We can’t overlook challenges of hydrogen transport, storage & emissions

The hydrogen network is coming! The UK strategy aims for five gigawatts of hydrogen production capacity by 2030 — enough to replace natural gas in powering three million homes plus transport and industry. But with innovation comes challenge, as Dr Liyun Lao of Cranfield University, reveals.

By 2050, hydrogen is expected to constitute 25-30% of national energy use. Last year the European Union backed a €5.4 billion investment in hydrogen technology projects around the continent, with billions in additional subsidies expected to follow to support industry decarbonisation. At the same time, the EU has approved increased proportions of hydrogen in natural gas supplies, up to 20%.

But the transition to low and zero carbon technologies like hydrogen comes with a raft of new challenges around the recovery and transport of natural gases: problems with ‘wet gas’ in particular: with the amount of energy needed for processing and transporting; the related carbon emissions; and during an age of crisis over energy costs, with making sure there is accurate metering and measurement.

Wet gas, also known as natural gas with condensation, is a type of natural gas that contains significant amounts of liquid hydrocarbons. Often found in the same geological formations as dry natural gas but requiring different processing methods due to the presence of these liquid hydrocarbons, wet gas can contain valuable liquid feedstocks — as little as 20 parts per million, or more like 5 parts per 100. But wet gas can also be a significant issue. Liquid builds up in pipelines, settles at the bottom of pipes over time. This can lead to a loss of momentum in the transport of gases, less efficiency and blockages.

The related problem is accurate metering. Just small amounts of moisture can have a significant effect on readings, an impact that existing technology is not able to account for, meaning unreliable figures, exaggerated over time, and a real impact on business modelling costs. Mixing hydrogen with natural gas supplies comes with additional problems for metering. Being lighter than natural gas raises questions over how supplies should be costed.

An important part of the shift to lower carbon technologies needs to be attention to process engineering plans, ensuring we are alert to new conditions, new issues for plant, transport and storage. That includes the supporting technologies around carbon capture storage and ways in which CO2 is transported into underground reservoirs etc.

Hydrogen is a good example of the need for close examination of unintended consequences in costs and carbon emissions. Fossil fuels, currently, are still needed for the production of around 97% of world supplies of blue hydrogen (as opposed to cleaner methods used for green hydrogen). With the growing emphasis on hydrogen technologies there is an urgent need to focus on the efficiency of all the processes involved in transport and storage and the ways in which any related carbon emissions can be minimised.

One example of how the package of issues of wet gas, energy consumption and carbon emissions can be tackled with relatively straightforward technological adaptations is in the use of an in-line separator.

Work at Cranfield has led to the development of a small device usable capable of removing build-up of wet gas during transportation. Traditionally, the separation process takes place at the end of transport, at a receiver station — but involves a large piece of plant, use of energy and related carbon emissions. The in-line equipment, designed as mini-separators stationed along a gas transportation pipeline, can remove the condensates from the main transportation channel saving on the energy needed for gas flows.

The use of in-line separation changes the whole formula of costs and consequences, & makes transport from more remote and long-distance locations – such as the subsea tiebacks needed to connect newly-discovered oil & gas deposits to a production centres — which have not been economically or technically feasible, commercially viable.

The transformation of the energy sector is inevitable, and the benefits of the alternatives to fossil fuels are clear. But all along the way of transition there needs to be a clear-eyed attention to the details of processes unless there are to be false starts and dead ends.

Dr Liyun Lao is Principal Research Fellow in Energy and Fluid Systems, Centre for Energy Engineering, Cranfield University, cranfield.ac.uk

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