(572a) A Novel Circulating Fluidised Bed Solar Receiver Design for Thermal Energy Conversion and Storage

A novel circulating fluidised bed solar receiver design for thermal energy conversion and storage

Mustapha
Hamdan¹, Harvey Arellano-Garcia¹, Daniel Sebastia-Saez¹,

¹Department of
Chemical and Process Engineering, University of Surrey, GU2 7XH Guildford,
United Kingdom

Abstract

The middle east and northern Africa (MENA) regions rely
heavily on fossil fuels as an energy source. The region consumes high amounts
of energy for their air cooling and water desalination needs. For the GCC region
this amounts to 60-70% of their energy consumption and has one of the
highest carbon dioxide emissions per capita in the world.

The GCC countries
are in an area of high direct normal irradiance from the sun and thus,
investigating the use of solar power as an alternative energy source is valid. Concentrated
Solar Power (CSP) technology is a promising energy capture technology that uses
optical devices to concentrate the power of the sun on to a surface and in turn
generates power by means of a thermal-to-electric conversion. CSP technology
integrates Thermal Energy Storage (TES) materials to store heat and thus enable
power production in the absence of sunlight, at night or in poor weather
conditions. While CSP technology is a promising alternative energy source its
high levelized cost of energy (LCOE) is a drawback to its widespread
implementation. A major factor to the high LCOE is the use of molten salts as
the TES material carrying with it, high capital costs and high operating and
maintenance cost. This is due to molten salts being corrosive and having a low
working temperature limiting its thermal-to-electric efficiency.

This contribution
introduces a novel conceptual design of a circulating fluidised bed as the solar
receiver for a CSP plant. The use of raw desert sand as an alternative TES
material was investigated.  An optimum heat
transfer fluid (HTF) was selected from Carbon dioxide, Nitrogen, Argon and Air.
This work will also argue that these changes to current CSP plants will
significantly reduce the LCOE. The results of this study show that the proposed
design can allow up to six times higher mass flowrates of the heat transfer
fluid to circulate the sand than current designs. Moreover, 1000 ^oC uniform outlet temperature was also achieved.
For this purpose, Carbon dioxide was found to be the optimum HTF, achieving the
highest heat transfer rates. Thus, the new configuration of a fluidised bed
receiver proves desert sand to be an effective alternative TES material leading
to high thermal energy outputs per m² and a substantial reduction in
the LCOE for CSP technology.