Producing more energy while accelerating efforts to reduce greenhouse gas (GHG) emissions and increasing energy independence is one of the world’s biggest challenges – technologically, politically and economically. This article will discuss how cryogenic technology is helping to shape the energy transition through a nexus of clean energy, comprising LNG, liquid hydrogen, and carbon capture.
As the cleanest burning fossil fuel, natural gas is often touted as the bridging fuel to net zero. It has increased its share of the global energy mix to almost 25%, predominantly through the displacement of coal. According to data from the International Energy Agency (IEA), natural gas emits between 45 – 55% fewer GHG emissions than coal when used to generate electricity and, between 2010 – 2018, switching from coal to natural gas-fired power generation prevented 500 million t of carbon dioxide (CO2) emissions from ending up in the atmosphere.1 Natural gas is also proven in industrial processes; is oftentimes a ‘quick fix’ solution for reducing emissions due to existing infrastructure; and is similarly proven as a transportation fuel for heavy goods vehicles and marine vessels. Further to this, it is a stable support for renewable sources, providing supplementary power generation during peak loading, and when the sun does not shine or the wind does not blow hard enough.
Hydrogen is taking centre stage in many energy roadmaps. With advancements in fuel cell stack technologies and continued cost reductions, hydrogen can be used as an energy carrier to fulfil several roles in the energy sector. With its ability to store renewable power, produce electricity, and power light and heavy-duty vehicles with zero tailpipe emissions, hydrogen has the capacity to be a global energy source at scale.
Traditionally, carbon capture and storage (CCS) has been used as a process to capture CO2 emissions from power generation and industrial processes that burn fossil fuels, compressing the gas and transporting it to areas where it can be injected deep underground. This method is therefore an important step in the decarbonisation of hydrogen that is produced from steam methane reforming (SMR) of natural gas, and coal gasification, which still dominate the energy mix. Blue hydrogen is the term applied to the hydrogen produced following the decarbonisation of grey and brown/black hydrogen.
Carbon capture, utilisation and storage (CCUS) is a further step change in the evolution of carbon capture where, instead of being securely stored as a waste product, CO2 is recognised as a valuable commodity and recycled for uses in many industries such as cement, brewing, and food processing.
Natural gas liquefaction
Natural gas is liquefied through cryogenic processing, reducing its volume to 1/600th of its gaseous equivalent. This makes it easy to transport and store. Until relatively recently, natural gas was predominantly liquefied in ever-larger baseload facilities, and transported across oceans in huge tankers before being landed and regasified for pipeline transmission at similarly large-scale import terminals. The only real exception to this rule are the much smaller peak shavers, which, as the name suggests, were deployed during periods of high load. However, by adapting and refining this small-scale liquefaction approach, a technically-feasible and commercially-viable solution for production and distribution of much smaller volumes of LNG revolutionised the landscape, bringing power to off-grid locations and providing an alternative transport fuel for trucks, ships, and even railway locomotives.
The key to the success of small-scale LNG is bringing gas to the market quickly, as well as simple plant operation. As a result, instead of a bespoke, custom design every time, a major feature is a range of standard, repeatable-design liquefaction plants. This significantly reduces the project timescale and delivers lower CAPEX. Small-scale cryogenic liquefaction plant sizes typically range from 15 000 gal./d (25 tpd) through to 450 000 gal./d (720 tpd), where the larger plants (50 000+ gal./d) are predominantly aimed at liquefaction of pipeline gas for virtual pipeline solutions, and plants below 50 000 gal./d are often applied to liquefaction of waste methane to produce liquified biogas (LBG). As with their much larger counterparts, there is also a choice of liquefaction technologies through mixed refrigerant processes, as well as the Reverse Brayton Nitrogen Cycle ...
Written by Bob Oesterreich and Peter Gerstl, Chart Industries.
Read the article online at: https://www.hydrocarbonengineering.com/special-reports/17052022/a-nexus-of-clean-energy/