Comment by nexuist | Hacker News Reader

Comment by nexuist | Hacker News Reader

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>At this point, I feel like the only reason fossil fuels are used anymore in new projects is inertia

Solar might work for boats and trains, but can it work for a plane? What about drones?

No renewable energy source can beat gasoline, sans nuclear power (which I think we should be transitioning to, along with the rest of the renewables). MIT built a gas powered drone that lasts 5 days (not minutes!) in the air[1] - that's simply impossible with today's battery tech. I know there are electric planes in development, maybe in production - but none of them match the passenger capacity or cargo volume of a Boeing 747. Until they do, there will always be a place for gas guzzling airliners.

Solar can work for households, skyscrapers, and apartments, and like you said, I think the advantages do outweigh the advantages of traditional coal plants so I'm excited to see that become more mainstream.

https://techcrunch.com/2017/06/27/mits-gas-powered-drone-is-...

You're right...I've got an availability bias that has limited my thinking. Any application where energy density is paramount will be dominated by fossil fuels for quite a while.

I'm curious to see what comes first: batteries that match the energy density of fossil fuels, or cost effective synthetic fuels created via renewable methods.

Perhaps this could be a good application for fuel cells?

One great one is machinery in factories. Faster recharge time, zero emissions.

You can make jet fuel from air, water and power, it's just hydrocarbons. If we had enough electricity from renewables we could just make all the fossil fuels we wanted.

How can you still think Nuclear is a good idea after reading that article? If a solar/battery farm is that cheap now, how cheap do you think it will be once you've spent 15 years building a nuclear power station that will either get flooded (rising sea for cooling) or have to be left turned off (fresh water no longer available)?

You might be interested in the sun seeker duo. It's in the ballpark for personal air travel:

https://www.youtube.com/watch?v=uBA4XeMddMY

In flight charging (refueling) could be a possibility too.

The drone based solar planes can stay up longer than 5 days. I think the defense companies can keep them up for months.

That’s incredibly cool. I see they’re using an audio variometer to determine sink/updraft lift as well as using the solar-powered motor during cruise, and operate it as a glider during landing. Assuming they could fly it as a glider as well, although I don’t know how its low-speed performance is wrt. thermalling or stall characteristics.

Also cool, the adventure of circumnavigation on solar:

https://en.m.wikipedia.org/wiki/Solar_Impulse

Captured on this Nova special: https://www.pbs.org/wgbh/nova/video/the-impossible-flight/

Planes will be decarbonized later. We can start with the low hanging fruit, coal, peaker plants, and preventing new coal in growing nations. Batteries are improving every year, Teslas costs suggest they will have thr density in 10 or 15 years to displace the lower range flights. We could also utilize hybrid tech in planes, we can add a small amount of electric power just for takeoff and regen it during descent. But still, planes and certain industry will be decarbonized last.

If the incremental cost of renewable energy drops much more, the cheapest way to make gasoline will be using renewable energy to reduce CO2 with steam at the output of a not-yet-decommissioned coal plant.

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