28 May 2010

Efficiency, Water Logic, Permaculture and Chainsaws.

The first icy blast of Winter-to-come has hit. Happily it's brought a little rain - 7mm last night, and a bit more (3mm?) through the day. And a good lump of what passes for cold in these parts. Cold enough to want a fire, anyway, and we've had one burning all day.

The design of the house makes it difficult - verging on impossible - to make the house Toasty Warm, but the fire does at least keep it livable. Really this is not a problem; we optimised the house design for passive cooling rather than heating, the former being a more serious problem in our climate.

The firewood is all harvested from our own land. We have many Australian Blackwoods (Acacia melanoxylon) on the property, and they keep us well supplied with kagelhout (firewood; as opposed to braai wood forbarbequeue barbacue BBQ. Blackwood doesn't make really good coals for cooking.)

In general I try my best to avoid messing with petrol motors. They're smelly, noisy and dirty things that need endless maintenance and care. Really, I can't understand the attraction these things have for petrolheads.

But I will confess that, reasonably well looked after, my chainsaw is a Great Boon. I would not relish the idea of having to cut firewood by hand (even if it would warm me twice.) 30 Minutes with the chainsaw will saw up enough wood for a good number of fires and braais, and keeps us warm for many, many hours. I'll get my twice-warming from splitting the logs, anyway!

And this brings me to the subject of efficiency.

Many times I've heard and read about the terrible efficiency of small petrol engines such as power our (currently defunct) weed-eater and chainsaw. This may be (and probably is) true in the very narrow sense that the measure of work coming out of the machine, as a ratio of the energy going in (mostly in the form of refined hydrocarbons) is probably very low. But this view - being typical of linear, bounded design thinking - hides a deeper truth. A truth about Water Logic. Water Logic asks us to consider "and then what?" Water Logic demands that we think about consequences.

Just like sustainable design does. Just like Permaculture does.

So consider that a few hours with my chainsaw produces enough fuel to warm us for... pretty much an entire Winter! And consumes... perhaps 2 or 3 litres of petrol in the process. (To be honest I lack the stamina to cut more than 2 petrol-tankfuls of wood in one session. The chainsaw tank only holds about 250ml.) So 2 or 3 litres of petrol produces a full Winter's house-heating fuel.

I happen to think that's pretty efficient.

The fuel - at current prices - costs me (say) R25. About €2.5 (2.65865 at today's rates, if you care!) For a Winter's worth of Warm.

I'd call that a bargain.

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