08 March 2012

Alternative Energies

Energy is the defining measure of sustainability. For any organism, not just for 21st Century humans.

For the past 130-odd years we've been surfing a tidal-wave of energy gathered and stored in the geological past, and the party is finally coming to and end. The chief question is how we humans will manage the coming energy descent; the emerging opportunity to redefine our relationship with the universe.

Back in the days when I was doing a lot of software design consulting, I used to travel down to Cape Town for a couple of days every fortnight for one particular client. Sometimes I would have my on-site days scheduled and planned to within a hair's breadth. Other trips I would find myself arriving at the client's offices with not the faintest clue as to how I was going to spend my time. More often than not the well-planned trips didn't pan out as planned. Often they were a near total waste of time. And, surprisingly often, the open-ended, unplanned trips were astonishingly productive and fruitful. Some 15 years later I am still not sure what the lesson is...

We recently returned from a brief trip to Gansbaai and Cape Town to visit with family for a few days, and to celebrate my in-laws' 50th wedding anniversary. And, quite unexpectedly, but very fruitfully, it turned into an Alternative Energy Trip.

Our first stop was at Witkrans Farm, home of brother-in-law and family, where we surprised the in-laws by pitching up unannounced at their anniversary party. While staying at Witkrans we were introduced to a lovely couple, Luke and Dianne (and their kids) who live in the area developing their permaculture farm.

Luke & Dianne's guest house.
They have recently renovated old farm-workers' housing, turning it into guest accommodation. Needless to say, the guest accommodation is completely off-grid. Hot water is supplied by a solar-thermal system, and lighting by a very modest photovoltaic setup.
Pelton wheel generator.
They are very fortunate to have a large, high-altitude dam on their property, so Luke has been tinkering with a Pelton wheel generator system as another way to supply their electricity wants, and he feels that he is finally ready to set it up in a more permanent configuration. The dam provides some 60m of head, so water pressure is more than adequate to generate >1kW of energy at above 200V. I was very interested to see his setup, since I've only ever read about Pelton wheel systems, and never yet seen one in action. They do "consume" a hell of a lot of water1, and one of Luke's future projects is to set up a wind-pump to pump the water so consumed from the lower catch-reservoir back up to the head dam. The Agulhas Plain is famously windy, so it's a very viable possibility.

Sadly both we and they were squeezed for time. I'm sure Luke and I could have continued long into the night discussing the worlds troubles and How To Fix them over home brewed beer (from me) and mead (from Luke.)

After a couple of days at Witkrans and Gansbaai it was time to trek on to Misty Cliffs in the Deep South of Cape Town.

A friend and neighbour of my parents, Ivan, has long involved himself in nature conservation and sustainability issues2. He owns a farm that covers a very substantial portion of the small mountain peak that defines Scarborough and Misty Cliffs, and has spent the last 20 years (and a significant amount of money!) eradicating alien vegetation from the mountains. Recently he has established an Alternative Energy resource centre on his farm, and we went to take a look.
Ivan (left) and his Alternative Energy Centre in background,
PV modules clearly visible on the roof.
The centre is incredibly impressive! Certainly an unexpected thing to find deep in the southern Cape Peninsula, no more than a few hundred metres from the Cape Point Nature Reserve. Ivan uses the centre as an educational resource and hosts conferences and informal information session on complementary energy technologies.

Walking from the car park, one is greeted by the visual surprise of two large wind generator systems: a large vertical axis turbine setup and a peculiar, twin-fan system the likes of which I've not seen before.
The wind generators.
The centre building is immediately to my left as I took this photo.
Wind is an extremely abundant resource over the Cap peninsula, and notoriously so over Cape Point! The South Easter roars up, and is concentrated and channelled by the valley visible behind the vertical-axis machine pictured below. Good place to harvest wind!

The very impressive vertical axis wind turbine...
 The VA machine stands (I guess) about 12m tall, and I confess that I wouldn't really want one close to my bedroom... it is really quite noisy. The noise - as with so many wind generators - comes not from the turbines or generators, but from the blades. As the blades move through the air, they create a partial vacuum at their trailing edge. The partial vacuum then collapses in on itself, creating some noise. It's exactly the same reason that passive sonar detection works for locating ships.
...And the even more impressive (but for more subtle reasons)
twin-blade machine
The Twin-Rotor machine was a fascination for me. The structure does not rotate to match wind direction, but is fixed in place. At Cape Point this is fine - there are only really two wind directions that matter, and they're directly in opposition to one another. The South-Easter dominates during Summer, and the North-Wester is the wind of Winter Storms3. The machine's blades are not oriented flat to the dominant wind direction as most wind machines are, but nearly in line with the wind, and they turn in opposite directions.

What struck me most about this machine was its silence! I don't believe I've ever heard such a quiet wind machine. I'm very keen to learn more about the intricacies of this design.

Ivan admits that they made a mistake in using cheap turbines in the construction of this machine, and they're due to be replaced by more durable units. On the other hand, he says that the Vertical Axis machine has been far more troublesome mechanically, and much more finicky to get working reliably in low winds and when starting up.

Wind and PV controllers, battery management and inverters.
Needless to say all this generator stuff requires quite a lot of management. Apparently integrating wind and solar electricity can get quite challenging for charge controllers and inverters. I'm pretty sure, though, that almost nobody will need as much management circuitry as Ivan has accumulated in the picture above, but then this is mostly for demonstration and education purposes.

The chief take-away for us, though, was that we Braamekraal ecotechies have long ago made the lifestyle changes necessary to live (and live comfortably and well) in a low-energy world. It was certainly interesting to learn just how the costs and technologies have changed in the 15-odd years since I last investigated alternative electricity technology in any meaningful way. Our chats with both Ivan and Luke have reawakened my interest and recharged my enthusiasm for kicking Eskom the hell off our land as soon as we can!

[1] Luke did tell me exactly how much water flows through the system to generate that much energy, but I confess I've forgotten.
[2] In fact, my Witkrans brother-in-law gathered much of the data for his Master's thesis on Fynbos ecology and alien clearance from Ivan's farm!
[3] And recall that it was rather more accurately named the Cape of Storms by Portuguese explorers long, long before it got named the Cape of Good Hope. Hope seems to me a bit unreliable, whereas the Cape winds are extremely reliable and consistent. I predict that the Cape's West coast will, in time to come, be developed as a major energy resource, as wind can be easily, abundantly and reliably harvested after its 5000km unobstructed trip across the Atlantic Ocean.

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