Adsorbed Natural Gas Technology Overview

Adsorbed Natural Gas Technology

Adsorption is a process where materials interact at interfaces between gases, liquids, and solids. In the context of energy storage and fuel transportation, adsorbed natural gas (ANG) refers to the liquid methane stored under moderate pressures (up to 70 MPa) in porous solid matrices such as activated carbons. ANG has several advantages over compressed natural gas (CNG), including higher energy density, reduced bulk volume, and lower storage pressure.

Advantages Over Compressed Natural Gas

The main advantage of ANG is its high energy density compared to CNG, which allows for more efficient use of space in storage vessels and transport. ANG can store up to 3 times more energy per unit mass compared to CNG. Additionally, ANG requires only moderate storage pressures, whereas CNG needs much higher pressures, which can lead to safety concerns with material selection and vessel integrity. This makes ANG safer in terms of handling and storage than CNG.

Moreover, ANG technology has potential environmental benefits because it reduces greenhouse gas emissions by approximately 65% when used in heavy-duty vehicles compared to diesel. It also improves air quality due to low particulate matter emissions from the engines using ANG as fuel. The combustion of ANG produces water vapor, carbon dioxide, and nitrogen oxides, similar to the exhaust produced when burning fossil fuels.

Applications in Energy Storage and Fuel Transport

One major application of ANG technology is in the field of hydrogen storage. Methane molecules have strong interactions with the surface of certain metals such as iron, which could control the desorption behavior of hydrogen from catalysts and multilayer films. This property could potentially allow for improved efficiency and capacity in hydrogen storage systems.

In addition to energy storage, ANG technology can be applied to fuel transportation through trucks, trains, ships, and aircraft. For example, ANG can replace traditional liquid fuels like diesel and jet fuels in these applications, providing significant reductions in greenhouse gas emissions.

Implementations and Future Prospects

Pilot projects for ANG trucks already exist in Europe, particularly in Switzerland, Germany, and Italy. Commercialization efforts are ongoing, and some companies, like Renewable Synergy BV, are investing in this area. In the United States, several entities are working on ANG projects, including the Department of Energy's National Renewable Energy Laboratory and the University of California, Berkeley.

Despite these promising developments, challenges remain in scaling up the technology and reducing costs. Further advancements in materials science, thermodynamics, and engineering will be necessary to overcome these hurdles and make ANG a viable alternative to conventional fuels.