Month: October 2020

PhD Insights: Novel recycling of lead batteries for people and planet

By Enrico Manfredi-Haylock, a member of the Transition to Zero Pollution cohort.

Did you know that the battery in your car is the most recycled item in the world? Its recycling process is considered as a gold standard example for the future circular economy of consumer goods.

The humble Lead Acid Battery (or LAB for short) was invented more than 100 years ago and today it is widely used for starting cars, keeping data centres running and storing renewable electricity. The lead used in these batteries is relatively easy to recover through a smelting process with no loss of quality of the recycled product so it can be used again and again. In fact, the metal in your car battery may have already gone through several incarnations of batteries before getting to you! In Europe and the USA it is estimated that over 95% of batteries are collected and recycled to make new batteries.

Close-up of car battery pile

But if LAB recycling is so successful, what’s the problem? Firstly, this process has a relatively high carbon footprint of 0.12kg of CO2 per kg of lead recycled. While that doesn’t sound too bad, consider that the world recycles millions of tonnes of lead per day! Secondly, batteries that are recycled improperly cause a pollution that is much worse than CO2.

In many developing nations, car batteries are recycled by hand in small cottage industries, in homemade furnaces, by workers who hack batteries apart with improvised tools for a pittance. These workers are fully aware that the lead in the batteries they break could cost them their life. Nonetheless, they choose to go ahead with this work because they have no other source of income. Used LAB recycling in developing nations was classed by the WHO and the Blacksmith Institute to be the most polluting industry of all, shortening life expectancy significantly for both workers and their families.

Headshot of Enrico Manfredi-Haylock
Enrico Manfredi-Haylock

It is therefore imperative to solve the pollution problems of lead recycling for these small informal recycling activities in the developing world; both to save our planet and our people. However, it is also important to recognise how many rely on this activity for a living. Restricting it may simply make the problem worse. Instead in this project we propose to introduce a novel chemical technique for the recycling of lead based on a new class of solvent that can be easily synthesised from everyday natural ingredients. The aim would be to develop this process to be as cheap and reliable as possible and to provide this technology directly to the people who need it with the help of local partners and charities. It is hoped that this approach can clean up the pollution from this industry, while keeping that invaluable economic lifeline in place for the world’s most vulnerable communities.

PhD Insights: New ways to deal with waste

By Alex Bowles, a member of the Transition to Zero Pollution cohort.

My work is focussed around decarbonising society through the enhanced recovery of waste materials. The UK produces 600,000 tonnes of waste tyres per year and in 2018 over half were exported to developing nations such as India (Source: UN Comtrade), where they are burnt in brick kilns or converted to oil in systems with negligible environmental and safety standards.

I am working on developing pyrolysis (heating in the absence of oxygen) as an upcoming waste-recovery technique for these tyres. Pyrolysis can be used to treat any organic waste material, such as biomass, plastics and rubber, to produce a mixture of solid (char), liquid (pyro-oil) and gas (syngas) products. The liquid and gas can be combusted for energy recovery or converted into recycled chemicals. Recycling mechanisms for the solid pyrolysis char product are still developing. I work on developing this pyro-char into activated carbon, a material used to filter air and water.

An aerial shot of a tyre dump

In my lifetime, atmospheric CO2 has risen by 15%. Abatement of further CO2 emissions to prevent catastrophic climate change is the biggest challenge facing humankind. My PhD focusses on utilising this recycled pyro-char derived activated carbon as a CO2 adsorbent, which can be attached to the end of a fossil fuelled power plant, cement kiln or factory that uses industrial heat to capture the CO2 through a carbon-capture mechanism. This system would prevent the release of CO2 into the atmosphere. Preliminary experiments have shown the potential to capture CO2 quantities of over 10% of the weight of the carbon reversibly and rapidly.

Headshot of Alex Bowles
Alex Bowles

I am working closely with my PhD sponsor, Pyrenergy, to develop pyrolysis as an effective recovery process for waste tyres. Much of the pyro-char feedstock for my PhD is a product of the Pyrenergy industrial process. Tyres are an especially challenging waste material due to the a) heterogeneity between brands and parts of a tyre, b) complex chemistry of rubber, c) high energy of production, and d) their abundance (>2 billion tyres are produced every year). I am working to contribute to the improved recovery of this important resource, which would support circular economy principles whilst reducing waste (tyre) and atmospheric (CO2) pollution to the environment.