Please read this first...

If you want to know what I'm on about in the shortest time then please read the introductory first post and my current action plan. Comments are very welcome. And if you like this blog, please tell a friend. Thanks!

Saturday 26 January 2008

Stats Update

Average daily consumption for the past 29 days: 7.56kWh of electricity, 160L of town water.
Rainwater in storage: approx 6.4kL.

Per-day stats are one way to think about consumption of resources, but it's a bit of a mental leap to associate those numbers with our actual behaviour. I've started another column on my spreadsheet which puts the electricity use into a different perspective, converting it to an average continuous load.

Our 7.56kWh/day figure is equivalent to using 315W continuously - like having five of the old 60W incandescent light bulbs (or the common halogen downlights) burning day and night.

Tuesday 22 January 2008

Sustainable Cooking

I've been pondering the issue of energy for cooking - the various energy sources and the technology for using them in the kitchen. Got a few comments and a couple of conclusions to share.

First, burning gas. If we're talking about the fossil fuel kind of gas, I'm opposed to it on the basis that it's a non-renewable, polluting source of energy. Pragmatically speaking it may be an essential part of our transition to sustainability but in the long-term the use of "natural" gas in the kitchen has to stop. I should also mention that in absolute energy terms it's rather inefficient: lots of energy used to extract and transport it, then lots of heat wasted into the air without performing any useful work.

Second, burning wood (or other biomass). In some cases wood is probably the best choice, but I suspect that'll be a minority. Wood is renewable, of course. It's also somewhat polluting especially in areas with dense populations. It's inefficient in terms of being able to direct the heat energy into the cooking but in cold climates that becomes a benefit rather than a problem. Not a good choice for my home though.

Next, solar. Do a web search for "solar oven" and you'll find lots of innovation around the basic theme of using the sun's heat to cook food in an insulated vessel. Absolutely top marks for being clean and sustainable. Not so great for cloudy weather, though, and hard to control in terms of temperature and therefore cooking time. I could imagine this technology becoming more common in the future if other energy systems are struggling to deliver the needs of society... but probably not my own family eating sun-cooked roast veges this coming winter.

Finally, heat from electricity - it's a broad topic. You have to look at both how the electricity is produced and how it is used. The production part of the discussion is well-trodden ground... everybody knows coal is dirty and non-renewable while wind/solar/wave etc offer far cleaner and sustainable sources. No, the really interesting bit is in how the electricity is used.

Most of us have heard that using our microwave oven is a more energy-efficient cooking option than using the standard electric oven or hotplate. That makes sense at first glance. It's not as cut and dried as it sounds, though: consider the case of my own microwave oven.

It's rated at 900W cooking power, which means in theory that it can generate lots of heat directly inside the food instead of heating the materials and air surrounding the food. But if it's putting 900W into the food, why is it drawing 1400W from my AC socket? 500W of power - more than third of the total draw - is being wasted by the machine, lost as heat into my kitchen without touching the food. That's not really very impressive. I've no idea whether other microwave ovens on the market perform any better.

What I do know is that induction cooking is often touted as the safer, more efficient alternative to traditional electric hotplates or gas burners. The technology is vaguely similar to microwave cooking, but instead of using radio waves to transmit energy into the food it uses magnetic fields to transmit energy into the metallic cookware. Proponents like to point out the 85-90% efficiency of converting electrical energy into useful heat (ie heat in the cookware, in contact with the food). Sure beats the 65% that my microwave is capable of.

But I reckon there's an even better electrical cooking technology that's being overlooked. It's cheap, and simple, and already well established in the marketplace. It's your regular old electric frypan. An electric pan has an embedded element which converts 100% of the energy it consumes into heat in the cookware. A portion of that energy is lost as heat radiates away from the pan, but the same could be said of induction cooking technology.

With some simple design improvements - mostly focusing on insulation - highly efficient cooking vessels with embedded electrical heating elements could be the eco-friendly kitchen technology of choice in the future, powered of course using electricity from clean, renewable sources.

Wednesday 16 January 2008

High Tech, Low Power and Less Nasty

I have deliberately kept my work and my blog separate. The high tech company I work for has a very strict policy about the way employees represent it in public and it's a line I never want to cross.

Suffice for me to say, my employer has just released a new model of ultra-portable no-compromise laptop computer. It has a full-size screen and keyboard, runs the full version of our latest operating system, uses a fully modern Intel processor... and according to the published specs has an average power consumption of just 8W. Yes I have a tradition of liking this company's products but that little stat particularly impressed me.

It's also nice to see attention given to things like the materials choices (making use of aluminium for its recycling value, eliminating PVCs and BFRs etc) and packaging (smaller packaging increases transport efficiency, materials also selected for recycling).

And the best thing is that it's not just my employer who's doing this - lots of other companies are making actual improvements in their environmental impact. I wonder how far they can go with it by 2050.

Tuesday 8 January 2008

Stats Update

Our mains water consumption for the past 11 days has averaged out to...

187L per day!


That's the total for the five of us, not per person. This is in line with the drop I saw in the last readings period after the tanks were connected to the laundry and toilet. Looks like sub-200 territory is here to stay, at least while there's water in the tanks.

With that qualification in mind, I'm going to start reporting our tank reserves along with these stats. With a specified minimum diameter of 2.2m and a current water height of 110cm in two tanks, we have approx 8.3kL in storage.

Looking at electricity, our hot water system narrowly avoided needing a boost late last week. I had a shower one evening in water that was merely "warm" but with a pause in the rain the next morning the temperature quickly went back up into "ouch" territory. Tariff 33 consumption remains at 0kWh.

Our general consumption is definitely up a bit from the previous trend though. The water pump would be contributing to that. We're using fans to keep ourselves cooler in the warm weather. And maybe we've slacked off a bit with turning things of and generally being frugal. For the past 11 days Tariff 11 usage has averaged 7.4kWh per day.

Just for comparison, here's a graph of our average daily usage per quarter (as per the electricity bill) for the past two years or so. The final column represents the current usage. Would love to get that blue bar down significantly but I'm not sure how I can do that without tossing out the fridge and not cooking food any more.

Pipes and Pumps, part 3

I've recently stumbled across the controversial figure of Amory Lovins, a high-profile American advocate of radical energy efficiency improvents through integrative design, improved technology and really obvious (once they're pointed out to you) common-sense actions. In March 2007 Lovins gave a series of five evening lectures at Stanford University and these are available for free download as podcasts through iTunes. I found these less than a week after my pump had been installed... and boy did I wish afterwards that those two events had occurred in the opposite order.

In the Tuesday night lecture on improving energy efficiency in industry, Lovins focused fairly heavily on pipes and pumps. Apparently a very large percentage of the electrical energy used by industry is consumed in the motors of pumps. The point is made that due to the compounding energy losses between electrical generation (usually in a coal-fired power station) and consumption in the motor, even a relatively small improvement in end-use efficiency will be multiplied back through the chain to deliver a far more significant drop in generating capacity requirements and associated pollution emissions etc.

In the pursuit of those end-use efficiency improvements, Lovins laid down a number of basic principles for designing energy-efficient pumping systems. I encourage you to watch the lectures for yourself, but my quick summary would have to include:

- If pipework looks neat, it's probably inefficient
- Short, fat, straight pipes are far more efficient than long, thin pipes with corners in them
- Engineers tend to optimise pipes and pumps separately focusing on up-front cost, when an overall cost reduction can be achieved by optimising them as a system for efficiency
- By optimising the efficiency of the system you can specify a much smaller pump which costs far less to buy, run and maintain
- It's usually best to design the pipework *first* and then lay out the equipment around them

That first point especially hit home. Have a look at the pictures in the previous post or two - I actually insisted that the installer do a "proper" job and fit two additional 90-degree bends in the pipe that takes water to the toilet instead of allowing it to curve smoothly (but untidily). I'm quite sure that if I'd watched this lecture beforehand I'd have spent some time carefully designing and specifying the pipes and pump which are going to be a fixture of our home for some years to come.

Oh well. On the bright side, check out the water use stats I'm about to publish in a separate post.