New two-stroke engine design could help keep internal combustion around longer

Re:New two-stroke engine design could help keep internal com... by avhon1 on Tuesday May 26, 2020 @06:26AM (#23309293)

It depends. Electric motors also have losses in their controllers, which removes another 5% or 10%. If you want mechanical power output and have 1kg of pre-charged batteries and 1kg of liquid fuel, the efficiency of electric motors might close the density gap. Lets assume 95% efficient controller+motor (slightly optimistic) and 30% efficient ICE (somewhat pessimistic).

1kg * 14 MJ/kg * 95% = 13 MJ mechanical

1kg * 47 MJ/kg * 30% = 14 MJ mechanical

It comes out pretty close!

If you want mechanical power and also heat (for keeping people, animals, or equipment warm, decreasing the viscosity of fluids, etc), ICE is definitely the way to go.

-- edit --

/u/ash points out Tesla's energy density is is 0.576 MJ/kg

1kg * 0.58 MJ/kg * 95% = 0.55 MJ mechanical

...not even slightly close.

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Re:New two-stroke engine design could help keep internal com... by varjag on Tuesday May 26, 2020 @08:10AM (#23310106)

You should factor in regenerative braking of EVs, which is lost as heat for fossils vehicles.

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Re:New two-stroke engine design could help keep internal com... by petre on Tuesday May 26, 2020 @08:21AM (#23310205)

One can't really charge a battery with power spikes from randomly hitting the brakes. Only part of the braking energy is recoverable, for example when braking to reduce speed while descending a long slope. Braking strategy should also be different in this case: similar to engine braking in regular vehicles. Since most EVs rarely have a multi speed gearbox, regenerative braking should be built into the brake pedal.

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Re:New two-stroke engine design could help keep internal com... by varjag on Tuesday May 26, 2020 @09:46AM (#23311023)

In practice it works fine on all EVs I driven. Doesn't take much getting used to.

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Re:New two-stroke engine design could help keep internal com... by rootusrootus on Tuesday May 26, 2020 @09:10AM (#23310662)

I'd wager there are far more fossil fuel vehicles on the road with regenerative braking than there are EVs.

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Re:New two-stroke engine design could help keep internal com... by varjag on Tuesday May 26, 2020 @09:44AM (#23311005)

Intrigued, how would that work?

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Re:New two-stroke engine design could help keep internal com... by organsnyder on Tuesday May 26, 2020 @10:03AM (#23311221)

I think OP is referring to hybrid ICE vehicles.

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Re:New two-stroke engine design could help keep internal com... by bluGill on Tuesday May 26, 2020 @09:39AM (#23310954)

Not very much when you are on the freeway.

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Re:New two-stroke engine design could help keep internal com... by varjag on Tuesday May 26, 2020 @09:43AM (#23310995)

I guess if you never ever use brakes it has no advantage.

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Re:New two-stroke engine design could help keep internal com... by Hypx on Wednesday May 27, 2020 @03:17AM (#23320300)

There's also hydrogen fuel cells to consider, which at 142 MJ / kg and 50% efficiency looks like this:

1 kg * 142 MJ / kg * 50% = 71 MJ mechanical

The dominant solution above all else.

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