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2nd International Conference on Sustainable Energy
and Resource Use in Food Chains
RCUK Centre for Sustainable Energy Use in Food Chains
Electro-osmosis Dewatering as an Energy Efficient Technology for Drying Food Materials
Abhay Menon, Tonderai Reuben Mashyamombe, and Valentina Stojceska*
Institute for Energy Futures, Brunel University London
Paphos, 18th October 2018
RCUK Centre for Sustainable Energy Use in Food Chains
2nd International Conference on Sustainable Energy
and Resource Use in Food Chains
Institute of Energy Futures, Brunel
University London
• Economic and environmental impacts of high
energy use in UK food industries.
• Policies implemented by UK Government to
solve this problem
• Introduction to electro osmosis (EO) dewatering
technology
• Design and setup of electro-osmotic dewatering
system
• Experimental parameters and food products
used for dewatering
• Performance evaluation and comparison of
moisture losses, energy consumption, tariffs and
environmental impact of EO with thermal drying.
RCUK Centre for Sustainable Energy Use in Food Chains
2nd International Conference on Sustainable Energy
and Resource Use in Food Chains
Energy consumption in UK food industries
• It is estimated that food chains are responsible for 18 % of total UK energy use
with ca. 176 MtCO2e emissions [1].
Institute of Energy Futures, Brunel University
London
• Approximately 65 % of total energy use in food industries are consumed in food
manufacture and processing.
• A huge proportion of this energy (36%) is consumed by heating processes
(dryers, boilers, pre-treatment, coating etc.).
RCUK Centre for Sustainable Energy Use in Food Chains
2nd International Conference on Sustainable Energy
and Resource Use in Food Chains
Government regulations imposed on UK food industries
• UK was the first country to imply Carbon budgets (Climate change act, 2008) to
curb the greenhouse gases that an organization can emit. The 3rd Carbon budget
(2018-2020) has proposed to reduce the GHG emissions by 37% from year 1990’s
level.
• UK is committed to reducing 10-15 % of energy consumption and water usage by
2020, in agreement with Kyoto protocol (EU, 2012).
Institute of Energy Futures, Brunel University
London
25 % below 1990 levels
31 % below 1990 levels
37 % below 1990 levels
51 % below 1990 levels
57 % below 1990 levels
-300 200 700 1200 1700 2200 2700 3200
1st Carbon budget (2008 to 2012)
2nd Carbon budget (2013 to 2017)
3rd Carbon budget (2018 to 2022)
4th Carbon budget (2023 to 2027)
5th Carbon budget (2028 to 2032)
Budgeted level of carbon dioxide emission (MtCO2e)
UK Carbon Budget forecasts (Climate Change Act, 2008)
RCUK Centre for Sustainable Energy Use in Food Chains
2nd International Conference on Sustainable Energy
and Resource Use in Food Chains
Institute of Energy Futures, Brunel University
London
• Drying uses 12-20 % of the total energy
consumed in food manufacturing industries
[2].
• Over 85 % of all industrial dryers are
thermal based with energy efficiency values
as low as 30 % [3].
• With such high GHG emissions and high
costs incurred, the development of
innovative drying technology with higher
energy efficiency for food industries have
become imperative.Image source: Amisy, China
• Hybrid dryers
• Spray dryers
• Freeze dryers
• Heat pump dryers
• Microwave based dryers
• Infrared dryers
• Vacuum dryers
• Adsorption dryers
• Refractance window drying
RCUK Centre for Sustainable Energy Use in Food Chains
2nd International Conference on Sustainable Energy
and Resource Use in Food Chains
Electro-osmosis dewatering system
Institute of Energy Futures, Brunel University
London
RCUK Centre for Sustainable Energy Use in Food Chains
2nd International Conference on Sustainable Energy
and Resource Use in Food Chains
Mechanical hoist
Water outlet
Beaker
Water outlet
Dewatered
moisture
Institute of Energy Futures, Brunel University
London
Temperature probe pH meter
Food material
(+)
(-)
RCUK Centre for Sustainable Energy Use in Food Chains
2nd International Conference on Sustainable Energy
and Resource Use in Food Chains
Food materials analysed and parameters
Institute of Energy Futures, Brunel University
London
Egg whites
Exposure time (min) Voltage (V)
15 15
30 30
Orang juice (pulp)Yogurt
RCUK Centre for Sustainable Energy Use in Food Chains
2nd International Conference on Sustainable Energy
and Resource Use in Food Chains
Moisture loss after dewatering
Institute of Energy Futures, Brunel University
London
83.74a
59.86d
75.65c 71.76cd80.41ab
68.80c76.45b
0
20
40
60
80
100
Initial moisture content EO 30 V 30 min EO 15V 30 min EO 30 V 15 min EO 15 V 15 min T 30 min T 15 min
Mo
istu
re c
on
ten
t (%
)
Yogurt
76.58a 74.13ab 76.10a 75.69a 76.24a 75.61a 76.24a
0
20
40
60
80
100
Initial moisture content EO 30 V 30 min EO 15V 30 min EO 30 V 15 min EO 15 V 15 min T 30 min T 15 min
Mo
istu
re c
on
ten
t (%
)
Egg whites
90.71a 89.85a 90.21a 90.25a 90.56a 90.07a 90.46a
0
20
40
60
80
100
Initial moisture content EO 30 V 30 min EO 15V 30 min EO 30 V 15 min EO 15 V 15 min T 30 min T 15 minMo
istu
re c
on
ten
t (%
) Orange juice
RCUK Centre for Sustainable Energy Use in Food Chains
2nd International Conference on Sustainable Energy
and Resource Use in Food Chains
EO/ Thermal dewatering Energy and Cost evaluation
The yearly evaluation of the performance of EO were calculated based on the
following assumption;
• Both EO and Thermal dryers were used on an average of 8 h a day, for 253 days
excluding weekends and bank holidays
• The unit rate for power consumption commercially is estimated as £0.11676
(npower, United Kingdom 2017)
• Therefore, the assumed working hours (X) per year is;
X= 8 * 253= 2024 h
The electrical energy (E) in kWh is calculated based on the following equation where
Voltage (V) is constant and Current (I) is measured [4];
𝐸 = 𝑉∗𝐼
1000𝑑𝑡
Institute of Energy Futures, Brunel University
London
RCUK Centre for Sustainable Energy Use in Food Chains
2nd International Conference on Sustainable Energy
and Resource Use in Food Chains
Electrical energy consumption per year
Institute of Energy Futures, Brunel University
London
91
40
198
52
1012
26 12
0
200
400
600
800
1000
1200
EO 30V EO 15V T
Ele
ctr
ica
l e
ne
rgy c
on
su
me
d (
kW
h)
Yogurt Egg whites Orange juice
Electro-osmosis
Thermal
Ep.y= E * X
RCUK Centre for Sustainable Energy Use in Food Chains
2nd International Conference on Sustainable Energy
and Resource Use in Food Chains
Institute of Energy Futures, Brunel University
London
Cost evaluation
Operating
parameter
Cost
per year
in GBP.
Yog 30 V £ 23.16
Yog 15 V £ 6.14
E W 30 V £ 3.07
E W 15 V £ 1.40
OJ 30 V £ 10.63
OJ 15 V £ 4.72
Thermal £ 118.16
An estimated
reduction of
80%
operational
costs per
annum could
be achieved by
implementing
EO in
industries!
E
O
Costp.y=E * X * 0.11676
RCUK Centre for Sustainable Energy Use in Food Chains
2nd International Conference on Sustainable Energy
and Resource Use in Food Chains
Institute of Energy Futures, Brunel University
London
Image source : Carbon trust
Carbon Footprint evaluation
Operating
parameter
Carbon dioxide
emission (kgCO2e)
Percentage
differences with
thermal drying (%)
Yog 30 V 56.04 81
Yog 15 V 14.71 95
E W 30 V 7.35 97
E W 15 V 3.39 99
OJ 30 V 26.32 91
OJ 15 V 11.32 93
Thermal 286.46
The emission conversion factor for electricity
is 0.28307 kgCO2e per kWh unit of
consumption (Department of Environment
Food and Rural Affairs, UK, 2018).
CFE= 0.28307 * Ep.y
RCUK Centre for Sustainable Energy Use in Food Chains
2nd International Conference on Sustainable Energy
and Resource Use in Food Chains
Institute of Energy Futures, Brunel University
London
Changes in pH during drying
0
2
4
6
8
10
12
14
pH
Yogurt 15 V
Yogurt 30 V
0
2
4
6
8
10
12
14
pH
Egg whites 15 V
Egg whites 30 V
0
2
4
6
8
10
12
14
0 5 10 15 20 25 30
pH
Time (min)
Orange juice 15 V
Orange juice 30 V
RCUK Centre for Sustainable Energy Use in Food Chains
2nd International Conference on Sustainable Energy
and Resource Use in Food Chains
Institute of Energy Futures, Brunel University
London
Conclusions
• A laboratory scale model of electro-osmosis dewatering system was
successfully implemented.
• Results showed enhanced energy efficiency, low costs and reduced carbon
footprints.
• Among the three food materials tested, the moisture content after dewatering
showed a significant reduction and pH values varied depending on the extent of
electro-osmotic flow of water and electrical interferences with food matrix.
• Prolonged exposure with high potential (30 min 30 V) showed an enhanced
dewatering rate compared to lower settings.
• Future research on EO shall be focussed on analysing the quality aspects
(phenolic compounds, AO, sensory evaluation etc.) of food materials after
dewatering.
RCUK Centre for Sustainable Energy Use in Food Chains
2nd International Conference on Sustainable Energy
and Resource Use in Food Chains
Institute of Energy Futures, Brunel University
London
RCUK Centre for Sustainable Energy Use in Food Chains
2nd International Conference on Sustainable Energy
and Resource Use in Food Chains
References
1. S. A. Tassou, M. Kolokotroni, B. Gowreesunker, V. Stojceska, A. Azapagic, P. Fryer and S.Bakalis, "Energy demand and reduction opportunities in the UK food chain," Energy, vol.167, no. EN3, pp. 162-170, 2014.
2. G. Raghavan, T. Rennie, P. Sunjka, V. Orsat, W. Phaphuangwittayakul and P. Terdtoon,“Overview of new techniques for drying biological materials with emphasis on energyaspects," Brazilian Journal of Chemical Engineering, vol. 22, no. 2, pp. 195 - 201, 2005.
3. N. Tippayawong, C. Tantakitti and S. Thavornun, "Energy efficiency improvements inlongan drying practice," Energy, vol. 33, no. 7, pp. 1137-1143, 2008.
4. S. K. Ng, A. Plunkett, V. Stojceska, P. Ainsworth, J. Lamont-Black, J. Hall , C. White, S.Glendenning and D. Russell, “Electro-kinetic technology as a low-cost method fordewatering food by-product,” Drying Technology, vol. 29, pp. 1722-1728, 2011.
Institute of Energy Futures, Brunel University
London