Let’s start with how the concept of ‘Waste as a Resource’ came about in the early 2000s. Although engineers involved in the industry initially welcomed the publication of the well-known Waste Hierarchy, it soon became apparent to them that it would be very difficult to implement in practice.

In the Hierarchy and subsequent legislation, ‘waste’ is viewed as a problem to be resolved, rather than as a resource for our futures.

To someone who is both a Chartered Engineer and a Chartered Environmentalist, with 30 years of experience in sustainability, the hierarchy appears inherently unsustainable.

Genuine sustainability requires us to look at the ‘big picture’, using whole life-cycle assessment and considering overall impacts on every aspect of the value chain. The current waste hierarchy, by contrast, considers only the extremely narrow field of waste management, which can be considered a traditional ‘silo’ that, for the most part, ignores external impacts (particularly energy) and current international best practice in engineering.

The hierarchy was developed largely without any engineering input and rather than achieving any significant reduction in waste (which has to be designed out of the system), almost all the focus has been on the third tier: recycle. Superficially, this seems attractive but ignores the fact that large quantities of energy (electricity, heat and transport) are needed for almost every form of recycling; this is energy that we would not otherwise be producing and using in the UK – bad news indeed at a time when every person in this country is suffering from an energy crisis.

Furthermore, not all materials are commercially recyclable and there is a very limited market in the UK for many recycled products. This was apparent to some engineering institutions in the early 2000s and led to the publication of IMechE’s ‘Waste as a Resource’ strategy document as long ago as 2009. This document was broadly welcomed by the waste industry and engineers in general but government preferred its own non-engineering-based policies.

A further problem with the waste hierarchy is that the fourth tier, recovery, has been relegated (in the UK but not in other northern European countries) to an ‘undesirable’ step by non-engineers and people who demonise ‘carbon’; they appear to have confused Energy from Waste (EfW) plants with old-fashioned municipal waste incinerators, the last of which, in the UK, closed over 25 years ago. Consequently, EfW plants which convert fuel derived from waste (RDF) into much-needed energy, receive much opposition from a prejudiced public. When EfW plants do get built, they are usually designed as ‘electricity-only’, with very low thermal efficiency and most of the co-generated heat energy (i.e. most of the energy converted!) is gratuitously wasted

to atmosphere and watercourses. This is not a sustainable engineered solution. Following decades-long practice in countries such as Denmark, where thermal

efficiency of EfW plants is greater 90 per cent (compared with around 25 per cent in the UK) would have a far greater positive impact on climate change mitigation than

many of the measures currently proposed in the UK.

Furthermore, recycling, at least as generally practised in the UK, i.e. ‘downcycling’, does not really conform to the principles of the circular economy (CE), which requires ‘upcycling’. On the other hand, converting otherwise wasted products into much needed and sustainable energy (electricity, heat and transport) can indeed be seen as a form of ‘upcycling’ and conforms well with the CE. A failure to understand this distinction probably implies a lack of understanding of engineering practice.

Of course, much the same can be said for the whole ‘Net Zero’ strategy itself. This has been developed from the scientific findings of the various IPCC reports published since 1992 and simply proposed as a ‘wish-list’ for the period to 2050; there is little evidence of engineers having been consulted along the way to evaluate what is both technically possible and commercially viable. The role of engineers has generally been regarded as ‘making what governments want to happen, happen’! Think how different it would be if technically and commercially aware engineers were involved in the decision making process rather than being presented with a largely unsustainable fait-accompli.

In the waste industry, as well as in most other aspects of British life, we need to get out of our comfortable traditional ‘silos’ and start engineering, rather than ‘sloganeering’ our way to technically and commercially viable, sustainable solutions.

Published in The Engineer.

Prof Ian Arbon is a Fellow of IMechE, where he chairs the Energy, Environment & Sustainability Group, the Renewable Power Committee of the Power Industries Division and the Working Group on Global Sustainability and is Co- Chairman of the joint IMechE/ ICE ‘Waste as Resource’ initiative with DTI/DEFRA.

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