Are you re-volted by the plug-in trend?

We produce our own electricity through solar PV and house heated by sustainable wood. We need to tackle climate change now – that means cutting back on fossil fuels straight away – using cars less etc. We are shifting from dirty petrol to electric. If you care about your grandchildren it makes perfect sense.

I wonder how the economics would stack up for using solar panels to charge your car. An investment of up to £10k might be needed, with the marginal unit cost difference now between feed in tariff and supplied electricity, does it make any financial sense? Better perhaps to charge overnight on Economy 7 or other off-peak tariff?

I agree, Malcolm, but financial sense does not always govern our choices when buying and running cars. Many buy new cars despite the well-known fact that their cost of motoring would be a lot less if they bought a similar car that was a year old. Many buy expensive cars, despite the fact that depreciation, fuel and servicing may cost significantly more than for a cheaper model.

I remain unconvinced that an electric car is of significant environmental benefit, but if I did then paying for solar panels might make more sense than buying a luxury model.

We can get too obsessed with “value for money”, can’t we. We do buy goods and entertainment for other, emotional, reasons that are just as valid as whether it is a “sensible” purchase. Clothes is perhaps a good example – how many pairs of trousers do you need? Don’t check my wardrobe.

That is my point. For anyone buying an electric car on the basis of the environmental benefits, generating the electricity to power it makes sense.

I’m not all that convinced about the environmental benefits of solar panels. Although I have not had an involvement in this area for some time, I remember that, at that time, the energy needed to produce a photovoltaic cell was greater than the energy it produced in its lifetime. No doubt improvements to the production methods have been made in the meantime but I suspect it’s still a pretty close run thing. The only reason that solar panels make economic sense at the moment is the level of subsidies being paid. The main environmental benefit from solar panels is that all the pollutants are being generated a long way away by the Chinese coal fired power stations.

As a side issue, really relating to another conversation, the ‘International’ ‘phone calls received here used to relate to accident and PPI claims. Now they are all trying to sell me solar panels!

In the early days of electricity supply there were many small scale local suppliers, just as you propose. The reason that the national grid system came into being is that of security of supply – if the local supply system failed then the gap could be filled in from the grid. The problem of supply security is still relevant whatever the means of local generation.

The problem with both solar and wind generation systems is that they do not necessarily provide power when it is actually needed so some form of storage is required. For small scale domestic applications this can be achieved with batteries but as the scale of generation is scaled up these become a very poor option. There are more sensible ways of storing the energy but these only make sense if the scale is large enough, which gets us back to the need for a national grid system!

I feel that the only sensible long term solution for automotive applications, amongst others, is to move to the use of hydrogen. The technology to use hydrogen already exists but the problems to be overcome are economic production, means of distribution and storage. The last of these is of particular importance in the automotive application. Petrol and diesel are very efficient in terms of the energy stored per unit volume. Batteries are very, very poor in this respect and, unless someone comes up with some new, revolutionary technology in this area, this situation will remain. Energy storage efficiency for hydrogen is not currently as good as for petrol/diesel but there are encouraging lines of research in this area. Production and distribution, though, still needs some work.

I can’t help but feel that battery-based electric cars are a dead end rather than a long term solution.

My concern with hydrogen is its explosive potential if there is a leak or a major impact. Presumably hydrogen would be produced at off-peak times – a good way of levelling electricity demand, but it will still require largely fossil fuel to produce it – is it that energy efficient?
.

The thought of using hydrogen as a fuel worries me too. In the 70s or early 80s it was suggested that the solution was to adsorb hydrogen onto palladium, but I guess this was too expensive to be practical.

I’m not too keen on the idea of large lithium batteries in cars. Quite apart from the amount of energy stored, lithium is a highly reactive metal that could cause problems in the event of an accident. At least it now seems unlikely that we will see sodium-sulphur batteries (using molten sodium) in cars.

I agree that the explosive potential of hydrogen is likely to be a problem, but then petrol, in vapour form, is not exactly inert! Cost effective in-car storage with good energy density approaching that of fossil fuels is one of the problems that needs to be solved. There are some encouraging lines of research taking place in this area and there does seem to be a willingness to come up with a solution.

Production of hydrogen is certainly an energy intensive process and using fossil fuels for this purpose does rather negate the advantages. However, it could be an effective solution to the problem of sporadic generation from such sources as wind power – perhaps hydrogen generation could make best use the off-shore wind farms.

It is certainly worth finding effective solutions to the problems relating to hydrogen as a fuel for automotive applications because I can’t see any other form of energy storage that comes anywhere near current petrol/diesel systems in terms of energy density.

Wavechange commented:

“I’m not too keen on the idea of large lithium batteries in cars”

You might be interested in this –

http://go.reg.cx/nl/6ce53/52631cff/05c276fa/287x

I suspect that ‘not too keen’ could well be understating the situation!