A comparative study to understand the economic and environmental impact of the two solutions: lithium battery and energy harvesting in smart parking. By: Anirban Roy Department of Industrial Design Engineering Delft University of Technology

1. Enabling smart parking:
Lithium battery vs energy harvesting
A comparative study to understand the economic
and environmental impact of the two solutions
Anirban Roy
Dept. Of Industrial Design Engineering
Delft University of Technology

2. This is a case study comparing battery technology and energy harvesting to power a distributed
grid of parking sensors from the economic and ecological perspective. The study is conducted
at the Delft University of Technology and Nowi Energy (a technology company founded at the
startup incubator program of TU Delft) has provided their product to benchmark against other
solutions in the market. Nowi was specifically chosen because of their superior product charac-
teristics with respect to available market competitions.
IoT Outlook: A Sought After Technology
Major consultancy firms are predicting an exponential growth of IoT in every sector, with use
cases ranging from industrial to smart cities to agricultural applications. Predictions suggest that
the number of connected devices will reach 21 billion in the next 5 years. The total market is
expected to reach 1.6 trillion dollars by 2025 (7). Some of the major implementation would be in
smart industries (Industry 4.0), logistics and smart infrastructure.
Introduction
In spite of such reports from different market
research agencies predicting a wider accep-
tance of IoT solutions across all industries,
uptake has been conservative. One of the
major reasons is the unclear Total Cost of
Ownership and ROI of these systems. Main-
tenance cost over a period of time plays a
significant role in the TCO of IoT systems.
This report focuses specifically on the smart
parking use case and helps take an informed
decision while deploying large scale smart
parking projects.
Bottleneck to Wider Acceptance of IoT Solutions
IOT PLATFORMS
The Gartner chart show that ‘IoT platform’ is
falling into the ‘Trough of Disillusionment’

3. Parking eats up an incredible amount of space and costs cities an extraordinary amount of mon-
ey. A new study (1) that looks in detail at parking in five U.S. cities: New York, Philadelphia, Se-
attle, Des Moines, and Jackson, Wyoming shows that the number of car parking spots in these
major cities in the US is far more than required. But people still find it difficult to quickly locate
good parking spots near their place of convenience (2).
“20 to 30% of motorists in inner city traffic are looking for somewhere to park, but 13 to 14%
of spaces remain vacant” - Mayor, Nice, France
This dichotomy comes from the changing mobility trends of the 21st century. The behavior of
vehicle ownership is slowly declining and being replaced by the trend of mobility access. The
young urban generation is less inclined to own a car, but rather use services like Uber and Lyft
for their mobility needs. This change directly affects the parking market: the growth of car shar-
ing services has transformed the parking requirement from continuous long hours to frequent
short time spans, thereby creating demand for smarter parking space management.
Smart Parking - Current Projects and Market outlook
A recent study by GSMA (3) found that enabling smart parking in the city of San Francisco re-
duced traffic volume by 8% and greenhouse gas emissions by 30%. The study also suggested an
increase of $93 / month / spot in parking revenue. As a secondary benefit, implementing smart
parking can enable new business models for cellular connectivity providers:
“Mobile operators can discover more meaningful intelligence about a cities’ parking usage
enabling a greater range of value added services.” - GSMA
Urbiotica started deploying smart parking in the city of Nice in France in 2011 with the manage-
ment of 120 parking spots in a pilot phase. In 2013, 4500 sensors were deployed increasing to
8.500 by the end of 2014.
A study by Allied Market Research suggests that the smart parking market is poised to grow
@11.2% CAGR with a projected size of $11B by 2025 (4).
Changing Vehicle Parking Market
Enabling Smart Parking with Parking Sensors
A key component to deploy smart parking, the parking sensor is able to
detect presence of cars in a spot and relay the information through NB-IoT
network. This provides real time information on the availability, usage and
billing of parking spaces. Like any other IoT sensor, the parking sensor is
comprised of 4 basic components:
Powering the Parking Sensors
Available sensors in the market are powered by lithium bat-
teries. But this is turning out to be a major bottleneck for
long term maintenance because they need frequent battery
replacement. The unclear TCO is slowing down the uptake
of smart IoT solutions (5). Energy harvesting may be a viable
solution to this problem

4. With the requirement of one sensor per parking spot, and more than 10 million parking spots in
5 major cities of the US alone, the number of parking sensors installed globally by 2025 is going
to be huge. Powering these sensors is a challenge and the current approach of using batteries is
going to be a major bottleneck for long term maintenance (5).
Battery Life - Current Industry Offerings
Parking sensors from different vendors advertise battery life between 3 to 8 years. However this
estimate does not take into account the high variation in operating temperature from -30° C to
+45° C which adversely affect battery life (6).
Another factor is the number of messages sent from the sensor to the base station - generally
it is kept to a few times per day in order to conserve battery life. Frequent data gathering will
improve usage time and hence revenue from parking.
Growing Cost of Ownership
These current battery powered sensors need maintenance every few years (8) which can quickly
drive up the ownership cost over a period of time. The chart below showcases a typical cumu-
lative TCO over 20 years for 100 million sensors with conservative assumptions (no change in
price of battery and service + embedded sensor allows multiple battery replacements).
Battery Powered Solution
Environmental Impact of Batteries
Also, the ecological footprint of lithium ion battery is significantly higher than solar panels or
other energy harvesters. The graphic below estimates the environmental impact of 10M battery
powered parking sensors for the first 5 years (it is ~200 million Kg CO2
over 20 years)

5. Activity Unit Energy / transmission Energy / day (mJ)
Uplink Power consumption (mW) 623 0.997 11.964
Downlink power consumption (mW) 62.5 0.1 1.2
RF unit PSM mode (microW) 10 72 864
Microcontroller run mode (mW) 1 2 24
Microcontroller low power mode (microW) 1.4 10.1 121
10 sec Handshake power (mW) 623 6230 74760
Data transfer rate (kbits / s) 250
Data packet size (bits) 400
Time required for 1 transmission (s) 0.0016
Total power required (mJ) 6315.2 75782.2
Energy Harvesting Use Case in IoT
Implementing energy harvesting in distributed sensor arrays like parking sensors is practical due
to their long operational life without any maintenance. This drives down the TCO and increases
ROI. The production cost (at high volumes) of one unit of the entire energy harvesting system
(including the power management chip, solar cells and other components) is less than $2. Solar
cells have an operational lifetime of >20 years and recent strides in technology have made them
more efficient in low luminous conditions (when the car is parked on top)
Energy harvesting technology has improved over the past decade to reach enough maturity
where it can be used to power devices with low energy requirement for very long periods of
time without any manual intervention / maintenance. Nowi energy harvesting chip has ad-
dressed some chronic problems often related to energy harvesting.
• ~30x smaller PCB footprint compared to leading
product in the market (TI)
• Need for external components to set up energy
harvesting brought down from ~10 to 2
• Advanced MPPT and world leading conversion
efficiency of ~92%
Energy Harvesting with Nowi PMIC
PMIC Characteristics - Nowi vs Industry Leader (TI)
Production cost of Nowi Energy harvesting system (at high volume) < $2 / unit.
Solar power harvesting with Nowi PMIC for a Typical Parking Sensor
A typical parking sensor with solar harvesting can provide enough energy for continuous usage
with the number of up-link messages exceeding more than 12 / day (once every 2 hours). A typi-
cal energy requirement table for NB-IoT operation is presented (9):
A tiny solar cell (2cm2
) with
Nowi PMIC integration
can provide enough pow-
er (3.5mW) for continuous
usage with only 6 hours of
energy harvesting in a very
cloudy day. The number of
up-link messages can be
increased based on longer
energy harvesting period.

6. Battery Power vs Energy Harvesting
The two methods of powering the sensors are compared on different parameters. As is evident
from the infographic below, energy harvesting is significantly superior from economic as well as
ecological standpoint. The price of batteries considered is based on current cost of Lithium Car-
bonate, which is poised to increase in coming years owing to the higher demand for large scale
EV production. The difference in the cost of ownership is significant due to required mainte-
nance of battery powered sensor systems every few years. Also, environmental impact of lithium
batteries is lower than fossil fuels but is several times higher than green energy like solar power
or other natural energy harvesting methods.
Power Component Cost
The production cost of a
10400 mAh lithium ion bat-
tery is $6 (mass scale produc-
tion) compared to the cost of
an energy harvester system
which is ~$2 / unit. This ratio
is skewed even more over
time as batteries need re-
placement every few years
where as solar powered ener-
gy harvesters can work more
than 20 years uninterrupted.
Ownership Cost
Ownership cost consists of
the product and the mainte-
nance cost of the system. In
case of energy harvesting,
the maintenance cost com-
prises of one time installation
(plug and forget) where as
battery powered sensors
need maintenance every few
years where the sensor is dug
out to replace the battery
and installed again.
Environmental Impact
As we move towards a sus-
tainable future, the ecologi-
cal footprint of every activity
will be highly monitored.
Using solar powered energy
harvesters in 10M sensors
can reduce the CO2
pro-
duction by 175M Kg over
20 years. This calculation is
made considering the current
production efficiency of lithi-
um batteries and solar cells.

7. Reference
1. https://www.citylab.com/transportation/2018/07/parking-has-eaten-american-cities/565715/
2. https://medium.com/@goparkr/this-is-the-truth-about-why-good-parking-is-hard-to-find-
scarce-6093ef4525a5
3. https://www.gsma.com/iot/wp-content/uploads/2017/09/iot_smartparking_guide3_09_17.
pdf
4. https://www.alliedmarketresearch.com/smart-parking-market
5. https://www.forbes.com/sites/forbestechcouncil/2018/09/20/five-reasons-why-iot-is-not-
ready-for-prime-time/#3a5e9b1c78aa
6. https://batteryuniversity.com/learn/article/discharging_at_high_and_low_temperatures
7. https://www.statista.com/statistics/976313/global-iot-market-size/
8. https://twtg.io/product/smartcity-parkingsensor-demokit/
9. https://www.semanticscholar.org/paper/Power-Consumption-Analysis-of-NB-IoT-and-eMTC-
in-J%C3%B6rke-Falkenberg/ad6a568775d83a1a730e8d6783229bd7ea333769