Saturday, January 14, 2017

Where are you now?

Back in the mid-1990s, I was sitting in the back row of my English class, in perhaps the most un-disadvantaged non-private school in the state. A school with a catchment so that not just anyone could send their children there. Where the wealthy (but egalitarian) and upwardly-mobile bought expensive houses to send their children to an elite public school subsidised by the less-well-off.

But, being a public school, there were no fees, and anyone who lived in the catchment could send their children there. Because there were plenty of rental properties, and as-yet un-gentrified pockets of houses, the students attending the school were more diverse than the equivalent pool in one of the nearby private schools. This diversity manifested as a general reluctance, on the part of the student body, to conform to the wishes of the school administration (whether it was uniform, attendance, homework, drugs, you name it).

Next to me, in the back row of class, was a girl I thought was pretty good. Sitting there, the English class passed me by. Perhaps I had reached an age where I could consider her sexy, instead of merely attractive. I never really knew what her thoughts were – she was very intelligent: maybe the smartest kid in class – and had a bit of a detached air that I liked and was a little intimidated by. Whether it was wishful thinking, or actual encouragement, I felt like we were a something.

This went on for some time, I can’t remember now. English class was a bit of a blur for me at that point. One day, I remember her laying her head in my lap and looking up at me – her eyes alive with intelligence, humour and irony.

But all things come to an end, and we drifted apart (from whatever it was that we were when un-apart). It occurred to me at some point that if I wanted to go to university, I might actually need to do some work (that, and I really liked English as a subject), or maybe she just got tired of my juvenile attempts at wit and insight.

By and by, school came to a close. I learnt some hard lessons about overindulgence in alcohol. Others were exploring other possibilities, maybe she was one of those. Either way, I didn’t have much to do with her after our brief and platonic affair.

When school finished, I saw her once or twice by chance, but essentially never spoke to her again. I’ve often wondered about her over the years. I always knew she was smarter than me, but felt that she had somewhat squandered her final school years. I also believed that for smart people there remained options – that she could make something of her life (whatever that meant to her). I now wonder what might have happened if I’d had a bit more guts – hadn’t been so perversely shy of self-exposure. Perhaps it would have only taken a nudge, at that point, to make all the difference – like the shoe that was lost for the want of a nail.

I never did find out what she was doing or how she felt about it.

This year is the 20th anniversary of my cohort finishing school and she was one of the people I particularly wanted to see – to hear about her tussles with life, and how she’d coped with some of the bitter lessons that adulthood brings. But I now know that conversation can never take place because she killed herself a few months ago and that door is closed.

All this time, she remained (I am sure) a friend of a friend of a friend. I could have contacted her, but never did. It probably would not have helped anyway to see this long-lost-forgotten person from school settled into some comfortable stereotype of middle-class suburbia.

I can only imagine, but not know, what feelings drove her to it. A rapid shutter-fire of thought-feelings flitted through me -
An emptiness of unknown, unappreciated and unrecorded days. Of drabness and aloneness (even in the presence of others), then
That my inaction could have led to this, then
The ridiculousness of that thought, then
What it must have felt like, standing there at that final moment, then
That such thoughts are but easy stereotypes, fettering the mind from the complexity of real life, then
There must have been some kind of moral miasma, long fermenting, to lead to such a strait, then
That despite the finality of death, her life must have contained many pleasures, then
Sadness that I never attempted connection to realise any such pleasures, then
A re-kindling of an echo of a crush on the now-dead, then
That the collective mind-image we, who knew her, hold, is now all that remains -- tethering her to the world. A tether that time and our own mortality will eventually sever.

Monday, December 12, 2016

Ahh... driving

What could be more normal than getting in the car and driving somewhere?

Driving is such a normalised activity. Almost everyone I know does it -- people that don't drive are a bit strange, and their options are greatly constrained.

I love a road trip. When we moved from Brisbane back (home) to Adelaide, we took 5 weeks to drive home along the coast, which we followed from Brisbane to Melbourne. It was a fantastic trip.

It's so easy to get in the car and watch the world rush by. It's also easy to forget just how much energy is being used in that process. Here's an example:
We recently went to visit Monarto Zoo which is (the only?) open range zoo in Australia and is about 65 km from my house. It's an easy drive, about 40 minutes up the freeway. Google Maps estimates it as a 4 hour bicycle trip (I'm presuming that is without kids)
So the round trip is about 130 km. Our car uses about 8 L per 100km on the open road, so that works out to about 10.4 L of petrol, which is about 100 kWh (each liter of petrol has about 10 kWh of energy). For us, that is a month's worth of energy (as consumed by our house of four people) used in 1h:20m of travel.

Faced with these numbers, it is clear just how much of a problem driving is for our carbon emissions, and how easy we make our lives elsewhere if we can just drive less. If we want to avoid damaging climate change, we simply need to drive less, and this will make our other goals (eg. renewable electricity, reduced consumption, more sustainable agriculture, etc) that much more achievable.

Wednesday, October 12, 2016

End of winter recap

Now that winter is over, how have we done?


My last post about my solar systems' performance has made me think a bit more about their performance, so I've done some analysis.

I have taken some meter readings over winter, which gives me
  • solar PV production over winter
  • grid draw over the same period
  • grid export over the same period
This gives these data (for the period June 1st to October 6th):
average total daily consumption (PV self consumption and grid-draw): 6.26 kWh
average Daily PV production: 6.13 kWh
average daily grid draw over winter: 3.9 kWh
average daily grid export over winter:  3.7 kWh

The same calculations for the period June 1st to August 2nd look like this:
average total daily consumption (PV self consumption and grid-draw): 6.29 kWh
average Daily PV production: 4.67 kWh
average daily grid draw over winter: 3.91 kWh
average daily grid export over winter:  2.66 kWh
 We tend to cook more with the electric oven in winter, which I think largely explains the higher daily consumption. Also, we use lights more, etc. We needed to boost the solar hot water system once, for about an hour, which used about 2.4 kWh.
Overall, I am fairly happy with these numbers. I think we're losing at least 0.5 kWh/day to phantom loads, but there's only so much energy I have for turning things off at the power point. Clearly, for our PV to cover our consumption in winter, we need ~50% more panels.

Propagation area

I've been busy building a spot for seed propagation. Seeds need constant moisture, and the requirement that we keep them moist for several weeks was just too much for us (forget to water them for a day and they're dead). I built this bench using almost 100% found or scrounged materials. Even the nails and bolts were mostly reused. It's also amazing what you can build with poly pipe and clothesline! It has a watering system that waters it for 1 minute every 6 hours. Bonza!

tomatoes and beetroot and basil, oh my!

does your propagation table have turned legs? ;-)

Composting loo

Now that we've had the last rain until about March (well, we can't expect much!) I'm again feeling unhappy about putting potable water down the toilet. I've started building a box composting toilet. It's designed to hold a 20 L plastic bucket and a urine diverter. It's made from pallet wood (and pallet nails), with a few bits of nice timber I found on an old air-conditioner facade that I found on the side of the road (they made them attractive in the old days!). Not quite finished, but getting there. As I said in a previous post, I'm using this device as a urine diverter, and they have some plans online for how to make the toilet. I am vaguely following those.

It is spring, and the garden is blooming. Here are some photos from the garden:
New citrus grove (sorry for the dark photo)

Broad beans

Monday, October 10, 2016

2 years on: System performance

We've now had our solar hot water and solar PV system for 2 years. I thought it was worth commenting on them.

Solar Hot water (main)

This system is detailed here and here. Based on my meter readings, I estimate it has saved us 4500 kWh (just over 6 kWh/day), which is worth $1350 on the standard tariff (we avoid the off-peak tariff because it supports fossil fuel power, even when buying Greenpower) At this rate, the system will pay for itself in about another 18-24 months (4 years total from new).

The tank looks a little weathered, but still in very good shape. Beacuse  it is low pressured, I am confident it will last many years. I partially shade the panels (with an old cotton blind) in summer, to stop it boiling, and we lose very little water from it.

Kitchen Hot water

This system performs poorly in winter. It's nice to have instant hot water, and it was a good learning project, but I wouldn't recommend people do this if they have other solar hot water. At some point I might re-purpose this system into a backyard shower.

Solar PV

Our system has produced almost 10 MWh. Since we got the new input/output meter we've exported about 7 MWh to the grid (which means we've self-consumed 3 MWh of our solar PV). We get paid $0.24 / kWh for exported power and pay $0.32 / kWh (including the GreenPower premium) for imported power. So, the return on our solar PV has been $2600, or about 1/2 the cost of the system.
As of the end of September, we lose the $0.24 feed-in-tariff, and will be paid about $0.08 / kWh. That will reduce the return on the system cost. In another 2 years, we'll have got back an additional $1500 at these tariffs. I think we'll pay back the cost of the system in about 3 years (5 years total from new).


Our 2 kW solar PV system has produced more electricity than we use almost every day (about 50 exceptions in two years) since it was installed. I've shown the economics here, because that's of interest to some people, but it's a great feeling to look at the roof and see the power we harvest. It's strange how people carefully consider at the economics of solar PV, but not of cars.
At some point, I think we'll install a hybrid battery system. I like the idea of self-consuming more of our power. But I don't think we'll try to go fully off-grid. I think that doesn't make sense in the city (firstly, we'd need a much larger battery to provide for the small number of days when we lack solar PV and secondly it has a bit of a gated-community feel to it). I might also install a second solar PV system. That will have much worse payback than the first, but that's ok.

Wednesday, September 21, 2016

A heater battery

I've been thinking about home temperature management, and the problem as I see it is:
  • We have a huge supply of existing housing stock, with limited options and money for retrofitting improvements
  • People are unlikely to be satisfied with a 13°C house in winter and a 33°C house in summer
  • As we move to a more renewables-based energy grid, the importance of storing energy increases
  • heating/cooling is, for most people, the largest energy user
  • I believe that the burning of firewood in the city should be minimised
  • If we want to use batteries to supply electricity for heating/cooling, we will need an enormous supply, which will be very expensive (in terms of money and energy) putting it out of reach for most people.
So, we need a heating solution that is
  • Relatively cheap
  • Able to store a large amount of energy during times of plenty – I think in winter it needs to store 4 days' heat (during summer, it really only needs 1 or 2 days as solar PV is very productive)
  • Suitable for retrofitting
 I think I have come up with a possible solution.

Heater-cooler design

In Europe, it is possible to buy a storage heater. It is designed to run on off-peak electricity, which it uses to resistively heat a “bank” of iron “bricks” to about 700°C. Then, during the day when heat is wanted, it blows air over the bricks to warm the room.
My idea is a variant of this, except it uses phase change materials to store heat and “coolth” (the ability to cool air).

Phase change materials (PCMs)

You are familiar with phase change materials if you have ever put ice in a cool box. Ice keeps your food cold not (just) because it is cold, but because ice absorbs a lot of heat as it melts. To put it another way, to it takes a lot of heat to turn ice at 0°C to water at 0°C. If you add the same amount of heat again to the 0°C water, you will raise its temperature to 80°C.

My design uses this principle to store large amounts of heat and coolth.

It uses a PCM that melts at about 30°C. This is encased in small containers (eg. 1L soft-drink bottles) with a large surface area, within a tank of water surrounded by insulation.


In winter, heat is put into the tank, which melts the PCM. Because the maximum temperature of the tank only reaches about 50 – 80°C, there are more options for heating it. Instead of using a resistive heater (such as used in the European storage heater) we can use a bank of evacuated tubes or heat pump and get either free heat, or 4 kWh of heat for every 1 kWh of electricity (it might even be possible to use a roof-top solar pool heater). This melts the PCM and stores the heat. Later, when the building occupants want to warm the room, a small fan blows room air over the heated tank and warms the room air.


In summer, a heat pump can be used to pump heat out of the tank. This can freeze the PCM first (at 30°C), and then the water surrounding it (at 0°C). This stores “coolth” and in the evening when people come home from work, they can use the tank to cool the air in the room.


I have done some analysis and modelling in a spreadsheet that can be found here.
I have modelled the heater’s performance under various design considerations. At the moment, here is what I have settled on:
  • Heat/coolth storage volume: 350 L (total size: 1.2 x 0.9 x 0.5 m, allowing for 50mm of insulation all the way around)
  • Volume of hot-melt PCM: 250 L
  • Volume of water: 100 L
This design gives the following (theoretical) performance:
Heat storage (for use in winter): 31.8 kWh equivalent
Coolth storage (for use in summer): 12.5 kWh equivalent (I’ve deliberately designed it with less coolth storage, because solar PV is abundant most days in summer, but it could be adjusted. This also assumes that the heat pump can efficiently freeze the water.)


If the home occupant has solar PV and a reverse cycle system anyway, and if the marginal extra cost of my system is $1500 (my unit would replace the internal component of the split system), then even if the installation cost of an equivalent-performance battery system reduces to about $5000 (about ½ current prices) then my system is about 25% cheaper (this calculation is on the basis of heat/coolth delivered, and considers that it won’t be used in spring/autumn. It allocates batteries as having more value, but only at the same rate as heat/coolth – ie. when my heater is unused). In other words: if the price of batteries halves, my heater is still 25% cheaper.
Despite this, I doubt that this can be successfully produced as a commercial product, for the following reasons:
  • It’s a one trick pony – it can’t store energy for general use, only for heating cooling. Batteries store electricity, which is more generally useful. Batteries also have a lot of “public mindshare” and will be hard to compete against
  • The cost of the PCM is significant. To be sold for $1500, it would need to be made for 1/2 that, which I don’t think is possible. I think a bespoke heater could be made for $1500, but that would be using “scrounged” parts wherever possible, since the retail cost of PCM would be about $1500.
Despite this, I think my system has some real advantages over using batteries to power heating/cooling:
  • Its embodied-energy is very low in comparison with batteries
  • It can be expected to have a very long useful life and is repairable (the only moving part is a fan which is replaceable). I could imagine a unit lasting for decades if well-made.
  • It is (relatively) easy to integrate with evacuated tubes to collect extra heat in winter


Most Australian houses have poor thermal performance. This device allows one to store heat/coolth that can be released when it is wanted. Because there are low temperature gradients (the internal temperature range in the device might not go outside -4 to 40°C) it should be easy to insulate. It is a cheap and easy retrofit (compared with improving the building envelope) that allows people to store large amount of heat/coolth to use as they please and is inherently compatible with renewable energy systems.

Sunday, September 4, 2016

Don't abandon the plebiscite

I am not LGBTI, but I am an ally. I strongly believe that all Australians are better-off with marriage equality, and I hope for a future that is more inclusive and less judgemental. I realise that I can’t understand the discrimination that LGBTI people suffer, but have had a few thoughts about the “debate” and how LGBTI people might strategise to get the outcomes they want.
I’m certainly not arguing that a plebiscite is a good outcome (John Howard's government changed the Marriage Act without a plebiscite -- there's no reason this government can't change it too), but it might be the only way of getting marriage equality during this term of parliament. If that’s the case, I think it should be pursued.
Note that I’m only thinking about the politics here, not whether a plebiscite on marriage equality would actually succeed, or any nastiness it might raise – I’m not very knowledgable on either of those things (and it's not for me to glibly talk about LGBTI people tolerating extra abuse for the greater good).

Thoughts in brief:

Marriage equality is a wedge-issue for the Coalition. The (small-l) liberal (progressives) like Turnbull support marriage equality, while the conservatives oppose it. Therefore, there are internal politics at play within the Coalition, with both the (small-l) liberals and conservatives hoping to use the issue to strengthen their power within the party. Turnbull wants to strengthen his prime-ministership, the conservatives want to replace him with someone like Abbott.

Labor is happy that they have found an issue on which to wedge the Coalition. The Coalition successfully wedged Labor on asylum seekers for two decades, and Labor are happy to pay them back. Because of this, politically, Labor are not in a hurry to resolve this. The longer they can prolong this issue, the more political mileage they get from it. The ideal outcome for Labor would be for this to drag on over several electoral cycles. Labor can keep ineffectively “trying” to get marriage equality to happen, and paint the Coalition as the breakers. If this continued, people for whom this is a big issue (ie. The LGBTI community) could become a captive constituency – they are forced to support Labor as the lesser-evil: they know the Coalition will never do it, so they can’t vote for them, but Labor is therefore not in a rush to do anything either. This would be a disaster for the LGBTI community.

For this reason, I think Labor are only too happy to vote against the plebiscite, especially if they can blame the Coalition and not expend political capital. Given the internal politics of the Coalition, the plebiscite might be the only realistic mechanism to get marriage equality – perhaps Labor don’t really want that, and would rather keep this as a hot-button issue that keeps votes coming to them.

There are people in the Coalition who support marriage equality. Since it is not coalition policy, they can’t vote for it (it would require that they cross the floor, and they would be kicked out of the party). But if there was a plebiscite and voting afterwards, perhaps they could. Labor and Greens defeating the plebiscite will weaken Turnbull’s leadership, and make it likely that he will be replaced by a more conservative leader. Is that what progressives really want?

Imagine that a plebiscite is the only option. It might pass or it might fail. If it fails, little is lost and another attempt can be made in a few years. If it passes and goes to parliamentary vote, a few conservatives in the Coalition might oppose it, but most of Labor will support it, as will many other Coalition politicians. It would easily pass. For this reason, if the lower-house fails to do its job and pass legislation on its own, the plebiscite should stay on the table as a fall-back option.

If it comes to a plebiscite, I think the question could be:
Should the government be able to prevent two adults from marrying?

Monday, August 8, 2016

turning our rose-coloured glasses towards the future

Everyone has a different idea about what the future holds, and our beliefs about likely future scenarios are largely defined by our beliefs about the present. This post aims to consider the way our beliefs shape our thinking about the future, without trying to ascertain which beliefs are probably correct.

The Christian Worldview

In the West, our thinking is hugely shaped by the Church. As a group, Westerners are romantic, idealistic and individualistic. We have a long history (which even predates the church) of skepticism about humanity's ability to be in control in a sensible way. A great example is the Greek fable of Icarus, or the story of Adam and Eve, but there are others, including more modern examples such as Frankenstein, Jurassic Park, etc. The issue is also deeper, and plays into the idea that the natural world is inherently beyond our comprehension or ability to control.
The Christian worldview also views humans as a mar on an otherwise-perfect landscape. A consideration of our flaws is fundamental here.

The Enlightenment worldview

In opposition to this is the Enlightenment worldview, which posits that rationalism and systematic research can reveal the workings of the world to us. It also views human potential as infinite and humans themselves as the apex of creation, with our intellect and reason elevated to near divine status. This view really began in the Renaissance, and gained traction with thinkers like Voltaire, Newton, Bacon, etc.
Since the Enlightenment, this view has been tempered somewhat by thinkers such as Godel and Schrodinger who have shown some of the limits to human knowledge. However, the enlightenment view persists, that people can continue to better themselves indefinitely through the application of knowledge about the universe.

The future

Many, perhaps most, people agree that humanity is at a crisis point when it comes to climate change. There is a smaller group who are aware of the dangers of resource depletion. We know that we cannot continue adding CO2 to the atmosphere without significant consequences for ourselves and Earth's ecosystems. There is disagreement, though, about what this forced change means for us and how we should achieve it.

The techno-utopians

The techno-utopians believe that technology will solve this problem for us without major changes to our society. Some even argue that market mechanisms, as they currently exist, will seamlessly transition us from fossil fuels in a timely manner. Others argue that government intervention (at least to remove market distortions) may be required.
The basic consensus in this group is that solar PV and wind turbine technology is currently the cheapest new form of power and that it will quickly displace all fossil fuel generation. To my mind, techno-utopians share the enlightenment worldview.


Doomers believe that we are on the way to collapse. They envisage that the disintegration of the West, industrial society, human civilisation, or even human extinction are the likely outcomes. They believe that humans have risen above their station by the exploitation of fossil fuels, that it won't be sustained, that there is no other alternative and we will revert back to some former, simpler, state. They believe that a sustainable society looks very different from our current society.
I believe that this way of thinking is close to the Christian worldview. Our punishment awaits us due to the pursuit of knowledge (that we shouldn't have) -- like the fable of Adam and Eve.


I'm not saying that one of these opinions is right and one is wrong (to my mind, it is not yet clear how this will play out). However, I think it is useful to be aware of the background and presuppositions to our thinking.
Also, the sketches of the two groups are very broad -- I realise that both groups are highly heterogeneous and have many distinct and conflicting opinions.


To my mind, a big question is: can humans discover/invent things that nature cannot?
A good example of this is solar power. Is it possible for humans to build solar PV systems that have a full-circle efficiency (ie. including materials provision, manufacture, maintenance and decomissioning) better than photosynthesis? I think that doomers would say we can't, and that techno-utopians would say we can.

Here is a restating of the question:

Evolution is our name for the process that leads organisms to possess traints that are well-fit to their environment. Because unfit organisms tend to produce fewer successful offspring, the tendency over time is for a trait to become optimal for its environment [1]. One thing to bear in mind is that evolution is incremental, and every tiny step in the development of a trait needs to be not only viable (ie. able to survive), but optimal (the currently most competitive solution) otherwise the progeny of that evolutionary step will be disadvantaged and the trait will tend not to persist.
This is not true for humans developing a new invention. Humans can mentally explore options, and use creativity and leaps of inspiration to create something fundamentally new. We don't need to arrive at a new idea, in tiny incremental stages, where each stage will be optimal -- we can "build" the invention, in our mind, all at once: exploring different designs and their strengths and weaknesses.
Clearly, humans' ability to make mental models of the world is constrained by our own evolution (eg. we retain a primate nervous system), but it seems possible to me that humans can still create inventions that are impossible for evolution to create. [2]

This doesn't answer the question of whether solar PV has a full-circle efficiency better than photosynthesis, but it indicates that it is possible it is true, while providing no evidence one way or the other. For this reason, I believe it shows that saying "if there was a better way to convert sunlight into chemical energy, evolution would have found it" is fallacious reasoning.

[1] This is clearly a gross simplification, but for the purpose of this sketch, it will do.
[2] There is a danger in this thinking though -- biological evolution has been occurring for such a long time that it could find circuitous routes around what appear to us as impossible chasms -- for this reason we should be careful before pronouncing that we have found an invention that evolution could not find.

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