A Smart New Fridge

We got a new fridge in June. The old one had stopped making ice and a guy had come to try and repair it several times before deciding that it needed replacing. It was still under a ten-year guarantee, but only just. I think the ice maker may have been damaged in the move. Not complaining about a new fridge. We have nothing to lose but energy, resource depletion and pollution from the extra parts on their way in and out of the world.

Looking for a silver lining, fridges seem to have become more efficient over the years since we got the last one. 

The sizes are comparable - 500 litres for the old one, 510 for the new - and the rated power consumption of the heat pump has improved around 10% from 110 Watts to 100 Watts. 

The defrosting power consumption has improved much more significantly, from 160 Watts to 93 Watts. That's around 40%.

In other words, the old fridge used more electricity to heat up the pipes inside to melt ice forming on them than it used to cool itself. The new fridge uses slightly less. Of course this is the power used when it's switched on, which is not all the time.

At least I think this corresponds to less power use. It may be that the defrosting is switched on 40% more of the time, and it's using exactly the same amount of power to do the job.

The new fridge has a rated consumption of 200 kWh per annum. That's less than 1 kWh per day. It works out around 23 Watts. So most of the time it's not using any electricity. Either the heat pump or the defroster is on around a quarter of the time.

Defrosting used to be a regular event for fridge-owners, requiring the fridge or freezer to be unloaded and switched off. Now the fridge switches on heating elements in the pipes to stop frost occurring. Presumably the improvement in efficiency that defrosting brings is much greater than the extra energy used defrosting. If the fridge is trying to cool through pipes coated in ice, it is going to do a very poor job since the ice will stop the heat flowing into the coolant in the pipes. The coolant will then get much colder, using much more energy. 

As we know, frost will occur where there is humidity in the air and low-temperature surfaces, which you are likely to get in a fridge. Another approach to defrosting would be to remove all the humidity from the air within the fridge, but this may be less reliable.

I was hoping that there would be more energy saving functions, or at least energy bill saving devices, for example running as much of the freezing and defrosting as possible at night. There is a "shift peak" function, but it just puts off heavier load activity for four or five hours. It doesn't actually have a clock in it, so it wouldn't know whether there is any cheap night-time electricity to use. If it doesn't even know the time, it's not really that smart. 

It has green lights coming on to say "eco", but it would be really nice to have a display of how much electricity it is actually using. 

Another thing that makes it less efficient is the drawer inside. The manual clearly states that to keep the fridge efficient, you should open the doors as little as possible. The most important power saver is probably knowing where everything in the fridge is, although this can be tricky if you have the kind of dietary habits that require 500 litres of fridge. The old fridge had double doors for the main section, with two drawers at the bottom. The one of the left had an egg tray. We used to keep cheese in the one on the right, so we'd open the left door for eggs, and the right door for cheese. 

In the new, but not necessarily improved, model there is only one drawer at the bottom. To open it you have to open both doors. Not the smartest of designs in terms of forcing you to open both doors. The egg tray is now in one of the shelves in the door on the right. Since they have enough headroom to hold a tin of beer, this is not the smartest use of space either. But it's new, so beggars can't be choosers.

DECC Consultation on Community Energy

Any UK-oriented armchair activists out there, here's an opportunity to make a difference to UK energy policy by responding to the Department of Energy and Climate Change. I heard about this from Energy4all, which supports community energy, mostly wind farms that are financed, owned and run by communities with support from more distant investors like me.

Community energy may not change the world in itself, but is definitely one piece in the jigsaw puzzle that is the change to a smart grid of energy democracy from the nineteenth-century model of large fossil-fueled power stations built as far from the urban rich as possible, into which nuclear power stations were neatly added in the latter twentieth century.

The closing date for submissions is 1st August 2013 so you will need to act quickly.

 

There is a long questionnaire on the DECC web site. But apparently DECC has said that it is interested in informal submissions, in particular understanding the barriers to community energy. www.gov.uk/government/consultations/community-energy-call-for-evidence

Emails can be sent here: communityenergycallforevidence@decc.gsi.gov.uk

Or by post to:

DECC

3 Whitehall Place
London
SW1A 2AW

"It is really important that as many responses as possible are sent to DECC as part of this Call for Evidence.  The more evidence DECC has the more of a case they will be able to make to support community energy, so please do take the time to reply."

Fwd: Power-Hungry Devices Use $70 Billion of Energy Annually

Here's the kind of fun story that gives us pause.

I got some ice cream yesterday from what is probably the best ice cream shop in the world (come to Matsumoto and taste it if you don't believe me). I took a small cooler box so I could put the stuff straight in there, along with some of the dry ice they provide for free. But they insisted on wrapping it in some expanded plastic sheet. I was tempted to take the ice cream and the dry ice out of the sheet, put them in the cooler box, and put the sheet back on the counter. In the end I just took the package they had made and put it in the cooler box.

I mean, if I was so worried about reducing excess resource use, what on earth was I doing getting ice cream?

How much energy is used freezing and keeping the produce frozen? Already there's a calorific calamity because many times more fossil fuel energy is used growing and transporting food than is contained in the food itself.

And dry ice is frozen carbon dioxide. Isn't that great that they're taking CO2 out of the atmosphere? Well actually it goes straight back into the atmosphere when it sublimes. The CO2 was probably made as a biproduct of some process and was not made specially. An estimate from ASCO inc's dry ice machine B207's spec suggests the manufacture of a kg of dry ice uses around 100 watt hours of electricity, in turn putting around 50 grammes of CO2 into the atmosphere, which is actually much less than I expected. Interestingly, this is similar to the production of regular H2O ice, but a kg of dry ice has twice the cooling capacity of wet ice. Not as good in drinks though. And more dangerous.

Anyway, after the fertilizers on the fields, the trucks, ships and planes speeding produce around the world, the freezers making the ice cream, and chilled cabinets displaying it, a little bit of extra plastic wrapping is not going to make a huge difference.  But that's not what I really wanted to talk about.

Back to the US and their profligate use of energy, "A new analysis of devices and equipment commonly found in U.S. homes and businesses concludes that these products, with more than 2 billion in use, consume more energy each year than many large countries use to power their entire economies."

They're talking about TVs, computers, ceiling fans, elevators, icemakers, and MRI machines. They use "more than the primary energy use of Mexico, Australia, New Zealand, or 200 other countries."

You can read the full report from American Council for an Energy-Efficient Economy (ACEEE) here: http://aceee.org/research-report/a133

Of course they are advocating energy efficiency, and state "these devices could be made to use 40-50 percent less energy with existing technology."

Because these devices "do not fit into traditional energy-use categories such as refrigeration, HVAC, or lighting" they seem to be off the radar. They are not subject to energy efficiency requirements, and efficiency standards are unevenly applied.

More obviously, not having the devices in the first place is going to use much less energy than any energy efficiency improvements. Energy efficiency gains are usually incremental, and often start from very low levels. The first steam trains converted a fraction of one percent of the coal's energy into motion. This was worth it because the economics of the day made this cheaper than driving horses to the pit heads.

Escaltors are a good example. Many of them have sensors and will stop when nobody is riding. Of course the point of escalators is often to transport people up and away to the higher levels of a shop, where they will spend more money and keep the cash tills ringing. The lights will keep everything bright, the heaters keep the rooms warm and the refrigerators keep produce cold. A moving escalator is a powerful symbol of this motion, as well as a delivery system for these life-supported wallets.

In terms of delivering a payload, namely human beings, the weight of the metal is going to make a huge difference to the efficiency. How does this compare with a lift? I imagine a whole lot less friction and more effiency for a lift, in terms of energy use, but perhaps not in terms of space use, constant movement of human traffic, and incidental advertising of shops and products that can be seen on the way. But how does this compare with the energy that would have been used if the customers had walked? In these terms, much less efficient, unless of course that energy came from ice cream.

AC DC fans

We were looking at fans in the electric shop the other day. There were a few new DC fans. The shop shows the rating of each fan, and DC seem to consume about half the electricity. This seems a little counter-intuitive since I thought AC motors were more efficient than DC motors. I guess DC fans are more efficient because the control circuit of a DC fan will change the current electronically. The AC fan, on the other hand, is probably going to use a variable resistor, turning some of the electricity into heat, and running the AC motor at a speed where it's not so efficient. 

But surely, if you're running the AC motor at the design value, it's going to be more efficient?

All electric motors basically work with electromagnets making a rotating magnetic field. AC electric motors can be very simple. Effectively the alternating current goes straight to an electromagnet making a rotating magnetic field.  A fixed magnet on the shaft then rotates. Depending on how well the frequency of the current synchronises with the speed of the motor will change the efficiency. 

I had a record player with a direct-drive AC motor that I brought to Japan many years ago. The UK has mains current at 50 Hz, while Japan has 60 Hz. This made my Bruce Springsteen records sound like Dolly Parton. 

I didn't use it to play heavy metal. 

Eventually I got a 60 Hz motor, then took it back to the UK where I briefly had the opposite problem, although unfortunately no Dolly Parton records. Now it's back in Japan but I'm not sure where the correct motor is.

DC motors can be brushless or with brushes. If they use brushes, the polarity of the electromagnet changes as the shaft rotates. The brushes cause friction which adds to the inefficiency.

Brushless DC motors, also called stepper motors, have the fixed magnet on the shaft, and two sets of electromagnets which are swithed on and off to create a changing magnetic field. 
Another loss of efficiency is in the resistance of the electromagnets, which will be more for DC with its constant current, rather than a current rising as the electromagnet needs more power. The electromagnets are going to be applying their full forcefield the whole time, even when their field is in the same direction as the fixed field and the power is not going to help move the shaft around. AC, on the other hand, is sinusoidal and the power will rise to the challenge of providing torque when it is most effective and most needed. The sine wave in the AC is just circular motion repeated onto the timeline, so it's going to convert easily back into rotation.

So AC motors would seem to be more efficient.

Or maybe the DC fans have AC motors in them, and an electronic inverter converts DC into AC at the optimum frequency, while the AC motors are stuck with the mains frequency.  Even then, the AC fans should be more efficient because there's no conversion from AC to DC in the power supply then back from DC to AC in the inverter.

It may just be that the DC fans aren't more efficient than the AC ones; just less powerful. Apparently they are really good at supplying a gentle breeze.

There's an interesting, but inconclusive, discussion of the efficiency difference between AC and DC in electric vehicles here.

A New Tradition of Futon Sofa Bed

The futon sofa bed is now working, and here are some reflections on the design. I can make some modifications and address some of the issues, but really I'd really like to make another one. To justify this I'd need to buy another futon, of course. 

The front should probably be higher. I kept the angle to about 7 degrees, so the base is around 20 cm off the ground at the front. This height is great for kids, or at least would be if their upper legs were longer, since the chair part is quite long. They seem to sit on it quite happily, when it's not being used to accumulate crap.

Another issue is that the back is vertical, and the frame at the back of the chair is a right-angled triangle. When you sit back, this rocks a little and I think an isosceles triangle, more like an A-frame, would be more stable. As it is there is a chance of it banging back into the wall behind. 

So geometrically speaking, I probably should have made the back a little taller and at more of an angle, the front a little higher, and the seat and middle seat-back sections a little shorter. 

As I predicted, it is possible for a small child to open the sofa into a futon, but after pulling it out half way, it crashes down with a large amount of noise and power, and the health-and-safety part of me is worried about other children's fingers or toes getting in there. So some kind of damping would be a good idea. It may be possible to get more sophisticated hinges, but these are likely to work in the wrong way. I'd like something that will provide more resistance the faster it moves, but simple damping on the hinges is likely to be the opposite and resistance will decrease as it gets faster. 

Also as predicted, putting the futon back into sofa position requires two hands, or a long arm, as the middle part needs lifting a little before it is pushed in.

It may be possible to work out a strap and pulley system that would both control the descent of the A-frame, and facilitate its return, but I think that's going to take at least another month, 12 envelope backs and ten sides of A4.

Also the spacing of the horizontal slats is a bit wide, and I think I need to increase it by three or six. There are four fixed slats, at the end of each of the movable parts, so they can only be increased in multiples of three. Currently there are 13 90 mm slats, with gaps of around 80 mm between each, which are big enough for little feet to push into when they are walking along the futon on top. Another three slats will bring the gaps down to about 45 mm, which should be small enough. Six extra slats will give a gap of just 25 mm, which may not be big enough to allow it to fold up properly.

Spruce, the material I used, seems quite stiff and pine may have been more springy. 

Since I last looked, another kids' futon seems to have found its way between the frame and the futon on top, which has made the seat a little more comfortable. It has also created a home for another piece of loose soft furnishing that was floating around the house, which was the main job of the device. Perhaps it can attract even more bits of soft furnishing, and solve the height and leg-length problems too!

Pictures on a blog. How difficult should that be?

It should be really easy. I shouldn't be spending an hour trying to get one picture into one blog. It should just be drag and drop. 

I have pictures on my telephone and have told it several times to upload them to the internet. There's a function in my blogging software to turn emails into posts, which I use most of the time. I can add photos to my blogs. There's a function on my phone to add photos to emails. How easy would it be to get the phots I send in emails to my blog to appear on the blog?

I used to use Picasa, but at some point google seemed to try to stop me from using that. There are various functions that will automatically send photos from my phone to the cloud somewhere, then it should be as simple as embedding a link to the picture. The latest I tried was on dropbox. It suggests that it's as  simple as clicking the image, sharing the link and then pasting it where you want, but blogger was having none of it. The photo was password-protected. There was nowhere in dropbox obvious to make a file public, except moving it to the public folder. This eventually worked, but the photo was rotated on its side, and not fit to the screen. So I got the picture of the plant pot knocked over on its side with grains of soil the size of moonrocks.

So am I being stupid or is it the internet?

No don't answer. I am just one person. One flawed human. The internet is the combined wisdom of millions, getting on for billions of people. It's bloody obvious that the internet is being stupid.

A picture paints a thousand words. So go to google image search if you want an picture. If you want the thousand words, you've come to the right place.

Lithium

I'm sure you've seen it on the periodic table, way up at the top, straight after hydrogen and helium. The most minimal of metals. There's also a lump in your phone.

And I have several cells charging the thermometer data loggers in my house. When I saw that these rechargeable batteries were cheaper than the disposal ones from the local electric shop, I pounced on them. What did I have to lose?

I despaired a little at the first two I got when they didn't seem to work at all. They came together with a charger, and I since bought several Ultrafire batteries, which seem to work OK. Then I realised I hadn't unpacked the first batteries, and they were still shrunk wrapped in clear plastic. They worked fine after that. In fact they were ready-charged. All rechargeable batteries should be ready-charged, and now many are. All batteries should probably be rechargeable, but that's another story.

I have 16 data loggers in the house, and the first set of batteries I got were only available with the charger. I only needed one charger, so I would have got the Ultrafire anyway.

So a couple of months later the new batteries start to need replacing. I find this out when I do the monthly download of data from each logger to the recorder. When it announces a communication error I know that the battery is flat, so I replace it. I've then been recharging the batteries that come out, and trying to put them in another data logger the next time a battery runs out.

And sometimes they don't work.

My initial reaction, of course, is that I now have an explanation for the price being lower than the disposable batteries.

Then I started investigating the charging technique of lithium ion batteries. Here's a good website called batteryuniversity.com on how to prolong them, from which I stole this graph demonstating the loss in capacity as their life goes on.

There seems to be a two- or three-step process: applying a high voltage, then balancing the voltage, then applying the target voltage.

Now that I've started watching the charger charge, I notice it goes from a red light when you put the battery in, to a flashing red light an hour later, presumably when it's balancing, to a flashing green light when it's ready.

The charger has two slots, and I've been charging batteries in pairs. This seems an obvious thing to do, and is sensible when the batteries are new and empty, or if the batteries had been together in the same appliance, discharging their power in lock-step.

As it is they have been on their own, discharging at slighly different rates over slightly different periods. We usually think of batteries being full or empty, as if they are tanks of fuel, but actually they don't work that way. As they lose charge their voltage gradually falls. If it's a battery connected to a bulb, then the current will keep flowing as the voltage gets lower until there is no current left. If they are driving something electronic, At some point the voltage will drop below a useful level for those transistors. The device will notice this and start taking action, primarily giving an alert that the battery needs charging, and switching off non-essential activities that use a lot of power. Like transmittting a couple of months of data. The data loggers will keep logging data for a while after telling us that the battery is fading, and I think only once or twice in two years have I lost data from a battery going below a level at which it can log data. 

So I need to recharge the batteries separately, or the charging cycle will start balancing before the batteries are ready, or after it's too late, and perhaps neither battery will be fully charged.

I should have done so from the very beginning, but since I got the rechargeables, I've started writing a note of when I changed the battery on each data logger. Perhaps I should be writing on each battery though.