This is the research paper that I presented to the recent Ceramics Triennial Conference in Hobart, Tasmania. On the ‘Sustainability’ Panel.
Steve Harrison – Sunshine Came Softly Through My Spy-hole Today.
I was raised in the 50’s in a home where the topic of ‘health foods’ and ‘natural living’ was at the forefront of conversation. I came from a loosely quaker/buddhist background with a grounding in ‘healthy’ living. As a child, I was brought up in this environment. Aristotle said “give me the child until he his 7 and I will give you the man”. I am that man. A ‘greenie’ before the greens were invented.
Since I decided to be a potter, I have always been a wood firer using a small, single chambered, bourry-box kiln. I wanted to fire my pots as cleanly as possible, in an environmentally sensitive way. In 1976 I moved to the country and bought a very old derelict school building, built in 1893, with seven acres of land and started planting a forest. By growing my own trees, these trees took their carbon out of the air, when I eventually burnt this timber to fire my kilns, it didn’t introduce any new carbon into the atmosphere. This was the best approach that I could think of to minimise my carbon footprint at that time. I’ve progressed!
We have also planted very large vegetable garden and 5 small themed orchards, with a dozen cherry trees, a dozen almonds, a dozen hazel nuts, a dozen citrus, a dozen stone fruits, a dozen apples, 5 avocados, 4 truffle oaks, 3 white figs, two berry vines and a bower bird in a pear tree!
My wood fired kiln has proven to be very fuel efficient, I have worked on the design for over 40 years and written the standard text on the subject. ‘Laid Back Wood Firing’ and it is as clean as a wood fired kiln can probably get, without using an after-burner. I tried adding afterburners to several kilns, but have since abandoned that idea as too wasteful and complex. There is no point in using a premium fuel like LP gas to burn the smoke from an inefficient wood fired kiln. I couldn’t justify it. So I stopped working on that project.
I did a lot of work on ‘flame tubes’. Fibre lined stainless steel tubes on top of the chimney that allows warm air in at the base, so that it mixes with the unburnt smokey fuel during reduction and combusts with-in the tube. All that is seen is a pale red glow at the top and bottom. The beauty of it is that it has no moving parts, and needs no external fuel source. The blue haze at the beginning of firings has always bothered me and flame tubes don’t fix that problem. That is a work in progress.
It is possible to fire in reduction at high temperature with very little smoke, but the cold blue haze at the beginning of the firing is a very difficult problem to overcome. It was only later that I came to realise that it isn’t just blue haze smoke at the beginning of the firing when we are releasing ultra-fine particles into the atmosphere from our wood kilns. Wood firing generates loads of fine particulate matter, all through the firing. Some of these are quite fine and are hazardous to inhale. They are known variously as PM 7’s to PM 2.5 particles, they are small enough to enter deep into our airways and lungs and can cause all sorts of unpleasant health effects, even cancer.
Clearly, one kiln, fired intermittently, isn’t the problem, but when it is added to the other emissions of diesel vehicles, wood heaters and industrial pollution from factories, cement works etc. It adds to and is part of the larger problem.
See the EPA web site. https://www.epa.sa.gov.au/environmental_info/air_quality/assistance_and_
Added to this less-than-up-lifting scenario, there is the growing problem of global warming. Contrary to the statements of conservative politicians and the hard right media shock-jocks, the science IS settled and has been for a long time. The man-made global-warming deniers are simply wrong! They are either being disingenuous or choosing to be ignorant. Perhaps I could be generous and say that they are choosing different truths.
We used to be able to fire for 8 or 9 months of the year at home, but over the past 42 years, living in the Southern Highlands, our window of opportunity for wood firing has been reduced now down to 5 to 6 months, May to August. September is now getting too unreliable to book wood firing workshops. We have had to cancel workshops in the past few years due to hot, dry, windy weather and therefore total fire bans, as early as September. Total fire bans in our area used to only occur in January and February.
Some time ago, I decided to develop a series of small portable wood fired kilns that could be wheeled out, packed and fired in one day. Then wheeled back away again until the next firing. These portable little wood kilns are very fuel efficient and can reach stoneware temperatures in 3 to 4 hours using a wheel barrow of wood. If you are careful, they can be fired very cleanly. They are a fun solution to minimising carbon emissions and avoiding the use of gas and coal. By collecting fallen branches from around our block, we can fire with a zero carbon foot print. This is the ‘vegan’ equivalent of wood firing . No trees were hurt to fire the kiln. The trees drop the dead branches. We have to pick them up to mow the long grass. We have to mow to reduce the fire hazard in summer. So fallen branches do not introduce any new carbon and are tree friendly. That’s nice, and the kilns are quick and fun to fire. But particulates are still a problem.
So where is all this leading? I realised that I needed to find another way to fire my work cleanly and efficiently into this uncertain, carbon constrained, globally warmed, future. The climate is changing, so we must change with it. Janine and I have had solar hot water for over 30 years and Solar Photo Voltaic panels on our roof, for the past 17 years. We installed 3,000 watts of Australian made, BP Solar, Photo Voltaic panels as soon as we could afford to do so in 2006/7.
We have been using our electric kiln for all our bisque, earthenware and oxidised stoneware firings ever since then and have always paid the little extra for sustainable green power since it became available. So that if we needed to draw power from the grid, it was sustainably generated power that we used. In the last couple of years we have been working towards firing our work in the summer months of fire bans, using a new low-thermal-mass electric kiln that I built from a pile of spare parts, left over from my kiln building factory, after I retired. I designed and built a kiln that is fired using our solar panels and backed up by our Tesla Powerwall II battery.
To allow us to fire in reduction, I made allowance to install 2 small pilot burners in the bottom of the kiln and built a small flue hole in the top. These burners aren’t used to fire the kiln at all. They are too small. The kiln fires to stoneware on solar power, the burners are only used to create a very small amount of flame to generate the reduction atmosphere needed to change the glaze colours. I attach the burners to the kiln and light them when the kiln reaches 1,000oC. They use about 200 to 330 grams of gas to reduce the kiln load of pots steadily over a couple of hours while the electrical elements heat the kiln load of pots. It’s the best solution that I can find at the moment to give us reliable, all year round access to reduction firings that are very, very, low carbon and as sustainable as I can make them.
The firing can take as little as 4 to 5 hours in total and give perfectly adequate reduced results. Experience with this kiln has shown that we can achieve all the normal reduced colours with our standard local milled rock glazes. I fire the pilots on 5 kpa gas pressure, but have recently experimented with pressure so low that the regulator gauge can’t register the flow and the kiln still reduces. We usually wait to start the firing until around 9 or 10 am, as that is when the sun is up high enough to give us the energy that we need to get the kiln going. It takes about 2 to 3 hours to get to 1000oC, then I attach the pilot burners and start reduction, around noon to 1 o’clock. I reduce for about 2 to 4 hours depending on what I’m experimenting with and finish the firing between 2 and 4 pm. as the sun is going down. We fire directly off the PV panels until 1 or 2 pm, then as the sun passes its peak, and the kiln is drawing its maximum power. The Tesla battery cuts in automatically to make up the short fall to finish the firing. If the weather is cloudy we can also draw down on our credit with the power utility. As we are on a ‘net’ metering system, and are always in credit. We never actually ever pay for any power that we withdraw from the grid. However, it is important to note that we pay the extra to contract to only use green power from sustainable sources when we do with-draw.
I don’t know if you have ever seen one of these graphs? It is the screen from the Tesla mobile app that tells me how much solar power I’m producing and consuming and/or selling/buying from the grid.The yellow area indicates the solar power generated. As you can see the solar energy starts off low at 7 am, then from 10.00 am it quickly rises to a peak at noon, hovers for a while, then drops away until 6 pm. and sunset.The green area is the energy required to re-charge the battery from its use since yesterdays sunset and running the house over night. This re-charging is usually complete by 9.00 or 10 am.The blue areas of tiny upward spikes is the fridge turning on and off regularly over night and all through the day. The sharp blue spike is the electric jug and toaster being used at breakfast time. On this day it was at 7.00 am. The white area below the line is the energy that we sell to the grid every day when we are not firing the kiln or charging the car. This generates a credit that we can draw down on in cloudy weather and covers our daily charges. This report tells me that I generated 35 kW/hrs of solar and used just 1.4 kW/hrs to run our home and pottery on that day. We sold 32.8 kW/hrs to the grid. It was obviously a quiet day with nothing much going on. I wasn’t welding in the kiln factory or ball milling rocks and pugging clay in the pottery.
This is what a firing looks like, We simply stop selling our excess to the grid and use it our selves. The blue block is the amount of energy used to fire the kiln. The taller blue spike on the left, is the car being charged at the same time. It is worth noting that we can do both at the same time and still recharge the battery after wards in the afternoon.
Just as an aside, we also have a solar powered electric car. A Hyundai, Ioniq, ‘plug-in’ electric car. I have written about this on my blog on a few occasions with regular up-dates to let readers know how it’s going. v< https://tonightmyfingerssmellofgarlic.com >
This is what happens when we charge our car. We simply stop selling our excess to the grid for 2.5 hrs. There is enough power to do this, even on a cloudy day, as is the case in the chart above.
We put our pots out in the sun to dry. We call it the ‘solar drier’. The solar drier makes sure that the pots are totally dry before bisque firing. We can charge the car as well in the back ground, both using sunlight at the same time! It’s amazing that there is enough sunshine to go around! The vegetable garden keeps growing and the orchard thrives! We can also walk and chew gum at the same time.
To help make this all happen, we recently bought into a community bulk purchase scheme and installed another 3,000 watts of Australian built solar PV from ‘Tindo’ in Adelaide. This allows us to run our house, fire our kiln and drive our car, all on our own sunshine. It’s a very nice feeling to be able to live, cook, work and drive, powered almost totally from our own solar power. We do all this and still have a little excess to sell to the grid. This covers our daily charges to be connected and even earns a little bit of extra cash. I haven’t paid an electricity bill for 17 years. You can see from our recent bill that we do all this and still use about half of what a single person household uses, and much less than half of what a two person household like ours uses.
Now, I know that someone is going to ask me what is the cost benefit analysis? It’s the most common question that I get asked along with the statement, “I wouldn’t put solar power on yet. you can’t make any money out of it!”Well, my answer is, when you bought your new car. How did you make money out of that? Or, when you flew to Bali for a holiday, How did you make money out of that?
The point is that I did this because it pleased me. I get a lot of satisfaction out of it. I did it to extract myself as far as is possible out of the coal and oil economy. I didn’t do it for money. I do very few things in my life solely for the money. I’m not very interested in acquiring ‘things’. This is the equivalent of my holiday in Bali, or my ‘walking tour of the vineyards of Provence’. I’ve never been to Bali, or walked the vineyards of Provence. We each choose to spend our discretionary dollars in our own way. This is mine.
Now finally, I will add that I bought carbon credits to cover the carbon off-set of my flight here. Real off-sets in the form of planted trees. I buy a few hundred dollars worth of carbon credits each year to cover all the damaging things that I do to the environment in my life, like air travel. I think that it is worth it. I’m not proselytising for solar. You will have already made up your own mind about that. You’ve had a couple of decades to consider it. I’m just telling you what is possible, because you won’t have heard it from the the Federal Energy Minister or any one else in the government. This however, may be food for thought, if you haven’t already though about it. I will end by telling you that the future is here and this just might be what it could look like.
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