Vaclav Smil on natural gas (ethane) and plastics

Preface. Vaclav Smil doesn’t mention using plastic for heat, but in a letter to The Guardian, David Reed suggests:

“The effort of collecting, transporting and cleaning plastics for possible recycling has largely failed, created much more pollution and contributed massively to climate change. The idea of burning plastics and using the energy to heat our homes was proposed by the plastics company Dow more than 30 years ago: it suggested treating all plastics as “borrowed oil”. At that time, ordinary domestic waste had a calorific value of low-grade coal, so the suggestion was that this waste should be burned in efficient plants with heat recovery and treatment of the gases produced, perhaps even trapping the carbon dioxide produced, rather than trying to recycle the complex (and dirty) mix of plastics.  Today, with higher use of more complex plastics, this makes even more sense. Mixed plastics cannot really be recycled: they are long-chain molecules, like spaghetti, so if you reheat and reprocess them, you inevitably end up with something of lower performance; it’s called down-cycling.”

While this could be polluting if not done right, people will certainly turn to burning plastic and anything else they can get their hands on at some point of energy decline. Better to do it correctly now in an incinerator than in backyards in the future as well as to protect our land and waterways from plastic pollution right now.

Thermal recycling processes require temperatures of between 300 °C and 900 °C (572 °F to 1,650 °F), consuming a whole lot of energy (Nakaji 2021).

Alice Friedemann  author of “Life After Fossil Fuels: A Reality Check on Alternative Energy”, 2021, Springer; “When Trucks Stop Running: Energy and the Future of Transportation”, 2015, Springer, Barriers to Making Algal Biofuels, and “Crunch! Whole Grain Artisan Chips and Crackers”. Podcasts: Collapse Chronicles, Derrick Jensen, Practical Prepping, KunstlerCast 253, KunstlerCast278, Peak Prosperity , XX2 report


Vaclav Smil. 2013. Making the Modern World: Materials and Dematerialization.  Wiley.

Polyethylene (PE) is by far the most important thermoplastic (it accounted for 29% of the world’s aggregate plastic output, or roughly 77 Mt, in 2010), polypropylene (PP) comes next (with about 19% or 50 Mt in 2010), followed by polyvinyl chloride (PVC, about 12% or 32 Mt in 2010).

In 2010, packaging consumed almost 40% of the total (mostly as various kinds of PE and PP), construction about 20% (mostly for plastic sheets used as vapor barriers in wall and ceiling insulation), the auto industry claimed nearly 8% (interior trim, exterior parts), and the electrical and electronic industry took about 6% (mostly for insulation of wires and cables).

All of these products begin as ethane. In North America and the Middle East ethane is separated from natural gas, and low gas prices and abundant supply led to surplus production for export and favored further construction of new capacities: in 2012 Qatar launched the world’s largest LDPE plant and, largely as a result of shale gas extraction, new ethylene capacities are planned in the USA (Stephan, 2012). The dominant feedstock for ethane in Europe, where prices of imported natural gas are high, is naphtha derived by the distillation of crude oil.

Plastics have a limited lifespan in terms of functional integrity: even materials that are not in contact with earth or water do not remain in excellent shape for decades. Service spans are no more than 2–15 years for PE, 3–8 years for PP, and 7–10 years for polyurethane; among the common plastics only PVC can last two or three decades and thick PVC cold water pipes can last even longer (Berge, 2009).

Some products made out of plastic:

  • Transparent or opaque bags (sandwich, grocery, or garbage)
  • sheets (for covering crops and temporary greenhouses),
  • wraps (Saran, Cling)
  • squeeze bottles (for honey)
  • HDPE garbage cans
  • containers (for milk, detergents, motor oil)
  • HDPE for house wraps (Tyvek) and water pipes
  • PEX for water pipes and as insulation for electrical cables
  • UHMWPE for knee and hip replacements.
  • massive LDPE water tanks
  • indoor–outdoor carpeting
  • lightweight fabrics woven from PP yarn and used particularly for outdoor apparel
  • insulated wires, water, and sewage pipes to food wraps and her car’s interior and body undercoating
  • disposable and surgical gloves
  • flexible tubing for feeding
  • breathing and pressure monitoring, catheters
  • blood bags
  • IV containers
  • sterile packaging
  • trays
  • basins
  • bed pans and rails
  • thermal blankets
  • lab ware
  • construction (house sidings, window frames)
  • outdoor furniture
  • water hoses
  • office gadgets
  • toys


Nakaji Y et al (2021) Low-temperature catalytic upgrading of waste polyolefinic plastics into liquid fuels and waxes. Applied Catalysis B: Environmental.

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2 Responses to Vaclav Smil on natural gas (ethane) and plastics

  1. Joe Clarkson says:

    Service spans are no more than 2–15 years for PE

    Surely this is Smil misreading Berge!

    I have experience with buried HDPE water line that has been in continuous service for over 30 years, with no apparent change in condition. I would much rather use any kind of plastic water pipe that metallic pipe, except perhaps for ductile iron if very rocky soil is present. Even then, a little bedding material can allow the use of most plastic pipe in buried service.

    And PEX has been used in domestic water service for many years now. Most manufacturers offer PEX with a minimum of 50 years service life and some offer 100 years.

    Using 2-15 years as a service life for polyethylene is ridiculous. I expect that future generations will come upon buried plastic pipe in perfect condition even after hundreds of years of burial.

  2. Mark says:

    “Better to do it correctly now in an incinerator”

    The problem is it is not possible to do this “correctly”

    Burning plastic makes “products of incomplete combustion” that are in many cases worse than the original compounds. The incineration industry hopes to capitalize on the failure of plastic recycling, but some folks pointed out plastic recycling was a scam three decades ago, without much success. PVC is a big reason for this failure, but that is rarely mentioned (it contaminates polyethylene and other non-chlorinated plastics) and impossible to practically separate out from the others.

    Waste is a terrible thing to mind.