Environmental Engineering Reference
In-Depth Information
side, for drawing on compensating sources of power. Integration of differ-
ent types of power will be key. This task will become more complex as the
percentage of renewable electricity in the national system increases, and
as the number of providers of that renewable electricity increases, with
the development of decentralized energy generation. This decentraliza-
tion refers to the new opportunity provided by smart grids for businesses,
communities and even individuals to provide heat and light to satisfy
their own energy needs - and, if they generate any surplus power, to sell
back the excess to the grid. This energy generation will typically be from
solar panels on roofs, wind turbines on the roof or on the ground, wood
boilers or from a variety of heat pumps.
Such electricity generation is often referred to as micro-generation. In
the UK there are now over 100,000 micro-generation units, though the
vast majority just produce heat and/or light merely for themselves and
without transmission through the grid. In Europe, sales of power to the
grid tend to get a fixed feed-in tariff as an extra incentive. The UK is plan-
ning to introduce such feed-in tariffs from 2010.
Micro-generation adds to the diversity of supply through wind, solar
and biomass power to the grid. It therefore, in theory, increases a coun-
try's home-grown (or home-blown) energy security. Short-term energy
stability, however, is more of a problem for the grid if, for example, a
sizeable number of wind farms were stopping and starting in unison. So
in order to check stability, another smart-grid technology has been devel-
oped using devices called phasor measurement units. These are high-
speed sensors, distributed in large numbers across a grid, which sample
the current and voltage several times a second, and display waveforms of
them. These waveforms show up any discrepancies, enabling electricity
companies and grid operators to react to any interruptions or blackouts
on the grid at great speed.
A different, constant problem of sending electricity long distances along
a wire is the transmission loss of energy , which can be as much as ten
percent of what was originally generated. Some of the electricity is always
wasted heating up the wires, which to varying extents resist the flow of
the electrical current. The bigger the electrical current, the more of it will
be lost.
One solution has been found: to reduce the
level
of electrical current,
but to increase the
force
behind it - the voltage - to get the electrical cur-
rent to its destination. This has been applied in the form of high voltage
direct current (HVDC). Most long-distance electricity transmission is
currently achieved using high voltage alternating current (HVAC). The
