Green Telecom & IT Workshop by IISc and Bell labs: Prof. Ashok Jhunjhunwala : Telecom Tower Energy

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

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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

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• 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

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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?

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• 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

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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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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

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Battery-coolingBattery-charging

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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

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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

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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

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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

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600Ah, 48V Lead Acid Battery + 5kW PV + 15kVA DG + 4 Hours grid availability


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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

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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

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But one can optimize much more 700Ah, 48V Lead Acid Battery + 7kW PV + 15kVA DG + 4 Hours grid availability


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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

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Green Telecom & IT Workshop by IISc and Bell labs: Prof. Ashok Jhunjhunwala : Telecom Tower Energy

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Transcript of Green Telecom & IT Workshop by IISc and Bell labs: Prof. Ashok Jhunjhunwala : Telecom Tower Energy