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Comment by endymi0n | Hacker News Reader

Let me quickly do the math to some more useful units:

0.18 μmol/cm2 in 6 hours is around... 1e-60.1810000*2 == 0,0036 grams of hydrogen for a square meter of panel on a day of sunlight.

That will move a Toyota Mirai (~1kg H2 for 100km) around 36 centimeters far.

Call me not convinced yet. Cool chemistry though.

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Just got to lab a few minutes ago and nobody is here yet, so why not a demo. I give you: "3.2 μL plated on a 60 cm² dish"...

https://www.youtube-nocookie.com/embed/2i7Xi9y2CFw?rel=0&amp...

n.b. this new PEC water splitting tech yields 3.2 nL/cm² H2O (nL not μL) but I don't have a pipette with that precision; so just imagine 10 of those droplets per square meter.

    .18 µmol H2O = 3.2 nL
    3.2 nL/cm² = 32 µL/m²

I understood some of those words.

The first wright brothers plane was a less efficient mode of transportation than a bicycle.

Bad example? I thought that the bicycle was _the_ most efficient mode of human transportation (provided you don't have an all-meat diet).

And for a typical solar panel you’d get what, 50m? Are you also not convinced about solar tech in general? Being able to cheaply produce hydrogen generating panels is a huge breakthrough, even if they do not yet have the efficiency or cost that would allow them to enter the market.

Why not do the math instead of rambling? A m^2 of buy it today solar can do 200 W, 3-4 hours at peak sunlight are ~700 Wh, enough to drive a Tesla 2 miles+.

Sono Motors [1] have plastered solar cells on the car body and claim that they could be able to cover 30 km of travel per day with them. Though even 10 km would be pretty helpful in a city, which is what your calculation implies (~4-5 m^2 usable surface area -> 10-15 km of additional distance).

[1] https://sonomotors.com/

Once you get past the various brand names they've applied to their technology (just go to the FAQ page), this is essentially a self-charging car, which is really cool.

Looks really interesting, specially for european cities I think. But It's a pretty expensive deal, €16k for a car without the batteries (+€4k for them).

Why the snark? Let's do the math real quick - a square meter of photovoltaic panel will give you an averaged 4 kWh per day, which gives you around 80 grams of hydrogen via electrolysis. That gives you 8 km of driving a Mirai with current indirect technology.

So whatever you're reading into my post, you're probably wrong (I'm a big advocate of green tech).

Yes, being able to cheaply produce hydrogen generating panels is a huge breakthrough, but if they don't have efficiency or cost that means they can't cheaply produce hydrogen.

These panels as-is have such a short lifespan you'd have to replace them on a daily basis, and the efficiency appears to be several orders of magnitude lower than PV, so this is not remotely close to being cheap. Maybe this line of research will lead to an actual usable technology a decade from now (and by then battery costs will have come down enough to make hydrogen make even less sense than it currently does), maybe it's a total dead end. It's certainly not a breakthrough right now.

Using my rooftop solar setup as a source of real-world numbers... Depending on time of year, an average clear day gets me between 15kWh and 25kWh generated with 18 "typical solar panels" of 230W each. Call it 1kWh per panel as a pessimistic estimate.

A Tesla Model S is quite heavy on the energy consumption because it's big and powerful. You'd expect around 0.2 kWh / km[1]. So if you're willing to go for a battery electric vehicle, a single rooftop panel could push it about 5km per day.

[1] https://pushevs.com/2016/11/23/electric-cars-range-efficienc...

No, 1m^2 @24% eff in a great location gives up to ~2kw per day (or more using very expensive panels or tracking). A Tesla get's 315 miles from 100kwh battery. So that 6.3 miles or 10,100 meters. In comparison to 0.36 it's ~28,000x as good.

I love solar, but this water splitting cell depletes over time (6 hr half life apparently) due to necessary oxidation, and must be refurbished or replaced. Your solar cell will in theory last indefinitly.

Accounting for the energy input in the annealing step, I wonder shat the cumulative power balance looks like.

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