Tag Archives: engines

Difficult or inconvenient data about electric vehicles

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photograph of a MDI Airpod 2.0The embodied carbon (i.e. the greenhouse gas emissions produced by its manufacture and assembly) of a typical small (compact) battery electric vehicle (BEV) is about 14 tonnes CO2 compared to about 7 tonnes CO2 in a compact internal combustion engine vehicle (ICEV) [see brusselblog.co.uk for overview of estimates from several sources].  This is mainly a result of the embodied carbon in the batteries.  My compact ICEV does about 50 mpg and we drive about 8,000 per year so we burn 160 gallons per year and one gallon generates about 9 kg CO2; thus, the carbon emissions from my ICEV are about 1.4 tonnes CO2/year. Hence, with our driving habits, building and using a compact ICEV car for five years is equivalent, in carbon emissions (= 7 + (1.4 x 5)), to just building a small electric car.  This does not account for the carbon footprint of electricity generation for the electric car which will not be zero and be dependent on how the electricity is generated; nor is recycling of your old vehicle included.  If you already have a ICEV car then your additional emissions resulting from its continued use will take about a decade to be more than buying a new electric car though by buying an electric vehicle you will move the pollution away from where you live and work.  If you buy an electric SUV, as about 45% of new car purchasers do worldwide [see IEA data], then many more years will be required to acheive a net reduction in carbon emission because the embodied carbon in an electric SUV can be five to ten times more than a compact ICEV.  The challenge for engineers is to develop vehicles that have both zero emissions in use and also zero embodied carbon.  Meanwhile, the bottom line is to use public transport whenever possible but if you need a car then have a small one and keep an electric one for much longer than an internal combustion engine vehicle – neither helps achieve net zero.

Image: the MDI Airpod that runs on compressed air [see ‘Hot air is good for balloons but cold air is better for cars‘ on May 19th , 2021.

Reasons I became an engineer: #2

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Decorative photograph showning the entrance to the Engineering Faculty at the University of SheffieldThis is the second in a series of posts reflecting on my route to becoming an engineer.  In the first one I described how I chose a degree in mechanical engineering so that I would have appreciation of the technical difficulties that engineers might cite when requesting operational changes for a ship that I hoped one day to command [see ‘Reasons I became an engineer: #1’ on April 19th, 2023].  I think I selected mechanical engineering because it provided a broader engineering education than other engineering degrees and I did not know enough to choose any other branch of engineering.  I went to the University of Sheffield and during vacations returned to the Royal Navy serving onboard HMS Active and flew out to join her wherever she was in the world, except when I went to the Royal Navy Engineering College at Manadon outside Plymouth to undertake engineering applications training.  I cast a brass nameplate, which I still have in my office, and made a toolbox that I also still have at home.  After graduation, I returned full-time to the Royal Navy as a sub-lieutenant and started my career as a naval officer in the executive or seaman branch.  However, I did not settle and missed engineering so I asked for and was refused a transfer to the Royal Corps of Naval Constructors who work on the design and development of warships.  As a result, I resigned my commission in the Royal Navy and got a job as a research assistant in the Department of Mechanical Engineering at the University of Sheffield where I registered for a PhD in engineering.  I had taken a positive step towards becoming an engineer but perhaps on the premise of what I did not want to do rather than what I did want to do.

Horsepower driving ambition

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A photograph of 'Physical Energy' in Kensington Gardens - a sculpture of a man on a horseWalking across Kensington Gardens in London last week, on my way to attend a conference on Carbon, I came across the sculpture in the picture.  It is ‘Physical Energy’ by George Frederick Watts (1817 – 1904), which really confused me because I automatically started thinking about the sort of energy that is associated with horsepower.  Horsepower is a unit of power (energy per unit time) developed by James Watt (1736 – 1819) to evaluate the output of his steam engines.  The plaque below the sculpture calls it a ‘sculptural masterpiece; a universal embodiment of the dynamic force of ambition’ and states that the artist described it as a ‘symbol of that restless physical impulse to seek the still unachieved in the domain of physical things.’  So, while the connections seemed obvious to me, it would appear that Watts was not inspired by Watt.

The conference was interesting too.  There were delegates from all over the world presenting research on a wide range of topics from new designs of batteries to using carbon as an sorbent for toxins, carbon-based composites and self-assembly of metal-organic meso-crystals.  Two students that I have supervised were presenting their research on establishing credibility for models of the graphite core in nuclear power plants and on algorithms for identifying the surface morphology in samples of graphite.

Letting the grass grow while learning some engineering

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Photograph of ATCO 17-inch petrol lawnmower in a gardenLast month was #NoMowMay during which we were encouraged to let the grass grow and allow bees, butterflies and other wildlife to thrive unmolested by your lawnmower.  Our townhouse in the centre of Liverpool does not have enough space for a lawn so I have not mown a lawn since we moved here from the USA nearly a decade ago.  In the USA we followed the convention and maintained our front lawn as manicured green carpet by watering daily, mowing weekly and feeding it monthly during the summer.  An automatic sprinkler system looked after the watering and a lawn service provided monthly doses of chemicals; however, we walked up and down behind the lawnmower each week.  Much to my disappointment, our garden was not really large enough to justify a garden tractor or sit-on mower which has been a dream since I learnt my first self-taught engineering by ‘repairing’ my father’s green ATCO lawnmower when I was about 10 or 12.  I was not allowed lift the bonnet or hood of the family car; and so as the only other piece of mechanical engineering in the garage that has an engine, the lawnmower became the focus of my attention.  I suspect that old lawnmower did not run any better as a result of my ministrations but I certainly understood how an internal combustion engine worked by the time I went to university.  I am an enthusiastic supporter of letting the grass grow, perhaps with a mown pathway so that the lawnmower has to be re-assembled periodically by whichever budding engineer has dismantled your lawnmower.

Source: Joy Lo Dico, How the lawn became a no-mow area, FT Weekend, 29/30 May 2021.

Image: An ATCO 17-inch petrol lawnmower similar to the one mentioned above, from http://www.lawnmowersshop.co.uk/atco-17-inch-self-propelled-petrol-lawnmower-b17.htm