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For prime use, Cummins Power Generation offers solutions for peo-
ple needing a 24/7 supply, typically a remote off-grid mine or a mine
under development, for example, and while diesel power generation
is always going to be more expensive than utility power, if access to
the grid is unavailable, then there are fewer options other than prime
units. There is nothing better for picking up a load than diesel engines.
Diesel engines are amazing when it comes to absorbing changes in
load, either up or down.
PM
Costs?
KG
With the price of diesel at around 1 US$ per litre, diesel gener-
ated power costs are somewhere upwards of $0,30 per kWh. About
73% of this cost can be attributed to the diesel fuel costs, with capex
and maintenance accounting for the remaining 27% of the levelised
cost of electricity (LCOE). The capex and maintenance costs are low
but the big issue is running costs due to fuel. This makes prime die-
sel generators ideal for use in hybrid solutions. We see companies
using solar during the day to reduce the fuel costs, with the diesel
being used overnight. Solar technology is now quite sophisticated.
Management systems can predict when the solar output is about to
drop due to cloud cover, for example, and the diesels can be started in
STANDBY + BACK-UP
time to prevent power dipping. The diesels ramp up in sync with the
solar coming off and the load doesn’t see any change in the supply.
These hybrid systems could see some 20% savings on diesel fuel
costs, which has a huge impact on the levelised kWh cost. Almost all
solar PV costs are capex –which can be recouped very quickly – and
in term of running costs, even the maintenance of solar systems is
minimal, limited to cleaning.
PM
Is there a problem with cloud cover in Africa?
KG
In Africa, particularly in North and West Africa, cloud cover can
be a big problem, causing the diesels to come in more often than they
would in sunnier places. The cost of solar has decreased significantly
in recent times, though, making hybrid diesel-solar solutions very
attractive for mining operations that are off-grid.
This also applies to cell phone towers in rural Africa, which use
generators, battery storage and PV panels in similarlymanaged hybrid
combinations. The generator charges the batteries at night while the
solar PV charges them when the sun is shining, with the batteries
supplying the direct load.
As is now common with modern control and power management
technology, remote monitoring capabilities are readily available and
Crown Publications editor, Pe-
ter Middleton, talks to Kenny
Gaynor, director of power gen-
eration for Cummins Southern
Africa, about the role of diesel,
gas and biogas engine-genera-
tor sets and some of the hybrid
options that are fast becoming
viable as grid replacement
options.
Cummins’ LNG-
fuelled QSV 91
generator sets
are ideal for CHP
(combined heat and
power) applications
such as data
centres, where
cooling dominates
the load profile: this
because the exhaust
gas stream runs
significantly hotter
– by about 200°C –
than diesel-engine
equivalents.
take note
IN CONVERSATION
Peter Middleton
Kenny Gaynor
• Natural gas and biogas engines are increasingly viable
alternatives to diesel gensets.
• By passing the exhaust gas through a heat exchanger, a second
andfreesourceofenergyintheformofheatbecomesavailable.
• The direct efficiency of a gas engine-driven generator is
around 40 - 42%… but a further 45% can be added to that
by beneficiating the heat.
33
May ‘17
Electricity+Control