A SOLAR ENERGY BASED ELECTRIC VEHICLE CHARGING INFRASTRUCTURE FOR THE CITY OF NAGPUR
India is witnessing a rapid urban growth trajectory with a projected increase of urban population from 340 million in 2008 to 590 million by 2030. Consequently, efficient ways to manage complexities, increase efficiency and improve the quality of life are required to accommodate this rapid urbanisation and make cities sustainable. Clean and reliable energy has been regarded as a key parameter for sustainable urban growth. Despite the government’s endeavour to transition to a cleaner energy source, penetration of renewables in urban areas remain low. Further, the growing urban regions also demand an improved and extensive transport network to connect different areas. This increased vehicular stock further puts pressure on the environment. The government is taking initiatives for the introduction and manufacture of full range of electric vehicles, to tackle pollution. Sadly, the lack of EV charging infrastructure dissuades many buyers. This leads to a chicken-egg conundrum impairing penetration of EVs on road.
Considering above challenges and opportunities, team MITIGATE (ISCF 2019) investigates cross-sectoral aspects and proposes an idea to bridge the gap between supply and demand, which is often seen problematic in the energy sector. A distributed energy resource system for a community area, encompassing a rooftop PV system connected to battery energy storage system, jointly will support the charging of E- buses and EVs, thereby reducing the reliance of power generated by fossil fuel driven power plants. The schematics and the framework for this system is developed for a pilot implementation, to charge Nagpur’s e-buses using top-up recharge concept.
The Government has identified multiple fronts to tackle environmental challenges. Team Mitigate has identified two such priority sectors, namely ‘electric mobility’ and ‘renewable energy’. India is energy deficit country, where most of the cities face problems with power cuts. Therefore, the current plan of aiming EVs on mass scale cannot be realized in view of electricity fluctuations. Our thermal plant have emission factor ranging from 0.8~0.9 t CO2/MWh, thus EVs would account for ~ 370 gCO2e/km if they are charged from the grid. Whereas, the conventional cars account for about 280 gCO2e/km. Thus, ICE cars are better than EVs, unless the thermal plants in the country are decarbonised. Other challenges including fast charging infrastructure, higher cost of electric vehicles, risk of energy theft etc. amongst others also needs to be address before large scale penetration of EVs
Parallelly, the Government has set ambitious rooftop solar target. Rooftop solar energy is beneficial in many contexts since it has no additional land requirement (if installed on existing structures), reduces AT&C losses and absence of transmission infrastructure. However, rooftop solar remains constrained due to institutional inconsistencies, sluggish processing of grants and funds, low awareness among consumers etc. Moreover, an increase in renewable energy generation at the grid-distribution level, leads to power quality issues. With an exponential increase in the energy demand and high RE penetration in the future, distribution grid network needs to be reinforced for higher bidirectional power flow.
There is a need to investigate in newer forms of clean energy for these e-vehicles such that the net impact of running these cars is lesser than existing vehicle stock. A new technological intervention may help overcome many challenges, by reducing tail-pipe emission as well as extended tail-pipe emission.
We propose a city agnostic turnkey solution enabling a DER system for a community area, encompassing an off-grid rooftop PV system connected to an on-grid BESS. The BESS will support a fast DC charge station to charge electric vehicles completely in less than 1 hour. Further, the BESS can support the DISCOMs to defer the additional infrastructure to be built just to support peak demands, lowering the CAPEX costs for the DISCOMs. The BESS can also support additional functions as and when needed. The idea of an off-grid rooftop PV in a DER system connected to BESS, which is further used for EV charging, effectively bridges the gap to manage the supply and demand of energy. Also, it breaks the self-consumption application rational which acts as a barrier for DISCOM’s loss of revenue. Bringing in DER system, increases the efficiency of the grid system by reducing transmission losses. The rooftop solar PV helps the residents save on their electricity bills by considerable amounts, without any initial CAPEX.
This disruptive solution will facilitate higher PV penetration without harming the existing grid network as feared by the DISCOM’s. This solution will help mitigate 40 tonnes of CO2 per kWh installed with an annual savings of ₹2.4 lac per kWh installed. The solution will also generate employment, incentivise the use EVs and create a mature ecosystem for penetration of green energy.
Proposed concept of using solar rooftops to charge EVs and support grid applications
Pilot City Identification: It was necessary to have a mature EV ecosystem in the pilot city to demonstrate the concept of PV2EV. Simultaneously, a good solar PV project penetration was necessary to allow us to tap into the renewable segment. A matrix was developed, to rank the cities based on different parameters. The best combination would have been a solar city which was also a smart city with mature technology and investment in the said domain. Nonetheless, a short online survey was created and circulated to various cities along with the project pitch and video. The aim being to capture the interest of the city. The results highlighted the activities undertaken and the enthusiasm of the administration to engage in new projects and investment in energy sector.
The outcome was that the city of Nagpur was chosen to execute the pilot. Nagpur receives abundant sunshine and penetration of solar energy projects on rooftops, along with a growing EV market. The city also boasts of being the first in the country to introduce multi-modal electric vehicle project, in partnership with Ola, with a total of 200 electric taxis and e-rickshaws operating on the aggregator’s platform. This project aimed to encourage the use of cost-effective, indigenous and pollution-free energy in our country. Apart from it, it also envisages reduction in fares of public transport. The confluence of following factors provided the precise environment that are responsible for Nagpur as an early mover in e-mobility-
- Nagpur municipal boundary is in comfortable size in order to cater whole city with fewer charging station
- Extreme weather condition ideal for testing the longevity and efficiency of battery performance
- Political will and proactive nature of governance
Project Development and Implementation:
The idea is to create a state-of-the-art depot facility, with a solar parasol covering the entire area to shade people from the sweltering Nagpur sun. Other facilities include seating areas and advertisement boards etc. The energy generated from the solar parasol (or roof) is stored in a battery energy storage system placed inside a 10ft container placed at the rear of the site. The stored energy is used to charge e-vehicles. Two EVSE equipment are installed allowing a bus and a 4-wheelers to charge simultaneously. Upgradation of the facility is carried out only in the area currently being used by NMC buses.
Electric buses halt at Sitabuldi bus depot for 30 minutes twice in a day. Once in the morning and once in the evening. These buses will be provided with fast top-up recharge (en-route charging) during the halt. These top-up recharge helps the battery installed in the bus to maintain good level of state of charge (SoC) thereby increasing the life of the battery. Also, performing top-up recharge provides an average of 3 - 4 trips for the bus and there is a reduction in the dead-mileage.
The proposed project i.e. PV2EV is a low-cost project to cater the need for charging station on pilot basis. Although the city is planning to install charging facilities to support their electric buses, nonetheless, there is need for fast charging station to supplement the proposed capacity and augment the available charging options by reducing the distance time gap between two charging stations. This project aims at:
- Supplementing the proposed charging infrastructure capacity
- Increase option for recharging
- Demonstration of a Distributed Energy Resource (DER) system for self-sufficiency of charging infrastructure
- Demonstrate transactive energy systems
- Decarbonizing the transport sector by ensuring clean energy source for EVs
- Generating public awareness about the technology and benefits it has for the society and the country at large
- Improving the life of battery by preventing overheating during charging as well as reduced number of operation cycles.
Siteplan of the proposed development at the depot
Over the course of a year, with multiple interactions and engagements with public officers and industry experts, the team has laid out a strategy for implementing a more efficient way of charging EVs and taking the benefit of DER systems. They have explored newer energy markets, demand responsive grid networks and energy secure neighbourhoods. The reports and ideas prepared along the way include-
- Concept video and project brochure to introduce the idea in simple terms to common people.
- Technical report describing the system architecture and requirements.
- Nagpur city specific DPR including site survey report, cost estimation, plan of execution and architectural drawings.
Suggested item-rate RFP to be included in the bid documentAfter ensuring that the DPR was technically sound, and covered all aspects of the project, the team handed over the document to the smart city team for further action. NSSCDCL received necessary permission from all concerned departments and is expected to float soon. The fellows took every precaution to ensure that accurate information was recorded and vetted by domain experts and consultants.
Along the way, the team also assisted MAHA Metro corporation to design their charging station based on the idea developed by the team. The team presented their proposal, PV2EV, to MAHA Metro, Nagpur, and recommended the use solar panels to directly charge 3-wheelers, with an intermediary storage system. The team was able to demonstrate the importance and benefit of such a system for metro’s last mile connectivity proposal.
A DER is a small-scale unit of power generation that operates locally and is connected to a larger power grid at the distribution level. Benefits of DER system are better system control, reduction in AT&C losses, deferment in distribution grid upgrades etc. A schematic representation of DER is shown below.