I've read most of the comments up to this point, and I'm certainly no expert, but it seems to me that despite the inefficiencies and emissions, this might be a useful process.
Firstly, it allows solar power to be stored chemically at a central source. This infers that the process to produce the zinc "fuel" need not occur close to the point of usage. No transmission losses, as compared to solar electric generation. There are plenty of desert areas that could be used for plants throughout the world. Seems like hauling zinc powder around is a lot easier and safer than trying to haul compressed hydrogen gas.
Secondly, when most petroleum products are burned, the problem isn't so much the CO2 and CO, its all those byproducts that are the products of incomplete combustion, like sulfer compounds, heavy metals etc - these are difficult to deal with, especially at the level of individual cars.
Additionally, the CO or CO2 emissions would occur centrally, where they would be much easier to deal with - hopefully they could be harnessed for some other industrial use.
Lastly, it appears that the zinc is a catalyst in the process, meaning that it can be recycled and reused.
As many have pointed out, there isn't enough info here to make a decent judgement, and I think the weight issue could be a deal-breaker. However, from a pollution control standpoint, this seems to have some merit. I'd rather have a heavy box of zinc in my car than the high-pressure tanks of hydrogen gas that are expected to be required for a hydrogen vehicle. Concentrating the emissions at large production plants and leaving vehicles to run cleanly has some merit, IMHO.
Again, I'm no expert and, as many have pointed out, it would be best to compare the overall emissions, transportation costs and energy usage against the same for our existing petroleum and/or coal infrastructures.
One last thing that occurs to me - it sounds like a zinc-powder infrastructure would be far easier to implement using existing transporation infrastructure than a hydrogren gas infrastructure would be.
It would also be deliciously ironic if the Israelis found a way to sever the world's need for the Arab's oil.
Just my initial thoughts...
I've often wondered if our existing petroleum infrastructure as it is could even be created today if it didn't already exist.
Imagine the pushback:
We're going to suck raw crude oil out of the ground all over the world - in some of the most volatile parts of the world. That in itself is a messy and expensive proposition, at least until the well is up and running. Then, we'll pump it in pipeline networks to ports, load it onto huge dedicated tankers, haul it all over the world using oceans - risking leakage, spills etc.
Then, we offload it at ports, pipe it inland to dedicated refineries, which themselves are pretty messy and power-consuming.
In the case of gasoline, once we have this dangerous, volatile, flammable liquid distilled, we put it into trucks and haul it all over the nation along side commuter traffic on our highways and roadways to service stations scattered right in the midst of our populated areas. Then, we store this dangerous liquid in tanks underground - risking fire, explosion and leakage into our water systems.
If that weren't enough, we expect consumers to pump this flammable liquid themselves into their own portable holding tanks of their vehicles and then cart this liquid around as they go as fuel for transportation.
The vehicles themselves are subject to leakage, fire, etc in the case of poor maintenance or collisions. Refining doesn't remove a lot of the more dangerous aspects of the fuel, so even with our best technology, we're still spewing dangerous chemicals into our air, and the engines themselves collectively leak all sorts of nasty substances onto our roads, which leach into soil and groundwater.
I doubt that anyone would consider petroleum-based transporation today if we had to start from scratch.
I'm a car guy, so I'm not saying this from an enviro-wacko perspective.
Some of the alternative fuel ideas start to sound pretty attractive in comparison, even if they might cost a little more. That's not to say its worth tossing our existing system overboard on a whim, but if there was a better alternative in the long run, I'd be the first to say lets pursue it if its viable.
I don't necessarily believe that the C02 emmissions are "bad", like the global warming fanatics, but just because they're bad, doesn't mean they're necessarily good either. If we had the choice, I'd rather we weren't collectively spewing anything into the air that we don't have to.