Austin Shackles

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since Jul 26, 2012
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Recent posts by Austin Shackles

Well said.  It's the mark of intelligence to be able to admit even an unintentional error.

I fear you're right about "free speech" - and I'm not sure in any case that it isn't now a myth.  As may be, this and countless other forums around the 'net are NOT public places, and you only have whatever freedoms the owner and their team allow.  

more generally, I do believe that, in public, anyone should be able to say whatever they want - but that freedom comes with the price of accepting not only that others can hold other views and have an equal right to state them, but also any consequences arising.  It's kind of academic these days anyway, what with laws against hate speech and so forth, I don't think genuine free speech actually exists.
I give this book 9 out of 10 acorns.

It's unusual to find a good mixture of simplicity and, from what I can tell, accuracy - David Mackay does a fine job of simplifying things and thus allowing us to focus on the big picture.  The whole subject is a huge one and as such it's easy to get bogged down in detail; or to produce a treatise which consists of 50% mathematics.  It's also easy to oversimplify and this, in my view is avoided.  

The first part of the book goes into various aspects of our lives and of sustainable power and, in a fine series of approximations such as I might myself do on the back of an envelope, gives us a broad picture of the issues, and moreover of what we might do about them.  Although the picture is simplified, he regularly brings in fact checks with known data to back up the approximations he uses, which lends credence.  He also debunks various popular ideas and myths, in itself a good enough reason to read the book; as everyone involved in the field generally has their own axe to grind or hobby horse to preach from, it's useful to have someone look at things and say well yes, doing *thing* does help (e.g.) reduce carbon footprint but the effect is tiny and even if everyone did it, it wouldn't have much impact - whereas doing *this* would have a significant impact.

At the other end of the book are various technical chapters where he goes into more rigorous detail about the concepts in the first part.  This is nice to see if, like me, you are by inclination a scientist:  I can look at his workings and say "oh yes, that makes sense" and there are some fascinating conclusions like the one about the costs of flying aeroplanes (I won't spoil it for you).

The only real fault I can find is that the whole book is slightly out of date: although much is still current and relevant, and I can hardly fault the author for the book not being updated, as he's no longer around to do so!  The only thing that really looks dated to my eyes is the stuff about battery electric cars.  The progress in BEVs over the last 5 years, even, has been surprisingly fast and it's now getting to be that a BEV would do most of what any normal driver would want, rather than being a niche market thing for nutters.  It still remains for the charging systems to catch up, but there is some sign of progress there too.
1 month ago
Can't add much to that scenario!

Just to add that striking clocks, alarm clocks etc have more than one spring/weight normally - the clock itself trips the additional mech to work to make the chimes or ring the bell of the alarm.  Even if an alarm has only one winder, it typically has 2 springs inside.  So I would reckon you'd use the clock to trip some other device that actually did the flap opening.

Another way would be a water operated thing, where a slow drip of water fills a container until it tips and thus makes something happen.  Generally those auto-reset by the water bucket emptying and becoming light again.
3 months ago

Matt Coston wrote:

Austin Shackles wrote:but 5000kg and 5m height would give you  25x the energy, say, and wouldn't be hard to build.  Obviously, you can't carry it around like a drill, but many things don't need so much power as a drill.  Take lighting, for example, if you use LEDs 10W will light a room.

5000kg at 5m = 245,000 J
10W LED light for 6 hours = 216,000 J
So you can basically illuminate 1 room for 1 evening. It's not even remotely economically viable - if it was, we would already be doing it everywhere.

Have you done an estimation on what your idea would cost? What $-per-kilowatt-hour do you expect?  

Austin Shackles wrote:It might be that for small scale, batteries are still the way to go - but town-sized, they are still way too expensive.

I assume you're aware of Tesla’s 100MW/129MWh Powerpack project in South Australia? The reported figures show that it will pay for itself in less that 2 years.

The Quartz guys have presumably gone into cost in much more detail - even building the pilot thing costs and they have that already.  They are looking to be about half the cost of current battery tech, according to that article that was linked.

As for Tesla, yeah, they do impressive things with what are, essentially, laptop power cells.   LOTS of 'em (check out what's inside a Tesla car battery) and while they have bigtime energy density, the cost in materials and so on could become a problem if you want to expand it to worldwide use.  The essence of using mass is that although the density is low, so are the costs.  The mass can be more or less anything heavy, if it's locally cheap or better still free (e.g. sand in the desert).  What I'm considering is making the thing as simple as possible, thus cheap to build in many possible places.  Batteries are amazing but when you look at the global scale of the power thing, especially (and drifting topic a tad here) if you look at automotive - right now, you can make batteries for Teslas and other such vehicles but you only see a tiny number of them.  The problems will show when you try to have ALL the vehicles running on batteries, or ALL the houses running on renewable.  You then need a LOT of energy storage, distributed around the place.  The Quartz crane thing is looking at 20MWh for the full sized one, and I assume they've done the math to back that up.

Yeah, you can also do pumped storage.  We have one here in Wales, been there for many years and it works well when you have a mountain and lots of water.   You can't do it without both, realistically.  
4 months ago

Matt Coston wrote:A simple calculation will show that gravitational potential energy (GPE) is a poor store of power unless you have access to enormous amounts of storage - i.e. a lake.

Austin Shackles wrote:Gravitational potential energy though is given by mgh:  so a 1 tonne weight (1000kg) lifted by only 1m has a potential energy of somewhere around 9.8KJ

Take a look at this cordless drill battery.

It's 18v 9ah. This converts to 162 Watt-hours, which converts to approx 0.58 megajoules.

So that hand-held battery has approx 60x more energy than a 1 tonne weight raised to 1 metre.

Storing energy as GPE just isn't practical unless you can do it on a massive scale.

but 5000kg and 5m height would give you  25x the energy, say, and wouldn't be hard to build.  Obviously, you can't carry it around like a drill, but many things don't need so much power as a drill.  Take lighting, for example, if you use LEDs 10W will light a room.  That guy in the other link is planning 35t blocks and a 120m tall crane.  It might be that for small scale, batteries are still the way to go - but town-sized, they are still way too expensive.
4 months ago
That's the same basic idea but I can't help feeling he's over-complicated it - although it's easy to scale like that - taller tower, more blocks, same crane.  I'd have thought one big block moving slower would also work, though.  The same crane motor that lifts (say) 500kg in (say) 100s would lift 5000kg in 1000s, or would lift 5000kg a tenth of the height; since it's a linear relationship, within reason 5000kg lifted 1m is as good as 500kg and 10m.   The other variable in that tower is that per block,  more energy is needed to lift them the higher they are going - and thus, the top layer stores more energy than the bottom layer.  That might not be an issue, though, in use.

With a single crane, the output is going to be intermittent, as well, although having multiple cranes would solve that issue, as one could generate while another is winding back up to hook another  block from the top.
4 months ago
Been thinking about energy storage, so here's something to kick around some.
These days we're getting ever better at harvesting the energy that's all around in the wind, sun, water and even tides (although more work needs doing in the latter) but they all have one massive problem, they don't always happen when we want to turn on the kettle for a cuppa.
So, what we need is a good way to store the spare power for when we want to use it and it's a still dry night and the tide is inconveniently not flowing for another 3 hours.
But I hear you cry we can do that, we put in a battery bank and an inverter.  Sure, that works, especially small scale - and with modern LED lighting, for example, you can remove the inverter and use low voltage DC, thereby removing one of the losses.  But batteries are expensive to make and can be tricky to keep working long term, and 'most all of them degrade over time, even with good charging systems.
Large scale is harder - and we need large scale, if it's gonna save the planet.  So I got to thinking -  we already have, in some places, pumped storage hydro - and that has a lot of merit; when there's surplus power at any time you pump the water uphill, then when you need power you can generate with it.  However, it needs the right geography and takes a lot of space to do it on any scale, and when it's hot and dry your water evaporates, also the pumps, pipework and turbines and stuff are costly to install and need a fair amount of maintenance
So here's my idea, starting from the pumped storage, which I hope to build a small scale prototype of sometime.  Rather than water, I propose to lift a mass. The mass can be anything that's handy and cheap - if it's in a desert, you'd use sand.  If you have rocks, you can use rocks, if you can afford it, make 'em into concrete.  When you have spare power, a motor winds the weight up, when you need power, you let the weight down, driving a generator.  It's all simple and mechanical and thus cheap and easy to build and maintain.  It's also readily scale-able - you can double the capacity by making the weight twice as big or lifting it twice as far or just by making 2 of them - and where the terrain is suitable it can go underground - in the basement of your house, say - so needn't be visually obtrusive.  You can of course also do mechanical energy storage with a big flywheel - but that involves either crazy speeds or a lot of mass spinning or both, because you're using the speed to store the energy.  It is more effective physically if you make the mass move faster, because energy is proportional to speed squared, but high speed has it's own issues.  Gravitational potential energy though is given by mgh:  so a 1 tonne weight (1000kg) lifted by only 1m has a potential energy of somewhere around 9.8KJ. (sorry, not going to make it into BTUs for you!) If you make it 5m high instead of 1, then you get 5x the capacity, and obviously, you can make the mass bigger (although making it too big will increase the cost for whatever holds it up.
It could be fully mechanical, with a cable hanging the weight; or hydraulic, with a ram underneath or maybe some other method I've not thought of yet.  It's not going to be super-efficient, but then every system is inefficient somewhere and they key point is if it's cheap enough to build, and uses power which would otherwise be wasted, it doesn't matter if it's not so efficient.
4 months ago
Anyone know if the OP is still around? Did the fishdishwasher work, or did they all succumb to some rare form of poisoning from the fish?

ah wait, was looking at the wrong dates, for some reason I keep looking at the date joined, not the posting date. Still wondering if it worked though

3 years ago
I guess you guys might already know about this place; I didn't though. Off-grid community on an island in Canada.
4 years ago