Hydrogen Blending with Natural Gas : An Overview

Satyesh Bhandari

Hydrogen energy is a key component of the global energy transition to reduce greenhouse gas emissions and address climate change. However, its high cost of production is a major challenge. An alternative solution is being worked out as hydrogen blending in natural gas.

Hydrogen blending in natural gas is?the process of injecting hydrogen into existing natural gas pipelines to create a blend that can be used to generate power and heat.?The resulting blend, known as hydrogen-enriched natural gas (HENG), utilizes the benefits of hydrogen while leveraging current natural gas systems. This blended gas produces lower emissions than natural gas alone.?

Hydrogen is an energy carrier that can be produced and consumed with nearly zero emissions in several key markets where natural gas is used today.?Blending hydrogen into natural gas pipelines is just one of these markets.

Maximum 20%?is the level at which it is expected that gas customers’ supply and usage will not be affected by the change in gas composition. However, existing gas-fired power plants or industrial processes may not be designed to tolerate hydrogen blending beyond a given limit; for many existing gas-fired power plants, this limit is?5% volume.

The major benefits to the hydrogen blending are:

1. Reduced Carbon Emissions: Blending hydrogen with natural gas can lower the carbon footprint, as hydrogen produces no CO2 when burned.
2. Utilization of Existing Infrastructure: It allows for the use of current natural gas pipelines, reducing the need for new investments in infrastructure.
3. Energy Transition: Supports the transition to a hydrogen economy by creating a market for hydrogen and encouraging further investment in renewable hydrogen production.
4. Flexibility: Blending can provide flexibility in energy supply and demand management, making the energy system more resilient.

It is understood that numerous challenges and uncertainties complicate this approach of hydrogen blending. The challenges and concerns that need to be considered about hydrogen blending in natural gas are:?

• Infrastructure Limitations: Existing pipelines may not be fully compatible with high levels of hydrogen, which can cause material degradation and leakage. Hydrogen is known to?reduce the mechanical strength of metals. Hydrogen can embrittle certain metals used in pipelines, leading to potential leaks and failures. Molecular hydrogen is smaller than methane and could escape more easily from typical gas containment measures. The main risks of pipelines transporting hydrogen are the?thermal radiation of continuous fire with the impact pressure of gas cloud explosion, and the fire hazard area is slightly greater than other events.
• Pipeline modifications: Converting natural gas pipelines to carry a small amount of blend of hydrogen and natural gas may only require modest modifications.?However, converting existing pipelines to deliver a higher percentage of hydrogen blending, say more than 20 %, may require more substantial modifications.?While green hydrogen with nil carbon emissions is being talked about as the future fuel, its tendency to corrode pipelines and equipment limits its usage. Tests have established that up to 10 per cent hydrogen can be blended into natural gas without any impact on pipelines or equipment.
• Hydrogen levels & Efficiency Losses: Hydrogen has a lower energy density than natural gas, which may lead to efficiency losses in combustion. The maximum level of hydrogen that can be mixed with natural gas is typically set at 20%.?This is the level at which it is expected that gas customers’ supply and usage will not be affected by the change in gas composition.?
• Transportation: Hydrogen and liquid natural gas (LNG) cannot be blended for transportation applications.?This is because LNG is liquid at atmospheric pressure between -162°C and -182°C, while hydrogen is gaseous at these temperatures.?

• Cost: Producing green hydrogen can be expensive, and blending may not be economically viable without supportive policies and incentives.
• Regulatory Challenges: There may be regulatory hurdles in terms of safety standards and usage limits for hydrogen in natural gas systems. Existing gas quality standards may need to be revised to accommodate blended fuels. There may be insufficient regulatory frameworks governing hydrogen blending, creating uncertainty for investors and operators. Gaining regulatory approvals for blending projects can be lengthy and complicated in absence of proper regulations.
• Safety : Hydrogen can reduce the mechanical strength of metals, which can lead to fractures.?Hydrogen is also smaller than methane and can escape more easily from gas containment measures.?
• Economic Viability : Green hydrogen production remains expensive compared to natural gas, affecting the economic feasibility of blending. Limited demand for hydrogen in certain regions can hinder investment in blending projects.
• Technical Limitations : Determining optimal blending ratios that maximize benefits without compromising safety or efficiency can be challenging. Moreover, accurately measuring hydrogen concentrations and controlling the blend in real-time requires advanced technology
• Public Acceptance : Public concerns about the safety Lack of awareness about the environmental benefits may slow down adoption of hydrogen blending. The variable nature of renewable energy sources used for hydrogen production can complicate blending efforts and overall energy stability.

Addressing these challenges will require coordinated efforts among governments, industry stakeholders, and researchers to develop safe, efficient, and economically viable hydrogen blending solutions.

Despite all the challenges, India has initiated several projects aimed at hydrogen blending, primarily focusing on blending of green hydrogen with natural gas in existing pipelines. Launching of new initiatives and projects are continually being announced.

Major initiatives include collaborations between government entities, private companies, and research institutions. Notably, the Indian government has set ambitious targets for hydrogen production and use as part of its National Hydrogen Mission.

India has?multiple projects?for hydrogen blending, including :

• NTPC Kawas township (first green hydrogen project in India's piped natural gas network blending up to 8% hydrogen). NTPC & Gujarat Gas Limited initiated India's first green hydrogen blending project in?Surat's Kawas township, with green hydrogen produced locally.
• Avantika Gas Limited (AGL), Indore, Blends 2% hydrogen into the CNG network and 5% into the PNG network.?

• The Adani Total Gas Ltd with TotalEnergies has also started blending green hydrogen in natural gas that is supplied to households for cooking purposes in parts of Ahmedabad, with a view to cut emissions and meet net-zero targets. The JV has started blending 2.2-2.3 per cent of green hydrogen in piped natural gas. Hydrogen produced through clean pathways is injected into natural gas pipelines, and the resulting blends are used to generate heat and power with lower emissions. The ATGL has started producing green hydrogen by using wind or solar power. The project is planned to provide hydrogen-blended natural gas to 4,000 domestic and commercial consumers. The plan is to slowly increase the green hydrogen blend in natural gas to 5 per cent and ultimately to 8 per cent and widen supplies to other parts of Ahmedabad.
• State-owned gas utility GAIL (India) Ltd is also doing a small pilot in Indore, Madhya Pradesh, to supply CNG that has been doped with grey hydrogen.

India's goal is to produce 8 million tons of green hydrogen by 2030. The country aims to become a global hub for the production, use, and export of green hydrogen.?

Overall, hydrogen blending is seen as a promising step toward decarbonizing energy systems, but it comes with challenges that need to be addressed.

https://ntpc.co.in/media/press-releases/ntpc-starts-indias-first-green-hydrogen-blending-operation-png-network

https://www.blackridgeresearch.com/news-releases/adani-total-gas-limited-commences-the-green-hydrogen-blending-pilot-project-in-ahmedabad-india?__cf_chl_tk=B_HIsIr3HHAGAE5YT.CqFKdUH8up7XCitihmh2KdzHU-1729157180-1.0.1.1-U4rp1CXEKqYMcPDD_TJRS.6tsRLPsk1H.1drAy5AqRs