I am resuscitating this thread. Very valid points were raised by people from all sides of the fence. It's been three years since, so maybe there are new arguments, maybe some people's points of view have evolved (nah...), and maybe new people want to pitch in.
We now have an electric racing formula with F1 drivers and fully electric cars in the roads that respond to any functional parameter commonly used to define a car. Also renewable generation is moving away from being a barely noticeable portion of the energy mix. In 2013 in Spain, eolic energy was the main single source of consumed electricity with 20.9% of the mix (20.8% for nuclear), and renewables produced 42.2% of the total. That's average over the whole year.
http://economia.elpais.com/economia/201 ... 04329.html
I also wanted to bring in what for me is new info. It was an often raised point back then that since only very small amounts of already produced energy can be stored, many renewables were a no-go, as similar back-up capacity is needed for low production periods, and that often comes from coal and gas (and more money). A completely new distrubution or storage infrastructure would have to be created at an enormous cost.
Recent reading has brought new possibilities in conversion of electricity to gas to my attention, and as it looks, slowly to mainstream media attention too.
http://en.wikipedia.org/wiki/Power_to_gas
To summarize some of the most important points. Electricity can be converted to H2 and then back to electricity with a 40% efficiency, 60% including electricity and heat.
This H2 gas can be mixed with our existing natural gas supplies to a 2% concentration without risks nor infrastructure changes, meaning that excess energy can simply be stored there.
If this H2 gas is further processed, it can be converted to methane with the Sabatier reaction:
CO2 + 4H2 → CH4 + 2H2O
The necessary CO2 can conceivably come from captured CO2 in the future.
The whole electricity -> methane -> electricity cycle has a 34% efficiency, up to 50% including electricity and heat.
Now the kicker:
This methane (natural gas) can simply be injected in the current natural gas distribution network.
http://en.wikipedia.org/wiki/Hydrogen_e ... wer_to_gas
Depending on the sources consulted
this includes 100 to 700 days worth of the energy consumption in many places. This is with the existing infrastructure, conduction pipes, etc. At zero cost. And it automatically includes both storage and transport.
To me this is new information, although WB hinted as much in page 11 back in the day. Not every country will have Germany's natural gas infrastructure, but other countries have other advantages, and all have a significant gas infrastructure. Simply the fact that more or less everywhere there are months worth of storage capacity, and storage in about the most convenient form possible (methane is also easy to liquify and transport), means that the technology to move away from carbon, natural gas or nuclear is here about now.
The production capacity of all renewables combined is not here yet, the electrolysis capacity is absolutely nowhere near enough; but if we accept to get back only 50% of the excess production from good days, the potential scenario in which there is no wind, no sun, no hydro, etc, has simply disappeared. The question of whether we use energy from coal, oil, gas, from nuclear centrals or energy that in one way or another comes from the sun or the moon is an economical and political one, and no longer a technological one.
Interestingly, this makes not only renewables a viable (expensive) proposition, but also 100% nuclear a valid proposition (that I don't want to be anywhere near, but that is another question). Nuclear is good at base load generation, but not at responding to load changes. It is slow to start or stop a reactor, and extremely slow to bring new centrals to the net if needed. Having the option of converting the excess to methane and burning it in the existing natural gas power stations, and capturing the CO2 produced, means that nuclear could potentially feed the whole grid, including load variations, with close to zero CO2 emissions. Technologically speaking at least.
Rivals, not enemies.