A circular, regenerative process versus A linear, polluting process
It is so simple … the difference between a circular, regenerative process versus a linear, polluting process. It describes a core difference between leather and synthetic materials.
The base material of Leather is collagen, a protein generated by the growth of a cattle. Such an animal is 100% vegan, which means the entire body mass was formed by eating grass. The grass is generated by photosynthesis made of CO2 from the air, rainwater, and sunlight. If leather gets converted into CO2 again after use, it is a climate neutral, circular process following the natural law of mass conservation: the same amount of CO2 gets generated as it was used to start the process.
Of course, there are some collateral effects to be considered, e.g. the generation of methane, a climate warming gas, or the generation of humus, the organic component of soil, formed by the decomposition of plant material by soil microorganisms and dung.
Methane is generated as a by-product by animals during conversion of grass into proteins. Although it has a much higher (28 times) climate warming potential than CO2, it will be in the atmosphere only on a temporary time frame of 3-5 years. After this period, it converts back to the same amount of CO2, as it was formed of.
Humus is generated by a grazing animal; it activates sustainable plant growth and significantly support biodiversity. Both effects are leading to a long-lasting CO2 sink.
Very often only methane gets mentioned in an argumentation against the farming or leather industry. This is not fair, because it is only one part of the equation. If you take everything into account, humus and methane, these effects get balanced out. All in all, it may happen, that the methane effect under some farming conditions is still bigger, however, this does not change the basic argumentation: the collagen mass is still a mostly climate neutral material.
In contradiction synthetic materials generally are made 100% out of oil, and after use – if they are not ending up in oceans or landfills – they are converted by incineration into 100% additional CO2. This additional CO2 has a long-term climate warming effect because it is in the atmosphere for thousands of years.
Therefore, leather industry is just calling for a scientific based, fair discussion …
Is really cow slaughtered to produce leather?
How many times have I read the statement that a cow is slaughtered to produce leather?
Everyone in the leather industry feels that such statements are misrepresented and would love to pick up the phone directly to correct this view of things.
There are clear facts and two simple reasons, why this statement is incorrect:
- A tanner of course is interested in producing a most beautiful, high-quality/valuable leather. This is only possible from high quality raw materials. The structure of a skin from an animal that has been fed healthy and raised naturally is of much higher quality. The tanner can use it to produce a much higher quality leather as if he has access to only lower quality raw material. For this reason, it is very important to every tanner that the animal food and animal welfare conditions are respected during the farming of an animal. Any kind of cruelty to animals, unacceptable transport conditions, etc. are abhorred by the leather industry: from an ethical standpoint, as well as even from a value aspect.
- In its pilot project “Product Environmental Footprint Category Rules”, the EU worked out that the value of the hide represents only 0.42% of the value of a cow prior to its end of life. This means that the clear reason for raising cattle lies in the dairy and the meat industry. No cattle breeding is worthwhile for the economic value of the generated leather. For this reason, the skin is a clear by-product of the farming industry, and leather production is a sustainable up-cycling of a renewable raw material source, the collagen.
Already today Animal Welfare conditions are even part of many laws and legal regulations. If they get not respected, I consider this to be “crime”. Unfortunately, the leather industry has no power and input to enforce these legal requirements more and push for a change.
The tanner must tan, what is available. If the leather industry is not going to use up the available hides, hides are considered to be waste and get dumped … up to 25% of hides in certain countries have been dumped in the last year, because the leather market is under pressure, and more and more synthetics are used instead of leather. This is a shame.
Each final application, where leather can replace a synthetic material, is a more sustainable solution.
Unfortunately, there is no “solvent footprint” analysis
Fresh water is a precious good on this planet, essential for all life that we need to protect and preserve – I think everyone agrees on that. For this reason, it is good to determine a water footprint for a process in order to optimize the process water demand. You can only manage what you measure.
There are so-called Water Footprint Calculators on the Internet that supposedly do this for interested people. If you specify the water requirement for 1 kg = 1 square meter of leather, a value of approx. 17,000 l water requirement is given. In LCA studies this is of course extremely negatively considered.
If you look behind it, you will see that well over 90% of this water requirement is rainwater, which nature needs to allow grass to grow in a photosynthesis process, which cattle needs as a food source. This rain falls, regardless of whether cattle are in the pasture or not, and regardless of whether the hide of the cattle is turned into leather or not. So, can we call that “process water” with a clear conscience?
The tannery only needs approx. 80 – 250 l of water per square meter of leather produced, depending on the water recycling systems that are installed. This water is not consumed, but used, then cleaned and released again as fresh water. You basically borrow it from nature for the duration of the process. Sometimes even the released water is cleaner than the water, which was taken before. If this water is taken from surface water such as rivers and bodies of water, and the treatment after the process is efficient, it should not have a negative impact on the environment and our lives.
By the way: more than 1,000 liters of real process water are required to manufacture a cotton denim fabric; Leather is better here by a factor of 10!
And further: what is necessary for the use of water in a leather manufacturing process is done with organic solvents in the manufacture of synthetic materials. So sometimes astronomical amounts of harmful solvents are needed to e.g. manufacture PVC. Is this the better alternative? Unfortunately, there is no “solvent footprint” analysis that evaluates this.
So be careful with water footprint information you get by standard calculators, especially if using them for sustainability benchmarks of leather versus synthetic materials.
Advocate for Sustainable Leather
Vice President, Business Unit Leather Innovation – LANXESS