Monday, June 23, 2008

I DO advocate switching off electrical gadgets on standby


Well, well, it's been an interesting few days... Since The Register posted an article about my draft book, I've received a flood of emails, and been shocked to observe the cacophony of people on blogs and bulletin boards all debating 'what the Professor said', plopping me in one camp or another of their running battles.

I'd like to make one suggestion to everyone: if you want to discuss what I said in the book, please read the book!.

Some readers seem to think that whatever the journalist wrote, I said. For example his introduction said that most people 'have no need to worry about the energy they use to power their electronics; it’s insignificant compared to the other things'. That was the journalist, not me! This attitude to standby power has provoked the mob to get out their flame-throwers, saying 'MacKay should know that 8% of all domestic electricity goes to power junk on standby!' Sigh!

For the record, here is my domestic electricity consumption for the last few years.
I started paying attention to my electricity consumption in 2007. I started switching off all my stereos, answering machines, cable modem, wireless, and so forth, in mid-2007. I am happy to confirm that switching off these vampires has reduced my domestic electricity consumption from roughly 4 kWh/d to below 2 kWh/d. This is an energy saving well worth making; I encourage everyone to bye-bye their standby, and read their meters to see the difference it makes.

39 comments:

Ryan said...

2 KWH/Day? I'm curious how big your house is. Is that for you, or per person in your household? Granted, I'm in the US (which you seem to have blasted in terms of our energy usage ;)) but some quick calculations based on spring energy usage show my wife and I using around 20KWH/day for our house... and that's the low point in the year. Do you have gas used for water/central heating and cooking? If so, shouldn't that be factored into your daily energy usage?

Patrick said...

I'm up to page 203.

Looking over my electric bills, my (2 person) household electric usage varies between 10KWH/day to 33KWH/day (High summer with A/C running to keep the house cooled to 25°C, a temperature I suspect a Briton would find uncomfortably hot)
Our summers are hot, and our winters are cold, here in Chicago. There's no way that my household's energy footprint would be comparable to that of a household in the UK with its comparatively milder climate.

That said, our sustainable energy alternatives in Illinois are fewer than those of the UK; no tides, no hydro power (no highlands), not much wind, cloudy winters, next to no oil, and only some very dirty coal. We do have a bunch of Nuclear Reactors; none recently built.

Mike said...

At 2 kWh/day I would assume that you are using natural gas for the water heater, the stove, and so forth.

In my modest all electric home in Phoenix my daily electric usage is around 100 kWh/day in the summer. It drops down to about 40% of that during the winter. I cool the house with a 60 kbtu/hr heat pump. I also have an electric water heater (I wish that someone would start selling a heat pump water heater), a electric dryer (another heat pump candidate), an electric stove, 2 PC's and a small swimming pool. The house is well insulated, the heat pump hqw decent efficiency (13 SEER) and I only use compact fluorescent bulbs.

Regards,
Mike

Damon said...

At home in London our family of 3 uses <6kWh/day electricity even ignoring our PV microgeneration:

http://www.earth.org.uk/saving-electricity.html

Yes, we have mains gas for hot water and space heating and cooking, but total gas consumption for that is <10kWh/day at the moment.

We have no other primary energy source.

It can be done, and it isn't all knitting yoghurt in the dark and cold! B^>

Rgds

Damon

PS. Finished the book!

John said...

Part of the problem here is that people want all or nothing answers. Sure some appliances do eat a bit on standby but as you proved on the phone charger exercise, many do not to any meaningful extent. However many people believe that if they see a red light on something it is worth switching off when we are actually talking about a few mW.

There seems to be a lot more focus on this than trying to get people to reduce the number of cups of tea people drink which would do a lot more to cut consumption.

Andrew S said...

The figures which are quoted for "typical" consumption for price comparison purposes in the UK(presumably Government stipulated) are:
4600kWh electricity annually
20500kWh gas annually
these are per household. I don't know whether they are mean, median etc.

In my modest terrace, we use about 3000kWh electricity and 11300kWh gas annually, with occupancy of 2-3 people. (about 3kWh/day/person electricity and 11.5kWh/day/person gas - averaged over the year)


You have to look at the Governments' housebuilding program and ask how flats and single-occupancy homes fit in to low-energy debates. Since energy for heating and lighting is mostly a fixed cost for a given building, a high number of occupants per dwelling is preferable (both for the enviroment and your wallet).

Andrew S said...

There's some Government figures for energy use, broken down by region of the UK, at

http://www.berr.gov.uk/files/file20328.pdf

Ryan said...

I feel better now, factoring in climate issues (I'm in Texas, we regularly hit 100 days a year 90F+) and natural gas consumption. We have a heat pump for use in the winter, and keep the AC at 84 during the day during the summer. The dogs don't appreciate it much, but it's better than sitting outside in 100F+ heat. 2KWH per day just seemed completely unreasonable.

tez said...

Hey, it could have been worse - you could have come out with an overt pro-nuclear label which would really bring out the knives from a number of lobbies.

This is such a touchy subject that you are bound to be misrepresented (even innocently). It does not help that there seem to be plenty of statistics available that will either support or contridict any argument you may wish to make.


I'm getting through the book and have a number of questions though once I get them down on paper

Richard said...

PS. Two questions

When is the "without hot air" book due out in print / is the web version now the final draft?

Can you make the talk that accompanies your slides available on the web, eg. via Google Video. Are you giving presentations on this topic in the near future?

Patrick said...
This comment has been removed by a blog administrator.
David MacKay said...

Ryan said "do you use gas for heating?" The answer is yes. "Shouldn't that be factored in?" NO, because this was a blog post about SWITCHING OFF ELECTRICAL DEVICES, not an article about "look how small my total domestic footprint is". But since you ask, my total (average year round) energy consumption in my house is 15 kWh per day - that's 13 kWh per day of gas and 2 kWh per day of electricity. I live alone and the floor area of my house is 88 square meters.

David Crookes said...

I just timed myself doing the switch off process, it took 1 minute. So that's two minutes a day, to allow for switch on, and this is generous, since switch on could result in thumb twiddling whilst things boot themselves.

The median household income for a house like mine (2 parents, 2 kids) is about 45k a year, last time I checked. So that income is interchangeable with approximately 260 days of 8 hours work, or ~21 pounds an hour, and more precisely it comes to 72p for every 2 minutes of median family work-life. To get 2 minutes more spare time, costs 72p. This 72p, according to my recent electricity bill buys me 72p/10.5p per kWh ~= 7 kWh a day.

i.e. it's a waste of time for my household to switch off these things, to get the 2 kWh saving Dave's post suggests. It starts to looks maybe worth the time if we see the median household income drop by a factor of 3 or so.

So, feel free to waste valuable time saving energy, but personally, I see that time is running out, yet there's no shortage of energy that can be bought at present prices. When the price changes, I'll worry, but we will need a tripling of electricity costs to start to care.

David Crookes said...

Some adjustments to my previous post. I assumed the yearly working time incorrectly, 260 days * 8 hours is a standard working year for one person only, and the median household discussed probably does more than that. How much is tricky to determine. If we assume both adults work full time, then it halves the 7 kWh to 3.5... However, I don't think this is representative of such households, from memory, with women in the household generally doing part-time work.

However, 45k a year for a household could be seen as 22.5k a year per adult in the household, and that maps well to the median income for the UK, so perhaps 3.5 kWh is a suitable cost for 2 minutes of time a day. Still, 3.5 kWh validates my argument, if I'd save 2 kWh from the power down. If I saved 3.5 kWh from the 2 minutes a day, I'm still only breaking even.

Charlie Stross performs a similar calculation here and finds the time not worth it either.

Beast said...

I began reading your book courtesy of The Register article. Page 199 so far ...

"I'd like to make one suggestion to everyone: if you want to discuss what I said in the book, please read the book!."

Exactly. About two years ago, I woke up to the whole climate change thing, followed by peak oil 6 to 8 months later.

At one point I noticed that, apparently, the whole discussion about AGM had become "politicised". But it had become so because people were arguing with each other based on what journalists said, or their interviewees said.

I say, go and get as close to the data as you can.

Beast said...

david crookes made a couple of comments about how it was not worth his/ her time to switch off stuff that is on standby.

"... To get 2 minutes more spare time, costs 72p..."

That reminds me of the one about how Bill Gates is so rich that if he drops less than $500 it's not worth his time to pick it up.

I don't understand the logic of the argument. What if you switch off the stuff during your free time? You're not paid for your free time, so you would be making a direct saving of 72p.

David Crookes said...

Beast asks:

What if you switch off the stuff during your free time? You're not paid for your free time, so you would be making a direct saving of 72p.

I am paid for my free time, in the sense that if I want an extra day of free time in life, I can swap my salary pro-rata for that day, up to a contractual limit in my T&C's of employment. Similarly in the other direction, I can sell a proportion of my holiday time, and work those days.

So at the margin, time is money, for me, and for most people who work. Ask anyone who works if they are willing to sacrifice a day holiday for no perceived benefit.

So if someone advocates I should spend my free time in one activity, displacing my normal free time activities, I have to value the new activity more than the displaced activity, in some way. For activities that have little emotional appeal, I tend to think, "What's this worth to me?". Life is short, is it not? Time is the scarce resource. If I felt good about powering down many items to save 2kWh a day, I might do it with no concern for the value of my time. But, frankly, I don't really see the point of saving 2kWh a day. I'd rather spend time debating the matter on blogs. That is something that is fun. Some people see that stance as a moral issue, but I see the energy sustainability issue as an economic issue, and the economics of 2kWh a day are insignificant at a certain cost of time.

Damon said...

DC, that comes down to saying that you cannot be bothered to avoid wasting more energy per day than much of the world's population even has access to?

So if your electricity supply over (say) 500kWh/month was taxed so as to give a 4-fold cost increase over the first units, it would suddenly be worth your while but nothing else has changed?

It's an ethical issue (not moral unless you believe in God) unless you feel it also OK to throw your litter on the ground and dump your engine oil in the nearest drain because of the time it would otherwise take you to DoTheRightThing(TM) being too valuable. Easily-avoidable energy waste is essentially equivalent to reckless pollution of our shared environment IMHO.

Rgds

Damon

Beast said...

Some people see that stance as a moral issue, but I see the energy sustainability issue as an economic issue, and the economics of 2kWh a day are insignificant at a certain cost of time.
I respect your viewpoint. But I don't agree with it. The world described by economics is not a very rich or accurate one unfortunately.

Economics is hardly even a science. And its explanatory power is quite limited. it has no equivalent to physic's conservation laws, Quantum Theory or General Relativity, nor Biology's Theory of Evolution.

It is energy, not money, that makes the world go around.

David Crookes said...

Damon says:

that comes down to saying that you cannot be bothered to avoid wasting more energy per day than much of the world's population even has access to?

The word "waste" represents is a value judgement, or a moral point of view. Wasting energy in this instance has a cost to me. I am happy to pay that cost. Some would also claim it has a cost to others (e.g. CO2 emissions, etc.). Fair enough, but the cost to others can be accommodated by typical public good type actions, e.g taxing the emissions associated with the energy. This is happening to some degree, and will probably increase in the future.

As regards the difference between my ability to afford huge amounts of electricity c.f. the rest of the world, so what? Most in the UK are in the top 10% of global wealth (I'm being care free with the numbers, but look up, say, benefit level income against global wealth). I am just lucky I was born here. What can we do about that apart from encourage the other 90% to grow their wealth? Wealth is not a fixed sum game.

So if your electricity supply over (say) 500kWh/month was taxed so as to give a 4-fold cost increase over the first units, it would suddenly be worth your while but nothing else has changed?

Yes. That is marginal thinking and is exactly right. If the cost at the margin quadruples, all my previous calculations quadruple or quarter at the margin.

It's an ethical issue (not moral unless you believe in God) unless you feel it also OK to throw your litter on the ground and dump your engine oil in the nearest drain because of the time it would otherwise take you to DoTheRightThing(TM) being too valuable.

You're associating two very different actions, which have their own costs/benefit set-ups, with my 2kWh a day wastage. I don't accept the association at all.

The fact that they are so different doesn't support the ethical position, which re-stated is, oil dumping is bad, so all waste is bad. Do you really believe they are morally equivalent?

Easily-avoidable energy waste is essentially equivalent to reckless pollution of our shared environment IMHO.

If you truly see them as equivalent, I find your moral view is out of kilter with most people.

For example, I will admit to all authorities that I waste 2 kWh a day in electricity. Most would think I'm weird for wasting their time. But if I admitted to dumping engine oils down the drain, I'd expect to be fined, punished etc. since society as a whole recognises this is a worse thing, has a large cost and I should be forced to pay that cost and extra to deter future polluters.

Still, your morals are your own and you are free to act upon them, saving 2 kWh a day since it's morally the equivalent of dumping engine oil down a local drain.

Me, my moral position is different and I'm free to act accordingly. I think most people are towards my point of view.

David Crookes said...

Beast says:

I respect your viewpoint. But I don't agree with it. The world described by economics is not a very rich or accurate one unfortunately.

I disagree, though perhaps our concept of economics differs.

Economics is hardly even a science. And its explanatory power is quite limited. it has no equivalent to physic's conservation laws, Quantum Theory or General Relativity, nor Biology's Theory of Evolution.

Well, I think you're being unfair to economics here. Economics is hard, because economics is largely about large collections of humans, who are extremely complicated creatures. The idea simple laws could be extracted from this, as per other physical theories, is perhaps the wrong expectation.

It is energy, not money, that makes the world go around.

I disagree. The oil we burn today was there before 1800, but had a very different value. Refined uranium is vastly more valuable today, than it would have been to a Roman.

The energy we use today is intimately tied to money.

Paul said...

"Wealth is not a fixed sum game"

What kind of game is capitalism/wealth/economics?

Isn't it based on the extraction of resources and conversion into liquid assets (ie - wealth)?

When the resources run out, what happens to the game and the players? Who will be the winners and who will be the losers? How do you quantify that?

David Crookes said...

Paul says:

What kind of game is capitalism/wealth/economics?

Non-fixed sum in my view, for the future anyhow. Mankind hasn't come close to peaking in development in my view.

Isn't it based on the extraction of resources and conversion into liquid assets (ie - wealth)?

No, not really. I suggest reading this but also other economics tracts. I take an optimistic view, as exemplified by people like Julian Simon and others. I think humans have yet to reach their technological potential and I think more wealth is to be gained and everyone who is able to join the game will see their wealth grow. The people who tend to lose tend to be oppressed. I take the William Easterly view on that, but if you read around "wealth development" type literature there is much interesting debate.

When the resources run out, what happens to the game and the players? Who will be the winners and who will be the losers? How do you quantify that?

The resources won't run out, for a very long time, in my view. As in, millenia. I feel very optimistic about the future. For most people on the planet, as well. Of course, huge problems remain for the poorest, but it's not the wealthy that prevents them rising. The wealthy do try and help. Some say we do the wrong thing, but I think the intent does exist. These are not clear matters, otherwise why so much debate?

Paul said...

I will read those links thanks.

I was actually thinking about the social mobility stats for the UK when I wrote that question. I saw an animated graph on the BBC's Politics Show a couple of Sundays ago. The bulk of the people have remained 'immobile' in a big blob on the left, while a single column of *very* wealthy people all the way over on the right has risen dramatically upwards and continues to do so.

Also - back to game theory - isn't there something of the prisoner's dilemma in both environmentalism and economics..?

When I refer to resources running out, I am of course referring to oil and other fossil fuels.

I understand that some people believe that we will be able to swap (in economic terms) the riches of oil for those of nuclear and hydrogen based riches, and allow the 'game' to continue for a few more centuries...

Damon said...

BTW, now featured on TreeHugger:

http://www.treehugger.com/files/2008/07/one_year_cell_p.php

Rgds

Damon

David Crookes said...

Paul said:

The bulk of the people have remained 'immobile' in a big blob on the left, while a single column of *very* wealthy people all the way over on the right has risen dramatically upwards and continues to do so.

Do you mean hear that they were indicating perhaps earnings/wealth, with lower levels being static, and higher levels shifting up? I am aware of this argument for US data, not so certain w.r.t the UK. Economists don't entirely agree with each other on the measurements here. I've heard argument from some that the use of earnings or share of GDP doesn't measure improvements in life comprehensively. For example, 200 quids worth of TV now is seen as equivalent to 200 quids worth of TV in 1970s, but this doesn't make sense to some. Economists are attempting to deal with this with so called hedonic measures of inflation. So this issue within a nation is not clearcut.

Also, the timeframe here is important. Over the very long run, e.g. generational timescales, it's hard to argue that the poorest in the UK haven't seen improvements in welfare, though I suspect over a decadal level, things might have stalled. However, there are other issues here since some claim that there are diminishing returns to wealth (see Easterlin paradox) However, this is becoming disputed. Let's say the question is somewhat open. So perhaps economically, the goal is to pull people out of poverty at a comfort level, i.e everyone is fed, sheltered, healthcare etc.

Also - back to game theory - isn't there something of the prisoner's dilemma in both environmentalism and economics..?

But the solution here is co-operation, which many people are trying to foster. I doubt the prisoner's dilemma covers the scenario suitably anyhow, since it's so basic.

When I refer to resources running out, I am of course referring to oil and other fossil fuels.

But here, we have a mechanism to deal with this. It's called prices. Prices will rise, and so either investment to discover/extract more will be made, and if it really has run out, and extracting more is unfeasible economically, the prices will rise a lot. High prices will shift spending and investment onto alternatives. The important thing is that these price signals are allowed to propagate. At the moment, may users of oil are protected from price signals, with many government subsidising the prices, notably China. Also, investment in getting more oil is made inefficient, since most of the world's oil is not really produced by market based organisations but generally by authoritarian regimes (Sauds, Russia, Venezuala) who protect against competition. With more market based competition we'd see better supply. The best thing would be for these regimes to become more accountable to their populaces. One thing to note is, supply _still_ increases. It's just that demand growth has been faster, ergo the price rise. Anyway, we shall see, but anyone who really feels oil is imminently running out can check futures markets to see if their hunch is priced in correctly.

There's also lots of coal but it's dirty, so cleaning it up is changing it's price. But this is good. It makes clean stuff competitive.

Beast said...

It is energy, not money, that makes the world go around.

I meant that quite literally.

The energy we use today is intimately tied to money.

I agree with that. But I think you misunderstood my point.

It is literally the angular momentum of the Earth that makes it go round. The Moon and the Earth do not undergo financial transactions as they interact gravitationally. However, their interactions can be explained very precisely using the idea of energy, Newton's laws, etc.

Nothing to do with economics as far as I am aware.

Peter said...

I was interested in your recommendation on electric cars. You separate usage and manufacture however and assume that electric cars will have the same life as standard ones. Batteries in a Prius last 10 years and a new set costs £3,500. Very few UK cars are worth more than £1,000 when 10. Who then is going to buy a 10 year old Prius and face that cost. End result is the Prius will be junked at 10. Since so much of the energy used by a car is in making it that makes it much worse. The same will apply to all electric vehicles.
Otherwise - keep up the good work

Andy Moose said...

Back to the phone chargers:

A phone charger without a phone draws a current that is almost 90 degrees out of phase with the voltage. Your power meter and the electricity board's energy meter both correctly measure very little power or energy used by the charger.

The current heats the wires in your house, and heats some of the wires and transformers in the national grid. The CEGB used to complain about this waste of energy and they used to charge industrial customers for it (perhaps they still do - I am out of touch).

Are there any figures for how much power an inductive load like a phone charger disspates outside your house?

Many computer power supplies are "Power Factor Corrected". I do
not have a good definition of what
it means, but I think is means such power supplies are effectively capacitive loads. If this is true, and you have a computer and a mobile phone charger both plugged in an doing nothing (and if they balanced out exactly) energy would switch between the two of them 100 times per second. Some of the energy would be lost heating the wires in your house - and you would pay for it - but there would not be a significant loss in the grid.

Do power factor corrected power supplies cancel out most of the inductive load of non-corrected chargers?

Nevi said...

I challenge the UN to call an energy summit where a solution can actually be aquired. I sent a direct note to Geneva H/O with zero response. The EU commissioners says the days of affordable energy are over..I disagree...and can ensure he eats those words.

With the current energy crisis escalating, I've come up with a flexible concept to sustain the cyclic generation of power on a continual, daily basis, that will systematically reduce dependence on gas, and is only limited by the ability of the implementation to store and distribute the generated power. Technically, as installations increase so does the power generation. The flexibility of it is, with differing models based on the same concept , it becomes applicable in numerous generation points , and if all generated power is cumulatively channeled , then the spinoffs become tremendous.

It creates new jobs, new developments, and new possibilities in the forms of electrical topup stations as opposed to gas stations etc. Full longterm implementation can reduce gas use by approx 30- 70% over time, and in strategic places, up to 90% ..It will however still be important for lubricants and a wide range of uses etc..but not to the extent of having to fill up a tank every few days in the domestic vehicles. Short term, simple models provide immediate and everyday renewable power . It also provides for high level refinement of the concept in technology departments. It will significantly reduce the need for biofuels, which also affect the food crisis.

The planet is changing, and so does everything along with it. In the light of the crisis, my concept threatens the global gas companies to an extent. I realise there are all kind of high level summits with the best minds on the globe talking about solutions..and Im fully aware of hydro,wind,solar etc..but all these are reliant on specific conditions which are natural. I heard that people with solutions that threaten gas profits, disappear...It doesnt rule out the use of oil..but really, emissions are killing the planet..and while people in Greenland are rejoicing that spring is arriving earlier,and sheep farming can boom..the reality of all that is scarier.

Perhaps you might find what Im saying laughable, but its based on currently active electrical fact, and implementation is a matter of some engineering genius...which is why I am hoping to hear from Germany too, because they are engineering mavericks, and very serious people.

If the world dies, and the rainforests are gone..the oil barons die with it. We all know the current options, efforts..yes, but ones that do not address the real problem, in any dimension necessary to save the planet. Ice shelves are collapsing..people cannot go about their daily lives..Fuel is unnaffordable..how much more until the nations snap??

Damon said...

If it's yet another overunity / perpetual-motion scheme that attempts to slip around the laws of thermodynamics please don't waste your time or anyone else's. My poor brother had to deal with such schemes at the EPO. Absence of understanding of physics is not the same as a conspiracy against the 'inventor'.

If it's real science then publish details without the mystery and heroics please.

Rgds

Damon

Ray Lightning said...

Hi David

I found your book to be very interesting, I am waiting to buy the print edition.

Recently, there has been talk of a type of color dyes which can almost double the efficiency of solar PV.

Also, they might slash costs of solar energy by concentrating energy and using less number of expensive solar PV collector cells.

I hope you put this new discovery into account while doing cost analysis in your book.

Cheers
Kiran

Hans said...

No, haven't read the book yet. Just came across a review.
Therefore, no arguments but a possible addition (the reviewer did not mention anything on this part written in the book).
What we really need to think about is a substantial change of lifestyle. Any energy scenario based on the lifestyle we have now ends up with very intolerable details. So while there has to be a major change in energy politics, there should also be a bigger change in the way we (the people living on this planet and maybe elsewhere in future; but first and foremost those who are very influential) organise our living. This includes economy might also help us to get rid of arguments which weigh obviously needed, but shortening basic resources against their very circumstantial time-to-money relation for the individual person.
But seeing as how long and difficult it was and is to make clear that thoughtful usage of natural resouces is a major issue for keeping the world a cosy place for human beings (this aim logically excludes any nuclear energy as long as we cannot sufficiently deal either with the waste nor the results of potential major accidents) , it seems to me almost impossible to convince the necessary number of and in particular influential people to think about promoting a complete and ethically acceptable way of changing major lifestyles. Like, i. e., rethinking the way we settle in cities and suburbs, spending a lot of energy on circumstantial goods and small pleasures (like rather having a bank account showing the pure fantasy figures of 72ct plus a day than taking the two minute effort to switch off unneeded appliances to save substantially existing resources), dealing with each other.
From the scenarios the reviewer drew from the book, I draw this: We need to change our habits of living at once. We can easiest change those that are man-made. This includes economy and any "laws" some people see in them. Other than natural laws, these laws can and must be changed. The opitimistic people who believe a theoretically free trade economy will deal with any troubles in the best and most sufficient way, are those who necessarily (though they won't admit) calculate the life of a human being against the necessary time so save it, weighed on the basis of their actual salary. If they don't, something's wrong with their idealistic economy.

Hans said...

Once more, a completely different hint/question: Any methods to extract "sustainable" energy from this planet have a limit. You can only build so much tidal generators without changing the natural balances based on tides. You can only build so much solar panels on the ground without having an impact on the energy balance on earth's surface, influencing plants, animals and geology. Does anyone know how much it takes? It might be pretty much, or very little, or result in interesting cross-effects when using different sources thoroughly. But it's ridiculous to think we could extract high amounts of energy from natural cycles without countereffects. Does anyone have any solid figures about that?

Damon said...

Hans,

Do read through the book. It deals with how much renewable energy is available and what might happen if we extract more and more of it.

The bottom line is that there is far far more than we need and use now, and so the dangers that you wonder about are not there it seems.

Rgds

Damon

bun-yip said...

Just downloaded and skimmed through. Looking forward to reading and reflecting.

I hope the final work will include some analysis of Algae Biomass production. The numbers look good. Or should that be 'too good'?

IH said...

You're saying you've saved 2kWh/day by "switching off all my stereos, answering machines, cable modem, wireless, and so forth".

Using my trusty Maplin power meter, I get the following: Set-top box, 7W; answering machine/DECT phone, 5W, modem/wifi 6W. If these were never on, I'd save 0.4kWh/day. If I just unplugged them overnight, I'd save one tenth of your figure.

How do you account for 80+ watts of standby power? Do you have a big class-A hifi? A valve answering machine? Two-hundred-odd phone chargers??

David MacKay said...

I got 45W of saving from switching off gadgets during the day and the night; and the other 35W probably came from changing bulbs to LED bulbs and fluorescent bulbs.
The 45W of gadget savings probably breaks down like this:
stereo 10W
stereo 10W
DVD player 10W
computer peripherals 5W
cable modem, wireless network, answering machine, bedside radio, lousy portable phone charger - the rest.

IH said...

It sounds like you have a lot of gadgets with 'fake standby mode', meaning that they'll turn the lights off and pretend to be asleep but nothing's actually powered down inside.

While I don't lose sleep over a few pence a day on electricity, fake standby mode annoys me greatly: it's sloppy engineering and has an impact on reliability.

I have my A/V setup on a wireless remote mains switch, which is under 1W when 'off' and considerably less faff than unplugging everything. Mind you, I wouldn't need even this if people put proper 'hard' power switches on the front panel where they belong...


To Andy Moose: don't worry about phone chargers as inductive loads. No, really.

The worst one in my collection I could find drew ~5VA (power factor 0.4 or so), in other words 20mA from a 240V supply. Plugging in an 8A hairdryer to the socket dropped the line voltage by 3V, giving a source resistance (let's assume entirely resistive) of about 0.4 ohm.

So that 20mA is giving copper losses (I^2.R) of 0.16 milliwatts. If you saved that energy, you'd have enough to boil a kettle in a mere 100 years.