MIT solar discovery - is it a big deal?

There is much hype at the moment about MIT's discover of an efficient way to convert sunlight into hydrogen which can be stored and converted to electricity via a fuel cell when required. This will pave the way for effective use of solar panels because we would not be dependant on the sun shining to generate electricity.

The big deal is if this is much more efficient than using a PV panel to generate electricity and storing the electricity in a battery, but I have not found the data that compares the two options. Intuitively I would expect the PV generation to be less efficient that solar to hydrogen, but the battery to be more efficient that the hydrogen to electricity conversion, but I'd like to see the data. Otherwise why the hype about being able to store electricity?

Future Cities and more Hydrogen

Watched a fun presentation on the kinds of technology we might find in a future city, from folding cars to desalination plant. Part of the infrastructure was algae producing hydrogen which was sent down pipelines to supply transport vehicles, cooling cables on the way. I have the feeling, and I may well be wrong, that we assuming hydrogen will be part of the future mix and are looking for solutions.

Supposing the best use of algae was to create hydrogen, would it not be more energy efficient to convert directly to electricity and put the electricity on the grid than creating an additional infrastructure for hydrogen, not to mention more complex engines? I would be very interested to see the capital costs and running costs of hydrogen vs. electric cars. Given that hydrogen cars are electric cars with the addition of a fuel cell and hydrogen storage, it must be considerably more?

Hydrogen vs. Electric Cars

It seems to me the "Hydrogen Economy" has gone a bit quiet and I wonder if that's because people have been doing some sums. Assume you start with 100kWh of wind power and you can either use that to create hydrogen for your hydrogen car or put into a battery for your electric car. Which is more efficient?

This diagram from Ulf Bossel of the Lucerne Fuel Cell Forum (see their reports). Because of the number of processes involved in converting electricity to hydrogen, compressing and transporting it and then converting it back to electricity, the process cannot beat the simplicity of the battery approach, even with significant improvement. That's not to say battery power for cars is without problems (weight, environmental) or that hydrogen doesn't have a big advantage (you can recharge in 5 mins). But to me the sums do not add up, especially when the additional infrastructure cost of getting hydrogen to filling stations is added.

Interestingly, reviewing other blogs comparing hydrogen with electric, many are keen to point out how electric cars are not really green because they are charged using electricity from coal etc. They don't seem to question where the hydrogen comes from though.


Hear a podcast by Ulf given to The Watt here: http://www.thewatt.com/node/78