electro-osmosis dewatering as an energy efficient ......electro-osmosis dewatering as an energy...

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




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.




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.).




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).


London

25 % 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)





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




Electro-osmosis dewatering system


London




Mechanical hoist

Water outlet

Beaker

Water outlet

Dewatered

moisture


London

Temperature probe pH meter

Food material

(+)

(-)




Food materials analysed and parameters


London

Egg whites

Exposure time (min) Voltage (V)

15 15

30 30

Orang juice (pulp)Yogurt




Moisture loss after dewatering


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




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


London




Electrical energy consumption per year


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





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





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





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





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.





London




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.


London

electro-osmosis dewatering as an energy efficient ......electro-osmosis dewatering as an energy...

Documents