Electric vehicles

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#1335108 1-Jul-2015 15:00

With NASA putting R&D resource into electric planes too, there should be some neat battery technology to trickle down into cars.

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#1335486 2-Jul-2015 07:15

I've been following electric planes for a while, and they're not a force for change in battery technology. On the contrary, I read that the big motivator is power tools.

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#1335495 2-Jul-2015 08:32

old3eyes: Anyone see Top Gear USA on Saturday?? The who program was devoted to EVs from the basic Leaf to Electric drags. Dispite the program being 2 years old they gave EVs the thumbs up with the only reservation being rang. Man the Tesla they took for a drive could sure go fast..

Got to test drive the Tesla Model S 70D here in Norway (4 wheel drive, 0-100 KMH in 5,4 seconds). Must say its a very nice car. The acceleration is great and its a comfortable ride with a car that feels like it is on rails and behaves very predictably.

Has been a car I have liked from what I have read and seen before, the test drive only solidified my fondness for the car.

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#1335557 2-Jul-2015 10:16

frankv: I've been following electric planes for a while, and they're not a force for change in battery technology. On the contrary, I read that the big motivator is power tools.

That makes sense - the power tools I use have 4AH batteries which from empty take a full charge in about 30 minutes - yet the battery packs themselves only get very slightly warm at that fast charge rate. No other devices I have (phones, tablets etc) come even close.

With planes, a quick and very approximate look at a typical jet airliner indicates that about 30% of maximum takeoff weight is fuel, about 25% payload. About 1/3 of that fuel is "wasted" (jet engine conversion efficiency). If (an impossible) 100% conversion was somehow possible with electric, then for equivalent energy storage to 10 tonnes of jet fuel, you'd need something like 500 tonnes of lithium ion battery. It's never going to fly - and neither are we in practical electric planes using anything like lithium ion technology. Fuel cell - perhaps - but if you could get that fuel up there safely (ie hydrogen, with 3x the energy density of jet fuel), then would it be better to convert it to electricity in a fuel cell - or just burn it?

markl

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#1335577 2-Jul-2015 10:38

Fred99:
frankv: I've been following electric planes for a while, and they're not a force for change in battery technology. On the contrary, I read that the big motivator is power tools.

That makes sense - the power tools I use have 4AH batteries which from empty take a full charge in about 30 minutes - yet the battery packs themselves only get very slightly warm at that fast charge rate. No other devices I have (phones, tablets etc) come even close.

With planes, a quick and very approximate look at a typical jet airliner indicates that about 30% of maximum takeoff weight is fuel, about 25% payload. About 1/3 of that fuel is "wasted" (jet engine conversion efficiency). If (an impossible) 100% conversion was somehow possible with electric, then for equivalent energy storage to 10 tonnes of jet fuel, you'd need something like 500 tonnes of lithium ion battery. It's never going to fly - and neither are we in practical electric planes using anything like lithium ion technology. Fuel cell - perhaps - but if you could get that fuel up there safely (ie hydrogen, with 3x the energy density of jet fuel), then would it be better to convert it to electricity in a fuel cell - or just burn it?

Solar power. Works great when you can get above the clouds. That way you don't have to have enough batteries/fuel cells to equate to a full flight when you take off, so your 500 tonnes of battery doesn't need to be anything like that much. Whether it's still necessary to have an impractical mass of batteries or not, I don't know, but at least it's not quite a 1 - 1 translation as you've described.

With aircraft, the bigger issue, I believe, is in developing electrical propulsion methods that can move a giant airliner through the sky...

dwl

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#1335707 2-Jul-2015 13:12

Fred99: It's never going to fly - and neither are we in practical electric planes using anything like lithium ion technology. Fuel cell - perhaps - but if you could get that fuel up there safely (ie hydrogen, with 3x the energy density of jet fuel), then would it be better to convert it to electricity in a fuel cell - or just burn it?

I agree that large airliners, with heavy payloads travelling at high speeds are going to need energy storage density that is unlikely to be provided by batteries in the coming years. However, I disagree that there cannot be practical electric planes using lithium ion technology.

The winner of the NASA Green Flight Challenge on 3 October 2011, the Pipistrel Taurus G4, can carry four people with high efficiency. From here "To win, the aircraft had to fly 200 miles in less than two hours and use less than one gallon of fuel per occupant, or the equivalent in electricity. Pipistrel's Taurus G4 achieved fuel efficiency of 403 passenger miles per gallon at a speed of 107 mph. The results show that "battery-powered electric flight is feasible for general aviation aircraft," according to Pipistrel team leader Jack Langelaan. "

There are multiple companies with prototypes or even production models but like cars the cost for what you get remains an issue. One recent example just spotted is the Pipistrel Alpha Electro . This is really new. It has a nominal one hour endurance (short) but could be well suited as a trainer - charge cost after their flight was 2 Euro. It has a special propeller that does regen. I would be very interested in comments from anyone who flies light aircraft - watch the video in the link and if you get Aviation Consumer magazine it is coming in the August 2015 edition (you can read a lot of the article in the video).

markl: Solar power. Works great when you can get above the clouds. That way you don't have to have enough batteries/fuel cells to equate to a full flight when you take off, so your 500 tonnes of battery doesn't need to be anything like that much. Whether it's still necessary to have an impractical mass of batteries or not, I don't know, but at least it's not quite a 1 - 1 translation as you've described.

With aircraft, the bigger issue, I believe, is in developing electrical propulsion methods that can move a giant airliner through the sky...

Propulsion systems are feasible with electric motors and propellers possibly being lighter than the piston or turbine equivalent (but not for jet speeds) but the amount of energy storage needed for larger aircraft is a huge, and I think insurmountable, barrier. While there might be some boost from solar during flight, the equation for kW per sq metre and the energy demands of the aircraft probably leave solar in niche uses such as the Solar Impulse or unmanned drones.

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frankv

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#1335712 2-Jul-2015 13:20

There are an increasing number of all-electric light aircraft e.g. Pipistrel Taurus-electro, NASA... endurance is typically an hour or less (vs 2-4 hours for gasolene-powered light aircraft). This just about makes electric usable for training, if you either have a fast charging option, or quick-change battery packs (and multiple battery packs).

Regarding Hydrogen... 3x specific energy (MJ/Kg) for compressed hydrogen gas is by weight... energy density (MJ/l) is 1/6. https://en.wikipedia.org/wiki/Energy_density So you would need tanks 6 times the volume to store the same amount of energy as kerosene, but the fuel would weigh 1/3 of the kerosene weight. But the weight of the tanks themselves would outweigh the weight savings in the fuel. (Compare with CNG, which has 20% more energy/Kg than petrol, but in cars with CNG conversions range on CNG was about half). So a complete redesign of the aircraft would be required.

Hydrogen fuel cells are not terribly efficient (typically 40-60% vs 25% for ICE). So putting hydrogen into a fuel cell to make electricity to run an 80% efficient electric motor would make it at best about twice as efficient as running an ICE on hydrogen. I wonder what a fuel cell capable of producing megawatts would weigh?

Large jets is another story...

Solar power would be great, except (a)at night, and (b) the plane would have to be the size of a small country (e,g, Monaco). Need one hectare/MW on the Earth's surface, probably a lot less at 30,000ft.... Boeing 777 at full power = 234MW.
Typically, a large jet aircraft can't land unless it has reasonably empty tanks. Unfortunately batteries don't lighten as they drain.
Propellors don't work well at 30,000ft
Regulators will take 50 years to approve.

MikeAqua

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#1335770 2-Jul-2015 14:11

In the article I was reading (magazine I picked up at the aero club) the battery more or less is the wing of the aircraft, so there are some weight savings.

Electric planes are interesting. Batteries need to do three things: -

1) Provide peak output for short periods to allow an aircraft to accelerate rapidly to take off speed.
2) Provide a lower level of sustained output to keep an aircraft flying.
3) Provider sustained output for a particular duration (total capacity).

Batteries have to be sized for peak output - compare the batteries in a land cruiser and a corolla. For a particular kind of battery total capacity is proportional to peak output.

Planes will always need to be capable of "go-round" power for safety, but does that exceed the output required for accelerating to take off speed from stationary?

Could an electric launch vehicle assist a plane (physically or as a temporary battery bank) to accelerate to take off velocity and release it as the plane develops enough speed for it's payload to get air borne?

Reducing total battery mass ultimately allows a more streamlined shape, reducing drag requirements, and therefore extending the range of a given battery.

frankv

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#1335820 2-Jul-2015 15:04

Regarding dwl's link to the Pipistrel Alpha.

I fly light aircraft, and I'd say that would be feasible to marginal as a trainer. This page says endurance is 1 hour, PLUS 30 minutes reserve. That's fine for training -- most training flights are less than an hour. But 45 minutes to recharge in the aircraft would be marginal. Your aircraft is available for only about half the time, unless you buy another battery pack.

Price of the aircraft at 100K euros is high, likely over $200K by the time you buy another battery and pay freight and GST.

Fuel cost of 2 Euros/hour would be great... typically we're looking at 15-20 litres/hour = about NZ$35-50/hour. But it really depends on battery life and battery cost. Last I looked, 1 hour worth of batteries cost about $10K, and lasted for 1000 charges. So that's $10/hour.

Also, license requirements include cross-country trips. Obviously, anywhere more than half an hour away is out of range, unless you take the charger with you (effectively reducing it to a single-seat aircraft, I guess) and wait 45 minutes there before coming back. So any students will have to transition to another aircraft to complete their licenses... i.e. you need to own *two* aircraft... the Alpha and a cross-country machine. So it's not for the tiny single-aircraft aero club.

Last time I looked, many years ago, flying costs were about 1/3 for fixed costs (hangarage, insurance, use of capital), 1/3 for fuel, and 1/3 for repairs and maintenance (especially the engine... $35K/2000 hours = $17/hr). The electric option reduces the fuel costs a lot (even including a battery replacement allowance), but increases capital cost & therefore insurance, repairs & maintenance are a bit of an unknown, but probably a lot less. So your flying costs might come down by a third or so?

But, transitioning to a second aircraft may take up to 5 hours (I guess), which will chew up a large chunk of the savings.

All in all, I'd say it's a good buy as the *second* aircraft of a flight training organisation, but otherwise not attractive at all because of the limited endurance.

Frank

dwl

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#1335869 2-Jul-2015 15:59

Thanks for the feedback franky. While Pipistrel claim the endurance is 1 hour plus reserves some other reviews suggest that by 1 hour most of the capacity might be used up. If we could get at least 50% and preferably 100% improvement in energy density (W/kg) without excessive cost it is coming into the quite viable range. The total package with battery management seemed well sorted.

The cost is high but then so are many new aircraft. We tend to look at the cost of old Tomahawks or Cessna 150s and they look cheap but often they are from the 1970s, the cost to recondition an engine to GA standards is high, and say $40 per hour for fuel over 2000 hours is $80k. The wiki entry on the Pipstrel Alpha trainer petrol version says "In particular the Alpha's price was initially set well below the then-current US$149,000 price announced for the comparable Cessna 162, although by 2014 Pipistrel had raised the price to US$103,000."

I agree that the limitations mean having electric as a second vehicle makes sense, much the same as for cars now, but I don't think flight schools can afford to have both. The sad fact is that when I was recently at an aero club on a weekend the amount of training going on was quite limited and a charge time of 45 minutes might not have been a big issue.

One area electric might work is glider towing where high peak power for maybe 3-5 minutes is then followed by quick descent (regen would help), no worries about shock cooling cracking cylinder head and maybe wait for next launch. Obviously if it gets busy doesn't work although topping up with 5-10 minutes wait time is something you could do with electric that you don't try (or need) with your Piper Cub. Several LSA aircraft have shown that small light aircraft can work well towing with the A22 Foxbats (plus Eurofox's and Tecnam) listed in the latest Soaring magazine comparison of tow planes. I assume these are the larger Rotax - 100 hp (75kW) is close to the Pipistrel Electro power.

Now just need to win Lotto to have the option of that "second" vehicle.

RUKI

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#1340582 10-Jul-2015 13:38

Is there anyone with Lexus GS450h or Highlander Hybrid here?

I've just finished building Rescue High Voltage Charger for those battery packs (288V nominal - 40x7.2V or 30x9.6V)

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dwl

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#1340868 10-Jul-2015 20:59

Another first happening as I write this - crossing of the English Channel by small Airbus E-Fan which has now crossed French coastline and just landed.

Big PR event for Airbus but some controversy with Pipistrel posting a letter about how they planned to do the trip on 7th July (both ways with landing in England on single charge for whole trip) but got notice from Siemens that approval to use the Siemens motor was withdrawn with Siemens saying "Our Motor in its current version is neither designed, nor tested, nor approved by us for a flight above water - we explicitly prohibit you to use or let anyone else use our Motor for any flight above water."

The Airbus E-Fan seems less practical than the Pipstrel Alpha Electro but shows that electric is being seriously looked at.

[Edit] The link in the blog post about a successful trip of first electric on Thursday translates by Google translate to "When the French pilot Hugues Duval learned that the formation of Airbus Siemens Slovenian manufacturer Pipistrel electric banned the first attempt to fly across the English Channel an electric boat, the venture embarked alone. By plane Cri-Cri E-Cristalina on Thursday night as the first in the history of successfully flew over the Channel and this for a few hours ahead of Airbus attempt and so the air just before the giant nose escaped the prestigious crown."

The rest of the translation gets more questionable about accuracy.

A better version has been posted by The Telegraph

Bobdn

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#1340913 10-Jul-2015 23:05

In the NZ Herald today: 3D printed electric car available in 2016.

http://www.nzherald.co.nz/technology/news/video.cfm?c_id=5&gal_cid=5&gallery_id=152250

dwl

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#1340979 11-Jul-2015 08:56

Bobdn: In the NZ Herald today: 3D printed electric car available in 2016.

http://www.nzherald.co.nz/technology/news/video.cfm?c_id=5&gal_cid=5&gallery_id=152250

Thanks for the link. They have some great ideas and seem to be relying on crowd sourcing. The project page has interesting chat messages about different plastics and how they might best bond together. They are looking for ideas - the page has this message:

"Our goal is to have 3D-printed cars on the road before the end of 2016. Pretty audacious, right? Well, this is where you come in. Your mission, should you choose to accept it, is to be part of history and join us as we co-create the next great car. What's in it for you? Other than the fun of being part of this project, you'll also earn points for each idea, comments, design, and other contribution you make to this project. We call it "Fair Trade Ideas," and promise to monetarily reward you based off your contributions once we get this car on the market. So, the more you contribute, the more points you'll earn plus the faster we'll be able to get the car on the market and the sooner you'll be able to get that money, honey. So go on, get started and let's show the world what we can do."

Electric makes sense as Tesla and Nissan have shown where you place the batteries where best and don't have to try and fit complex engines. The body is a key part but there are many challenges getting the other mechanicals sorted and making a body shape that appeals for mass use. I wish them well.

frankv

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#1342566 13-Jul-2015 21:00

dwl: Another first happening as I write this

See http://www.avweb.com/eletter/archives/101/3097-full.html?ET=avweb:e3097:220868a:&st=email#224415 -- the first electric-powered aircraft to cross the Channel was the Solar Challenger, 34 years ago.

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