Why green hydrogen presents both major opportunities, significant challenges

Subject: Science and tech

Section: Msc

Context:

The Ministry of New and Renewable Energy (MNRE) has announced a Rs-496-crore (until 2025-26) scheme to support pilot projects that either test the viability of green hydrogen as a vehicle fuel or develop secure supporting infrastructure such as refueling stations.

Hydrogen as a fuel:

Hydrogen is a clean fuel that, when consumed in a fuel cell, produces only water.
Hydrogen can be produced from a variety of domestic resources, such as natural gas, nuclear power, biomass, and renewable power like solar and wind.
Hydrogen is a versatile energy carrier that can be produced from a wide range of sources and used in many ways across the entire energy sector.
It can be produced from Solar-driven processes using light as the agent for hydrogen production
Water can be separated into oxygen and hydrogen through a process called electrolysis

Types of Hydrogen:

Hydrogen is colorless, and green hydrogen is ‘green’ only by virtue of the way it is produced, and the source of the energy used to manufacture it.
Green hydrogen refers to hydrogen that is produced from the electrolysis of water — splitting it into hydrogen and oxygen — using an electrolyser powered by renewable energy.
This is considered to be a virtually emission-free pathway for hydrogen production — it is ‘end-to-end’ green because it is powered by green energy, uses water as feedstock, and emits no carbon on consumption.
Currently, most hydrogen produced for industrial consumption and applications is ‘gray’ hydrogen, which is produced from natural gas through energy-intensive processes, and has high carbon emissions.
Except for a difference in the production pathway and emissions, green hydrogen is essentially the same as gray — or hydrogen categorized by any other color.
When hydrogen is produced from natural gas but carbon emissions are captured and stored, or reused it is called “blue” hydrogen.

Transport sector scheme

The major objectives of the MNRE scheme, guidelines for which were issued in February, include

(i) validation of technical feasibility and performance of green hydrogen as a transportation fuel,
(ii) evaluation of the economic viability of green hydrogen-powered vehicles, and
(iii) demonstration of safe operation of hydrogen-powered vehicles and refueling stations.

The Ministry of Road Transport & Highways will appoint a scheme implementation agency that will invite proposals for pilot projects.
The selected company or consortium will be the project’s executing agency.
Based on the recommendation of a Project Appraisal Committee, the MNRE will approve viability gap funding (VGF) for the project.
The VGF amount will be finalized after considering specific needs, merits, and feasibility of each project.
The executing agency will be required to complete the pilot project within two years.

Hydrogen fuel cell vehicles

A hydrogen internal combustion engine (ICE) vehicle utilizes hydrogen through combustion — which is similar to cars running on diesel and petrol, except there are no carbon emissions.
A hydrogen fuel cell electric vehicle (FCEV) utilizes hydrogen electrochemically by converting hydrogen stored in a high-pressure tank into electricity, leaving water as the byproduct.
Even though hydrogen ICE vehicles do not emit carbon, research suggests that burning hydrogen is far less energy efficient than converting it into electricity in a fuel cell.
Compared to battery electric vehicles (BEVs), in which the battery is the heaviest part, hydrogen FCEVs are typically much lighter because hydrogen is a light element, and a fuel cell stack weighs lesser than an electric vehicle (EV) battery.
This makes hydrogen fuel cell technology a viable alternative to EV battery technology, especially for heavy-duty trucks that can benefit from an increased payload capacity — without coughing clouds of smoke from burning diesel.

A number of challenges

There are significant challenges to the large-scale use of green hydrogen in the transportation sector.
The foremost among these is the prohibitive cost of production, followed by challenges of storage and transportation at scale.
With more innovation in technology and scaling-up of production though, costs are likely to come down in a few years.
Green hydrogen-powered vehicles are not yet seen as a suitable alternative to four-wheel BEVs due to challenges arising from fuel costs and building supporting infrastructure.
Currently, most cylinders manufactured in India are designed to carry compressed natural gas (CNG).
But hydrogen is stored at a much higher pressure, and CNG cylinders cannot carry hydrogen.
For cylinders to carry a high mass of hydrogen, the carbon fiber needs to be stronger, which makes high-pressure hydrogen cylinders expensive.
This is a key barrier to the adoption of hydrogen as a transport fuel.
For the same reason, the existing natural gas pipeline infrastructure is also not seen as viable.
Hydrogen is extremely flammable, which means that special care would be needed in handling the fuel at retail stations compared to diesel, petrol, or even CNG.