1. Grant Ellington North Carolina State University
On-Farm Energy Assessment of New Curing Barns
Grant Ellington
North Carolina State University

2. LP Gas and Natural Gas Price Outlook
$15 / $1.10/gal
$9.40 / $0.75/therm
Source: U.S. Energy Information Administration (LP Gas – Wholesale/Resale; N.G. – Commercial)

3. Variables Effecting Energy Consumption
Barn energy efficiency (insulation, structural air leaks)
Heat exchanger efficiency
Burner firing rate
Ambient temperatures
Curing management
Quantity of tobacco
Quality of tobacco
Curing energy efficiency quantified as pounds cured leaf per unit of fuel (lbs/gal LP)

5. Tytun

6. Long

7. World Tobacco

8. New Barn Specifications
Long (10-box)
Long 350,000 Btu/hr
World Tobacco (15-box)
Evans 500,000+ Btu/hr
2” insulated panels
Tytun (14-box, 32T)
Powermatic 400,000 Btu/hr
4” insulated panels
All fan motors 10 hp, 1-phase
All barn pads insulated (3/4” blue board)
Suretrol controllers

9. Foam Rubber Gasket Material Added to All Barns
2” x 1” Polyurethane foam or Neoprene/EPDM/SBR polymer – both with self-adhesive strip

11. Exhaust Gas Temperature (oF) Thermal Efficiency (%)
Stack Gas Analyzer Results
(Averages)
World Tobacco
Long
Tytun
Existing Long
2-Aug
29-Aug
16-Sep
Barn Temperature (oF) NA
150
145
168
Exhaust Gas Temperature (oF)
575
616
601
312
355
345
352
370
369
360
387
Thermal Efficiency (%)
79.2
76.9
77.5
82.1 80
80.4
86.8
86.5
85.8
84.3
83.5

12. Temperature Profiles
Cures 6-8

13. New Barn Cumulative and Daily Energy Usage
(Cure 7)

14. New Barn Daily Fuel Usage
(Cure 7)

15. Static Pressure Across Tobacco vs Time
(Cures 4 & 5)
lb/ft3
10.0
10.4
lb/ft3
12.5
12.2
12.0

16. Season Energy Efficiency Comparison

17. World Tobacco - (15 Box - 128 ft3)
2013 On-Farm Barn Performance Summary
Cure
Loaded
UnLoaded
Cure (hrs)
LP (gal)
kWh
Green Wt. per Box (lb)
Bulk Density (lb/ft3)
Total Green Wt. (lb)
Cured Wt (lb)
lb Cured /galLP
World Tobacco - (15 Box ft3) 1
19-Jul
26-Jul
168
319
1174
1300
10.2
19,500
2905
9.11 2
29-Jul
6-Aug
190
336
1381
1333
10.4
20,000
2888
8.60 3
7-Aug
14-Aug
275
1272
1536
12.0
23,000
4747
17.26 4
15-Aug
23-Aug
192
294
1294
3729
12.67 a5
24-Aug
2-Sep
213
223
1427
5097
22.86 6
3-Sep
11-Sep
174
311
5425
17.44 7
12-Sep
19-Sep
162
325
1281
1600
12.5
24,000
5470
16.83 8
20-Sep
28-Sep
184
316
1360
5691
18.01
(Avg. or Sum)
181
2,399
10,483
176,500
35,952
15.35
Long - (10 Box ft3)
278
1950
10.1
2908
10.46 b2
180
333
1442
2000
2904
8.72
164
272
1364
2350
12.2
23,500
4811
17.69
1470
3705
11.92 5
31-Aug
256
1443
2352
4993
19.50
314
1445
5393
17.18
18-Sep
1403
2450
12.7
24,500
5483
16.47
27-Sep
160
1462
5720
17.60
172
2,422
11,301
179,000
35,917
14.94
Tytun - (14 Box (32T) ft3)
25-Jul
156
267
1230
9.1
18,200
2847
10.66
5-Aug
161
283
1240
1429
10.0
2937
10.38
163
247
1290
1716
5088
20.60
22-Aug
158
248
1273
3790
15.31 b5
1331
1788
25,000
5268
21.24
9-Sep
141
286
1079
5828
20.38
146
300
1163
1859
13.0
26,000
5875
19.58
157
292
1256
1800
12.6
25,200
5825
19.95
2,171
9,862
183,400
37,458

18. Total Electrical (kWh) Existing DeCloet (13 Box)
2013 Energy Performance Summary
Cures
Avg. Cure Time (hrs)
Total Fuel (gal)
Avg. per cure (gal)
Total Electrical (kWh)
Total Green Wt. (lb)
Total Cured Wt. (lb)
lb /gal LP
World Tobacco (15 Box) 8
181
2,399
300
10,483
176,500
35,952
15.35
Long (10 Box)
172
2,422
303
11,301
179,000
35,917
14.94
Tytun (14 Box)
156
2,171
271
9,862
183,400
37,458
17.26
Existing Long (10 Box) 6
206
*1,584 NA
9,127
132,500
23,849
13.25
Existing DeCloet (13 Box)
184
2,223
278
7,748
149,930
27,283
12.64
* 5 Cures

19. Energy Efficiency and Estimated Cost per Pound Cured Leaf (fuel only)
Fuel Cost ($/unit)
0.80
1.00
1.20
1.40
1.60
1.80
2.00
lb/gal
$ / lb Cured 7
0.114
0.143
0.171
0.200
0.229
0.257
0.286 8
0.100
0.125
0.150
0.175
0.225
0.250 9
0.089
0.111
0.133
0.156
0.178
0.222 10
0.080
0.120
0.140
0.160
0.180 11
0.073
0.091
0.109
0.127
0.145
0.164
0.182 12
0.067
0.083
0.117
0.167 13
0.062
0.077
0.092
0.108
0.123
0.138
0.154 15
0.053
0.093
0.107 17
0.047
0.059
0.071
0.082
0.094
0.106
0.118

20. Summary
New barn energy efficiency was approximately 22% higher compared to existing barns on average
New barns purchased to replace aging curing infrastructure and to better handle existing production
5 barn manufacturers made and sold barns in 2013
Energy performance alone is not the single justification for purchasing a given barn make, but is an important factor
Performance comparisons and competition should result in improving barn design
Plan to continue work in 2014 and include additional barns

21. Acknowledgements NC Tobacco Research Commission
Philip Morris International
Altria Client Services
Alliance One International
Japan Tobacco International
Lake Wendell Farming Co.
Triple B Farms
Scott Farms
DMG Farms
Patterson Farms
Allen Newton
Mac Grady Farms
R.A. Wood Farms
Dennis R. Wood