of wind capacity, delivering 10 GW of power on average.

Here’s one way this match could be exploited: electric cars could be
plugged in to smart chargers, at home or at work. These smart chargers
would be aware both of the value of electricity, and of the car user’s
requirements (for example, “my car must be fully charged by 7am on Mon-
day morning”). The charger would sensibly satisfy the user’s requirements
by guzzling electricity whenever the wind blows, and switching off when
the wind drops, or when other forms of demand increase. These smart
chargers would provide a useful service in balancing to the grid, a service
which could be rewarded financially.

We could have an especially robust solution if the cars’ batteries were
exchangeable. Imagine popping in to a filling station and slotting in a set of
fresh batteries in exchange for your exhausted batteries. The filling station
would be responsible for recharging the batteries; they could do this at the
perfect times, turning up and down their chargers so that total supply and
demand were always kept in balance. Using exchangeable batteries is an
especially robust solution because there could be millions of spare batteries
in the filling stations’ storerooms. These spare batteries would provide an
extra buffer to help us get through wind lulls. Some people say, “Horrors!
How could I trust the filling station to look after my batteries for me? What
if they gave me a duff one?” Well, you could equally well ask today “What
if the filling station gave me petrol laced with water?” Myself, I’d much
rather use a vehicle maintained by a professional than by a muppet like

Let’s recap our options. We can balance fluctuating demand and fluctu-
ating supply by switching on and off power generators (waste incinerators
and hydroelectric stations, for example); by storing energy somewhere and
regenerating it when it’s needed; or by switching demand off and on.

The most promising of these options, in terms of scale, is switching on
and off the power demand of electric-vehicle charging. 30 million cars,
with 40 kWh of associated batteries each (some of which might be ex-
changeable batteries sitting in filling stations) adds up to 1200 GWh. If
freight delivery were electrified too then the total storage capacity would
be bigger still.

There is thus a beautiful match between wind power and electric vehicles.
If we ramp up electric vehicles at the same time as ramping up wind
power, roughly 3000 new vehicles for every 3 MW wind turbine, and if we
ensure that the charging systems for the vehicles are smart, this synergy
would go a long way to solving the problem of wind fluctuations. If my
prediction about hydrogen vehicles is wrong, and hydrogen vehicles turn
out to be the low-energy vehicles of the future, then the wind-with-electric-
vehicles match-up that I’ve just described could of course be replaced by
a wind-with-hydrogen match-up. The wind turbines would make electricity;
and whenever electricity was plentiful, hydrogen would be produced
and stored in tanks, for subsequent use in vehicles or in other applications,