Pipelines for Hydrogen Transportation

Pipelines represent the primary option for the most efficient transportation mode in a hydrogen energy environment. There are some issues for gaseous hydrogen delivery via pipelines:

1. High initial capital investment costs.

Although pipeline transmission offers technical and economic advantages as compared to other transportation methods, new pipeline construction imply high initial capital costs. Transporting gaseous hydrogen via existing natural gas pipelines can be a possible option to solve the costs, however more substantial modifications may be required for delivering hydrogen-natural gas mixture.

2. Material challenge.

The pipelines has always been troubled by hydrogen attack in the form Hydrogen Embrittlement (HE), Hydrogen Induced Cracking (HIC), Sulfide Stress Cracking (SSC), and Stress Corrosion Cracking (SCC) issues. Gaseous hydrogen via pipeline also need very high pressure levels (up to 3000 psi). The use of composites, fiber-reinforced polymer (FRP), for pipelines may be an alternative to resolve that issues. But, the challenges for adapting FRP pipeline technology still appear, such as:

- Evaluating the pipeline materials for hydrogen compatibility

- Developing a method for manufacturing large-diameter pipelines

- Developing a plastic liner with accpetably low hydrogen permeability

3. Hydrogen leakage and integrity monitoring sensors

Hydrogen is odorless, colorless, and tasteless and therefore undetectable by human senses. Because of that, hydrogen pipelines requires sensors for detecting hydrogen leaks and monitoring pipeline integrity. There are several sensor technologies currently available for monitoring mechanical integrity of pipelines. To apply those sensor technologies for hydrogen pipelines, some issues need to resolved, such as: characteristics of leak signal from light atomic weight of hydrogen gas, special distance resolution along the pipeline, response time, and the accuracy of alert calls.

4. Hydrogen compression

Compression is an integral aspect of gaseous hydrogen delivery via pipelines. Utilizing natural gas compression technologies for hydrogen is unreliable because (a) the hydrogen molecule is much smaller and ligher than natural gas (b) gaseous hydrogen contains only one-third he energy of natural gas. For example: this requires up to 60 stages of centrifugal compression of hydrogen as compared with four to five stages for natural gas.