Wednesday, 11 May 2016

Hydrocarbons for peace.

There are few people more enthusiastic about electric cars than Robert Llewellyn, better known to some of you as Kryten from Red Dwarf, here is one of his video blogs regarding Orkney.I don't have a problem with most of it but I'm a little concerned about some of Rob's attitudes to hydrocarbons, not the fossil variety or even the biologically variety but the totally synthetic stuff. You can see Rob's opinion when he is shown the old diesel plant, which, I imagine is still kept in good condition to back up the wind.
Orkney's power system is a hierarchy. the first tier is power being generated and then used immediately, the next stage is the large battery, followed by presumably the interconnector or the diesel, then the other.
One a windy sunny and warm day, Orkney will be generating more power than it can use, the batteries will be full and the interconnect will be maxed out, what to do then? Well, the hierarchy seems to be different for using excess generated power that it is for generating power, the diesel section is missing.
Storing electrical power in batteries is highly efficient but the energy density is low and over time the batteries discharge, this means they are good for short term storage. I wonder how long Rob has left one of his cars to see how good the batteries are, it something I'm having trouble finding out.
The US Navy has been developing a system for producing Jet Fuel from sea water on its Nuclear Powered Aircraft carriers. See Fueling the Fleet, Navy Looks to the Seas  and US Navy Announces $3/Gallon Jet Fuel from CO2. So the diesel's part in the hierarchy could be restored.
Rob's criticism of the diesel as being "dirty", might be seen as a reason not to do it, but the dirty bit of diesel comes from impurities in the fossil fuel, others comes from the incomplete combustion of diesel due to a large variety of hydrocarbon compounds in the natural mix. The production of wholly synthetic fuel eliminates most of the impurities and allows the fine tuning of the compounds in the synthetic hydrocarbon, which allows the combustion process to be optimised to minimise particulate output. My own choice for the compound would be Hexadecane (C16H34) but chemists might pick a better compound.
There are other alternatives for longer term storage, such as Cryogenic energy storage, which may be more efficient in the short term, but the one thing that is know about hydrocarbons is that they are stable for a long term, they can survive underground. So while over a few months or years the Nitrogen will boil off, if extra power isn't added.
We also have large amounts of infrastructure to transport and store hydrocarbons, if we one day our fuel stores are full and our environmental plants are producing the power that is needed then, we can put some of the hydrocarbons back where the fossils came from back underground, helping to reduce the excess CO2 in the atmosphere.
Synthetic diesel is a very high-density energy store, there might never be a day when batteries have a high enough energy storage for long range air travel or to produce the power for some of the world's biggest machines, they may but synthetic fuels will be there as a backup and very long term store.
If and when we move to a fusion powered world, we can get rid of windmills we can still make synthetic diesel for those off grid needs, we still pump it underground and Rob's mate Chris can still drive around in his vintage motors.
Whatever we do we need a hierarchy of storage and synthetic diesel seem to be a good candidate for the long term tier as well as for various niche applications. It is no use being sniffy about it, we cannot waste the ideas and material we have invested in hydrocarbons.
The one thing that is gone for good for future cars is the mechanical transmission, the superiority of electric transmission and it ability to match the prime mover speed to produce the energy need efficiently is better than mechanical CVT. 


  1. Surely if you end up with too much power in the batteries, the answer is simply to turn the windmills into giant fans until the batteries are sufficiently drained?

    1. But if you pump the power back into the Windmills which are already going at full tilt, they are going to over speed and blow up, which would be rather expensive.