More than 75 per cent of the urban infrastructure to be built by 2050 remains underway across the world. A similar scenario is seen in countries including India, where growing aspirations coupled with an increase in disposable income and urbanisation rate are driving the need to expand city limits periodically. The construction sector, holistically, contributed to 9 per cent of India’s GDP in 2021 and is expected to reach $1.4 trillion by 2025. Typically, the sector includes real estate (buildings) and urban development (enabling infrastructure including schools and healthcare) segments.From an ecosystem perspective, it encompasses all materials (such as glass, brick, cement, steeland concrete) and mechanisation (including trucks and heavy machinery) in addition to other enabling infrastructure.This viewpoint allows us to examine the role of green hydrogen to substantiate the decarbonisation potential of the construction industry. Both the material and mechanisation aspects are heavily reliant on fossil fuels (mostly coal and diesel) for their thermal energy dependency. This article provides an exploratory analysis to see the merits of utilising green hydrogen in the construction industry.

Green hydrogen

Green hydrogen is produced fromelectrolysers using water and renewable electricity. Water is split into hydrogen and oxygen through electrolysis. Hydrogen is stored for further energy requirements and oxygen is vented out.

Decompartmentalising construction: Through the energy lens

The energy sector in India is heavily dependent on fossil fuels. Typically, energy needs in the construction industry can be bifurcated into electricity and heat (thermal energy). In this regard, coal and diesel are two of the most commonly used fuels in this industry. Coal is used in manufacturing of cement, steel and bricks, whereas diesel is used in heavy machinery and vehicles like trucks, bulldozers, cranesand concrete mixers.Additionally, other oil derivatives and natural gas are used in industries to produce glass, cement and steel. Given the dependency on fossil fuel, it is imperative that some of these energy sources are effectively decoupled through scalable alternative fuels, such as hydrogen.

At construction sites, hydrogen can be used to power heavy machinery and equipmentor to replace diesel generators for power backup. It must be compressed and stored in cylinders under pressure to increase storage density. Depending on the application, it can be stored under 350 and 700 bar. It can be stored as compressed gas or cryogenic liquid and transported as such in cylinders and cryogenic tanks for ex-situ application.

The application of hydrogen in the construction industry across the globe is at a nascent stage or being carried out on a pilot basis. However, owing to safety and poor standardisation issues, most projects to date rely on fossil fuels to supplement their energy needs. This will change as countries standardise the application of hydrogen in various segments of their economy.

For material production

Most of the steel produced today comes from the blast furnace route. Typically,directly reduced iron (DRI) uses coal as a reducing agent. However, it is proven that hydrogen can be used as a reducing agent without compromising the quality. As the sector continues to explore innovative ways to decarbonise, the share of steel produced through the DRI-based route and secondary steel-based electric arc furnaces must be proportionately increased.

In case of cement production, substituting coal in rotary kilns with hydrogen should be judiciously explored. Further, a combination of electrolyser-based solutions can be used to produce electricity at source, instead of captive power plants. While these options are technically feasible, their economic viability is currently a distant dream. The recent nudge from the Government through the National Green Hydrogen Mission is expected to bring down the costs over the next few years through economies of scale. There is a clearupside to embracing hydrogen-based solutions. For every 1 per cent of coal substituted with green hydrogen, approximately 0.93 kg of CO2 can be abated. Similarly, replacing natural gas and coal in DRI routes with green hydrogen is estimated to reduce 1.3-1.6 tonne of CO2 for every tonne of crude steel produced. However, thechallenges that may deter the rate of adoption should also be addressed.

Adoption of hydrogen

The rate of adoption is going to be dependent on resolving four key challenges: inflated cost of production,lack of effective storage options,ill-established supply chain, andpolicy and regulatory hurdles. While the cost part is expected to reduce gradually as the market grows, the safety aspects associated with efficient storage and retrieval of hydrogen might hinder progress.A well-established supply chain taking into accountproduction, consumption, storage and delivery aspects will serve the sector a world of good. At present, the supply chain is either non-existent or available at a miniscule level. Finally, the lacuna in policy and regulatory aspects is expected to be filled as nodal agencies that administer the sector implement timely policies across all three aspects of the hydrogen ecosystem. Under the ambit of the National Green Hydrogen Mission, an outlay of Rs 197.44 billion has been allotted.Atmanirbhar Bharat and production-linked incentives (PLIs) are other instruments that can drive the investments around the hydrogen supply chain.

In conclusion, the need for hydrogen in the construction industry is well established. Given the national goals around energy security and the voluntary commitment to the net-zero goal, stakeholders will be empowered to join the bandwagon. However, cost-effectiveness coupled with improved technology readiness (in terms of storage and delivery) will determine our ability to achieve the target of the National Green Hydrogen Mission.

About the author:Dr N Rajalakshmi is an Advisor at the Centre for Study of Science, Technology and Policy (CSTEP), a research-based think tank.

Murali Ramakrishnan Ananthakumar is a Research Scientist and leads the Hydrogen Group at CSTEP. He holds a masters in public policy from the Lee Kuan Yew School of Public Policy, The National University of Singapore.