Professor Julia Stegemann, UCL, UK
Industrial symbiosis in the cement industry
In industrial symbiosis, waste from one enterprise becomes the resource for another, in an analogy with natural ecosystems in which organisms cycle resources for mutual benefit. For example, Portland cement is traditionally manufactured by heating limestone and clay at high temperature in a kiln. Consequently, cement production uses about 11,000,000,000 GJ of energy, is responsible for about 7% of global CO2 emissions, and consumes more than 5,000,000,000 tonnes of raw materials. Replacing both the fuels and minerals used in cement production with industrial wastes can help to conserve both fossil fuels and natural mineral resources. However, there is frequently a contrast between ideologies regarding proposals for utilisation of wastes, where some oppose utilisation of waste on principle; on the other hand, those who want to take advantage of practical benefits may be unwilling to engage with potential environmental risks. This presentation will explore some of the issues that can arise in industrial symbiosis, using waste utilisation in the cement industry as an example.
Professor Julia Stegemann is Director of the Centre for Resource Efficiency & the Environment at University College London, and also Co-Director of CircEL, a UCL-wide research hub for the circular economy. Her research is on sustainable technologies and systems to enable return of wastes to the resource loop. She studies physical, chemical and biological processes of accumulation and transformation of waste, in relation to prevention, treatment and utilisation. Julia has Bachelors and Masters degrees in Chemical Engineering from McMaster University and a PhD from Imperial College London, as well as more than 30 years of research experience gained also at Oxford University, Karlsruhe Institute of Technology, and Environment Canada.
Roberto Werneck, BRASKEM, Brazil
An industry view of the key role of science in the quest for the circular economy
The introduction of renewable polyethylene, announced in 2007, quickly positioned Braskem as a major player in a nascent bioplastics industry that was still trying to define its value proposition. Most bioplastics were then touted as biodegradable, often without a clear definition of what was meant by that attribute, an approach that left the door open for greenwashing.
Braskem made what seems, in retrospect, to have been a key decision: to use only science-based arguments when talking about the renewable product attributes. Starting with an eco-efficiency study, the company went on to certify each batch with a bio-based carbon content analysis. It then made data from the process available to an external team that conducted a peer-reviewed life-cycle assessment. A label, I’m green™, was created to differentiate the material; to use it, a client must state the minimum bio-carbon content in the product.
Science plays a crucial role when making decisions to minimize the social, economic, and environmental impacts. This presentation introduces science as an essential component of Braskem’s commitment to the Circular Economy, which includes supporting and taking active part in scientific research and participating in initiatives such as the Alliance to End Plastic Waste. One example is the development of new renewable materials based on disruptive scientific advances such as molecular biology and catalysis. The circular economy will benefit from a well-conceived, consistent environment of materials, processes, and policies – and science plays an important role in all these dimensions.
Roberto Werneck is a Chemical Engineer with an MSc degree from the Federal University of Rio de Janeiro. He has worked in many industries such as Chemical, Petrochemical, Oil & Gas, and Mining & Metals with activities ranging from consulting to engineering design, start-up and commissioning. He teaches Process Control at the Catholic University in Rio de Janeiro. After seven years leading the Process Technologies for Renewables in Braskem, a team that develops new processes and supports the Green Ethylene plant in Brazil, Roberto is now in charge of Technology Intelligence, within the Innovation & Technology area in Braskem.
Professor Arthur Garforth, University of Manchester, UK
Enhanced feedstock recycling
There are two major routes for the recycling of plastic waste; mechanical and feedstock. The most widespread approach to feedstock recycling is the pyrolysis (or cracking) of the plastic waste. However, this process requires high operating temperatures (typically 500°C – 900°C) with a subsequent large adiabatic temperature drop across the reactor (fixed bed or fluidised) which combined with catalyst deactivation results in significant processing issues. In addition the products are wide ranging from C1 to upwards of C50 and post pyrolysis separation/fractionation is required.
A more energy neutral option to catalytic cracking of plastics is that of hydrocracking, which in the presence of a suitable catalyst not only offers the potential for the selective recovery of useful chemical fractions, but is also is tolerant of the presence of heteroatoms such as chlorine or fluorine in the plastic. The hydrocracking process offers the opportunity to produce medium chain hydrocarbons such as naphtha and diesel fuel and the use of hydrogen in the reactor minimises the generation of coking and thus extends the viable lifetime of the catalyst before regeneration is required.
The work at Manchester showed it was possible to carry out the slightly exothermic reaction at much reduced temperatures (200°C–350°C) whilst maintaining production/conversion yields comparable to the cited literature values. Most importantly, the significantly shorter reaction times (typically 5 mins) now make continuous processing of polymer waste a possibility
Arthur obtained his PhD at Manchester on the artificial maturation of kerogen and first worked on heterogeneous catalysis as a BP extramural researcher until 1987. This was followed by several years in the petrochemical and chemical industry sector before becoming an academic at UMIST in 1998. From 1998 to 2005 he developed 'waste' catalysts for 'waste' polymers using the highly endothermic FCC process. A shift in emphasis to more energetically favourable hydrocracking of mixed plastic waste streams resulted in a Royal Society Brian Mercer Innovation award in 2008 and two patents using zeolite catalysts to produce naphtha. Arthur also has a Royal Academy of Engineering Exxon Mobil Excellence in Teaching award also in 2008. Currently, he is a lead investigator on the Catalysis Circular Economy theme (“Keeping Platform Chemicals in Play”) and is a Reader in Chemical Engineering and a Fellow of the Royal Society of Chemistry.