Process to Produce Hydrogen from Water Using Sunlight Reaches 16.2% Efficiency, on Its Way to Meeting DOE Target

On Wednesday, February 27, 2019 at 7:08:15 AM UTC+11, snipped-for-privacy@yahoo.com wro te:

the CO2 emissions of 1MW coal fired electricity production. Then there is t he little problem of leaf litter decay and methane production, which the sc ientific community is just now realizing is extremely significant. Atmosphe ric physicists tend to not know much about things like soil microbiome and methane production, and have all but ignored it until recently.

Science is never settled, but more CO2 and more methane in the atmosphere m eans a warmer planet, and the way soil microbiome affects the observed leve ls of these greenhouse gases is interesting, but not exactly game-changing.

The Merchants of Doubt will play up any scientific discussion to contribute to fear, uncertainty and doubt, but this particular controversy isn't abou t anything remotely crucial.

Hey, what 'other poster'? No one made any such claim.

My statement, thermodynamics-based, was that an equal and opposite ountereffect makes a zero net effect over a full day/night cycle.

More to the point, look with an FLIR from orbit, and note that white roofs at night don't read accurately, they just aren't radiating enough heat into the darkness to get a good temperature.

True. Night happens, and sunlight peaks don't happen then, What does? ... once again, you dodge the radiant heat out to space which dominates nighttime.

Unbelievable, possibly fraudulent. That site is a howler. FIrst page (first paragraph)

"black's reflectance is negligible and its emittance is zero"

which we know is wrong: silver teapots and silvered Dewar flasks are intended for low emittance, black anodized heatsinks are for high emittance.

rote:

When Larkin correctly stated that a black parking lot is hotter on your feet than a similar white surface because it absorbs more heat from sunlight, while white reflects it, I didn't see you say, "that's right". Instead you gave some babble about your feet getting hot by conduction. So, which is it, wrong on the science, dishonest, or both?

And if you don't think he's right, that white reflects sunlight heat back into space, reducing warming of the earth, take it up with NASA and the other global warming folks. I provided links where they say exactly what Larkin and I said. They are lamenting the loss of ice at the polar caps, because white snow/ice reflects sunlight, while dirt and water absorb it, so the loss of ice is leading to INCREASED WARMING. Quite amazing that someone spouting about climate science doesn't know this.

Why is Arctic sea ice important?

Arctic sea ice keeps the polar regions cool and helps moderate global clima te. Sea ice has a bright surface; 80 percent of the sunlight that strikes i t is reflected back into space. As sea ice melts in the summer, it exposes the dark ocean surface. Instead of reflecting 80 percent of the sunlight, t he ocean absorbs 90 percent of the sunlight. The oceans heat up, and Arctic temperatures rise further.

-sunlight

View Both Images

NASA satellite instruments have observed a marked increase in the amount of solar radiation absorbed by the Arctic since the year 2000, a trend that a ligns with the steady decrease in Arctic sea ice during the same period.

While sea ice is mostly white and reflects sunlight, ocean water is darker and absorbs more of the Sun?s energy. A decline in Arctic albedo (r eflectivity) has been a key concern among scientists since summer Arctic se a ice cover began shrinking in recent decades. As more solar energy is abso rbed by the ocean, air, and icy land masses, it enhances the ongoing warmin g in the region, which is more pronounced than anywhere else on the planet.

This report details everything. It's tedious.

Ahh OK. Well albedo does change with wavelength. Snow reflects in the visible and less so in the IR. The same could be true of white paints. If you want to assume a single number for the albedo across all wavelengths, then what you say is true.

George H.

John Larkin was dishonest on the science. The temperature of the surface doesn't tell us both the incoming and outgoing radiation during a full-day cycle, it just captures a peak in the cycle. That peak value is not relevant to the time-scales of climate; it's just a red herring. John Larkin deliberately ignored the radiation of heat from Earth into cold space.

Ice/snow isn't 'white', it's transparent. It doesn't scatter sunlight and longer wavelengths similarly, so it is not the same as 'white'. The change in albedo pattern will affect weather by changing convection in the atmosphere, and the sea, but that isn't the same as radiant heatflow balance.

Yes, an ocean covered by ice does have long-term (seasonal) temperature variations and 'moderates the weather' . It doesn't change global heat balance, though. There's nothing in that data that says it directly affects heat balance, just 'change climate patterns'.

Global heat balance does melt ice, and that changes the local weather (wind and water makes different weather than wind and ice).

The emissivity at peak solar wavelengths determines whether most of the sunlight heats the surface or is reflected back into space. Emission at long, thermal wavelengths, is a separate issue. My point was that there is a differential earth heating effect between visually white and visually dark surfaces. I don't see why that would be controversial. Go feel some cars in the sunlight.

Last time I went skiing, I had to wear sunglasses because the snow was too bright. Deep underneath the snow is brown dirt, but the snow is brilliant white. Can you explain that?

Maybe you never get snow where you live. Or have cars.

Oh, the one-day average doesn't apply to polar regions: when the sun never sets but once a year, you have to do a full YEAR average, and weather during that year is not an unrelated effect like global warming. When the AC signal goes up, it matters (but the DC level was the proper concern for long-term warming).

Sure. Snow does inefficient reflection at each air/ice interface, but many random reflections does, in random-walk fashion, return most incoming light to the sky (or your face). Like fog, though, which is similarly 'white', it can be penetrated by microwaves or long IR, so that brown dirt under a light dusting of snow may look white to your eyes, but it might radiate heat to the sky like a nonwhite clod of mud.

So, one cannot rule out a greenhouse-effect-like deviation from the reciprocity that makes black asphalt irrelevant for global heating. Even CO2 in the atmosphere makes a difference, as you know.

Not 'never', but fog is the more familiar white watery substance.

Like this:

and forget cars, it's easier to get around with that saucer depicted at altitude. :-{D

No. Snow (and ice, and water) have near zero emissivity at thermal wavelengths, roughly 10 microns. That are black as far as thermal emission at night goes.

Both the white and black cars will probably have about the same emissivity, day or night, at thermal wavelengths.

Oh, you never get sun.

Nonsense: black means HIGH emissivity not low. I didn't address the emissivity of the snow, I thought its transparency to longwave IR meant the emissivity of the mud underneath was important.

Blacksmiths deal with oxidized (black) iron that glows. Silversmiths deal with hot silver that DOESN'T glow when hot. Play with a forge and some alloys sometime.

Guessing? The planet isn't composed of white and black cars, so there's no real utility in those details. Snow and ocean ice are visible from orbit, though, that's a LOT of area.

Right. I meant near unity. A cup of water with a thermocouple in it is a good way to test an IR thermometer. Stir in some crushed ice and get witin 20mK of 0C.

I didn't address the

But it's not transparent to longwave IR. It's black.

It's easier (and more quantitative) to play with thermocouples and a FLIR.

If snow looks white from orbit, a lot of incident visible light energy must be returned to space, so can't heat the surface. That was my original point.

Thanks. Tedious indeed.

Jeroen Belleman

By 'good way to test' do you mean it's a hard test for an IR thermometer to pass? Yeah, transparent means much the same as white, nonabsorbent and nonemissive.

How do you know that? And why did you say snow is white before?

The FLIR, like a good thermometer should, is intended to give indication independent of white/black nature of the target. It can't do that if the displayed data discriminates on emissivity or blackness. Emission, it analyzes. Emissivity, it doesn't.

Metals that stay solid at red heat are a direct way to test, if you have eyes.

It is a fourth repeat of your original faulty analysis, that notes daytime-only behavior instead of the full diurnal cycle. Bad science, that. Night happens.

At night, white surfaces are dismally bad at sending heat into space, but black ones aren't. So, white doesn't win that race: it's a tie.

It means that a cup of water has an emissivity close to 1 and its temperature can be measured accurately with s thermocouple and you don't have to order it from Omega.

For some values of "much."

Good grief, you really don't understand this thermal stuff.

Good grief, you really don't understand this thermal stuff.

He is right though. There is a feedback once there is permanent snow on a land mass since during the day more sunlight is reflected into space and at night the snow still radiates surface heat away fairly well.

Night happens but for thermal emissions in the 10um band almost anything that isn't a shiny metallic surface is a pretty good approximation to black. White TiO2 paint supercools observatory domes overnight and there has been a move towards other grey paints with metallic additions to it.

It helps that modern observatories have active thermal management of the space inside the dome so can allow the outer skin to warm up in daytime.

No they aren't. Observatories used to be traditionally painted in the whitest of white paints to manage the internal dome temperature. But at night this results in the outer dome surface supercooling by radiation.

Black and white surfaces in the visible have rather similar radiation coefficients in the thermal IR band. A shiny metallic surface does not.

Anything that isn't shiny metallic is approximately black in the thermal IR band - colour in visible spectrum affects how hot it gets in daytime when the sun is shining on it with black getting a fair bit warmer.

Summary:

• white titanium oxide paint: day=ambient ; night=ambient-5deg

• grey Lomit paint: day=ambient+20deg ; night=ambient-2deg

• aluminium foil: day=ambient+5deg ; night=ambient+2deg

I know at least one place using a custom mix of Lomit, glitter and TiO2 in an attempt to get the dome to be neutral at night.

Black paint would be hotter than the grey in daytime and about the same as the TiO2 pure white at night (when there is little visible light)

Huh, thanks. Does the aluminum foil stays above ambient at night because it's still a good reflector at thermal IR wavelengths?

I guess this also explains why on cool clear mornings, but with the temperature above freezing, I can get frost on the windshield of my car.

George H.

That's a kind of greenhouse effect (and atmospheric H2O And CO2 also play a part here). The original analysis, though, modeled incoming sunlight and neglected radiant emission entirely.

That's outrageous; it would support a prediction that Earth will become hotter than the Sun.