Conference on Rural Telecom Markets by Tele.net

1. Energy Optimization & Alternative
sources of Energy
A.K. Nagpal
16th September 2009

2. Energy Requirement:
Current Base Stations
1. Global: Number of mobile telephones currently is 4.1billion and is
expected to reach 5 billion by 2015. In India currently (2009 Q1)
the mobile subscriber base is 420 Million and is expected to
reach 500 Million by 2010
2. More than 90% of the additions will come from emerging
economies globally, with 60 to 80 % of them located in rural
areas.
3. In India we expect that the number of new Base stations to be
setup by 2011 will exceed 2,00,000.
4. Energy related expenditure accounts for nearly 70% of total
operating cost per cell site in the rural areas.

3. Energy Requirement:
Current Base Stations
1. The Power requirement of a BTS currently varies from 1300 –
2500 watts.
2. A large percentage of these deployments are still indoor type
needing air conditioning.
3. Current SLAs (with operators) need shelter temperature to be
maintained between 22 – 300 C range.
4. Powering systems are based on grid supply as primary source
with diesel generators as stand by sources and Storage batteries
as secondary sources

4. Energy Requirement:
Current Base Stations
5. In case of indoor shelters where specified temperature needs to be
maintained:-
a. Rise in temperature is faster than decrease in battery voltage to
its threshold
b. DG set needs to be switched “on” to power the A/Cs and
maintain the temperature
c. Battery Capacity is not fully utilized.

5. Drawbacks of existing Powering Model
for BTS
1. Base Stations are very power intensive
2. Diesel generators need regular maintenance
3. Diesel thefts are very prominent – they could be as much as 20
% diesel theft
4. Prices of petroleum products are continuously increasing
5. Grid supplies in rural areas are often erratic and unavailable
requiring long runtime of DG sets.

6. TOTAL COST OF OWNERSHIP(TCO) OF A CELL SITE
Model A Model C Ground Rent
Ground Rent 5% Energy Cost
4%
Cost of 9%
Funds
31%
Security
Energy Cost Exp.
33% 9%
Cost of
O&M
Funds
2%
48%
Depreciation Security
21% O&M Exp. Depreciation
3% 8% 27%
Normal site configuration Solar DG hybrid

7. TOTAL COST OF OWNERSHIP(TCO) OF A CELL SITE
Ground
Model B Rent
Model D Energy Cost
5% Ground Rent 4%
5%
Security
Exp.
Cost of 9%
Funds Energy Cost
26% O&M
34%
2%
Cost of
c
Funds
52%
Security
Exp. Depreciation
Depreciation
9% 28%
24% O&M
2%
Solar flow technology battery
DG Flowtech by hybrid

8. Optimizing Energy
Requirement of a Cell Site
Realizing a OBTS
(Optimized Energy Base Stations)

9. Cell site configuration
Base Station Equipment Base Station Site-level Equipment
RF parts Cooling and/or heating unit
Power amplifier (PA) Rectifier
Digital signal processing (DSP) Antenna line (feeder)
Transmission Antenna
Control Mast-head amplifier (MHA)

10. Cell site Energy Optimization
Traditional Base Station Energy-Optimized Base Station
WCDMA GSM WCDMA
GSM
Component Component % Energy
%Energy %Energy % Energy
(s) (s) Consumptio
Consumption Consumption Consumption n
RF + PA 50% 40% RF + PA 85% 75%
DSP, DSP,
transmission, 10% 20% transmission, 10% 20%
MHA MHA
Feeder, Feeder,
35% 35% N/A N/A
Cooling Cooling
Rectifier 5% 5% Rectifier 5% 5%

11. Key Strategies for Optimizing Power
Requirement of a BTS
1. Deploy mainly outdoor BTS equipment which does not require Air
Conditioning and intrinsically have low power consumption
2. BTS with Remote Radio Heads (RRH) placed next to the
antennae mount thereby eliminating feeder loss.
3. The connectivity between RRH and Base Band can be Fiber
based Ethernet eliminating the Coaxial Feeder
4. BTS with Standby Mode Systems that shut down TRX’s during
off-peak periods dynamically.

12. Typical Industry Offerings for Energy
Optimized BTS (OBTS)
Sno. Equipment Type Configuration Power Consumption
1. LME 2111 (4-4-4) 450 watts
2. ZTE R 60 U (4-4-4) 400 watts
3. Vanu SDR (4-4-4) 650 watts

13. Adapting Alternative Sources
of Energy
for
Powering BTS Sites

14. Adapting Alternative Sources of Energy for
Powering BTS Sites
• The first step towards adapting alternative sources of energy for
powering cell sites is to realize OBTS.
• The CAPEX for adopting alternative source of energy for
powering such sites will become sustainable.
• A number of technologies amongst alternative sources are in
different stages of evolution
• Often a combination of one or more sources of alternative energy
needs to be deployed with / without DG sets.

15. Adapting Alternative Sources of Energy for
Powering BTS Sites: The Rationale
1. These sources are CLEAN, GREEN & FREE (RUNNING COST)
2. The capex levels although high at present will come down as
technologies mature and volumes attain critical mass.
3. The operating costs are almost nil as these sources are free.
Maintenance and replacements are very low compared to diesel –
driven sites.
4. Carbon credits can be a revenue stream on green sites (Estimated
Rs. 20 K per annum per site)

16. Adapting Alternative Sources of Energy for
Powering BTS Sites: Available
technologies
1. SOLAR – DG HYBRID
2. WIND – DG HYBRID
3. SOLAR – WIND HYBRID
4. BIOFUELS
5. FUEL - CELLS

17. Adapting Alternative Sources of Energy for
Powering BTS Sites: Solar Energy
1. MOST MATURED amongst all such technologies.
2. Power converted from light per m2 – efficiency*
Polycrystalline Silicon: 12 – 15%
Monocrystalline Silicon: 13 – 15%
Saturn Monocrystalline Silicon: 15 – 18%
*The percentage of sunlight falling on 1 Sq. Meter surface of a Solar Cell
that is converted into Electrical power is defined as efficiency of solar cell.
Thus a Solar cell with 15% efficiency delivers 150 Watt of Power converted
from light falling on 1 Sq. Mtr. Surface at Noon.

18. Adapting Alternative Sources of Energy for
Powering BTS Sites: Solar Energy
3. Main advantages
Free, Clean, Green
No Moving Parts – No Maintenance Cost
4. Suggested configuration
a. Solar – DG Hybrid
b. Solar – Wind Hybrid

19. Adapting Alternative Sources of Energy
for Powering BTS Sites: WIND – BASED
SYSTEMS
FREE, CLEAN & GREEN
1. Advanced systems are widely available
2. Smaller systems can be mounted on existing radio-masts, reducing costs.
3. Horizontal wind turbines are more efficient
4. Systems available with low “cut – in” speeds of 2.4 m/sec
CHALLENGES
– Site – selection must be carefully done for deployment of wind – turbines, ISO – 820
wind maps must be studied before deploying wind turbines
– Wind velocity is often erratic. Thus we need a very efficient charge controller and a sink
for excess power
– Sink for excess power can be a tube well for example

20. Adapting Alternative Sources of Energy
for Powering BTS Sites: Bio-Fuel
1.Biodiesel is commonly produced by the transesterification
of the vegetable oil or animal fat feedstock. There are
several methods for carrying out this transesterification
reaction including the common batch process, supercritical
processes, ultrasonic methods, and even microwave
methods.
2. Much of the world uses a system known as the "B" factor to state
the amount of biodiesel in any fuel mix: fuel containing 20%
biodiesel is labeled B20, while pure biodiesel is referred to as
B100. It is common to see B99, since 1% petrodiesel is
sufficiently toxic to retard mold. Blends of 20 percent biodiesel
with 80 percent petroleum diesel (B20) can generally be used in
unmodified diesel engines.

21. Adapting Alternative Sources of Energy
for Powering BTS Sites: Technology
Solutions
Sample Solar-Wind Solution
Application Power Required
(Depending on Conditions)
GSM base station (2/2/2) 600W-1800W 4kW solar array and 6kW turbine
GSM base station (4/4/4) 900W-2300W 6kW solar array and 6kW turbine
UMTS Node B macro/fiber
750W-1000W 3kW solar array and 2.5kW turbine
(2/2/2)
UMTS Node B macro/fiber
1300W-1700W 4kW solar array and 2.5kW turbine
(4/4/4)
Large WiMax base station 1.3kW (4-sector) 4kW solar array and 2.5 or 6kW turbine
<30W,includes a
Metro WiFi 100W solar array and small turbine
backhaul solution
1kW solar array and 600W or 2.5kW
P2P link (two heads) 110W for two units
turbine

22. Case Study
Solar Powering of SBI ATM Sites

23. Assumptions
• Peak load of an ATM is 1600 watts.
• Activity curve of an ATM site varies from locality to locality and area attributes such
as rural, semi-urban and urban.
• Grid availability varies considerably throughout the state. No authentic data can be
given. However, in rural/remote sites, it varies from 0 hrs a day to 8 hrs a day. In
semi-urban areas, it may be 8 hrs a day to 12 hrs a day and in urban areas it may be
12 hrs a day to 20 hrs a day.
• Rural, semi-urban and urban areas have different activity curves and peak hit hours.
• There are approximately 400 ATM hits/day.
• Average transaction time is 30 sec. Power consumption during this time is peaky
when mechanical movement is involved and low during data feeding and idle time.
• For a rural ATM, main activity time would be 10 AM to 4 PM.
• For a urban site, main activity time would be from 9 AM to 8 PM.
• For a rural site, it is estimated that the average power consumption will be 1000 watt
during main activity time and 100 watt during other time of the day.
• For a urban site, it is estimated that the average power consumption will be 1000 watt
during main activity time and 150 watt during other time of the day

24. Design parameters for Solar Powering
Power output per panel (W) 100
Rated Voltage (V) 17.2
Output voltage per panel (V) 12
DOD 0.6
Inverter Efficiency 0.9
System Voltage (V) 50
Peak Load 1000
Duration for peak load 6
Off-peak load 100
Duration for off-peak load 18
Grid Availability (hrs) 4
Battery charging rate (Solar) (C/?) 15
Battery AH 274.0741
Battery charging current 18.2716
No. of panels in series 4.166667
No. of panels in series (actual) 4
No. of strings in parallel 6.582716
No. of strings in parallel (actual) 7
Total number of panels 28
Total power output 2800

25. Component Costs
Price of Battery bank Price of Solar panel
S.No AH Number Price S.No Cost per watt Panel Wattage Price
1 90 0 0 1 150 2800 420000
2 100 0 0
3 120 0 0 Price of Equalizer (12V)
4 135 0 0 S.No Unit Price Requirement Price
5 150 0 0 1 3000 1 3000
6 165 0 0
7 180 0 0 Price of Battery Coolant
8 200 0 0 S.No Unit Price Requirement Price
9 220 0 0 1 5000 4 20,000
10 250 0 0
11 300 4 108000 Price of PCU (2 KW, 50V)
Total price of the battery bank 108000 S.No Unit Price Requirement Price
1 45700 1 45700
Installation & Commissioning charges 119,340
Total 716,040
(Note: All prices are in INR)

26. Return on Investment (ROI)
Assumptions
Diesel Price (Rs./liter) 35
Diesel usage by DG (Liters/hour) 2
Fuel pilferage/wastage (%) 5%
DG service running hours 250
Life of DG (Years) 10
Price of DG (7.5 KVA) 200000
Scrap value of DG 20000
Cost of DG Service 1000
DG running hours per day 6

27. Return on Investment (ROI)
6 Hr 12 Hr 18 Hr
OpEx
Usage Usage Usage
Running cost 153300 153300 306600 459900
Fuel pilferage/wastage cost 7665.0 7665 15330 22995
Fuel filling/transportation
12000 12000 12000 12000
charges/year
No. of services required 9 9 18 26
Service cost 9000 9000 18000 26000
Maintenance+Consumable
10000 10000 16000 22000
spares
Depreciation cost (Straight
18000 18000 18000 18000
line)
Total per year cost (In Rs.) 209965 209965 385930 560895
Break-Even Time (Years) 3.41 3.41 1.86 1.28

28. Thanks
Su-Kam – Morphing into a Green Company