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Powering the Remote Rural Base Station Rural Base Station Can it make Indian telcos profitable?
ashok Jhunjhunwala, IITM [email protected]
N. Sriram, IITM
04-04-2012
Green Telecom & IT workshop, Bangalore 1
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 • rural / remote areas have huge cuts
04-04-2012
Green Telecom & IT workshop, Bangalore 2
04-04-2012
Green Telecom & IT workshop, Bangalore ‹#›
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• India grid availability varies between states
1 unit BTS consumption: 1.5 units consumed by AC, SMPS loss, PIU loss, battery leakage• India grid availability varies between states
• 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
04-04-2012
Green Telecom & IT workshop, Bangalore
by AC, SMPS loss, PIU loss, battery leakage
4
• 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
Energy Storage
• 1 kWh back-up will cost Rs 16 per kWh assuming single charge per day• Assuming Rs 25000 per kWh battery and 10% interest
Battery cost (per kWh) Rs. 6,000.00 Battery cost (to deliver 1kWh) Rs. 15,000.00discharge 40% depreciation (years) 4.11Number of cycles 1500 Storage cost per unit -Rs. 14.09interest rate 10%cycles used per day 1Losses 10%
Lead acid battery
04-04-2012
Green Telecom & IT workshop, Bangalore 5
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 doesnot 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?
04-04-2012
Green Telecom & IT workshop, Bangalore 6
• 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 7per 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
Sun shines brightly over India
Installation costs may add another 10% to costs
• As opposed to Rs 3 to 7 per kWh for grid power
04-04-2012
Green Telecom & IT workshop, Bangalore
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
7
Strategy• What are the sources?
• at what costs and available when?
• What are the Loads?• Can we reduce some loads?
Grid: Rs 5 per unitSolar: Rs 5 per unitBattery back-up: Rs 15 per unitDiesel Generator: Rs 15 per unit
BTSAir-conditionerBattery-cooling• Can we reduce some loads?
• 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
04-04-2012
Green Telecom & IT workshop, Bangalore
Battery-coolingBattery-charging
8
IITM Simulator• Designed to compute
• Battery, PV current, Total Loadcurrent as a function of ambienttemperature at different point of time
• When do DG and grid turn on and off?• What happens to battery charging / discharging?
• Assumptions in simulations• 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
04-04-2012
Green Telecom & IT workshop, Bangalore 9
15kVA Generator, No PV, NO Battery, 4 hours grid availability
04-04-2012
Green Telecom & IT workshop, Bangalore 10Rs 35 per unit
600Ah, 48V Lead Acid 600Ah, 48V Lead Acid 600Ah, 48V Lead Acid 600Ah, 48V Lead Acid BatteryBatteryBatteryBattery, 4 Hours grid , 4 Hours grid , 4 Hours grid , 4 Hours grid availability, 15kVA availability, 15kVA availability, 15kVA availability, 15kVA DGDGDGDG
Linear Battery Charging Model
04-04-2012
Green Telecom & IT workshop, Bangalore 11Rs 23 per unit
Non-linear Battery Charging Model
600Ah, 48V Lead Acid 600Ah, 48V Lead Acid 600Ah, 48V Lead Acid 600Ah, 48V Lead Acid BatteryBatteryBatteryBattery, 4 Hours grid , 4 Hours grid , 4 Hours grid , 4 Hours grid availability, 15kVA availability, 15kVA availability, 15kVA availability, 15kVA DGDGDGDG
04-04-2012
Green Telecom & IT workshop, Bangalore 12Rs 23 per unit
150Ah, 48V Lithium 150Ah, 48V Lithium 150Ah, 48V Lithium 150Ah, 48V Lithium Polymer batteriesPolymer batteriesPolymer batteriesPolymer batteries, 4 Hours , 4 Hours , 4 Hours , 4 Hours grid availability, 15kVA grid availability, 15kVA grid availability, 15kVA grid availability, 15kVA DGDGDGDGLinear Battery Charging Model
04-04-2012
Green Telecom & IT workshop, Bangalore 13Rs 22 per unit
600Ah, 48V Lead Acid Battery + 5kW PV + 15kVA DG + 4 Hours grid availability
Non-linear Battery Charging Model
04-04-2012
Green Telecom & IT workshop, Bangalore 14Rs 15 per unit
150Ah, 48V Lithium Polymer 150Ah, 48V Lithium Polymer 150Ah, 48V Lithium Polymer 150Ah, 48V Lithium Polymer battery + battery + battery + battery + 5kW PV 5kW PV 5kW PV 5kW PV +4 Hours +4 Hours +4 Hours +4 Hours grid availability+15kVa grid availability+15kVa grid availability+15kVa grid availability+15kVa DGDGDGDGLinear Battery Charging Model
04-04-2012
Green Telecom & IT workshop, Bangalore 15Rs 14 per unit
Simulation Conclusions
• Use of proper battery reduces daily energy OPEX by one-thirdby one-third
• Use of PV panel further reduces daily energy OPEX by one third
04-04-2012
Green Telecom & IT workshop, Bangalore 16
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
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)• 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
04-04-2012
Green Telecom & IT workshop, Bangalore 18