Commercial buildings or shopping malls are characterized by large thermal and electrical energy consumptions with high
variability of energy demand. Therefor
e, there is a large interest to explore novel renewable energy generation systems for these
applications. A novel flexible configuration of biomass
-
fired CHP system with organic Rankine cycle
(ORC)
is here proposed
and
applied to the case study of Sainsbur
y’s supermarkets in the UK
.
The proposed configuration
adopts
a molten salt
(MS)
circuit
to
transfer heat from
the
biomass furnace to the ORC plant.
A thermal Energy Storage (TES)
is proposed
to
improve the flexible
operation of the plant
and reduce the si
ze of the biomass boiler
. Molten salts have been preferred
to thermal oil as they have no fire
risks and low environmental impact
and can be used as medium for a Two Tank TES with a “direct heating” scheme.
Th
e plant
has been
analysed
using real input dat
a of
biomass boiler installed,
conversion efficiency and heat demand from the store.
The model is informed by hourly energy costs
and electricity feed in tariff in order to d
efine optimal size and operation of the
bottoming ORC for the specific case study
of large commercial energy
end user
in the UK.
The results show that the use of thermal
storage in a biomass
-
fired ORC plant can improve the boiler efficiency and reduce the biomass consumption in thermal
-
load
following operating mode and increase the inve
stment profitability.