(396f) Sustainable Steam on Demand for the Bayer Process

Sustainable Steam on Demand for the
Bayer Process

Alicia Bayon and Andrew Beath

CSIRO
Energy, PO Box P.O. Box 330, Newcastle, NSW 2300, Australia

In this work, we explore the
coupling of Concentrated Solar Thermal (CST) to produce the steam required for
the Bayer Process used for the
conversion of bauxite to aluminium hydroxide.
Specifically, we present the
use parabolic trough and central receiver tower technologies to produce the
required steam for the digestion and electricity demand of a commercial-scale
Bayer Process plant (392 MW_th). This work
explores the integration of different configurations for the production of
steam using annual simulations with real direct normal irradiation data. The
effect of the solar field size as a critical parameter towards the economic
optimisation of the plant is investigated. In addition, we analyzed plausible sites based on physical and
operational constraints. We fixed two targets, a minimum CST capacity factor of
29% and a minimum NPV of $20 million. The internal rate of return (IRR) is also
used to find the optimum design conditions at a specific location.

Results for
trough systems are shown as an example at Learmonth. Other sites in Australia
like Gladstone, Pinjarra and Darwin (Australia) are also explored. In this
abstract, Learmonth is shown as an example of achieving the target CST input of
minimum 29% at relatively small field and small storage sizes (see white line
in Figure 1.a), and achieving positive net present value (NPV) results that
increase as the system size increases (see background in Figure 1.a). Other
sites like Gladstone also achieves good results, with a local NPV maximum at
solar multiple 2 with 2 hours of storage providing a CST input of approximately
34%. Darwin, does not appear to be as promising for the technology and negative
NPVs result from all combinations meeting the target CST input. Selection of
the optimum at Learmonth is limited by the maximum IRR obtained which occurs at
solar multiple 2 with 6 hours of storage. The IRR values are over 12% in most
of the design conditions for Learmonth and Gladstone. The maximum is localized
in solar multiple 2 and 6 hours storage for Learmonth where the IRR is 17.0%
(Figure 1.b).

Figure

1

: Net present
value (NPV), internal rate of return (IRR) and capacity factor (CST) of
parabolic trough plants (392 MW_th) using
the cost model at Learmonth.