Decarbonisation Technology - February 2022 Issue

Flue gas to FGD/SCR/CCS as required

Air

Air separation unit

O gases

Natural gas + hydrogen

Steam

Oxygen

ATR

Fired heater

Recycle compressor

Condensate

Ammonia product

Air Fuel Steam

Raw syngas

Hydrogen-rich gas

Boiler feed water

Air separation units can provide oxygen to the ATR and nitrogen to the ammonia reactor in decarbonised ‘blue-energy islands’

retrofits onto existing carbon-intensive processes, such as decarbonisation of coal fired power plants and carbon capture from SMRs. Since these have been retrofits projects, reforming technologies and CCS have been developed in parallel. They have never been optimised synergistically as an integrated process. Regarding blue hydrogen production, a paradigm shift is required: the system must be optimised in a holistic way. Downstream of the reformer, some blue hydrogen schemes will also integrate a blue ammonia plant. Like hydrogen, ammonia is a carbon-free energy vector. Use of ammonia as a fuel will expand its range of applications and drive significant growth in ammonia demand. Ammonia production would require nitrogen as a feedstock to react with the hydrogen to make ammonia. The nitrogen could be produced on the ASU alongside the oxygen that feeds the ATR. The reforming, air separation and ammonia processes would be interdependent, and the integrated equipment can be viewed as a decarbonised ‘blue-energy island’. Giga-scale oxygen for gas-to-liquids The use of natural gas and ASUs to make syngas for fuels goes beyond their proposed application to make hydrogen. In 2006, the Oryx gas-to- liquids (GTL) project in Qatar was built to add value to natural gas and produce liquid fuels as

proposes a 600 MW autothermal reformer (ATR) to make hydrogen-rich syngas. Conventional steam methane reformers (SMRs) do not require pure oxygen. On the other hand, ATRs do. To enable 600 MW of hydrogen production, the air separation unit (ASU) would need to produce about 1200 tonnes of oxygen per day. That would make it one of the largest in the UK. Producing hydrogen from natural gas using reformers means that carbon dioxide (CO 2 ) is generated from the process chemistry and the heat energy requirements. ‘Blue hydrogen’ is produced through the integration of carbon capture and storage (CCS) with the reformer. To qualify for the ‘blue’ hydrogen label, the captured CO 2 will be sent to a CCS scheme under the North Sea, where it will be stored underground permanently in natural geological formations. CCS in the North Sea is a proven technology. Equinor commenced capture and sequestration of CO 2 on the Sleipner West field in the Norwegian sector more than 20 years ago. The components of a CCS scheme, from the absorption tower to the multi-stage CO 2 compressor with integrated drying system, are all highly developed. Beyond Norway, CCS, or carbon capture and usage (CCUS) combined with enhanced oil recovery (EOR), has also been used in Australia, Canada, and the United States for many years. Most major schemes have involved carbon capture