>> the economics >> the
At every second of every day, the National Grid
must ensure that electricity supply precisely matches the continually
Although most of the large changes in demand are
predictable (such as the peak which occurs around 6pm each day,
when people all over the country get home from work, switch on lights,
and turn on many electrical appliances) there are continuous smaller
fluctuations which are essentially random. And there is also
always the possibility that a sudden large fluctuation could occur
at any time if a power line or generating station fails.
For these reasons, the National Grid pays for
reserve which involves certain power plants running at reduced
output so they are able to inject extra power into the grid as it
is needed. The National Grid also has to pay for some of these generators
to go into a special "response" mode whereby they
continually change their power output to respond to random changes
These so called "ancillary services"
are expensive. Response alone costs in excess of £80m
per year and is likely to increase in price. Also, the need
for these services will increase because of the added unpredictability
of renewable energy sources*.
The good news is that Dynamic Demand Control could
provide many if not all of these services for a fraction of the
cost. (Instead of the supply responding dynamically to unpredicted
changes, certain sections of the demand react instead.)
This means, in principle, for example, if a refrigerator
manufacturer incorporated cheap controllers into their units, they
could be earning millions each year from the National Grid;
with only a tiny increase in the unit cost. Not only that - at the
same time they could help the shift towards greater use of renewable
energy and help reduce carbon dioxide emissions from the operation
of the power system.
So why hasn't it happened already?
* Most experts say that unpredictability will
not pose a problem until renewables account for more than 20% of
generation capacity. However, it is important to start planning
now for greater proportions than this.