Consultation about operation cost of cellulosic_ethanol model

For the operation cost in the excel file of cellulosic_ethanol model, may I ask you the following questions. I use BioSTEAM 2.43.1.

a) Why is the cost of ```cooling water, chilled water, and low pressure steam``` for each unit in the Utilities worksheet 0? For ```cooling water, chilled water, low pressure steam```, why is the flow sum of each unit 0?
In contrast, why is the sum of the electricity of each unit not zero, and why is the cost of electricity not zero?
Screenshot as follows:

b) For utility cost, why not use the sum from cells ```D30 to D62``` in the utilities worksheet? The sum from cells ```D30 to D62``` in the utilities worksheet is ```-1488.32 USD/hr```, but it is actually ```-1097.59 USD/hr``` with the code ```print(tea.utility_cost/tea.operating_hours)```
Code and screenshot below:
```
from biorefineries import cellulosic
import biosteam as bst
from biorefineries.tea import create_cellulosic_ethanol_tea
cs = cellulosic.Biorefinery('corn stover ethanol')
tea=create_cellulosic_ethanol_tea(cs.cornstover_sys)
print(tea.utility_cost/tea.operating_hours) # output is -1097.59 USD/hr
```

c) The utility cost of ```Boiler turbogenerator and Process water center``` in ```Itemized costs``` worksheet seems different from the electricity cost of ```Boiler turbogenerator and Process water center``` in the ```utilities``` worksheet (I have converted them into USD/hr), but the other units are the same?
Screenshot as follows:

d) Are the following two codes for checking Material cost of cellulosic_ethanol model both correct?
```
from biorefineries import cellulosic
import biosteam as bst
from biorefineries.tea import create_cellulosic_ethanol_tea
cs = cellulosic.Biorefinery('corn stover ethanol')
tea=create_cellulosic_ethanol_tea(cs.cornstover_sys)
list = [i for i in cs.cornstover_sys.feeds]
for i in range(29): # 29 is the number of the feeds
print(list[i].cost) # view material cost of different feeds in cellulosic_ethanol model
material_cost = 0
for i in range(29):
material_cost += list[i].cost
print(material_cost) # view material cost of cellulosic_ethanol model
```
Or
```
from biorefineries import cellulosic
import biosteam as bst
from biorefineries.tea import create_cellulosic_ethanol_tea
cs = cellulosic.Biorefinery('corn stover ethanol')
tea=create_cellulosic_ethanol_tea(cs.cornstover_sys)
print(tea.material_cost/tea.operating_hours) # USD/hr
```

Start by running the provided BioSTEAM 2.43.1 example and compare tea.utility_cost/tea.operating_hours with the Utilities and Itemized costs worksheets. Trace the cellulosic.Biorefinery, corn stover system, and create_cellulosic_ethanol_tea objects to explain the utility and material-cost differences. Done means each discrepancy in parts a–d has a documented, reproducible explanation.

Written by the indexing model from the issue text.