Decarbonizing Mumbai’s grid and building energy-resilient infrastructure

Mumbai is drafting a Climate Action Plan, led by the Municipal Corporation of Greater Mumbai (MCGM) and the Ministry of Environment & Climate Change, Government of Maharashtra, scheduled to be completed by the end of the year. The MCAP will serve as a systematic framework to measure impacts and guide the city towards low-carbon, resilient and inclusive development pathways. WRI India has been engaged as a knowledge partner for this endeavor.

The Plan will focus on six key action areas to build sector-specific strategies for mitigation and adaptation. This blog looks at the ‘Energy & Buildings’ action area.

The Energy & Buildings sector accounts for over 60% of total GHG emissions in Mumbai. Electricity consumption in residential and commercial & institutional buildings is responsible for over 45% of the city’s total emissions and presents the biggest mitigation opportunity for Mumbai. Refer to figure 1 for a break-up of stationary energy emissions by subsector.

Figure 1: Stationary energy GHG emissions by subsector 2019 (top), Mumbai’s Electricity Grid Mix 2019 (bottom)

Increasing the proportion of renewables in Mumbai’s energy mix

The electricity generation mix is currently dominated by coal, natural gas and fossil fuel based thermal power at 95%, followed by hydro, wind & solar power at 5% (Refer to figure 2 for a detailed breakup). Mumbai’s energy demand was at its peak during last summer at 3400-3600 MW, which was 24% of Maharashtra’s total energy demand in 2020. With push towards electric mobility and demand for cooling, the city’s energy demand is only going to increase. According to a 2017 study, the city has a potential of 1,724 MW of solar energy across rooftops of residential, educational, commercial & municipal buildings and industries, which could help meet almost half of the city’s total energy demand. Rooftop solar installation in residential buildings alone can generate up to 1,300 MW, followed by industrial buildings at 223 MW and educational buildings at 71 MW. Andheri West area (K West Ward) and Borivali (R Central Ward) have the highest solar potential in Mumbai. The Maharashtra Electricity Regulatory Commission (MERC) in 2021 allowed a ‘Green Power Tariff’ of ₹0.66 /kWh to be levied on consumers opting for 100% green energy. Accordingly, the DISCOMs owned by Adani and Tata Power are both offering their consumers including corporates, industrial, commercial, hotels, restaurants, and residential consumers the option of a green power tariff in Mumbai. The cost of procurement of RE is only borne by specific consumers who opt for the RE option. Consumers have the flexibility to decide the percentage of RE in their total energy consumption and can opt for 100% RE too.

Improving energy efficiency in new and existing infrastructure

Building emissions in Mumbai are dominated by electricity consumption at 75%, followed by LPG at 10%. Thus, buildings & households are important urban sites in developing city-level mitigation strategies. Cooking, cooling, and heating water are key activities in the buildings sector that consume the most amount of energy, leaving a large footprint. Saving energy through energy efficiency improvements can often cost lesser and be implemented faster than generating, transmitting, and distributing energy from power plants. Energy efficiency upgrades to efficient cooling systems, stoves and water heaters can also increase overall comfort and improve respiratory health due to improved indoor air. In fact, cost of electricity can disproportionately burden households with older, lesser efficient equipment and facilities. Thus, planning and implementing programs to improve efficiency would not just help in reducing emissions but also reduce the electricity-cost burden.

Promoting green buildings

Mumbai has 144 certified green buildings out of 373 green buildings in Maharashtra. The Maharashtra Energy Development Agency (MEDA) is the designated agency to co-ordinate, regulate and ensure ECBC compliance, promote and develop energy efficiency in the state, and facilitate RE development. Although ECBC has not been made mandatory in Maharashtra yet, Mumbai can facilitate & mandate ECBC compliance, setting a precedent for the state and other cities, in not just commercial but also residential buildings, and mainstream green building certification. Earlier this year, WRI India conducted consultations on decarbonizing the buildings and construction sector through a value-chain approach. The value chain includes all stakeholders from planning to service provision stages: including governments, architects, material manufacturers, suppliers, builders, contractors, service providers, and companies involved in O&M works. It would be essential to explore interventions at every stage to decarbonize buildings in a holistic manner. Buildings with large glass and concrete facades, with no trees or adequate setbacks, reflect excess heat on streets resulting in heat island effects; certain areas are much warmer than others with better green cover and lesser reflective surfaces. Poor choice of building materials increases indoor temperatures and building energy demand and increases heat risk on public streets. Figure 2 shows an increase in land surface temperature over a decade before and after the Metro Line 1 was built resulting in increased temperatures along the corridor due to densification.

Figure 2: Land surface temperature increase over 10 years (range from 2005-2010 [top] and 2015-2020 [bottom]) along Andheri-Ghatkopar link road due to heat island effect

Integrating passive design strategies for thermal comfort

In Mumbai, the energy decarbonization story is as much about grid decarbonization and green building regulations & ratings, as it is about thermal comfort and affordable cooling solutions. Mumbai is home to the world’s largest slums: Mankhurd and Dharavi, and over half of the population live in informal settlements built with temporary building materials that absorb and reflect heat, unhabitable during extremely hot days. These areas are almost 5-6 degrees warmer than residential societies with adequate trees and open spaces. According to WRI India’s analysis, one-third of all heatwaves from 1973 onwards occurred in the last ten years in Mumbai. With rising temperatures, the demand for cooling, and thereby electricity will also go up; however, poor communities have limited access to cooling equipment and in many cases have poor access to electricity. Due to increased indoor temperatures, the lack of space, light, and ventilation, these communities are most vulnerable to vector borne diseases, causing perpetual health concerns. LIG housing schemes, and rehabilitation and redevelopment projects must follow green building codes, get certified by established rating systems, and ensure adequate light and ventilation to build energy resilient housing. Towards a just transition to decarbonize Mumbai’s energy sector, it is essential for EWS and LIG housing schemes to follow green building codes a.

To tackle Mumbai’s energy sector emissions, an approach that addresses both the supply side – increasing renewable energy, and the demand side – improving energy efficiency is required. Additionally, Mumbai’s large building stock requires a value chain approach to help identify hotspots and suggest corresponding actions to decarbonize the buildings sector for all. It is also essential to integrate passive design strategies to improve thermal comfort and reduce heat islands in the city.

This blog is written by Avni Agarwal & Mehul Patel

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