these cascade and update other name servers. Yet this distributed system is much more reliable, scaleable and (analogous to safety) resistant to failure than a system with a single server. So, when a server fails in the Internet, traffic routes around it. There is a slowing of traffic but it still gets through. This is the inherent, passive reliability of the Internet that translates to intrinsic passive safety for power supply.

I am arguing that Danny is wrong to throw away the national grid but right about localising generation. Which means I am arguing the Physics Teacher is wrong about Central Generation. Which may not best please him - being told he is wrong by a mere Biologist. I suspect Danny is likely to take it in better humour than Physicist who, realistically, does not think towards solutions but answering questions.

For example, the above claims are suggestive of putting solar panels onto every available sun facing surface. You can generate say a fifth of a kilowatt hour per day on average. Given an estimate of eleven Million Homes with an average of one panel each that would be almost 1.9 Giga watt hours generated per day. Thrown back onto the grid during times when each generator is not locally at peak use, this distributed system would lower the amount of central generation required.

And it would likely be a good deal safer - although less secure. Yes you can point out lots of flaws in the scheme - but at least it is a bloody damn site more constructive than bitching about AC/DC and other minutiae because someone refuses to contemplate a different world.
As a Biologist I get heartily pissed off at the endless importance of Physicists whose sole skills in the world are measuring things then hitting them until they break and measuring again. It does not impart any viewpoint other than the immeasurable is inexistent. The original article by Webber was a good deal more interesting and deserves constructive commentary rather than the ego driven bollocks of rehashing the particulars of the Edison-Tesla dispute. Yes, power transmission costs energy, AC or DC, now get over it and make a reasoned, relevant, contribution or shush. (Yes, transmission and distribution is relevant but it is not the sole substance of the original article).

In retrospect not all Physicists are egocentric - just the egocentrical ones.

"I am arguing that Danny is wrong to throw away the national grid but right about localising generation. Which means I am arguing the Physics Teacher is wrong about Central Generation. Which may not best please him - being told he is wrong by a mere Biologist. I suspect Danny is likely to take it in better humour than Physicist who, realistically, does not think towards solutions but answering questions."

I have always had the greatest respect for biologists ! Simply as I know nothing about the subject...The genome is the library, the chromosome is the book, the gene is the page, and the words only consist of 4 letters...mutations are typos...or something like that. Don't try to explain to me.

I would like to point out though that I wasn't arguing for throwing away the national grid, just for supplimenting it with local micro-generators that would reduce the amount of electricity transmitted over it from fewer centralised power stations. This argument isn't even anti-nuclear necessarily - if you want a tiny nuclear generator in your kitchen and are prepared to bury the waste in your back-garden, then fair enough, just don't move into my neighborhood. I think most people would choose a 'not-in-my-back-yard' solutions though in this case, such as renewables.

Biologist, I've been following the debate on biodiesel, and while I decry the deforestation of rainforests to produce palm oil, and the voracious increase in corn-to-ethanol production, I am interested in the concept of grasses being used to produce fuel. I don't understand though, is there an efficent mechanism to convert the energy in cellulose to make a carbon-negative fuel as implied by these two links ?

 http://environment.newscientist.com/channel/earth/dn10759-humble-grasses-may-be-the-best-source-of-biofuel-.html
 http://www.reap-canada.com/bio_and_climate_3_2.htm