Scott Adams is the smartest cartoonist I know of — I learn something from almost every one of his blog posts. John Morgan linked this Dogbert cartoon to illustrate the innumerate green energy techno-spam that we see – from Time to Scientific American. Even MIT Technology Review publishes a lot of these warmed-over press releases. Here’s John in the BNC Comments:
Modified carbon nanotubes can store solar power indefinitely… but at what cost? And when can I buy one for a few extra bucks? 😉
I didn’t comment on this before because there wasn’t enough info in the nextbigfuture link to figure out what was going on. We’ve known about state flipping azobenzenes for decades – why attach them to a nanotube? (Other than that it turns research in “chemistry” into research in “nanotechnology” and is therefore much more buzzworthy.) And how do you use these things? Do you spread them in a very thin film because thats the best solar collecting configuration? But its also the worst possible energy recovery configuration – regenerated heat would be lost. Do you scoop the stuff up and put it in jars? Sounds like a recipe for an incendiary.
Then this morning I saw Ars Technica has also covered this story and gives a better account. The nanotube attachment provides stabilization to ground and excited states, increasing shelf life of the high energy state.
But the real kicker here is that the molecule doesn’t exist.
This material has never been made. It exists only as a computer simulation. There is no guarantee that the material behaves as designed. There is no knowledge of other relevant material properties or chemical stability. There is no guarantee that the material can even be synthesized. There is no tested synthetic pathway. For any synthesis you might conceive, there is no knowledge of percentage yield, and many other things. Without knowledge of synthetic pathway, yield or or conversion processes, you cannot say anything about the cost of the material. But I can tell you that Sigma Aldrich is selling the nanotube feedstock for $1500 a gram.
Nowhere in the nextbigfuture coverage is it mentioned that this compound only exists in a simulation. Its reported as if it has been made. This is really irresponsible.
A couple more comments on the claims in that article:
storing the solar energy indefinitely
Ars Technica states the half life is “over 1 year”
volumetric energy density of Li-ion batteries
We don’t know anything about the bulk material properties of the stuff so take any discussion of energy density as completely unreliable. But the bigger issue is recoverable energy density. The recoverable energy is proportional to the temperature rise above ambient that can be achieved. High efficiency requires high temperatures. The proposed molecule is an azo-benzene functionalized nanotube. The azo compounds are, shall we say, not renowned for their stability. How hot can you heat this stuff in air before it decomposes, or bursts into flames? Not hot enough to drive a turbine, or recover any meaningful amount of energy in any other form. [Hint – its the kind of molecule you could brown in your oven at 180 C, if it doesn’t catch fire. In fact taking the rule of thumb that chemical reaction rates roughly double for every 10 C temperature increase, and based on a 1 year half life, 30 mins at 180 C would see it nicely cooked.]
So the stored energy can only be recovered as low grade heat, not a more useful form like electricity, except at conversion efficiencies that make the whole exercise laughable. As far as I can tell we’re talking about a very expensive pocket warmer.
less expensive than the earlier ruthenium-containing compound
Maybe. But astronomically expensive all the same, and an outrageous claim for a material that hasn’t been made.
while this process is useful for heating applications, to produce electricity would require another conversion step, using thermoelectric devices or producing steam to run a generator
Which it couldn’t do because the decomposition temperature is way below that required to run a steam turbine, or achieve useful conversion efficiency regardless the technology.
This sort of reporting verges on criminally irresponsible. And for the academic involved, I don’t care that he’s from MIT, talking up the potential of these materials in this way is professionally negligent.
Lets have a look at the other article linked from nextbigfuture, this time from our very own Monash university:
Graphite + water = new battery with storage as good as Lithium Ion but recharges in seconds.
What has been reported by nextbifuture is:
“When used in energy devices, graphene gel significantly outperforms current carbon-based technology, both in terms of the amount of charge stored and how fast the charges can be delivered.”
What has actually been done is to report a new gelling process, presumably water intercalation between layered graphene sheets at there edges (I can’t access the abstract). In other words, no battery or supercapacitor has been made, there is no knowledge of energy densities of any device that might use this material, no knowledge of charge, discharge rates, power densities, self-discharge rates, cost, etc. This is drawing a very long bow from observation of a gelling behaviour.
So once again nextbigfuture is reporting breakthoughs in imaginary devices.
This kind of journalism is a real problem. It is breathless and uncritical reaction to what is essentially a marketing hook for what is otherwise scientifically interesting research. Both of these pieces you’ve linked to, taken in the context of a scientific research exercise, are interesting reports. Neither of them have any basis for any claim on future deployment, but both of them have been reported as if they have already enabled energy storage for renewable energy.
The state of journalistic coverage of renewable energy technologies is deplorable and reminds me very much of where scientific coverage of biochemistry etc. was at a decade or two ago. That is, some researcher would find some legitimately interesting metabolic pathway or somesuch, and it would be reported as a cure for cancer, to the detriment of the scientists, the doctors, patients, and the journalist. Science journalism has cleaned up its act a lot in this regard – I think there is less of this sort of outrage in the biological sciences than there used to be (though there are constant howlers). But renewable energy breakthroughs are the new cures for cancer, and material science journalism really needs to go through the same process of maturation as medical science journalism seems to have.
Dilbert absolutely skewered this sort of reporting here: