Hydrogen blending as a path towards US decarbonisation

U.S. natural gas infrastructure is expanding, servicing 32% of the nation’s energy consumption by 2021. To reduce emissions from natural gas service, hydrogen mixing into natural gas pipelines could prove to be a promising and cost-effective avenue. It will not only utilize existing natural gas infrastructure but also serve key end users where electrification is uneconomical.

Hydrogen is an energy carrier that can be produced and consumed with near-zero emissions in several key markets where natural gas is used today. mix hydrogen into natural gas pipelines is just one of these markets, but numerous challenges and uncertainties complicate this approach.

A technical report co-authored by researchers at the National Renewable Energy Laboratory (NREL), Sandia National Laboratory, and Pacific Northwest National Laboratory examines the state of hydrogen blending technology to provide direction for future hydrogen mixing research. Report titled “Hydrogen blending into natural gas pipeline infrastructure: A state of the art assessment,” which explores the physical, economic and operational factors that must be considered, including summarizing studies that develop relevant mathematical models used to study how hydrogen mixing affects operations of natural gas transmission and distribution infrastructure.

“The concept of mixing hydrogen into natural gas pipelines is not new and has been around for decades, but there are still gaps,” said Mark Chung, head of hydrogen systems analysis at NREL. big consciousness. “We hope this study serves as a useful reference for those who are considering mixing demonstrations or related research areas in the future.”

Anti-fatigue

One of the main challenges for hydrogen mixing is hydrogen-induced cracking. Solid metal can easily permeate hydrogen because it is the smallest element in the universe. Like hydrogen atom absorbed and diffused in pipeline steel, they can affect the fatigue and fracture resistance properties of the material. These impacts can make pipe steel more susceptible to cracking.

The technical report discusses the research needed to combat this phenomenon. Although there are design guidelines for evaluating suitable operating pressures for common piping materials, additional fatigue and fracture testing of classical steels used in piping systems is required. U.S. natural gas pipelines to determine limiting behavior in hydrogen environments. In addition, the effects of hydrogen on various materials and equipment, such as plastic piping, compressors, valves and other non-pipeline equipment, such as storage facilities, should also be assessed. price. For example, the presence of hydrogen in some geological storage formations can stimulate and grow pre-existing subsurface microorganisms so that the hydrogen contained therein is consumed to produce harmful substances. hydrogen pollution.

The effects of hydrogen on microorganisms in geological storage facilities have not been well studied but are essential to understanding how to ensure the integrity of the hydrogen mixing process. Through the SHASTA (Subsurface Hydrogen Technology Assessment, Storage and Acceleration) project, multiple national laboratories are working together to determine the viability, safety, and reliability of storage. store pure hydrogen or a mixture of hydrogen natural gas in a subsurface environment.

consider activity

Degradation of pipeline materials is not the only challenge that hydrogen presents. The energy density of hydrogen also presents energy transfer challenges. At a fixed pressure drop along the length of the pipeline, the lower energy per unit volume of hydrogen compared to natural gas reduces the energy-carrying capacity of the pipeline and may not be sufficient. end-user energy needs. The increase in the flow rate of the blended hydrogen gas although the pipeline can compensate for the reduced capacity, the energy used to compress must also increase to compensate for the drop in pressure along the pipeline. Doing so may result in additional costs for the pipeline operator and ultimately the end user.

The technical report summarizes these operational considerations for the economic evaluation of hydrogen mixing opportunities. The opportunity costs associated with reducing the energy transfer capacity of the hydrogen mixture as well as the steps required to prepare the pipeline network and end-use applications for the hydrogen mixing process should be taken into account.

Real world performance

Another challenge for the implementation of hydrogen mixing systems is the lack of research and demonstration of hydrogen mixing. Several demonstrations around the world in recent years have demonstrated that low-hydrogen mixtures with natural gas are feasible, but these demonstrated scenarios are limited to end uses.

Small case studies are just the beginning. Further research is needed across the entire hydrogen and natural gas supply chain to fill current knowledge gaps and better inform policymakers and decision makers about future projects. future hydrogen mixing projects. Projects are currently underway to demonstrate larger-scale pipeline systems with higher mixtures and pure hydrogen flows.

The HyBlend initiative, which generates the technical report, was created by the US Department of Energy’s Office of Hydrogen and Fuel Cell Technology to address technical barriers to hydrogen mixing in pipelines. natural gas pipeline. NREL leads a collaborative R&D project in HyBlend that includes three other national laboratories—Sandia National Laboratory, Pacific Northwest National Laboratory, and Argonne National Laboratory—and more than 30 research partners. from industry and academia. The report provides information on the development of analytical models and tools to evaluate the technical requirements of hydrogen blending as part of the goals of the HyBlend initiative, including open source. nature Air pipeline upgrade tool for release late 2023.