Friday, April 13, 2012

Pie Pushers

Eli has to admit it, the Pielkesphere and the Breakdown Boys have nothing on the MIT Press office as Pie PushersTM ER.  There is a lot of Pie over the Cambridge sky.  In the comments, Paul K2, brings word of the latest, that has indeed metastasized across the net.  The science itself is interesting, a new, more effective, catalyst for reacting CO2 formed by gold coating copper nanoparticles of a particular size and composition, but, of course, those remain to be optimized.  More research is needed.  The claims are ridiculous

Co-author Kimberly Hamad-Schifferli of MIT says the findings point to a potentially energy-efficient means of reducing carbon dioxide emissions from powerplants.

“You normally have to put a lot of energy into converting carbon dioxide into something useful,” says Hamad-Schifferli, an associate professor of mechanical engineering and biological engineering. “We demonstrated hybrid copper-gold nanoparticles are much more stable, and have the potential to lower the energy you need for the reaction.”
and the hopes pie in the sky high
Hamad-Schifferli acknowledges that coating industrial-scale electrodes partly with gold can get expensive. However, she says, the energy savings and the reuse potential for such electrodes may balance the initial costs.

“It’s a tradeoff,” Hamad-Schifferli says. “Gold is obviously more expensive than copper. But if it helps you get a product that’s more attractive like methane instead of carbon dioxide, and at a lower energy consumption, then it may be worth it. If you could reuse it over and over again, and the durability is higher because of the gold, that’s a check in the plus column.”
Let us temper our enthusiasm here.  It's these kinds of press releases that give public relations offices bad reps and make the S&E faculty look foolish

Did anybody ever do the thermochemistry??  If all you do is recycle methane the reaction will be thermoneutral or worse depending on the energy cost for your hydrogen (from water??  Graetzel and friends have been chasing catalysts for splitting water for decades with scientific but not economic success). 

So in a rough sketch, what is being proposed is

CO2 + 2H2 + catalysts---> CH4 + O2 + catalyst  Heat needed = 318.7 kJ/mole

Even without worrying about the energy barriers involved in breaking the CO double bonds (the catalyst lowers that, that is what catalysts do), you need a considerable amount of energy and then you burn the methane

 CH4 + 2O2 ---> CO2 + 2H2O        Heat released = -890.3 kJ/mole (the - shows it is released)

Ah, you get the energy back plus some, but you have to get the hydrogen from somewhere.  From water

2H2O + other catalyst ---> 2H2 + O2    Heat needed = 571.6 kJ/mole

No problem here.  It's all free energy even though it adds up to zero net heat.  If you tell Eli you are going to get the hydrogen from biofuels, burn the biofuels, but even there, that only accounts for one cycle, which given the cost of the catalyst makes no sense.  If you are going to get it from petroleum or natural gas, to make this a cyclical process you are going to have to get your hydrogen back from the water you made.  Welcome back to zugzwang.

The only thing that CO2 cracking makes sense for is production of higher value hydrocarbons which stay buried (e.g. plastic/solvents) and fuel for motor vehicles and those have huge economic barriers as well as issues of volume.

This is press release abuse at it's worst.

Premature is a very kind description and yes, the Science Churnalists all bit.  Spread the word.

Eli will have some words later in the day for the JSC Black Knights defending their budget.

15 comments:

Russell said...

To judge by his lede, Watts enthusiasm for a post- Victorian water gas revival stems from a weak grasp of the difference between methane and methanol, endo- and exo-...

Anonymous said...

Carbon is a funny element anyway, created in the generation II stars and trying to find its place in the universe among tens of other elements which are less prone to bond and still being light enough in its core and the cloud of electrons with their relatively wide orbits to not be easily incorporated even among silicons of the universum hence bonding easily with other carbons multiple times over still being heavy enough to be blown away in a detonation of a star and ending up orbiting the star in question at the distance of carbonaceous asteroids lest it ends up on the possible crusts of a planterary system with planets made of more dense materials at the cores of them but also possibly happily forming cores of gaseous planets rich in carbon.

sub-arctic bunny being long-winded.

EliRabett said...

Russel, do we have a link??

Russell said...

The New Alchemy was Top O' the column chez Watts Wednesday:"

"From MIT, a possible solution to allow coal fired power plants to meet the new draconian CO2 emission requirements imposed by the EPA. Hybrid copper-gold nanoparticles convert carbon dioxide to methane CO2=>CH4"

Russell said...

On a more worthwhile note, here to get the taste of cadmium out of your fillings is the first and last word on the Titanic, from the guaranteed Dellingpole-free April 20 1912 issue of The Spectator

http://www.spectator.co.uk/coffeehouse/7783298/from-the-archives-the-loss-of-the-titanic.thtml

John said...

Burn hydrocarbon, get CO2.
Then convert CO2 to methane.
Then burn the methane. Get back CO2

What's wrong with this picture?

This is the chemical equivalent of a perpetual motion machine.

Anonymous said...

Another one of Pie Pushers greatest hits:
'Major discovery' from MIT primed to unleash solar revolution"

In a revolutionary leap that could transform solar power from a marginal, boutique alternative into a mainstream energy source, MIT researchers have overcome a major barrier to large-scale solar power: storing energy for use when the sun doesn't shine.

Until now, solar power has been a daytime-only energy source, because storing extra solar energy for later use is prohibitively expensive and grossly inefficient. With today's announcement, MIT researchers have hit upon a simple, inexpensive, highly efficient process for storing solar energy.

Requiring nothing but abundant, non-toxic natural materials, this discovery could unlock the most potent, carbon-free energy source of all: the sun.
"This is the nirvana of what we've been talking about for years," said MIT's Daniel Nocera, the Henry Dreyfus Professor of Energy at MIT and senior author of a paper describing the work in the July 31 issue of Science. "Solar power has always been a limited, far-off solution. Now we can seriously think about solar power as unlimited and soon."

http://web.mit.edu/newsoffice/2008/oxygen-0731.html

Mike 22

Hank Roberts said...

Ooooh, applause for the PR guy who wrote that one from 2008 that Mike points out:

"This is just the beginning," said Nocera, principal investigator for the Solar Revolution Project funded by the Chesonis Family Foundation and co-Director of the Eni-MIT Solar Frontiers Center. "The scientific community is really going to run with this."

Nocera hopes that within 10 years, homeowners will be able to power their homes in daylight through photovoltaic cells, while using excess solar energy to produce hydrogen and oxygen to power their own household fuel cell. Electricity-by-wire from a central source could be a thing of the past."

Has anyone noticed anything since 2008 about that? Six years to go. I guess the electric grid must be about gone by now?

EliRabett said...

Mike, those actually tie together because the Nocera catalysts can be used to catalytically decompose water. If you look around there are lots of cites to the Nocera paper and a couple of patents, but as a practical application which will save the world?

Hank Roberts said...

Oh, sure enough:
http://nocera.mit.edu/SolarEnergyConversion

They got pictures of the grid falling down, too:
http://nocera.mit.edu/templates/nocera/images/header.png?1311460575

Well, I can wait six years for this.

Hank Roberts said...

PS, I guess I'd watch for rapid buildup in industries making gear for handling hydrogen gas in residential settings -- have they factored in the cost of compressing the stuff, or will each home have a big bag o'gas at atmospheric pressure, in the attic or the basement?

They'll have to add straps and ballast, won't they?

David B. Benson said...

Another non-starter.

Hank Roberts said...

p.s.

> What's wrong with this picture?
> This is the chemical equivalent
> of a perpetual motion machine.

Is it fair to say there's no clean input (solar pv, infrared waste-to-electricity pv, tidal, geothermal? ...) that is sufficient to provide the energy needed? What about all of them?

We want a slow intermittent distributed source of small amounts of energy from all sources that can run whenever feasible, to run the storage of 'waste' heat and exhaust CO2 and the later use of that for back-conversion of CO2 to fuel.

There's no economic way to do that. But there's a worst case event we know will happen -- a Carrington flare -- and after that such installations will be invaluable, if they're in place.

Meanwhile put that trickle of fuel or concentrated energy into the storage tanks for the occasional high energy draw activity.

But is there enough of any (or many) of such sources that they can even hypothetically be installed and used?

I've agreed that we (sigh) need nuclear, not because it's enough or even economic but because some big sources are needed. Eventually Gen4 reactors ought to go in where we have coal burners now; keep the turbines running.

But Gen4 isn't here yet. I've argued that each current fission pile and fuel pool needs to be surrounded by every locally available alternative fuel source, (1) as a development/demonstration of the alternative, and (2) to run the cooling pumps by any means necessary including burning the furniture, after the next Carrington Event takes down the electric grid and transportation system for many months.

Even the supposedly self-cooling plants only rely on that for a few days, not for the months needed when there's no grid, no refineries, no transportation.

Seems to me that's the opportunity to fund and install _all_ the alternatives, sooner rather than later. Let'em run at a loss for development and investigation, because even the most inefficient and incompetent new alternative energy source is going to be a damn cheap bargain after a Carrington flare.

And nobody's promised us that Carrington is the worst case.

David B. Benson said...

Here is a better artificial photosynthsis:
http://www.sciencedaily.com/releases/2012/04/120412105430.htm

Hank Roberts said...

ooh, shiny!

"... measured energy densities (energy per base area, kWh/m2) higher by a factor of 2–20 than stationary flat PV panels for the structures considered here, compared to an increase by a factor of 1.3–1.8 for a flat panel with dual-axis sun tracking. The increased energy density is countered by a larger solar cell area per generated energy for 3DPV compared to flat panels (by a factor of 1.5–4 in our conditions), but accompanied by a vast range of improvements."

http://web.mit.edu/newsoffice/2012/three-dimensional-solar-energy-0327.html

"I think that I shall never see,
PV as lovely as a tree ...."

But they're getting closer.

Just figure out a way to paint it green ....