Hybrid Plant : Photovoltaic Systems
By their very nature solar power stations are incapable
of supplying power in early mornings and late afternoons and after
dark. This is not a real problem in grid connected systems in industrialised
countries where grids have a strong supply base and peaking capacities.
In developing countries with weak grids and for stand alone systems,
expensive storage systems have to be integrated in both thermal
and PV systems to supply the daily as well as seasonal non-sunshine
hour loads. The storage systems also lead to energy losses and reduce
the financial viability of these plants.
None the less, PV systems are high on the list of
DESI Power for the following applications and are included in the
programme for energy services where ever suitable.
In areas where neither grid supply exists nor is biomass available
for energy applications:
Solar Home systems
Street and public lighting systems.
Pumping water
In fact, a biomass growing programme can be started with solar pumping
combined with water management and ground water recharging schemes
to gradually change semi-arid areas.
Building and operating solar thermal plants in tandem with natural
gas has already been shown to be possible in California (Luz plants).
Recent project studies for India, Morocco and Greece have attempted
to improve the financial viability of these systems by linking them
with either oil or gas fired Gas Turbine Combined Cycle Plants.
Similarly, wind generators have been linked to diesel engines in
many stand alone applications in Australia and elsewhere.
Studies have also been made for hybridising Wind and PV, but such
stand-alone plants will still need battery storage systems for the
times when there is neither wind nor sunshine.
The solution of combining PV (without battery storage) with biomass
gasification based power plants combines two mature RETs, which
jointly can meet all the power needs of any load situation with
very low pollution and a negative CO2 emissions. Biomass, like fossil
plants, can deliver power at any time at financially viable costs.
PV, on the other hand, is still expensive and non-competitive, but
has the immense potential of supplying clean power all over the
world, once its price can be brought down by very large volumes
of production.
Operational studies will be carried out in this plant to examine
optimum ways of operating the plant to meet day and night loads,
peak and off-peak loads, loads during the monsoon season, etc. The
possibility of siting such plants in semi-arid regions where there
may not be adequate biomass to run the plant at high load factors
in pure biomass mode will also be studied. Experience will also
be gained on building and operating local distribution lines, and
on metering electricity and collecting dues. Innovative ways of
integrating PV tiles in the roof of the power plant will also be
attempted in this plant.
In bazaars of small towns and shopping and commercial centres of
cities, the choking smell of exhaust gas pollutants and the high
decibel noise of engines are encountered all during the day, and
in the evenings when the shops are busiest. The diesel or petrol
engines are owned by the larger shopkeepers in the cities and by
a new breed of entrepreneurs who have sprung up in the smaller towns.
These entrepreneurs do not sell electricity but sell light by the
watt and the hour, e.g., 3-4 Rupees per evening for delivering light
for 5 hours from a forty watt tube.
The cost of delivered electricity works out to be Rs 15 to 20 per
kWh, with which even a PV plant can compete.Plants of this type
are planned to be built and operated in the bazaar of a small town
and in a commercial centre of a city to gain experience.
It is on the list of DESI Power's planned activities to gain experience
about the local ownership and management structures of such plants
with different types of plant configurations and PV solutions to
get the most cost effective solution.
| 
