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Posts Tagged ‘battery technology

notes on the electrification of air travel

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stolen from NASA – hope I didn’t let the batt out of the bag

Air travel has become noticeably more popular over the past few decades – due largely to affordability. Even I can afford to catch a plane occasionally these days. And yet …

I realised something was out of kilter when I discovered that, in Europe, you can fly relatively cheaply from one major city to another by plane, whereas travelling by train costs more (sometimes much more) while being more efficient in terms of carbon emissions. So why is that, and what can be done about it?

Planes are generally more costly to run and, especially, to maintain than trains, and labour costs, too, are higher. Yet some of the larger airline companies are prepared to lose money on high-demand short-haul flights to maintain their profile, knowing they can gain on international flights. They can also be (or are) more flexible with their pricing, as this article points out, so that they can get bums on seats at suddenly slashed rates, filling their aircraft for each flight, unlike trains, which have basically operated under the same half-arsed system for over a century.

So, with the steady increase in domestic and international flights, and the lack of government oversight – e.g. taxation – of international airlines that transcend political borders, the carbon footprint of air flight (if that makes sense) is growing. A 2018 report on CO2 emissions stated that ‘using aviation industry values’ there was a 32% increase in aviation emissions in the previous five years. Which of course raises the question – how do we solve the problem of over-use of costly, environmentally-unfriendly jet fuel? The answer, of course, is electric propulsion. No? An electric motor is far simpler and easier to maintain than a jet engine (a turboprop engine has between 7000 and 10,000 moving parts). Energy costs are also cheaper, once a few problems are worked out – ahem.

The biggest problem, of course, is the battery. I’ve heard that AA batteries mightn’t be enough. Nor are the current generation of lithium-ion batteries, though innovation and research in this area is being driven by electric cars hoho. Clearly electric aircraft have to start small and short-haul, and they’re already doing so. I’ve written about this before, but it’s time for an update. Some of the companies involved include Pipistrel, Harbour Air and Eviation, but this is still extremely small-scale stuff as everybody waits for the battery boffins to perform the next miracle. Meanwhile, as with the motor vehicle industry, hybrids have been developed as a kind of stop-gap for larger capacity flights. Another company, Ampaire, has developed small hybrid aircraft with which it hopes to start daily operations in Hawaii in the near future. It’s also working in Norway, where they’re hoping to have all flights of 90 minutes or less to be be either fully electric or hybrid by 2040. I’m glad to hear that my birth country, Scotland is also investing in electric and hybrid planes for similar purposes. If these planes could be shown to be economically viable, then larger aeroplane companies will surely invest in them, as they tend to lose money on regional routes (small turbine engines being very inefficient). This could be the real game-changer, providing reason to invest in battery and other technology for longer electric flight. Changes in technology, combining standard aircraft design with helicopter design, are likely to make air flight more personalised in future, with less need to depend on airports. Of course this will come with regulatory and other issues, but it all makes for a more interesting future in the sky….

References

https://www.independent.co.uk/travel/news-and-advice/cheap-flights-ryanair-train-tickets-rail-price-fares-budget-plane-a8969291.html

Why don’t we have electric planes yet? CNBC video

Written by stewart henderson

December 29, 2019 at 4:14 pm

Electric aircraft? It’s happening, in a small way

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the Ampaire 337

I no longer write on my solutionsok blog, as it’s just easier for a lazy person like me to maintain the one site, but as a result I’ve not been writing so much about solutions per se, so I’ll try to a bit more of that. The always entertaining and informative Fully Charged show on YouTube provides plenty of material about new developments in renewable energy, especially re transport, and in a recent episode, host Robert Llewelyn had a bit to say about electric planes, which I’d like to follow up on.

Everyone knows that plane travel has been on the up and up haha for decades, and you may have heard that these planes use up a lot of fossil fuel and produce lots of nasty emissions. According to the Australian government’s Department of Infrastructure and Many Other Things (DIMOT – don’t look it up) Australia’a civil aviation sector contributed 22 million tonnes of CO2-equivalent emissions in 2016. That’s of course a meaningless number but safe to say it’s dwarfed by the emissions of the major aviation countries. I assume the term ‘C02-equivalent’ means other greenhouse gases converted into equivalent-impacting amounts of CO2. For aircraft this includes water vapour, hydrocarbons, carbon monoxide, nitrogen oxides, lead and other atmosphere-affecting nasties. More innovative and less polluting engine designs have failed to halt the steady rise of emissions due to increased air travel worldwide, and there’s no end in sight. It’s really the only emissions sector for which there is no obvious solution – unlike other sectors which are largely blocked by vested interests.

So, while few people at present see electric aircraft as the big fix, enterprising engineers are making steady improvements and trying for major breakthroughs with an eye to the hopefully not-too-distant future. Just a couple of days ago, as reported on the nicely-named Good News Network, the largest-ever hybrid-electric aircraft (it looks rather small), the Ampaire 337, took flight from Camarillo airport in California (of course). The normally twin-engine plane was retrofitted with an electric motor working in concert with the remaining fuel engine to create a ‘parallel hybrid’, which significantly reduces emissions. After this successful test run, there will be multiple weekly flights over the next few months, and then, if all goes well, commercial short-haul flights are planned for Hawaii.

Of course, here in Australia, where electric cars are seen by power-brokers as some kind of futuristic horror set to destroy our way of life, there’s no obvious appetite for even wierder flying things, but our time will come – or perhaps we should all give up and invade western Europe or California. Meanwhile, Fully Charged are saying ‘there’s no shortage of aircraft companies around the world [including Rolls Royce] developing electric aircraft’, as well as converting light aircraft to electric (the Ampaire 337 mentioned above is actually a converted Cessna 337). A Canadian airline, Harbour Air, is converting 3 dozen seaplanes to electric motors, with first passengers flights expected by late 2021. These will only be capable of short flights in the region of British Columbia – range, which is connected to battery weight, being perhaps the biggest problem for electric aircraft to overcome. Again according to Fully Charged, there are over 100 electric aircraft development programs going on worldwide at present, and we should see some results in terms of short-haul flights in five years. Perfect for Europe, but also not out of the question for Adelaide to Melbourne or Port Lincoln, Canberra to Sydney and so on. Norway has a plan to use electric aircraft for all its domestic passenger flights in the not-too-distant future.

A name dropped on Fully Charged, Roei Ganzarski, seems worth following up. He says ‘By 2025, 1000 miles in an electric plane is going to be easily done. I’m not saying 5000 miles, but 1000 miles, easily.’ Ganzarski is currently the CEO of magniX, an ‘electric propulsion technology company’, based in Seattle. His company made the motors for the Ampaire 337, I think.

It should be pointed out that UAVs (unmanned – or unpersonned? – aerial vehicles), aka drones, are small electric aircraft, so the principle of electric flight is well established. It’s also worth noting that electricity doesn’t have to come from batteries, though they’re the most likely way forward. Solar cells, for example, can directly convert sunlight into electricity, and in 2015/16, using two alternating pilots, Solar Impulse 2 became the first fixed-wing, piloted, solar-powered aircraft to circumnavigate the globe. Fuel cells, particularly using hydrogen, are another option.

At the moment, though, hybrid power is all the go, and the focus is on light aircraft and short-haul flight. General aviation is still a long way off because, according to this Wikipedia article, ‘the specific energy of electricity storage is still 2% of aviation fuel’. As to what that means, I have very little idea, but this steal from a Vox piece on the topic helps to clarify:

The key limitation for aircraft is the energy density of its fuel: When space and weight are at a premium, you want to cram as much energy into as small a space as possible. Right now, some of the best lithium-ion batteries have a specific energy of 250 watt-hours per kilogram, which has already proved viable in cars. But to compete on air routes up to 600 nautical miles in a Boeing 737- or Airbus A320-size airliner, Schäfer estimated that a battery would need to have a specific energy of 800 watt-hours per kilogram. Jet fuel, by comparison, has a specific energy of 11,890 watt-hours per kilogram.

So, specific energy is essentially related to energy density, and I know that getting batteries to be as energy-dense as possible is the holy grail of researchers. So, until that ten-fold or 100-fold improvement in energy density is achieved by the battery of batteriologists beavering away at the big plane problem, we should at least push for light aircraft and short-haul flights to go completely electric asap. Ausgov, do us proud.

Written by stewart henderson

June 12, 2019 at 9:47 am