Cambridge versus global warming

In the media and in politics, global warming is (finally?) being discussed. Have you ever considered what profession is responsible for solving this problem, or what training is needed? I admit I didn’t think about this much before starting university. However, Cambridge University Engineering Department has a clear answer: preventing global warming is the responsibility of the engineer, and he must be educated accordingly. By this I don’t mean the specialisation in “Energy, sustainability, and the environment” offered at the Department; I mean every engineer, in every field.

Cambridge in particular is fertile soil for this holistic idea. The Cambridge engineering course is unique in that it is general, i.e. all subjects from all areas of engineering are compulsory for its first two years. In another environment, it may not have taken root as well.

Why does this concern absolutely all engineers? Absolutely all human activity requires energy, and its production usually leads to production of greenhouse gases. Therefore, two simple concepts are introduced in the first year of the engineering degree: embodied energy and life cycle assessment.

Embodied energy is the energy consumed in the manufacturing of goods or materials. Everything has an embodied energy, and therefore an environmental impact. Plastics aren’t recycled because oil could run out, but because recycling PET consumes half as much energy per kilogram as producing new PET; the recycling of 250 PET bottles saves as much energy as the average Brit uses in a day.

The life cycle of a building or machine consists of three stages: manufacturing (or construction), operation, and disposal (demolition, recycling etc.). Each consumes energy. An increase in the energy cost of one stage may lead to savings in another and vice versa; e.g., an electric car has greater embodied energy than an internal combustion car, but consumes less energy in operation.

These concepts can be explained in a single lecture and, in my opinion, it is a great pity that they are not in the public consciousness and aren’t taught in schools; many myths about sustainability come from ignorance of them. One such myth is that rules of thumb, like the belief that plastic is bad and anything “natural” is good, are useful in determining environmental impact. This can only be determined by calculation. E.g., a blanket ban on plastic packaging would be environmentally harmful because it would lead to spoiling of food, which has high embodied energy.

Other myths are that global warming can be stopped quickly, easily, or painlessly. Extinction Rebellion’s demand that carbon neutrality must be reached by 2025 is completely absurd. Carbon neutrality means sweeping changes in all areas of industry, transport and everyday life, which cannot be carried out in five years; e.g., most cars in use today will remain in use in 2025.

Last year, the UK (and subsequently the EU) set a target of carbon neutrality by 2050. The good news is that this target is technically achievable. The bad news is its cost: a total ban on fossil fuels, air transport, the production of new concrete and steel, and cattle farming. The fossil fuel ban will require a threefold reduction of the UK’s total energy consumption, because the growth of renewable and nuclear energy is slow and, on such a short timescale, no new technologies can be counted on. This cannot be achieved except by heating buildings three times less, travelling by car three times less (even after making all cars electric), and using domestic appliances three times less.

A large fraction of the European public demands carbon neutrality, and demands it as soon as possible. Politicians promise it and engineers know how to reach it by the given deadline of 2050. However, does the public realise the cost of what it demands?

Most ideas and numbers in this article come from the lectures of Prof J. M. Allwood, Dr C. Y. Barlow, and Dr H. R. Shercliff; however, responsibility for its content rests solely with the author.