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Comment by grapesodaaaaa | Hacker News Reader

Suggesting a turbine could go in a gas car on size/weight alone isn’t a great idea.

I’m saying this as someone in the aviation industry. Turbines are amazing pieces of machinery and incredibly reliable, BUT incredibly expensive to operate.

They require all kinds of specialized maintenance and what I would call “exotic” oils that won’t break down in the harsh environment.

It’d make a really great generator for a vehicle, but I don’t think the economics will work out for a family car anytime soon.

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There's millions of radial turbines in cars around the world today. They use an internal-combustion engine for their combustor, and they're called turbo-chargers.

While true, they are not sustaining combustion within the turbo. I believe this is what makes the problem more difficult, and it sounded like what the OC was suggesting.

Turbos float on a layer of motor oil, and have a crude design compared to combustion-sustaining turbines.

What about for “microgrids”? If it was possible for a household (or neighborhood) to install one and run completely on corn based ethanol… that might be something better than the IC generators we have today (I understand that corn ethanol isn’t completely green).

> corn based ethanol

This is an idea that needs to go away. We should not burn food for fuel, and there are a lot of externalities in growing corn and then turning it into ethanol that people are not considering.

Corn-based ethanol is just a very inefficient form of solar energy. Use solar panels instead and skip the middleman.

All fuel comes from the sun (or other star activity). Food is a stupid argument invented by the oil companies.

> Food is a stupid argument invented by the oil companies.

It's not that stupid, we still have many millions of people in utter food insecurity, and not just in the "third world" but also across our Western nation.

IMHO, people should come before cars when it comes to distribution of food, and we should electrify automotive to get rid of the entire issue anyway. What few renewable fuels we have, we will sooner or later need to power air flight and ocean-crossing ships, as we do not have any alternative to some sort of combustible fuel for either purpose.

We have a food distribution problem. The world makes more than enough food to feed everyone.

As an aside, corn ethanol is not made with the type of corn that could be used for human consumption. We could use those same fields to produce human food, but refer back to the first paragraph of this post for why we don't do that.

I think efficiency isn’t great.

A diesel ICE engine can be surprisingly efficient and is not particularly expensive compared to a turbine.

You can also run a diesel engine on green fuels.

Yes, the marine diesels run very slow, are two stroke, and approach 50% efficiency. Turbines have an advantage of weight though.

The GP was talking about microgrids in neihgborhoods (presumably fixed, permanent installations), so there isn't really a reason to worry too much about weight.

Reliability, efficiency/cost of operation, and noise is probably the priorities that come way ahead of weight.

Small and micro gas turbines are already used in the sort of Combined Heat and Power plants used to power commercial / retail buildings, refrigerated warehouses, light industrial units and the like. There's no reason why they shouldn't be used for residential neighbourhoods, especially in colder areas where district heating would be a major selling point.

Compared to reciprocating engine-powered CHP, they tend to produce a slightly higher proportion of their energy output in the form of heat than electricity, and the plant is about about 60% of the volume and half the weight - so they make most sense in constrained spaces or for rooftop installations.

Maybe for a remote cabin? One thing I think might be a problem when grid-connecting them is their lower rotational inertia might make it harder to match/keep frequency. Unless it has very good speed regulation.

Why wouldn't this remote cabin be better off with wind or solar?

Those would be my first choice too but there might be trees that block the sunlight, or are taller than a wind turbine tower.

They'd certainly be quieter than a microturbine and not need fuel brought in.

So it makes sense for Batman, but not for my next car. Got it.

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