Category Archives: Soapbox

Hot air is good for balloons but cold air is better for cars

photograph of a MDI Airpod 2.0Cars that run on air might seem like a fairy tale or an April Fools story; but it is possible to use air as a medium for storing energy by compressing it or liquifying it at -196°C.  The MDI company in Luxembourg has been developing and building a compressed air engine which powers a small car, or Airpod 2.0 and a new industrial vehicle, the Air‘Volution.  When the compressed air is allowed to expand, the energy stored in it is released and can be used to power the vehicle.  The Airpod 2.0 weighs only 350 kg, has seats for two people, 400 litres of luggage space and an urban cycle range of 100 to 120 km at a top speed of 80 km/h.  So, it is an urban runabout with zero emissions and no requirement for lithium, nickel or cobalt for batteries but a limited range.  A couple of years ago I tasked an MSc student with a project to consider the practicalities of a car running on liquid air, based on the premise that it should be possible to store a higher density of energy in liquified air (about 290 kJ/litre) than in compressed air (about 100 kJ/litre).  His concept design used a rolling piston engine to power a family car capable of carrying 5 passengers and 346 litres of luggage over a 160 km.  So, his design carried a bigger payload for further than the Airpod 2.0; however, like the electric charging system described a few weeks ago [see ‘Innovative design too far ahead of the market’ on May 5th, 2021], the design never the left the drawing board.

Certainty is unattainable and near-certainty unaffordable

The economists John Kay and Mervyn King assert in their book ‘Radical Uncertainty – decision-making beyond numbers‘ that ‘economic forecasting is necessarily harder than weather forecasting’ because the world of economics is non-stationary whereas the weather is governed by unchanging laws of nature. Kay and King observe that both central banks and meteorological offices have ‘to convey inescapable uncertainty to people who crave unavailable certainty’. In other words, the necessary assumptions and idealisations combined with the inaccuracies of the input data of both economic and meteorological models produce inevitable uncertainty in the predictions. However, people seeking to make decisions based on the predictions want certainty because it is very difficult to make choices when faced with uncertainty – it raises our psychological entropy [see ‘Psychological entropy increased by ineffective leaders‘ on February 10th, 2021].  Engineers face similar difficulties providing systems with inescapable uncertainties to people desiring unavailable certainty in terms of the reliability.  The second law of thermodynamics ensures that perfection is unattainable [see ‘Impossible perfection‘ on June 5th, 2013] and there will always be flaws of some description present in a system [see ‘Scattering electrons reveal dislocations in material structure‘ on November 11th, 2020].  Of course, we can expend more resources to eliminate flaws and increase the reliability of a system but the second law will always limit our success. Consequently, to finish where I started with a quote from Kay and King, ‘certainty is unattainable and the price of near-certainty unaffordable’ in both economics and engineering.

Innovative design too far ahead of the market?

computer rendering of street with kerbstones fitted for chraging electric vehiclesThe forthcoming COP26 conference in Glasgow is generating much discussion about ambitions to achieve net zero carbon emissions. These ambitions tend to be articulated by national governments or corporate leaders and there is less attention paid to the details of achieving zero emissions at the mundane level of everyday life. For instance, how to recharge an electric car if you live in an apartment building or a terraced house without a designated parking space. About six years ago, I supervised an undergraduate engineering student who designed an induction pad integrated into a kerbstone for an electric vehicle.  The kerbstone looked the same as a conventional one, which it could replace, but was connected to the mains electricity supply under the pavement.  A primary coil was integrated into the kerbstone and a secondary coil was incorporated into the side skirt of the vehicle, which could be lowered towards the kerbstone when the vehicle was parked.  The energy transferred from the primary coil in the kerbstone to the secondary coil in the vehicle via a magnetic field that conformed to radiation safety limits for household appliances.  Payment for charging was via a passive RFID card that connected to an app on your mobile phone.  The student presented her design at the Future Powertrain Conference (FCP 2015)  where her poster won first prize and we discussed spinning out a company to develop, manufacture and market the design.  However, a blue-chip engineering company offered the student a good job and we decided that the design was probably ahead of its time so it has remained on the drawing board.  Our technopy, or technology entropy was too high, we were ahead of the rate of change in the marketplace and launching a new product in these conditions can be disastrous.  Maybe the market is catching up with our design?

For more on technopy see Handscombe RD and Patterson EA ‘The Entropy Vector: Connecting Science and Business‘, World Scientific, Singapore, 2004.





Reasons for publishing scientific papers

A few months ago I wrote about how we are drowning in information as a result of the two million papers published in journals every year [see ‘We are drowning in information while starving for wisdom‘ on January 20th, 2021]. As someone who has published about 10 papers each year for the last couple of decades, including three this year already, I feel I should provide some explanation for continuing to contribute to the deluge of papers. I think there are four main reasons for publishing scientific papers. First, to report a discovery – a new contribution to knowledge or understanding.  This is the primary requirement for publication in a scientific journal but the significance of the contribution is frequently diminished both by the publisher’s and author’s need to publish which leads to many papers in which it is hard to identify the original contribution. The second reason is to fulfil the expectations or requirements of a funding agency (including your employer); I think this was probably the prime driver for my first paper which reported the results of a survey of muskoxen in Greenland conducted during an expedition in 1982. The third reason is to support a promotion case, either your own or one of your co-authors; of course, this is not incompatible with the reporting original contributions to knowledge but it can be a driver towards small contributions, especially when promotion committees consider only the quantity and not the quality of published papers. The fourth reason is to support the careers of members of the research team; in some universities it is impossible to graduate with a PhD degree in science and engineering without publishing a couple of papers, although most supervisors encourage PhD students to publish their work in at least one paper before submitting their PhD thesis, even when it is not compulsory. Post-doctoral researchers have a less urgent need to publish unless they are planning an academic career in which case they will need a more impressive publication record than their competitors. Profit is the prime reason for most publishers to publish papers.  Publishers make more money when they sell more journals with more papers in them which drives the launch of new journals and the filling of journals with more papers; this process is poorly moderated by the need to ensure the papers are worth reading.  It might be an urban myth, but some studies have suggested that half of published papers are read only by their editor and authors.  Thirty years ago, my PhD supervisor, who was also my mentor during my early career as an academic, already suspected this lack of readers and used to greet the news of the publication of each of my papers as ‘more stuffing for your chair’.


Patterson, E.A., 1984, ‘Sightings of Muskoxen in Northern Scoresby Land, Greenland’, Arctic, 37(1): 61-63

Rose Eveleth, Academics write papers arguing over how many people read (and cite) their papers, Smithsonian Magazine, March 25th, 2014.

Image: Hannes Grobe, AWI, CC BY-SA 2.5 <;, via Wikimedia Commons.