1. Powering the Remote
Rural Base Station
Can it make Indian telcos profitable?
ashok Jhunjhunwala, IITM ashok@tenet.res.in
N. Sriram, IITM
04-04-2012
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Green Telecom & IT workshop, Bangalore

2. India’s 15% average
power deficit is deceiving
As evident from the fluctuating prices
at Power Markets
• Day variation of Rs 2000 to 4500 per
MWh
• Prices vary from Rs 2000 to 12000 per
MWh in one week
• Huge power shortage during peak hours
• rural / remote areas have huge cuts
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3. ‹#›
04-04-2012
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4. Some statistics from
ACME
• 1.5 to 3% energy in developed countries consumed by telecom
operators and data centers
• Energy consumed by wireless operator doubles every 3 -5 years
• Cooling infrastructure consumes > 50%
• DG operation average 6 hours per day
1 unit BTS consumption: 1.5 units consumed
• India grid availability varies between states by AC, SMPS loss, PIU loss, battery leakage
• Battery maintenance neglected
• 15% batteries are non-functional
• 1800 MHz TRX consume more power
• Passive site equipment dominates CAPEX
• $25K for active (electronics) and $62.5K for passive
• Tower, shelter, Power system, Battery (VLRA),
AC unit, Earthing
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5. Energy Storage
• Batteries are expensive proposition for back-up
• Lead acid battery: 1500 cycles if operated between 60 to 100% capacity
• 1 kWh back-up will cost Rs 14/ kWh assuming single charge / discharge
per day
• Assuming Rs 6000 per kWh battery and 10% interest rate
• LiFePo battery: 5000 cycles if operated between 10% to 90% capacity
• 1 kWh back-up will cost Rs 16 per kWh assuming single charge per day
• Assuming Rs 25000 per kWh battery and 10% interest
Lead acid battery
Battery cost (per kWh) Rs. 6,000.00 Battery cost (to deliver 1kWh) Rs. 15,000.00
discharge 40% depreciation (years) 4.11
Number of cycles 1500 Storage cost per unit -Rs. 14.09
interest rate 10%
cycles used per day 1
Losses 10%
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6. Diesel generator
• Diesel generator generates 3 kWh of power per litre of diesel
• But this is true only if generator is working at 80% load
• Efficiency drops significantly at lower loads
• Increasing costs of diesel power
• DC diesel generator does
not have this problem
• Fuel consumption is almost
linear with load
• For charging battery and driving
BTS, why not use DC generator?
• Why convert to ac at all?
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7. Sun shines brightly
over India
• India can certainly use solar energy, as capital goods prices fall
• Solar photo-voltaic provides DC power for about six hours a day
• Rs 60 per W capital cost: with 10% interest and payback in 20 years, amounts to Rs 7
per year (not computing costs of land)
• Total Cost of Ownership gives a little over Rs 4.35 / kWh assuming 10% losses
assuming no land cost
• Installation costs may add another 10% to costs
• As opposed to Rs 3 to 7 per kWh for grid power
Solar PV power price computation
PV cost per kWp 60000 sun-hours per day 6
interest rate % 10% sun-days / year 300
depreciation (yrs) 20 total units gen per year 1800
yearly payment Rs. -7,047.58 Losses 10%
price per unit Rs. 4.35
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8. Strategy
Grid: Rs 5 per unit
Solar: Rs 5 per unit
• What are the sources? Battery back-up: Rs 15 per unit
• at what costs and available when? Diesel Generator: Rs 15 per unit
• What are the Loads? BTS
Air-conditioner
• Can we reduce some loads? Battery-cooling
Battery-charging
• In existing installations
• In new installations, for example
• reduction of BS power: 147W -> 130W -> 120 W Diet-BTS
• Reducing / eliminating Air-conditioner requirement
• Use of battery chiller
• Will require one to optimize usage of sources to
minimize total cost of operation
• OPEX + CAPEX converted into EMI
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9. IITM Simulator
• Designed to compute
• Battery, PV current, Total Load
current as a function of ambient
temperature at different point of time
• When do DG and grid turn on and off?
• What happens to battery charging / discharging?
• Assumptions in simulations
• Grid Availability: 4 h
• Diesel Generator Sizes: 15 kVA
• Load Power factor: 0.8
• Diesel Cost per liter: 45 Rs
• BTS Load: 0.8kW
• BTS Cooling Load: 1.8kW
• Battery Cooling Load: 0.5kW
• Total Peak Load excluding Battery Charging: 3.1kW at 48V
• PV and battery CAPEX built into energy costs as EMI
• DG CAPEX and fuel-pilferage not included
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10. 15kVA Generator, No PV, NO
Battery, 4 hours grid
availability
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Green Telecom & IT workshop, Bangalore Rs 35 per unit

11. 600Ah, 48V Lead Acid Linear Battery
Charging
Battery,
Battery, 4 Hours grid Model
availability, 15kVA DG
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Green Telecom & IT workshop, Bangalore Rs 23 per unit

12. 600Ah, 48V Lead Acid
Non-linear
Battery,
Battery, 4 Hours grid Battery
Charging Model
availability, 15kVA DG
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Green Telecom & IT workshop, Bangalore Rs 23 per unit

13. 150Ah, 48V Lithium
batteries,
Polymer batteries, 4 Hours
grid availability, 15kVA DG
Linear Battery Charging Model
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Green Telecom & IT workshop, Bangalore Rs 22 per unit

14. 600Ah, 48V Lead Acid Non-linear
Battery + 5kW PV + 15kVA Battery
Charging Model
DG + 4 Hours grid availability
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04-04-2012
Green Telecom & IT workshop, Bangalore Rs 15 per unit

15. 150Ah, 48V Lithium Polymer
battery + 5kW PV +4 Hours
grid availability+15kVa DG
Linear Battery Charging Model
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Green Telecom & IT workshop, Bangalore Rs 14 per unit

16. Simulation
Conclusions
• Use of proper
battery reduces
daily energy OPEX
by one-third
• Use of PV panel
further reduces
daily energy OPEX
by one third
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17. But one can optimize much more
700Ah, 48V Lead Acid Battery + 7kW PV
+ 15kVA DG + 4 Hours grid availability
Non-linear
Battery
Charging Model
04-04-2012
Green Telecom & IT workshop, Bangalore Rs 10 per unit

18. How does one go
forward?
• For new sites
• Reduce power consumption in BS and associated electronics
• Eliminate air-conditioner (make systems workable at 500c ambient)
• Place Battery in chiller
• Use dc diesel generator of right sizing -- critical
• But more important (for existing and new sites)
• Add solar panels
• Revitalize batteries – choose Lead Acid or Lithium Polymer
• Balance current load and power-sources
• Optimize when to use what based on simulations
• Have powerful remote management
• With the aim of using diesel generator only as an exception
• Key is to reduce total cost of operation of towers
• Taking CAPEX / OPEX
• Much can be done today
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04-04-2012
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