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First all-electric seaplane takes flight in B.C.

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Re: First all-electric seaplane takes flight in B.C.

#161

Post by hoseja »

SEJeff wrote: post #110
eloff wrote: post #96

Earlier quoted context omitted.

We can accomplish the same by producing the jet fuel using electricity. Realistically this will likely involve methane (natural gas) extracted from the ground and water, but it could one day be carbon neutral using captured carbon. The trick is to use clean energy like nuclear of renewables. There was an article on HN just recently about doing that with portable nuclear generators like those used on ships, this could…

Methane can be created via carbon capture entirely. It is in the SpaceX TODO list to create a factory to literally create metholox (methane + liquid oxygen is what they use as fuel for the new Starship / Superheavy rockets they want to use to go to mars) via carbon capture. Elon has already discussed this before. The end goal that the rocket launch is carbon neutral when you are using carbon already captured from the…

The goal is not being carbon-neutral. The goal is Mars ISRU.

Re: First all-electric seaplane takes flight in B.C.

#162

Post by leoedin »

Robotbeat wrote: post #79
semi-extrinsic wrote: post #27

You can do small aircraft like this, no problem. The trouble is you can't scale it up, due to how quickly the power and energy demands go up. This thing is 560 kW and gets a range of 86 nmi; an A320 is around 40 000 kW and has a range of 3 500 nmi, while an A380 is around 80 000 kW and has a range of 8 500 nmi. Going from this DHC-2 to the A380 requires an increase in energy storage by a factor of around 14 000x, whi…

This is not true. It's easier to scale up. You get more efficient. Scaling up an electric motor is not particularly hard. Some of the largest machines in existence are electric. Power is not a challenge for electric. In fact, this electrified seaplane has much more power (560kW) than the original radial piston engine one (336kW), and even more than the turboprop conversion (510kW). A LOT of very confident people on t…

It's almost like you didn't read the comment you're replying to. It makes the absolutely valid point that the power requirements of a small jet airliner are many orders of magnitude greater than the power storage capabilities of any current battery technology. I don't really see how you refute that. Nobody's arguing you can't make a small electric plane work (clearly - the article is about one which works). Big ones are another thing altogether.

Re: First all-electric seaplane takes flight in B.C.

#163

Post by leoedin »

tim333 wrote: post #136
semi-extrinsic wrote: post #95

Earlier quoted context omitted.

I'm not saying it's impossible to make a 5, 10, 15 seater all-electric work. I'm saying a 100 passenger all-electric will never fly without a revolution in battery tech. You say "just increase mass of the vehicle which is battery". If you read about this airplane you find that since they are using batteries with an appropriate safety rating for aviation, they've used all the space and mass already: "this eBeaver isn’…

>I'm saying a 100 passenger all-electric will never fly without a revolution in battery tech. I don't think you're right from an engineering point of view. Just multiply the aircraft size and battery number by some amount. For example: >In September 2017, U.K. budget carrier EasyJet announced it was developing with Wright Electric an electric 180-seater aircraft to be developed by 2027. https://www.nextbigfuture.com/…

There's a lot of mistruth in green technology. You need to get to first principles - the numbers. Look at the power requirements and weight budgets of large airliners, look at the best case energy density of lithium batteries and do the calculations yourself. That's what the parent comment did.

Re: First all-electric seaplane takes flight in B.C.

#164

Post by leoedin »

mcsb4 wrote: post #104
manigandham wrote: post #100

Earlier quoted context omitted.

Cars are not airplanes. Electric cars are much heavier but weight isn't a big problem on the road. That's why they work, and they're still catching up to traditional range expectations. With airplanes, you have to lift that weight using the same energy stored within. In that case, energy density is the absolute issue. Nothing else matters. There's no magical solution, a high-school physics class will teach you how to…

> the potential energy requirement to lift up a certain amount of weight, and dividing by energy density and volume of current battery tech does not lead to a working jet any time soon. E=mgh E=(1kg * 9.81m/s^2 * 10.000m) / 3600s = 27.25Wh. Tesla currently is at around 260Wh/kg thus roughly ten times the amount of potential energy needed to get to 10.000m altitude. I'd assume that till 2030 we get to ~500Wh/kg by imp…

Potential energy is only one component of the power required by aircraft. If you want to actually go somewhere, you need speed, which means drag.

Drag increases the square of the velocity. That means going at 500knots (as an airliner does) uses a lot more power than going at the 150knots this seaplane might fly at.

You can calculate an approximate power requirement for the aircraft based on its glide ratio [1] or look at the power based on engine thrust [2]. In all cases you get figures in the 14-80MW range (engines don't tend to be full throttle during cruise)

That means your 260Wh/kg battery would need to weigh somewhere between 54 and 308 tonnes to sustain an hour of flight. That doesn't include takeoff, which is only a few minutes but might reach towards 200MW.

For reference, the 737 (low end power calculation) max takeoff weight is 62 tons and the 747-400 max takeoff weight is 397 tons. So in both cases you're looking at basically 30 minutes of useful cruise with current battery tech.

The range loss is additionally confounded by the fact that current aircraft lose fuel, so lose weight, during the flight. This accounts for a not-insignificant portion of the range.

[1]: http://large.stanford.edu/courses/2013/ph240/eller1/ [2]: https://aviation.stackexchange.com/questions/19569/how-many-...

So basically for electric passenger aircraft with even remotely comparable performance, we need a battery revolution. It definitely won't be by 2030.

Re: First all-electric seaplane takes flight in B.C.

#165

Post by alex_duf »

eloff wrote: post #96
semi-extrinsic wrote: post #27

You can do small aircraft like this, no problem. The trouble is you can't scale it up, due to how quickly the power and energy demands go up. This thing is 560 kW and gets a range of 86 nmi; an A320 is around 40 000 kW and has a range of 3 500 nmi, while an A380 is around 80 000 kW and has a range of 8 500 nmi. Going from this DHC-2 to the A380 requires an increase in energy storage by a factor of around 14 000x, whi…

We can accomplish the same by producing the jet fuel using electricity. Realistically this will likely involve methane (natural gas) extracted from the ground and water, but it could one day be carbon neutral using captured carbon. The trick is to use clean energy like nuclear of renewables. There was an article on HN just recently about doing that with portable nuclear generators like those used on ships, this could…

Assuming we have infinite renewable energy supply to produce kerosene from electricity and therefore carbon neutral flights, it still doesn't quite solve the air quality issue.

A step in the right direction, but I hope this doesn't get used as an excuse to fly more.

Re: First all-electric seaplane takes flight in B.C.

#168

Post by dboreham »

WalterBright wrote: post #142
SEJeff wrote: post #110

Earlier quoted context omitted.

Methane can be created via carbon capture entirely. It is in the SpaceX TODO list to create a factory to literally create metholox (methane + liquid oxygen is what they use as fuel for the new Starship / Superheavy rockets they want to use to go to mars) via carbon capture. Elon has already discussed this before. The end goal that the rocket launch is carbon neutral when you are using carbon already captured from the…

The whole "carbon neutral" think is a crock. Coal is, after all, just dead trees, so coal plants run on "biofuel" and are "carbon neutral".

There's an implicit time window on the sum. Burning fossil fuels is evaporating all the carbon captured in the past billion years, over a few hundred years.

Re: First all-electric seaplane takes flight in B.C.

#169

Post by ppf »

m-i-l wrote: post #149
WalterBright wrote: post #142

Earlier quoted context omitted.

The whole "carbon neutral" think is a crock. Coal is, after all, just dead trees, so coal plants run on "biofuel" and are "carbon neutral".

> The whole "carbon neutral" think is a crock. Coal is, after all, just dead trees, so coal plants run on "biofuel" and are "carbon neutral". The difference is in the timeframes for capture and replacement - with coal it is millions of years, and with wood it is years. That means burning coal releases carbon which was trapped millions of years ago, and it would take millions of years to trap equivalent amounts of car…

True, but what is a sustainable level of tree harvesting to feed the world's energy needs?

Re: First all-electric seaplane takes flight in B.C.

#170

Post by ppf »

davedx wrote: post #151
semi-extrinsic wrote: post #27

You can do small aircraft like this, no problem. The trouble is you can't scale it up, due to how quickly the power and energy demands go up. This thing is 560 kW and gets a range of 86 nmi; an A320 is around 40 000 kW and has a range of 3 500 nmi, while an A380 is around 80 000 kW and has a range of 8 500 nmi. Going from this DHC-2 to the A380 requires an increase in energy storage by a factor of around 14 000x, whi…

> Going from this DHC-2 to the A380 requires an increase in energy storage by a factor of around 14 000x First of all: citation needed. Secondly: it's a disengenious argument to say "you can't scale it up", then give the largest passenger aircraft in operation as your first scale up target. What about scaling up to the size of the propellor aircraft regularly carrying people between Amsterdam and many cities in the U…

If we are looking at an energy-conscious (or energy-scarce) future, then we really have to consider what forms of transport are feasible at all. For these kind of short-hop journeys, flight is probably not efficient enough.
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