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How to Escape From the Iron Age?

Mon, 18 Mar 2024 00:00:00 +0000

Image: Steel rebar construction for the concrete foundation of a wind turbine in Gilliam County, US. Image by Goose Chap, Wikimedia Commons (CC BY-SA 4.0)

Trapped in the Iron Age

In 1836, Danish antiquarian and curator Christian Jürgensen Thomsen distinguished three prehistorical eras based on the dominant materials used for weapons and cutting implements: the Stone Age, the Bronze Age, and the Iron Age.¹ Thomsen’s classification refers to the past, but according to his criteria, we have never evolved beyond the Iron Age. Even in the 21st century, iron remains the dominant material, not just for weapons and cutting implements but for about every modern technology.

We now use most iron in the form of steel. However, according to Thomsen’s criteria, we cannot speak of a “Steel Age.” First, steel is merely an alloy of iron (>98%) and carbon (<2%). Second, humans have been producing steel since the beginning of the Iron Age. That is a little-known fact in the Western world, where steel production only took off in the nineteenth century with fossil fuels. However, Asian and African metallurgists developed high-quality steels much earlier, and this knowledge eventually allowed Europeans to do the same – on a much larger scale.²

By 2021, the global iron and steel output reached 1,950 million tonnes (Mt). That is 22 times larger than the combined aluminum and copper output (88 Mt). The global iron and steel output corresponds to five times the global plastics output (391 Mt) and dwarfs the worldwide production of silicon (8.5 Mt) and lithium (0.1 Mt).³⁴ Steel is the fundamental material of industrial societies. Without plastics, lithium, or silicon, we would still be in an industrial society. Without iron and steel, we would be thrown back 3,000 years into the Bronze Age.

Where is all that steel?

The massive presence of steel in industrial society is not so obvious.⁵ At home, we find several steel appliances such as the refrigerator, washing machine, water boiler, bathtub, and cooking, heating, and cooling appliances. However, only 2-3% of total steel production ends up in domestic appliances.⁶⁷⁸ Outdoors, there’s a lot of steel in the form of vehicles. These are especially passenger cars that use around 10% of all steel globally (20% in rich countries). Busses, trucks, trains, and ships add another 4-5%. Altogether that is still less than 20% of the global steel output.

Most steel is embedded in other materials, located underground, or far away from residential areas.

Most steel is embedded in other materials, located underground, or far away from residential areas. More than half of global steel production goes into construction, which includes buildings (residential, commercial, industrial) and infrastructures (bridges, tunnels, harbors, canals, runways, oil rigs, refineries, pipelines, power plants, transmission lines, railways, subways, and so on). Much of that steel is embedded in concrete. Reinforced concrete is the world’s primary building material, and concrete is the only material that can match the output of steel (1,819 Mt in 2021).

Roughly 15% of global steel production serves to make machinery, including machine tools, industrial equipment, electrical hardware, and construction, mining, and farming machines. Even products made of other materials – such as other metals, plastics, and wood – are shaped by steel tools.⁵ The final 15% of steel production ends up in a variety of objects, from screws over food packaging to furniture and shipping containers.⁶⁷⁸

Image: Reinforced concrete is the world’s primary building material. Hole on Interstate 84, US. Image by Tony George, Oregon Department of Transportation, Wikimedia Commons (CC BY 2.0).

The environmental footprint of the steel industry

Steel is often presented as one of the most sustainable materials. Unlike plastics, steel can be recycled without any loss in quality. The steel industry has made great advances in energy efficiency, more so than many other industries. Making one ton of crude steel now requires roughly 20 gigajoules (GJ) of primary energy on average – three times less than in 1950.⁹ This compares very favorably to other materials such as aluminum (175 GJ/t), plastics (80-120 GJ/t), or copper (45 GJ/t).⁷ Unlike plastics, steel is a biodegradable material.¹⁰ Finally, iron ore is not in short supply. It makes up 5 percent of the Earth’s crust and is fourth in abundance among the elements.¹¹ For comparison, copper only makes up 0.01%.⁵

However, despite all these advantages, the global iron and steel industry consumes more energy and produces more carbon emissions than any other industry. The total primary energy use of crude steel production was 39 exajoules (EJ) in 2021, which corresponds to 7% of all energy used worldwide in that year (595 EJ). The greenhouse gas emissions are even higher because around 75% of energy use comes from coal – the fuel with the highest carbon emissions. In 2021, the iron and steel industry produced 3.3 Gt of carbon emissions, roughly 9% of global emissions (36.3 Gt).¹² The concrete industry follows closely with 8%.

The iron and steel industry consumes more energy and produces more carbon emissions than any other industry.

The estimates above come from the World Steel Association and the International Energy Agency. These data are available for all metals and have been documented over a long period, allowing for historical comparisons. However, they only refer to the smelting of the metal. They do not include the energy use and carbon emissions for mining and transporting iron ore, coal, limestone, scrap, and steel products. Nor do they include the energy and emissions for coke production and ore preparation – all essential to the steel production process.⁷

Scientific studies that have set wider boundaries for the iron and steel industry conclude that the energy cost of steel production increases by 50% to 100%.¹³ One report concludes that the methane emissions from metallurgical coal mining alone could increase emissions by 27%. Another study estimates that seaborne transport of iron ore and steel adds 10-15% extra emissions.¹⁴¹⁵ Iron and steel production also create other environmental problems, such as high water use, solid waste production, and significant air and water pollution.

The carbon footprint of the iron and steel industry is incompatible with current ambitions to eliminate net carbon emissions by 2050, even less so because steel production is very likely to expand further. Steel production grew tenfold since 1950 and doubled between 2000 and 2020, growing faster than many researchers had predicted.¹⁶ Furthermore, efficiency gains have decreased, and there is a scientific consensus that current technologies have reached their thermodynamic limits.⁷⁹¹⁷ During the last two decades, the average energy use for the production of 1 ton of steel has remained around 20 GJ/t.⁹¹⁸

How to make steel without fossil fuels?

There are two ways to make steel, and one is much more sustainable than the other.¹⁹ On the one hand, there is the blast furnace or basic oxygen furnace, in which steel is made from iron ore and coal. This technology is – in its essential form – 2000 years old. On the other hand, there is the electric arc furnace, in which steel is made from steel scrap and electricity. The electric arc furnace, which is a relatively new technology, consumes much less energy than the blast furnace, makes use of a recycled resource (no need to mine iron ore), and works without the direct use of coal or other fossil fuels (the electricity can be supplied by solar, wind, or atomic power).

The most energy-efficient electric arc furnaces now consume less than 300 kilowatt-hours of electricity per ton of steel produced.⁹²⁰ Hypothetically, if we had produced all steel in 2021 (1,950 Mt) in such furnaces, the total power consumption of the global iron and steel industry would have been only 585 terawatt-hours (Twh). That corresponds to just one-third of all electricity generated by wind turbines worldwide in the same year (1,848 Twh). Unfortunately, more than 70% of global steel output was made in blast furnaces fed by coal and iron ore.⁹²⁰ A blast furnace consumes twenty times more energy and cannot be operated by electricity because coal is both the fuel source and the chemical reductant. The combustion of coal produces carbon monoxide that reduces the iron from its ore.⁷

Not enough scrap available

The solution seems obvious: let’s produce all that steel in electric arc furnaces. However, this is impossible. There’s not enough scrap available: the continuous growth of the global steel output makes a circular flow of resources impossible.²¹ It takes decades before most steel becomes available for recycling. For example, there is 543 Mt of steel stocked in ships.²² The scrap available for recycling in 2021 corresponds to the production level of 1965 when global steel production was less than one-quarter of what it is today (450 Mt).⁹¹⁰¹⁵²³ Consequently, the other three quarters need to be produced in blast furnaces using coal and freshly mined iron ore.

Image: Cars for scrapping at the Port of Cardiff. Gareth James via Wikimedia Commons (CC BY-SA 2.0).

Nowadays, China produces roughly half of the steel in the world and does that almost exclusively (+90%) in blast furnaces using coal and iron ore. Many other steelmaking nations have a higher share of electric arc furnaces. However, it makes little sense to point the finger at China. First, the US and Europe have outsourced many of their industries to China since the 2000s, a trend that corresponds neatly with the growing steel output in that country. Furthermore, twenty to forty years ago, China hardly used any steel. Consequently, there is almost no scrap available. China has no other choice than to use blast furnaces.²⁴

Ever higher grades of steel

A second obstacle is the continuous development of higher grades of steel. There are now over 2,500 different types of steel with a variety of properties, such as increased strength, tolerance to high temperatures, or corrosion resistance.⁷⁹²³²⁵ Although these higher quality steels can be produced in electric arc furnaces, they are not made from scrap, and they have much higher energy use.

Steel available for recycling forms a mix of steel grades. That mix is suitable for making plain carbon steel but not highly alloyed steels, which require scrap with similar qualities. However, that scrap is not available. For example, stainless steel, the most produced special steel grade, has a recycling rate of only 15%. Almost 60 Mt of stainless steel was produced in 2021, compared to only 4 Mt in 1980.²⁶ The traditional use of stainless steel was in cutlery, surgical tools, and medical and food processing equipment. However, it is now also used in the construction of tunnels and outdoor furniture, wastewater treatment, seawater desalination, nuclear engineering, and the production of biofuels.⁷

The low recycling rate and the need for the extraction of additional elements such as chrome and nickel make higher grades of steel more energy-intensive to produce. For example, stainless steel production requires almost 80 GJ per ton, four times more than the production of plain carbon steel.⁷²³ The continuous development of higher-grade steels is stimulated by environmental legislation (such as the use of lighter steel in cars) and by competition from other materials, mainly aluminum and plastic composites.⁷⁹²³²⁵ Ironically, the competition with these materials, which consume even more energy, makes steel less and less sustainable.

Steel and renewable energy

The steel industry is heavily dependent on the energy supply, but the energy supply is also heavily dependent on the steel industry. Almost 10% of the global steel output goes into building and maintaining energy supply infrastructure. That amount corresponds to the entire steel output in 1950. A great share of that steel goes to gas and oil infrastructure.²⁷. Oil and gas mining, production, and transportation require steel for offshore drilling platforms, pipelines, refineries, tankers, and storage tanks. Coal mining depends on steel for cutters, loaders, conveyors, excavators, and trucks.⁷

Unfortunately, the planned switch to low-carbon energy sources and the electrification of heating and transport technologies will not decrease our dependency on the steel industry – on the contrary. A low-carbon power grid requires much more steel (and other materials) than an infrastructure based on fossil fuels. Wind and solar power are very diffuse power sources compared to fossil fuels. Therefore, it takes much more materials (and land) to produce the same energy. In jargon, wind and solar have low “power density” or high “material intensity.”²⁸²⁹³⁰³¹³²

A low-carbon power grid requires much more steel than an infrastructure based on fossil fuels.

The “steel intensity” of thermal gas and coal power plants is between 50 and 60 tonnes of steel per megawatt of installed power.³³ Hydroelectric power plants have a lower steel intensity, with 20-30 tonnes of steel per MW.⁷³³ Atomic power’s steel intensity is also lower at between 20 and 40 tonnes of steel per installed MW.³³³⁴ On the other hand, solar PV requires between 40 and 170 tonnes of steel per installed MW.³³³⁵ Although there is little or no steel in the solar panels themselves, it’s the material of choice for the structures that support them.

Steel and wind power

The most steel-intensive power source – by far – is the modern wind turbine. The steel intensity of a wind turbine depends on its size. A single, large wind turbine requires significantly more steel per megawatt of installed power than two smaller wind turbines.³⁶ For example, a 3.6 MW wind turbine with a 100-meter tall tower requires 335 tons of steel (83 tons/MW), while a 5 MW wind turbine with a 150-meter tall tower needs 875 tons of steel (175 tons/MW).³⁷ The trend is towards taller wind turbines and a higher steel intensity.

Image: Steel towers for wind turbines in the port of Rotterdam. Image: Melle Smets.

Steel consumption further increases for offshore wind turbines. Onshore wind power plants rely on reinforced concrete for their foundations, but offshore wind turbines need massive steel structures such as monopiles and jackets.³⁸ The steel intensity for offshore wind turbines is calculated to be around 450 tonnes per MW for a 5 MW turbine – eight times higher than the steel intensity of a thermal power plant.³⁶. As these wind turbines get taller and move into deeper waters, their steel use further increases.

The most popular offshore wind turbine nowadays has a capacity of 7 MW, while the largest ones have a capacity of 14 MW.³⁶ If we make a conservative estimate based on the data above (the steel intensity doubles for every doubling of the power capacity), a 14 MW offshore wind turbine would require 1,300 tons of steel per MW or 18,200 tonnes in total. Such a wind turbine thus consumes 24 times more steel than a coal or gas power plant of the same power capacity.

Shorter life expectancy

The difference between renewable power sources and fossil fuels becomes even larger if the steel intensity is calculated per unit of energy rather than power (MWh instead of MW). In contrast to coal and gas power plants, the output of wind and solar power plants depends on the weather, and they do not always produce their maximum power capacity. Therefore, replacing 1 MW of fossil electricity generation capacity requires the installation of (on average) 4 MW of solar power or 2 MW of wind power.³⁹ A 14 MW offshore wind turbine thus has a steel intensity that is almost 50 times higher than a fossil fuel power plant for every kilowatt-hour of electricity produced.⁴⁰

A 14 MW offshore wind turbine has a steel intensity that is almost 50 times higher than a fossil fuel power plant for every kilowatt-hour of electricity produced.

Solar and wind power plants also have shorter lifetimes (20-30 years) compared to thermal power plants (30-60 years).³¹ While this does not affect the steel intensity per MW of power installed, it again increases the steel intensity per unit of energy produced over time. That does not always lead to a doubling of steel use because foundations for offshore wind turbines and structures for solar panels may have longer lifetimes than the power sources they support and could thus be reused.⁴¹

Power transmission infrastructure

The data above only include the steel used in the power plants themselves. For fossil fuel power plants, they do not include the steel used in the pipelines, oil rigs, coal excavators, and the like. However, the same goes for the low-carbon power sources. Because they need much more resources than thermal power plants (steel but also other metals and materials), they depend on a global mining and transport infrastructure that is just as steel-intensive as the supply chain for fossil fuels.

Furthermore, because they are more diffuse power sources with intermittent and unpredictable power production, often located far away from energy consumption centers, renewable power plants drive the expansion of transmission infrastructure. That infrastructure is also based on steel – from switchyard equipment over towers to conduction cables.²⁸²⁹³⁰³¹³²⁴²

Finally, low-carbon power sources also have a high need for special grades of steel, which are more energy-intensive to produce. Steel for off-shore wind turbines should resist corrosion, and stainless steel is increasingly used for solar panel support structures.⁴³ Electrical lamination steel (iron-silicon) is indispensable for transformers in the power network.⁷ Nuclear power plants may have a relatively low steel intensity but are completely built up of energy-intensive specialty steels. For example, cladding the fuel elements containing fissionable uranium requires zirconium steel, while all structural elements contain austenitic stainless steel.⁷⁴⁴

Low carbon grid cannot be made from recycled steel

The high steel intensity of low carbon power sources confronts us with a so-called “catch-22”, a situation in which there seems to be no escape from a problem no matter what we do. We need much more steel if we replace thermal power plants with renewable ones. Because there is not enough steel scrap available, we can only produce that extra steel from iron ore in blast furnaces burning fossil fuels. To address climate change, we need to build low-carbon sources quickly and in great numbers. However, to achieve circular material flows and build low-carbon power sources from scrap and renewable electricity, we would have to do the opposite: slow down the development of a low-carbon power grid.

Image: Steel foundations for off-shore wind turbines. Image by Glen Wallace, Wikimedia Commons (CC BY 2.0).

A well-cited study from 2013 concluded that if wind and solar power would supply 25,000 Twh of electricity – which corresponds to total global electricity demand in 2021 – we need about 3,200 Mt of steel to build the power plants alone.³³⁴⁵ Global electricity demand is projected to grow to between 52,000 and 71,000 terawatt-hours in 2050, which would increase the extra steel demand to between 6,400 and 8,960 Mt.⁴⁶ Spread out over the lifetime of solar panels and wind turbines (25 years), we would have to produce 256 to 358 Mt extra steel per year to make wind turbines and solar panel structures – comparable to the steel demand for passenger cars (195 Mt) and other transportation modes (98 Mt) combined.

That is still a very optimistic estimation. Electricity demand only makes up around 20% of total energy demand. If the total energy demand (177,000 Twh in 2021) would be supplied by wind and solar, we would need 22,400 Mt of steel. That’s an extra 896 Mt steel per year – as much as the global production in the early 2000s. You could argue that electricity can be used more efficiently than fossil fuels, for example, in cars and heating systems. However, at the same time, total energy demand is expected to rise further, countering the gains made by increased energy efficiency.

The high-tech solutions

The steel industry counts on technological solutions to make steel production carbon neutral. One option is to replace coal by gas, an approach that is already common in the Middle East and North America. Gas-based steelmaking results in somewhat lower carbon emissions, but they are still much higher than in the case of the electric arc furnace. Therefore, most attention goes to hydrogen, which can replace purified coal (coke) as a reducing agent in a direct reduction shaft furnace.⁴⁷ However, hydrogen-based steelmaking does not offer an escape from the catch-22 because it further increases the need for a steel-intensive infrastructure.

The production of hydrogen is energy-intensive. It takes 50-55 kilowatt-hour to make 1 kg of hydrogen and 60 kg of hydrogen to make 1 ton of steel.⁴⁷ The production of 1 ton of steel from hydrogen thus consumes 3,000 kWh of electricity, which is ten times higher than the electricity use of an electric arc furnace making steel from scrap. Consequently, hydrogen-based steelmaking requires roughly ten times more wind turbines and solar panels than scrap-based steel production – and thus ten times more steel. On top of this comes the steel for building the pipelines and storage tanks that are part of the hydrogen infrastructure.

Image: Worker in a blast furnace. Bundesarchiv, B 145 Bild-F079044-0020 / CC-BY-SA 3.0.

Carbon capture and storage, in which the carbon emissions of steelmaking plants are captured and then stored underground, faces the same problems. It requires a steel infrastructure and extra energy, thus indirectly raising the use of fossil fuels. Reverting to older, preindustrial steelmaking processes is not the answer either. Today’s blast furnace is essentially still the blast furnace from earlier centuries, only much more energy efficient.⁷

The low-tech solutions

The picture painted above seems to offer little hope for carbon-neutral steelmaking and power production. However, there is a low-tech solution that could achieve it. We could adjust steel production to the available scrap supply both in quantity and quality. That would allow us to produce all steel from scrap in electric arc furnaces, dramatically reducing energy consumption and eliminating almost all carbon emissions. Of course, the intent should not be to replace steel with plastic composites and aluminum because they are even more energy-intensive to produce. The only solution is to reduce material use overall.

We could adjust steel production to the available scrap supply both in quantity and quality.

Reducing the steel output and using more common steel grades would not bring us back to the Bronze Age. As noted, global end-of-life ferrous scrap availability was approximately 450 Mt in 2021, which would allow us to produce roughly one-quarter of the current steel output. Furthermore, the scrap supply will continue to rise for the next 40 years, enabling us to produce more and more low-emission steel each year. By 2050, scrap availability is expected to rise to about 900 Mt, almost half of today’s global steel production.⁴⁸ All that extra steel could be invested in expanding the low-carbon power grid without raising emissions first.

There is a lot of room to reduce the steel intensity of modern society. All our basic needs – and more – could be supplied with much less steel involved. For example, we could make cars lighter by making them smaller. That would bring energy savings without the need for energy-intensive high-grade steel. We could replace cars with bicycles and public transportation so that more people share less steel. Such changes would also reduce the need for steel in the road network, the energy infrastructure, and the manufacturing industry. We would need fewer machine tools, shipping containers, and reinforced concrete buildings. Whenever steel intensity is reduced, the advantages cascade throughout the whole system. Preventing corrosion and producing steel more locally from local resources would also reduce energy use and emissions.¹⁰¹⁴

The continuous growth of the steel output – the increasing steel intensity of human society – makes sustainable steel production impossible. No technology can change that because it’s not a technological problem. Like forestry can only be sustainable if the wood demand does not exceed the wood supply, steel is sustainable or not depending on the balance between (scrap) supply and (steel) demand. We may not be able to escape the Iron Age, but we have an option to escape the catch-22 that inextricably links steel production with fossil fuels.⁴⁹

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Forthcoming article, Kris De Decker, Low-tech Magazine. Subscribe to Low-tech Magazine’s newsletter. ↩︎
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See, for example: Hatayama, Hiroki, et al. “Outlook of the world steel cycle based on the stock and flow dynamics.” Environmental science & technology 44.16 (2010): 6457-6463. This paper predicted steel demand to reach 1.8 billion tonnes only by around 2025. ↩︎
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About 5% of global steel is produced by a third method: gas-based direct iron reduction. These furnaces use gas instead of coal and have therefore lower carbon emissions. However, emissions are still much higher than in the case of the electric arc furnace. Gas-based steelmaking mainly happens in the Middle East and North America. ↩︎
He, Kun, and Li Wang. “A review of energy use and energy-efficient technologies for the iron and steel industry.” Renewable and Sustainable Energy Reviews 70 (2017): 1022-1039. This source gives a value of 1-1.5 GJ/ton of crude steel. ↩︎ ↩︎
This also holds true for many other materials. See: “How circular is the circular economy?”, Kris De Decker, Low-tech Magazine, November 2018. https://qelnixcor.cloud/2018/11/how-circular-is-the-circular-economy/ ↩︎
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In the West, the expansion of steel use happened over a period of 150 years, in tandem with technological evolution. In contrast, China compressed this technological evolution in just a few decades: shipping and railways, electrification, steel buildings, the car and the airplane, the internet, and renewable power technologies. There are still large parts of the world where the steel intensity of society is very low, such as India and Africa. There is thus still a lot of room for the growth of the steel output. Source: Smil, Vaclav. Still the iron age: iron and steel in the modern world. Butterworth-Heinemann, 2016. ↩︎
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Gervásio, Helena, et al. “Comparative life cycle assessment of tubular wind towers and foundations–Part 2: Life cycle analysis.” Engineering structures 74 (2014): 292-299. & Rebelo, Carlos, et al. “Comparative life cycle assessment of tubular wind towers and foundations–Part 1: Structural design.” Engineering structures 74 (2014): 283-291. ↩︎
Assessing the significance of steel to the global wind industry, S&P Global, Commodity Insights. December 2021. https://www.spglobal.com/commodityinsights/en/ci/research-analysis/assessing-the-significance-of-steel-to-the-global-wind-industry.html ↩︎
Bolson, Natanael, Pedro Prieto, and Tadeusz Patzek. “Capacity factors for electrical power generation from renewable and nonrenewable sources.” Proceedings of the National Academy of Sciences 119.52 (2022): e2205429119. https://www.pnas.org/doi/10.1073/pnas.2205429119 ↩︎
This result corresponds well with Vidal, Olivier, Bruno Goffé, and Nicholas Arndt. “Metals for a low-carbon society.” Nature Geoscience 6.11 (2013): 894-896. The data are in the supplementary info: https://www.nature.com/articles/ngeo1993#Sec5 ↩︎
For off-shore wind turbines, the lifetime of the foundations is estimated to be 100 years, so in principle they could serve for replacement wind turbines of the same size. On the other hand, it is not self-evident that these steel foundations will eventually be recycled. First, only around 10% of decommissioning costs can be recovered by recycling the metal, meaning that it is not economically and perhaps even energetically interesting to do it. Second, in some cass marine life has flourished around the foundations. The four offshore wind farms that had been decomissioned in 2019 lasted for 15, 18, 20 and 26 years. Source: Topham, Eva, et al. “Recycling offshore wind farms at decommissioning stage.” Energy policy 129 (2019): 698-709. ↩︎
See https://www.fedsteel.com/insights/steels-role-in-the-us-power-infrastructure/ ↩︎
See https://industry.arcelormittal.com/products-solutions/Products_in_the_spotlight/magnelis ↩︎
Maziasz, Philip J., and Jeremy T. Busby. Properties of austenitic stainless steels for nuclear reactor applications. Oak Ridge National Lab.(ORNL), Oak Ridge, TN (United States), 2012. ↩︎
Part of this has already been built. The researchers start from the solar and wind power production in 2013, which was 400 Twh, while both power sources produced 2,894 Twh in 2021. ↩︎
Electricity consumption worldwide from 2000 to 2022, with a forecast for 2030 and 2050, by scenario. Statista. https://www.statista.com/statistics/1426308/electricity-consumption-worldwide-forecast-by-scenario/#:~:text=According%20to%20a%20recent%20forecast,on%20the%20energy%20transition%20scenario ↩︎
Bhaskar, Abhinav, et al. “Decarbonizing primary steel production: Techno-economic assessment of a hydrogen based green steel production plant in Norway.” Journal of Cleaner Production 350 (2022): 131339. ↩︎ ↩︎
Scrap use in the steel industry, World Steel Association. May 2021. https://worldsteel.org/wp-content/uploads/Fact-sheet-on-scrap_2021.pdf ↩︎
Another motivation for reducing the steel intensity of modern society is to limit the consequences of geopolitical conflicts. The more steel we produce for peaceful purposes, the more steel becomes available for war and destruction. Remarkably, the production of military equipment is absent from modern steel statistics, and if mentioned, its share is very low. However, in times of war, steelmaking facilities switch to producing steel for military purposes. The steel industry can thus be converted into a weapons industry at any moment, and there is now a lot more steel production capacity available than there has ever been in history. ↩︎

Plastic Waste in the Fuel Tank?

Thu, 16 Nov 2023 00:00:00 +0000

Image: This car drives on plastic. Image credit: Gijs Schalkx.

From wood gas to plastic waste

During the Second World War, many motorized vehicles in continental Europe were converted to drive on firewood. ¹ That happened as a consequence of the rationing of fossil fuels. Wood gas vehicles were a not-so-elegant alternative to their petrol cousins, but their range was comparable to today’s electric vehicles. In Germany alone, around 500,000 wood gas cars, buses, and trucks were operated by the end of WWII. An even more cumbersome alternative was the gas bag vehicle. ²

Nowadays, there’s much less firewood available than in the 1940s, especially in industrialized regions. So, what would be the solution to the disruption of gasoline or electricity in the Third World War? Dutch designer Gijs Schalkx found another fuel supply, which is abundant: plastic waste. The production of plastics only started in the 1950s, after the Second World War. Since then, plastic has become an increasingly popular material, growing to a global annual production of 460 million metric tons in 2019 – twice as much as in 2000 and eight times as much as in 1976. ³⁴

Image: Diesel production on the roof. Image credit: Gijs Schalkx.

Plastics are made from fossil fuels, and the process can be turned around. Gijs Schalkx converted an abandoned Volvo 240 to run on diesel that he makes from the plastic waste he collects. The “de-refinery” converts plastic waste back into fuel and is installed on the luggage carrier of the car, making the vehicle independent of the fossil fuel infrastructure. The plastic waste is heated in a boiler to about 700 degrees Celsius, after which it evaporates. The gas is then cooled down and turns into a diesel-like liquid one hour later. Gijs collects it in plastic bottles – themselves the raw material for the diesel they contain. The fuel looks like Coca-Cola – one of the largest producers of plastic waste.

How far can we drive on plastic waste?

Making fuel can happen while the car drives, but Gijs has kept the two activities separate for safety reasons. At a speed of 80 km/u, his Volvo 240 drives a distance of 7 kilometers per kilogram of plastic (which corresponds to 14 kg of plastic per 100 km driven). That includes the fuel used to heat the plastic waste on the roof (1 kg of plastic gives 0.5 liters of diesel, so the fuel economy is 7.14 liters per 100 km). Plastic waste is a rather voluminous material, and it takes several garbage bags full of plastic waste to make one liter of fuel. Schalkx plans to use a small shredder to reduce the volume of the plastic waste he collects, but for now, he relies on a supply of discarded plastic granulate from a neighbor, consisting of PET and HDPE.

Image: Gijs Schalkx adds plastic waste to the de-refinery. Image credit: Gijs Schalkx.

How far could we drive if we would convert all plastic waste into fuel? The Netherlands produced roughly 1,650 kilotons of plastic waste in 2017 (1,650,000,000 kg), enough to drive 11.55 billion km (11,550,000,000 km). ⁵ That corresponds to about 1/10th of the kilometers driven by all passenger cars in the Netherlands in 2021 (114.3 billion km). ⁶ On a smaller scale, the average passenger vehicle in the Netherlands drives 12,000 km per year, requiring each driver and their passengers to collect 1,714 kg of plastic. On the other hand, even the current amount of plastic waste per capita in the Netherlands (97 kg) would be enough to drive 679 km – perhaps sufficient for those who use their automobile wisely. The amount of plastic waste grows faster than the number of cars so that we can drive increasingly longer distances in the future. ⁷

How sustainable is driving on plastic waste?

Being able to drive a vehicle on plastic waste has benefits in terms of resilience. For example, it could allow medics to operate ambulances without a regular fuel supply in a war zone. However, how does a vehicle driven on plastic waste perform in times of peace? After all, plastic waste is a huge problem, and Gijs Schalkx’s car gets rid of it. With less than 10% of plastic waste recycled worldwide, would it make sense to encourage people to convert their vehicles to run on diesel oil made of plastic waste? Sure, it would be a more affordable alternative to electric cars, but what about the carbon emissions?

On the one hand, the embodied carbon emissions of the Volvo 240 are almost zero: Gijs found most components – including the car itself – in the dump, others on the second-hand market. ⁸ In contrast, manufacturing new vehicles – especially electric ones – adds a significant carbon footprint before they drive their first kilometer. They also need an extensive infrastructure to produce and distribute fuel and electricity, adding more carbon emissions. In contrast, the Volvo has its fuel infrastructure on the roof, built from scrap.

Image: Gijs Schalkx in his car. The design is a nod to wood gas cars built by other Dutchmen, Dutch John and Joost Conijn. Image credit: Frank Hanswijk.

Image: The interior of the car. Image credit: Frank Hanswijk.

On the other hand, the CO2 emissions from fuel production and combustion are not praiseworthy. First, there is the burning of plastic on the roof. Making 1 liter of diesel requires burning 1 kg of plastic, which results in 2-2.7 kg of carbon emissions. ⁹ Second, there is the combustion of diesel fuel while driving, which emits 2.7 kg of carbon dioxide per liter. ¹⁰ Together, that becomes 4.7 to 5.4 kg CO2 per liter. Consequently, with a fuel economy of 7.14 liters per 100 km, the Volvo emits 33.6 to 38.6 kg of greenhouse gases per 100 km.

In contrast, the emissions of the average fossil fuel-powered car in Europe amount to 25.8 kg/100 km, including crude oil production, fuel refining, and vehicle manufacturing. ¹¹ The emissions of a small electric car like the Nissan Leaf amount to 10.9 kg/100km in Europe, including the emissions of electricity production. ¹¹ The Volvo thus emits 1.5 times more CO2 than the average fossil fuel-powered car in Europe and 3 to 4 times more than a small electric car. The difference will be somewhat smaller because the results for the other vehicles do not include the emissions for building the oil and power infrastructure. However, this is unlikely to tip the balance.

There are several reasons for the high carbon emissions. First, fuel production by burning plastic on the roof is four times more carbon intensive than producing fuel from crude oil in a refinery. ¹² Second, the Volvo dates from 1980, when cars had lower fuel economy. Gijs Schalkx: “Hypothetically, you could convert a newer car to drive on plastic waste and have much lower carbon emissions. Likewise, the de-refinery is one of the first of its kind and could be made more efficient by real engineers. Oil refineries have been developed for more than 100 years. However, newer cars have proprietary electronic motor controls that prevent using alternative fuels.”

Externalizing pollution

Carbon emissions are not the only worry. Because of the chemicals added to plastic, burning it to make fuel creates a lot of nasty air pollution. Nobody in their right mind would propose a switch to cars fuelled by plastic waste. However, it is instructive to examine the motives behind this unanimous conclusion. Much of the plastic waste that the Volvo 240 burns burns anyway. Not in cars but in incinerators. That is the case for 44% of plastic waste in Europe. ¹³ That plastic waste burns to produce electricity, which can then charge electric cars. How is that more sustainable than burning plastic on the roof?

Image: Burning plastic. Image credit: Gijs Schalkx.

The carbon emissions are the same. So is the air pollution, although it’s easier to put a flue gas scrubber on thousands of incinerators than on millions of cars. The main difference is that burning plastic waste in incinerators to power electric cars allows many of us to externalize the side effects of car driving. An incinerator can be (and always is) located in a poor neighborhood, where it causes high incidences of cancer and other health problems despite air pollution control. Meanwhile, it produces electricity that charges electric cars that drive around low-emission zones in well-to-do neighborhoods.

Internalizing pollution

In contrast, Schalkx’s Volvo internalizes all the side effects of driving automobiles. The car is not a pleasure to drive, at least not regularly. It is dirty. Its interior stinks of plastic, which cannot be healthy – Gijs keeps the car windows open no matter the weather. Furthermore, he needs to spend a lot of time collecting plastic and making fuel, and all these disadvantages make him think twice before he gets behind the wheel. It’s unlikely that Schalkx will drive 12,000 km per year, and so, ultimately, he will produce less pollution than the drivers of more sustainable-looking cars that face none of these problems.

Somehow, the Dutch authorities, who are not known for their permissivity, officially approved the car after inspection. Schalkx drives tax-free and – thanks to his car being an oldtimer – can enter low-emission zones, where he parks alongside the latest electric SUV. Justice is not yet out of this world.

Image: Plastic fuel bottles. Image credit: Kris De Decker.

Image: Part of the de-refinery on the roof, showing the air blower for the oil burner. It was made from an old heater fan from the Volvo. Image credit: Gijs Schalkx.

Image: Part of the de-refinery on the roof, showing the Ursutz-style oil burner that stokes the refinery hot. Image credit: Gijs Schalkx.

Image: Gijs Schalkx repaired the car with scrap steel. Image credit: Gijs Schalkx.

Image: Gijs Schalkx stripped the car down to its essentials. Image credit: Kris De Decker.

Woodgas vehicles: firewood in the fuel tank, Kris De Decker, Low-tech Magazine, 2010. https://qelnixcor.cloud/2010/01/wood-gas-vehicles-firewood-in-the-fuel-tank/ ↩︎
Gas Bag Vehicles, Kris De Decker, Low-tech Magazine, 2011. https://qelnixcor.cloud/2011/11/gas-bag-vehicles/ ↩︎
https://www.statista.com/statistics/282732/global-production-of-plastics-since-1950/ ↩︎ ↩︎
https://www.oecd.org/environment/plastic-pollution-is-growing-relentlessly-as-waste-management-and-recycling-fall-short.htm ↩︎
https://ce.nl/publicaties/plasticgebruik-en-verwerking-van-plastic-afval-in-nederland/ ↩︎
https://www.cbs.nl/nl-nl/visualisaties/verkeer-en-vervoer/verkeer/verkeersprestaties-personenautos#:~:text=Van%20de%20114%2C3%20miljard,overige%20kilometers%20werden%20zakelijk%20gereden. ↩︎
The plastics industry now consumes 14% of all oil production, compared to only 4% in 2012. By 2050, the share of the plastics industry is forecasted to be 20% of oil production. Sources: https://e360.yale.edu/features/the-plastics-pipeline-a-surge-of-new-production-is-on-the-way & https://www.reuters.com/business/environment/big-oils-plastic-boom-threatens-uns-historic-pollution-pact-2022-03-04/ & https://oilprice.com/Energy/Energy-General/How-Much-Crude-Oil-Does-Plastic-Production-Really-Consume.html See also ³ ↩︎
New parts in the car are fuel hoses, coolant hoses, paint, tyres, brake lines and brake pads. Most of these were required to pass vehicle inspection. ↩︎
Rubio-Domingo, Gabriela, et al. “Making Plastics Emissions Transparent.” COMET. Last modified February 2022. https://ccsi. columbia. edu/sites/default/files/content/COMET-making-plastics-emissions-transparent. Pdf (2022). https://ccsi.columbia.edu/sites/default/files/content/COMET-making-plastics-emissions-transparent.pdf. ↩︎
https://iopscience.iop.org/article/10.1088/1742-6596/2307/1/012025/pdf ↩︎
https://www.carbonbrief.org/factcheck-how-electric-vehicles-help-to-tackle-climate-change/ ↩︎ ↩︎
https://publications.jrc.ec.europa.eu/repository/handle/JRC85326 ↩︎
https://www.oecd.org/environment/plastic-pollution-is-growing-relentlessly-as-waste-management-and-recycling-fall-short.htm#:~:text=Another%2019%25%20is%20incinerated%2C%2050,environments%2C%20especially%20in%20poorer%20countries. ↩︎

Too Much Combustion, Too Little Fire

Sun, 29 Dec 2019 00:00:00 +0000

Illustration: [Diego Marmolejo](https://www.instagram.com/ddidak/).

The fire – which we have used in our homes for over 400,000 years – remains the most versatile and sustainable household technology that humanity has ever known. The fire alone provided what we now get through a combination of modern appliances such as the oven and cooking hob, heating system, lights, refrigerator, freezer, hot water boiler, tumble dryer, and television. Unlike these newer technologies, the fire had no need for a central infrastructure to make it work, and it could be built locally from readily available materials.

From Open Hearth to Power Plant

The habitual use of fire dates back at least 300,000 to 400,000 years. ¹² Until the twentieth century, the biomass-fuelled fire was the only energy using “appliance” in the household – whether people were living in a cave, a temporary hut, or a permanent building. The earliest shelters were often erected with the express purpose of keeping fire alive, protecting it from wind and rain.

For most of history, the fire appeared in the form of an open hearth, which was built on an earthen floor in the middle of a shelter. The smoke of the fire escaped through a hole in the roof. Beginning in the fourteenth century in Europe, the open hearth was gradually replaced by a fireplace connected to a chimney, most often built against a wall. In colder regions (such as Scandinavia), people built more energy efficient tile stoves, while in milder climates (such as those around the Mediterranean), people continued to use braziers – portable metal baskets in which charcoal was burnt. In the 18th and 19th centuries, fireplaces were starting to be replaced by metal stoves.

The fire remained central in the household until the 20th century, when it was replaced by a wide range of appliances, plugged into central infrastructures. Today, in industrial societies, even metal stoves have become rare in households. Open burning has been all but banned, especially in cities. New buildings no longer have fireplaces, chimneys, or a hole in the roof.

The fire remained central in the household until the 20th century, when it was replaced by a wide range of appliances, plugged into central infrastructures.

“Paradoxically”, writes Luis Fernández-Galiano in Fire and Memory: On Architecture and Energy, “the dwellings that began as places to promote the fire, today shun open burning”. ³ In Fire: A Brief History, Stephen J. Pyne observes that: “Urban residents can pass years without seeing a fire. It appears mostly by accident or arson, and almost always as a danger”. ⁴

However, the fire has far from disappeared. Thousands of individual fires in households have been replaced by a few giant fires in central power plants. And the fire also burns elsewhere. “In our economy of abundance”, writes Stephen J. Pyne, “fire is at the heart of the magic – in factories, automobiles, homes and power plants… Modern cities remain fire-driven ecosystems… Shut down combustion and you shut down the city. But open flame itself has vanished. Like a black hole in space, fire has shaped everything around it without itself being visible.”

Industrialisation has only altered, not abolished burning. Most importantly, fire started using another energy source: fossil fuels instead of biomass. Until the twentieth century, almost all human-made fires were the product of renewable energy sources: wood, grass, dung – peat and some early uses of coal being the exceptions. Today in industrial societies, almost all fire “at the heart of the magic” burns on gas, coal or oil.

Fire vs. Electricity

Globally, a few billion people still live in households built around an old-fashioned fire, often in the form of an open hearth. Some people in the Western world consider this a backward and primitive practice that needs to be abolished – even though it is based on the use of renewable energy sources.

For example, in 2011, the UN and the World Bank launched the Sustainable Energy for All initiative, aiming to “ensure universal access to modern energy services” by 2030. ⁵ The concept of “modern energy services” is vague, but it essentially refers to the use of electricity and gas – and thus, in practice, the use of fossil fuels.

“Urbanites see fire as a technology for which other, more advanced technologies can substitute”

Initiatives like this imply that “modern energy services” are “better” than the traditional open hearth or fireplace. “Urbanites see fire as a technology for which other, more advanced technologies can substitute”, writes Stephen J. Pyne. “If fire is a device, they want an improved flame- and smoke-free upgrade”.

Examples of such flame- and smoke-free upgrades are today’s solar PV panels and wind turbines, which are supposed to end our dependence on fossil fuelled fires to produce “modern energy services”. However, how do open hearths and “modern energy services” – including those based on renewable energy sources – actually compare in terms of efficiency, sustainability, health and safety? What are we really saying when we argue that electricity or gas are “better” than a traditional fire?

The Versatility of a Fire

One reason why people in industrial societies regard open fire as inefficient and unsustainable is because they simply don’t know how their ancestors actually used it. If these days a fire is considered to be inefficient, it’s because we only measure the efficiency of one of its functions, usually space heating. However, our ancestors did not only use the fire to warm themselves. They also used it for cooking, illumination, food preservation, hot water production, clothes drying, and protection from predators and insects, among other things.

Illustration: [Diego Marmolejo](https://www.instagram.com/ddidak/).

Fire is extremely versatile: it’s hard to say which of its functions were most valued by our ancestors. Therefore, if we measure the energy use of a household fire and compare it to modern technology, we should not compare it to the energy use of a heating system or a cooking stove alone, but to the energy use of the entire household.

Cooking With Fire

As a cooking device alone, the fire can accommodate a wide variety of cooking methods and replace a surprisingly large number of modern kitchen appliances. The fire not only functioned as a cooking stove, but also as an oven. For roasting and grilling, food was held on a turning spit and cooked by direct exposure to the fire. Baking happened in a clay container (a “Dutch oven”) which was put in the ashes of the fire. Alternatively, a separate bake oven was built into the jamb or the rear of the fireplace, or as a freestanding structure outside the house. Boiling and frying happened in a pot that was hanging above the fire. ⁶⁷

The functions of many smaller electrical kitchen appliances were also enabled by the fire. For example, you may think that people started eating toast when the electric toaster appeared in the twentieth century, but before that time they simply held a “toasting fork” into the fire. Likewise, quickly preparing warm drinks did not begin with the invention of the electric immersion heater: earlier on, people immersed a red-hot iron tool in a cup, producing hot beverages in a matter of seconds. ⁸

As a cooking device alone, the fire can accommodate a wide variety of cooking methods and replace a surprisingly large number of modern kitchen appliances.

The fire also substituted for today’s refrigerator and freezer. In The Food Axis: Cooking, eating, and the architecture of American houses, Elizabeth Collins Cromley describes how meat and fish were suspended for several weeks in the smoke of a fire to preserve them for longer. ⁶ At the simplest level, our ancestors hung their cuts of meat or fish in the kitchen chimney or – if there was no chimney – high above the hearth, suspended from the ceiling. Smoking fish and meat could also happen in a chimney smoke chamber, which was either an adjunct to the kitchen fireplace, or a chamber built off the chimney in the basement or attic. The smokehouse could also be a separate building.

Several other food preservation methods were dependent on fire. Fruits, vegetables and herbs were dried by fire if the local climate wasn’t sunny enough. Sugaring fruits and making butter and cheese all depended on heat from a fire. Salt, essential for food preservation, was kept in a box hung against the fireplace to keep it dry. ⁶

Distributing Heat and Light

A fire not only produces heat and smoke – it also produces light. As a light source, fire was just as versatile as electric lighting is today. The light of a fire resided not only in the hearth or the fireplace, but also in torches, rushlights, and later candles and oil lamps. ⁹¹⁰ Heat from a fire could also be spread all over the household. Although the kitchen was usually the only space in the house that was heated, embers from the fire could be put into portable heating devices, such as foot stoves and bed warmers. ¹¹

The fire was also used to heat water for cleaning and washing, a practice that continued when cast-iron wood-stoves appeared – many of these had hot water tanks. Furthermore, the fire took care of drying clothes, substituting for today’s tumble dryer. And people didn’t just start ironing their clothes when the electric iron came along. Since the middle ages, our ancestors used plain metal irons that were heated by a fire or on a stove, or a “box iron”, which held glowing charcoal inside – some of these had a small chimney to keep smokey smells away from the clothes. ¹²

People didn’t just start ironing their clothes when the electric iron came along. Since the middle ages, our ancestors used plain metal irons that were heated by a fire or on a stove.

There was also the function of the fire as a focal point of communication and socialisation. For thousands of years, the hearth was the “ancient focus of conversation and the crackling soul of the house”. ³ Televisions and mobile phones have taken over these roles, although it is doubtful whether they hold the same appeal for people as a fire does. A host of electronic consumer products that imitate the effects of a fire – electric candles and fireplaces, led-bulbs with flickering flame effects, video’s of crackling fires – seem to indicate that humans miss open fire.

Sustainability and Efficiency

In a household built around a fire, the making of hot beverages and toast, the drying of clothes, or the illumination of the space does not raise the energy use of the fire: it simply makes more efficient use of the fire that is already there for other purposes – like space heating. To achieve the same result today, we have to turn on several appliances, and all of them require extra energy use: the heating system, the immersion heater, the electric toaster, the tumble dryer, and the lights.

Furthermore, we should also take into account the mining and the energy use required to replace one fire with dozens of factory-made appliances, which all need to be distributed to individual consumers. Finally, we should take into account the energy and materials that are required to build and maintain the infrastructures that these appliances depend on to operate, like the power grid, gas infrastructure, or the cold chain. In contrast, an open hearth can be built locally with readily available materials, and it operates independently of centralised infrastructures.

Illustration: [Diego Marmolejo](https://www.instagram.com/ddidak/).

Today’s renewable power plants, such as solar PV panels or wind turbines, don’t properly address the energy question: they also need to be manufactured, transported, maintained and discarded of, and they imply that we can keep designing, producing and discarding an increasing range of electric household appliances in order to satisfy our needs. Neither would biomass electricity make this system sustainable: although it eliminates the use of fossil fuels, a great deal of energy is lost in the process of converting biomass to electricity, and we still need factories to manufacture the electric appliances and the infrastructures.

Energy Use Compared: Ancient vs. Modern Households

If we look at the energy use in European households today, we see that on average 64% of all energy goes to space heating, 15% to water heating, 14% to lights and appliances, 5% to cooking and 1% to other services (including cooling). ¹³ Most of these services can be supplied by fire. So, how does the energy use of a traditional household with open hearth compare to the energy use of a modern household built around appliances and infrastructures?

Obviously, the energy use of modern houses is better documented than that of buildings and shelters from times gone by. However, there is research documenting the energy use of households that still rely on a traditional fire.

If we measure the energy use of a household fire and compare it to modern technology, we should compare it to the energy use of the entire household.

A 2002 investigation of firewood consumption in traditional houses in Nepal measures the annual firewood consumption per household to be between 6 and 33 m3, which corresponds to between 35 and 165 Gigajoule (GJ) of energy. ¹⁴¹⁵¹⁶ This seems quite a lot in comparison to the total energy use in contemporary households, which is around 75 GJ per year in Germany and around 105 GJ in Canada.

However, the average Nepalese household participating in the research consisted of 5 to 12 people, while households in modern societies have shrunk to little more than two people. In the Nepalese households under study, energy use was between 2 and 33 GJ per capita, while another, more recent research paper on firewood consumption for heating, cooking and lighting in Nepal calculates a per capita use of roughly 2.5 to 10 GJ of energy per person per year. ¹⁷¹⁸ In comparison, total household energy consumption per capita is around 30 to 40 GJ in countries like the Netherlands, Germany and Canada.

10 Billion People Around the Hearth

Even without taking into account the extra resources needed to build the appliances and the infrastructures, energy use in the pre-industrial household seems to have been significantly lower than it is today. In fact, a quick calculation reveals that – at least in theory – 10 billion people using an open hearth as their only energy source would be a perfectly sustainable practice.

Assuming an average firewood consumption of 6 m3 per capita, we would need 60 billion cubic metres of wood annually. One cubic metre of wood requires an annual yield of 0.2 ha of coppice, so we need 12 billion ha or 120 million square kilometers of forest if we want to avoid deforestation. That’s three times as much as we have today, and about 80% of the total land area of our planet (150 million square kilometers).

Because we don’t need extra space for factories and roads to make and distribute consumer goods, we actually could go back to the open hearth without destroying our environment. The same cannot be said of 10 billion people going forward using fossil fuels and modern infrastructures.

Health vs. Sustainability

If not for their sustainability or efficiency, then why do we consider “modern energy services” superior to a traditional fire? The suppression of open fire in modern cities is supported by two extra arguments: fire is unhealthy (it produces air pollution), and it is dangerous (it carries the risk of an uncontrollable fire). These risks are real, but how does the fire compare to “modern energy services” in terms of health and safety?

There is no doubt that the replacement of the household fire by modern infrastructures has advanced air quality, health and safety in cities. However, this may only be a temporary gain: modern infrastructures are at least as hazardous to safety and health because of their dependence on fossil fuels.

How does the fire compare to “modern energy services” in terms of health and safety?

For example, the heat waves and forest fires which are ravaging Australia while I write this, are killing people and destroying properties, and they are producing thick smoke that continues to blanket some of the largest cities. These fires are not caused by people using open hearths. These fires are the consequence of climate change, which is mainly caused by people’s use of industrial infrastructures – powered by fossil fuels.

The heavy dependence on central infrastructures for so many vital needs is another health and safety risk: cut the power supply to a large city and almost everything stops working – including the sewer network, the food storage, and the burglar alarms.

Our troubled view of the old-fashioned fire is partly rooted in the conflation of two distinct concepts: “health” and “sustainability”. Indeed, something can be healthy, safe and sustainable at the same time, like walking – lest there is no sidewalk. But something can also be healthy and safe but not very sustainable (like a refrigerator, because it depends on an energy-intensive cold chain), and something can be sustainable but not very healthy or safe (like a smokeroom for meat and fish in the basement).

Health and longevity are things that we, as individuals, “need”, want, desire, or feel entitled to. Just like we feel entitled to certain levels of comfort, convenience, speed or cleanliness. On the other hand, defining sustainability requires us to question what levels of human comfort, convenience, cleanliness, speed, safety and health our environment can support before it collapses. We can choose safety and health over sustainability when they are in conflict with each other, but only at the expense of the safety and health of younger and future generations.

Roebroeks, Wil, and Paola Villa. “On the earliest evidence for habitual use of fire in Europe.”. Proceedings of the National Academy of Sciences 108.13 (2011): 5209-5214. ↩︎
Berna, Francesco, et al. “Microstratigraphic evidence of in situ fire in the Acheulean strata of Wonderwerk Cave, Northern Cape province, South Africa.” Proceedings of the National Academy of Sciences 109.20 (2012): E1215-E1220. ↩︎
Fernández, Guillén, and Luis Fernández-Galiano. Fire and memory: on architecture and energy. Mit Press, 2000. ↩︎ ↩︎
Pyne, Stephen J. Fire: a brief history. University of Washington Press, 2019. ↩︎
https://www.seforall.org ↩︎
Collins Cromley, Elizabeth. The food axis: cooking, eating, and the architecture of American houses. University of Virginia Press, 2010. ↩︎ ↩︎ ↩︎
Unlike today’s gas or electric stoves and ovens, a fire has no buttons to control its temperature. For boiling and simmering, this was solved by hanging the pots on a crane, which could be raised or lowered. In ovens, cooks decided to bake pies or bread first while the oven is the hottest, then, successively as the oven cools down, gingerbread, custards, then grains could be put in to dry. [6] ↩︎
Marcoux, Paula. Cooking with fire: From roasting on a spit to baking in a tannur, rediscovered techniques and recipes that capture the flavors of wood-fired cooking. Storey Publishing, 2014. ↩︎
Hough, Walter. Fire as an agent in human culture. No. 139. Govt. print. Off., 1926. ↩︎
The energy source for these distributed fires were wood, resin, wax, fat, grease or oil. Needs for special concentration and position of the source of illumination stimulated the invention of holders, brackets, and stands. [9] ↩︎
Heating people, not spaces: restoring the old way of warming, Kris De Decker, Low-tech Magazine, 2016. ↩︎
History of ironing, Old & Interesting, retrieved December 26, 2019. ↩︎
Energy consumption and use by households, Eurostat, 2019. ↩︎
Rijal, H. B., and H. Yoshida. “Investigation and evaluation of firewood consumption in traditional houses in Nepal.” Proceedings: Indoor Air (2002): 1000-1005. ↩︎
The energy content of 1 m3 of wood also depends on the type of wood and how it is stacked. I’ve compared apples to apples when it was possible, but this was not always the case so the result is only a rough estimate. ↩︎
The annual firewood usage in 18th century Austria (Carinthia) was limited to 35 m3 per household. Source: Peter, Sieferle Rolf. The subterranean forest. Cambridge: The White Horse Press, 2001. ↩︎
Rijal, Hom Bahadur. “Firewood Consumption in Nepal.” Sustainable Houses and Living in the Hot-Humid Climates of Asia. Springer, Singapore, 2018. 335-344. ↩︎
The results are 0.5 to 2 m3 of firewoord per person per year, which I have converted to 2.5 to 10 GJ of energy per person per year. ↩︎