TL:DR burning waste in specific circumstances could be the best option for the environment.
by Edward Hill, co-founder and Chief Scientific Officer at Materra
As a quick heads up, for the sake of brevity I’m going to simplify a few things and leave references for those of you who want to deep dive.
Recycling vs Incineration
When I talk to people about waste disposal, this is the common response I get:
Waste to landfill = BAD; recycling waste = GOOD; burning waste = BAD.
Two common solutions proposed to prevent waste ending up in landfill are as follows: a) consider ways of changing the process creating the waste, thus removing the need for these products or b) redesigning the product itself to enable recycling.
However, sometimes these solutions are not employed for the following reasons:
- The process has great efficiency, therefore outweighing the impact of the materials used.
- The alternative materials for the product are too expensive.
- The alternative materials for the product do not meet its specification requirements.
In these cases, instead of focusing on recycling, I believe the lens should be on energy recovery.
Let’s assume that a product has enabled an environmental or energy efficient process compared to current norms, but the output is a non-recyclable plastic object such as the covering of a greenhouse.
Polyethylene or PE is commonly used to cover greenhouses to help create a microclimate inside that can dramatically increase the productivity of a farm. This plastic, however, is constantly exposed to the sun and will need replacing in 4–7 years.
Unfortunately, during its lifetime it will get covered in dirt and dust and therefore is impossible to be processed by local recycling plants unless it can be cleaned. While the technology for cleaning plastic objects such as bottles has advanced, the viability of many other plastic objects remains limited due to their shape or thickness. Also as the quality of plastic degrades during the recycling process, recycling plants often focus on the highest grade plastic waste they can source, meaning that the greenhouse cover is less likely to be reclaimed. Now a quick bit of chemistry; I know, scary right?!
The majority of plastics we interact with are all oil based, having the chemical name hydrocarbons as they are made up exclusively of hydrogen and carbon atoms. In the case of polyethylene, it is made up of repeating units of ethylene composed of 2 carbon atoms and 4 hydrogen atoms. If we combine this in a lab with oxygen and burn it in what is called complete combustion, the results should simply be water and carbon dioxide.
2 ethylene + 7 oxygen = 6 water + 4 carbon dioxide (+ heat energy as a bi-product)
CO2 is produced, which isn’t the best, but water isn’t that bad and energy is very useful. An additional bonus is that the plastic sheeting will not end up in landfill, saving valuable space and creating an end-of-life solution. The Dutch have been leading the way with this approach to waste processing, reducing their landfill usage down to 2.1%,¹ compared to the USA at 50%².
It should be noted that additives are often found in plastics to change their properties or colour. These additives when burned are released and can cause damage to the environment so require capturing during the incineration process.
Waste and Energy in India
Materra’s mission is to build resilient farming systems to empower more sustainable cotton supply chains. This mainly means focusing on farms in lower income countries in South Asia and East Africa. With India being the largest producer of cotton in the world but with some of the lowest yields per hectare we thought it would be a good place to start.
Some quick facts about India:
- The UN predicts India will be the most populated country by 2027.³
- India is the second largest user of coal in the world.⁴
- India’s recycling systems are limited, with large volumes of solid waste ending up in informal landfills.⁵
- India’s is predicted a 2.6x increase their municipal solid waste production by 2030.⁶
India has an abundance of coal and, with a growing population and limited movement from the government in regards to committing to renewable energy, coal consumption is expected to rise in the coming years. With the growing demand for energy due to population growth and increased need for landfill locations, efficient incineration plants could actually solve both of these problems with one solution.
Let’s walk through these two different scenarios:
- Coal is dug out of the ground to be used in a power station to create energy, releasing CO2 into the atmosphere. This is combined with the environmental impact from mining the coal initially.
- Plastic sheeting that was used to cover a greenhouse has come to the end of its functional life. The use of the plastic has already helped increase farm efficiency, thereby helping to balance the initial impact of extracting the oil and the plastic manufacturing. This plastic could now be sent to landfill, but the valuable resources embedded in the plastic will be lost.
My suggestion is to instead focus on a new scenario:
Instead of sending the plastic sheeting to landfill, it is sent to an ultra-efficient incineration plant where it can be transformed into energy. This process maximises the potential value we can extract from the plastic sheeting, and prevents new coal from being dug out of the ground for the creation of energy.
Now I know what you are thinking, I’ve heard this one before:, “burning waste is not very efficient and it often can prevent efforts to focus better recycling systems as these materials are still burned”. This is where I would like to focus again on the Dutch. According to the Dutch Ministry of Infrastructure and Water Management, 77% of their waste is recycled, with only 2.1% ending up in landfills, leaving roughly 20% that cannot be recycled and instead is diverted towards energy production.¹
There are certain applications where the use of a specific material or product hugely outweighs the negative impact of its end-of-life disposal. My suggestion is that since this material usage is currently unavoidable, we should focus on trying to recover as much good as we can from them before burying them in the Earth. This does not mean that we should stop funding research into new materials and processes that can be recycled back into new products again in the future.
So, going back to my initial provocation.
Waste to landfill = BAD; recycling waste = GOOD; burning waste = GOOD, if one or more of the following is true:
- The waste provided an invaluable increase in performance or a reduced environmental impact during its lifetime.
- The waste could not be recycled in an energy efficient manner.
- The burning of the waste will prevent fossil fuels being burned instead for the production of energy.
First up: cotton We’re helping cotton farmers build more future-proof farms without harming the planet. Cotton is the…
¹ Elements of Dutch waste management
² National Overview: Facts and Figures on Materials, Wastes and Recycling
³ UN: Population
⁴ IEA: Report extract - Demand
⁵ Why India’s solid waste management system needs a digital overhaul
⁶ Waste management crisis in India