Page 64 - Piston Engine-Based Power Plants

56 Piston Engine-Based Power Plants

POWER GENERATION APPLICATIONS OF DIESEL ENGINES

Diesel engines are one of the most common reciprocating engines for
use in power generation applications. High-speed diesel engines are
often used as emergency and backup generators to provide power dur-
ing grid outages. The ability of a diesel engine to start rapidly, often in
less than 10 s, makes them particularly attractive in this respect. Where
even faster cut-in is required, a diesel engine can be combined with a
fast-acting energy storage system such as a supercapacitor or flywheel.
Similar high-speed diesel engines are also used to provide power to
remote communities that are not grid connected. The growth of renew-
able generation based on wind and solar power has reduced the reli-
ance on the engines but modern off-grid systems often incorporate a
diesel engine as backup for renewable generation to provide a reliable
supply.

Medium-speed diesel engines can also be used to both backup sup-
ply and supply power to remote communities. However these engines
are larger and more expensive than the high-speed engines so economic
considerations become important. This type of engine is often used to
provide power for industrial units that require their own power supply
or cannot afford to lose grid power. Medium-speed engines can also be
used for distributed generation applications where they provide power
into a distribution system close to consumers. Medium-speed engines
can be used for grid support too, particularly to provide power when
intermittent, grid-connected renewable power is not available.
However this type of grid support is most common in developed
nations where there are strict emission codes and natural gas engines
are often preferred.

Medium-speed diesel engines are easy to install and they can be
used to provide base-load power in developing countries and to rein-
force weak grid supplies. Capacity can be added by increasing the
number of engines and the power plants can be relocated if necessary,
making them very flexible.

Slow-speed diesel engines are the largest of the diesel fleet and these
are usually used for base-load duty. The engines are particularly attrac-
tive when there is a source of heavy fuel oil because it provides an eco-
nomical source of power. However the engines can also be used in a
grid support role or in a situation where the power demand fluctuates.