What are the factors which contribute to the environmental impacts of ceramic processes? This article explores the different facets of working with clay in ceramic studios and contextualizes energy and resource usage in relation to activities of daily life and big picture environmental issues.
Check out the activities of the NCECA Green Task Force if you would like to get involved in environmental initiatives within the ceramics field.
One of the biggest impacts that ceramics has on the environment of the planet is from mining operations. Ceramic materials are obtained mostly from surface mining which is the most detrimental type of extraction because it causes the largest change to the land. Mining strips nonrenewable resources from the earth resulting in some negative effects which can include;
- Biodiversity loss
- Soil erosion
- Contamination of surface water
- Formation of sinkholes
Surface mining can destroy the ecological balance of an area, sometimes wiping out entire species. Despite efforts, many times an area can not be restored to its former state after extraction has commenced. The materials displaced during the process are called spoil piles. These have perhaps the most immediate effect on the surrounding areas. Minerals not previously available to erosion processes can travel into local water supplies contaminating it chemically and suffocating local flora and fauna which live in the water. A 2019 study from the Associated Press found that 50 million gallons of contaminated water pour daily from mine sites in the U.S.
An Alternative to using clay from industrial mining sites is to locally harvest clay. However, this still alters the landscape, albeit on a much smaller scale, and can affect the ecology and biodiversity of the area. Through the removal of topsoil, sediment is exposed. Piling the soil over untitled land will inevitably disturb the soil nutrient cycle. Heavy rainfall can then wash the sediment into nearby bodies of water which can smother organisms living in the water and make it unsuitable for drinking for larger fauna.
Another aspect of the environmental impact of mining is processing and transportation. Clay, feldspar, fillers, and fluxes come from all over the world. With these transports come whole sets of pollutants from each. See the shipping section at the end of this page for more information.
Which ceramic materials are especially harmful to the environment?
Frits – While most materials that we use go through the extensive processing of mining, frits are a whole other can of worms. Ceramicists use frits for their reliability, melting properties, and convenience. These highly precise materials are manufactured by an intense melting and cooling process which homogenizes the mix of chemicals. The most commonly used frit company for studio ceramicists is Ferro, which is a U.S. based company with 72 locations worldwide.
“In our case, the main environmental aspect associated with the production of ceramic frits is that it is an energy-intensive, high-temperature process. This entails emissions of combustion products and the oxidation of atmospheric nitrogen due to the high temperature.” – (Qualicer.org -World Congress on Ceramic Tile Quality). Oxidation of nitrogen creates nitrous oxide (also known as laughing gas) which is 300 times stronger than carbon dioxide as a greenhouse gas. It has a lifespan of 110 years and depletes the ozone
How does firing an electric kiln compare to the use of a home appliance (such as a water heater) in energy cost?
Find the Kiln Wattage which may be written on the kiln or in the manual. You can also multiply volts x amps of the kiln to calculate the wattage. Since energy is measured by the electricity companies in kilowatt-hours, divide watts by 1000.
The medium Skutt 1027 has a rating of 11.52 kW. To find this much energy this kiln uses for one firing, multiply the kW by the duration of use. Electric kilns elements cycle on and off during a firing to control the ramp of temperature rise. Skutt estimates that most kiln cycles are only “on” for about half of the duration of the firing. For a 12 hour firing (11.52kW x 6hours) this kiln uses 69.12 kW.
In comparison, a typical electric water heater uses 4 kW per hour and is on for about 3 hours a day for a total monthly usage of 360 kW. To meet the amount of energy used by a typical water heater in one-month, a medium electric kiln would have to get fired 5 times.
To put all this information in terms of greenhouse gases emitted use this calculator from the EPA. The medium kiln which uses about 69 kW for a 12-hour firing is equivalent to 121 miles being driven by an average passenger vehicle or 54 pounds of coal burned.
Using the same line of logic, how can we better understand the carbon impact of gas kiln firings? A soft brick gas kiln uses approximately 10,000 BTU’s per hour for every cubic foot for a cone 10 firing. A 30 cubic foot kiln will use 300,000 BTUs per hour to reach cone 10. Because you do not use the gas at full power for the whole firing, we will calculate for 6 hours of full power. To reach cone 10 in our 30 cubic foot kiln it will take 1,800,000. This is equivalent to about 18 therms of energy used. This firing would match the greenhouse gas emissions of a car driving 236 miles.
“With regard to atmospheric firing, I worked in a studio that used an Olsen Fast-Fire wood kiln. While the results were not superlative by wood-firing standards, it did fire a nice cone 10 reduction. It seems plausible that a quick-firing wood kiln or a gas-assisted wood kiln could be adapted for reduction, soda, or salt firing. By using wood from the scraps generated at a lumberyard or mill (they even delivered them to the studio I worked in), waste from a renewable resource is repurposed while reducing reliance on fossil fuels. If you are fortunate enough to own wooded property or have access to a school forest, it may even be possible to harvest trees in a manner that increases the health of the forest while providing fuel for your kiln. This same forest could offset the emissions produced by firing kilns.” – Jennifer Harnetty From Ceramics Arts Daily
Soda and Salt
Salt firing has a byproduct of hydrochloric acid. Produced largely by the burning of coal, the acid enters the atmosphere and is deposited into the soil via precipitation changing the acidity affecting soil nutrient cycles. How do we put the amount of acid produced by salt firing in the context of another acid producing process?
“Sustainable Ceramics” by Robert Harrison, addresses this question. Wil Shynkaruk conducted research on salt and soda firing’s impact on the environment. After working with a team of a chemist, they determined that in the worst-case scenario a 24 cubic foot salt kiln fired and salted 12 times would produce roughly the same amount of acid as a single-vehicle does in two months of typical driving in the United States. See the book for more details about his research.
Stefan Andersson’s veggie oil burner system. He uses a low pressure siphon nozzle operating in the range of 20-60psi. He preheats the oil to 50 degrees celsius. The whole process uses about 30 litres of veggie oil (wvo) to achieve stoneware temperatures in a mixed reduction/oxidation firing.
Robert Harrison says this “The most important thing that an individual can do to save the planet is to save water.”
With the hazards of silicosis, cleaning methods in ceramics are heavy on water usage.
Sustainability and the Ceramics Studio – Article by Kristin Schimik, Ceramics Arts Daily. Three Universities share their creative disposal methods in the studio.