Wednesday, March 30, 2011

Artificial leaves and old Buicks

Image from "blondygirl"

Back in the early 1980s, in the depth of the first energy crisis, someone in Berkeley invented a way of splitting water into hydrogen and oxygen by using iron oxide and sunlight. That was claimed to be a solution to the energy crisis, it was the object of press releases, and it obtained a lot of coverage in TV.

At that time, I was post-doc in Berkeley with the group that originated the idea and I remember very well how we were bombarded by phone calls from people who wanted to know how they could obtain hydrogen using rusty iron; from "old Buicks" as someone said.

The idea of solving the energy crisis using old Buicks died out in silence in a few months. The efficiency of the process was something like 0.1%, to say nothing of the fact that the oxide became inactive in a few days. You couldn't expect much hydrogen to come out from that old pond in your backyard after you had dumped a wrecked car in it. But, in the hype of press conferences and media report, everyone had conveniently ignored the problem or, at best, mentioned it in passing in terms of "we need more research".

Periodically, the idea of solving the energy crisis by some miracle that involves "artificial photosynthesis," that is water splitting, reappears. Of course, there are many oxides that can split water under sunlight, but the process is usually very inefficient. So, it does make sense to try to improve it and - maybe - a practical process could be developed one day. What doesn't make sense, in my opinion, is to keep producing hyped press reports in the style of the one made in Berkeley long ago.

Something like that - a hyped press report on "artificial leaves" - came out a few days ago from Daniel Nocera at MIT, who described how:

The artificial leaf shows particular promise as an inexpensive source of electricity for homes of the poor in developing countries. Our goal is to make each home its own power station,” he said. “One can envision villages in India and Africa not long from now purchasing an affordable basic power system based on this technology.

Nice, but it sounds a lot like the promise of energy from old Buicks. There is no mention in the report of the efficiency of the process. Talking in terms of duration, Nocera mentions that "an artificial leaf prototype could operate continuously for at least 45 hours without a drop in activity." At least 45 hours??? I mean, even the old iron oxide from Berkeley could last more than that. And a silicon based photovoltaic cell can last for at least 25 years.

Then we read that:

The hydrogen and oxygen gases would be stored in a fuel cell, which uses those two materials to produce electricity, located either on top of the house or beside it.

A fuel cell in a rural village? Do you realize how much a fuel cell  - even of the simplest kind  - costs? Is it clear that, in addition to a fuel cell, the system needs equipment to separate hydrogen from oxygen, a compressor to pump it into something, valves, control electronics, safety precautions and all the rest? And does anyone remember that a fuel cell needs platinum at the electrodes? And that is presented as good idea for a house in a village in Africa or India?

The fact that it should be done "on top of the house or beside it," seems to be taking into account the fact that rural houses in India or Africa, probably, don't have basements. That's a nice touch, maybe; but get real, please, about what the energy return, the EROEI, of the process could be.

Now, that is not meant to disparage Dr. Nocera's "artificial leaf" concept. I am sure it is much more efficient than old Buicks in splitting water and I am perfectly willing to believe that it may be a major breakthrough in terms of what it can do by itself - apart from fantasies such as fuel cells in rural villages.

What I object to is this style of science based on press releases which are only hype and no substance. I understand that scientists are human beings and they like to be in the spotlight once in a while. I understand also that one may need to use these methods in order to get research grants. But, in the long run, this is something that only generated false hopes and disillusion. It is also a way to provide ammunition to those people who have found a lucrative job in disparaging serious science; such as it happens all the time in climate science.


Ugo Bardi is a member of the Club of Rome, faculty member of the University of Florence, and the author of "Extracted" (Chelsea Green 2014), "The Seneca Effect" (Springer 2017), and Before the Collapse (Springer 2019)