The International Energy Agency has just predicted a second natural gas revolution based on a boom in liquefied natural gas. Its annual World Energy Outlook forecast that gas demand would rise almost 50% by 2040, but long distance LNG trade would more than double. The analysis recognises that gas is the cleanest fossil fuel, and LNG its most flexible form, but misses another important quality: LNG is extremely cold. If this were properly exploited, the IEA's predicted LNG revolution could also provide a massive boost to the emerging 'cold economy'.
LNG is natural gas that has been refrigerated to -162°C - consuming large amounts of energy - to make it compact enough to transport by tanker. But this 'coolth' or cold energy is normally discarded during re-gasification at the import terminal.
At the same time, current cooling technologies are energy intensive and highly polluting, already causing around 10% of global CO2 emissions, 3x that attributed to aviation and shipping combined. Cooling is vital to our modern society through food and pharmaceutical cold chains, data centres and air conditioning, and demand is accelerating, especially in fast-growing developing economies. Global energy demand for space cooling will overtake space heating by 2060, and in fact, the IPCC has projected that by the end of the century air conditioning will consume almost half the electricity generated worldwide today.
There is therefore an urgent need to 'green' the provision of cold, and one major opportunity could be to recycle the waste cold of LNG to provide lower carbon, zero-emission cooling services. In developing nations, this could form the basis of an entirely new 'cold economy', which not only cuts emissions and cost, but also tackles critical social and economic challenges by reducing waste of food, water and other resources.
Of the 111 LNG import terminals worldwide, only 23 do any form of cold recovery. Even here the use of the waste cold is usually limited to industrial plants close to the terminal, and only at times when LNG is actually being re-gasified. These factors limit the amount of cold recycled, but this could be raised by converting it into novel energy vectors that store and transport it for use on demand such as liquid air.
Recycling waste cold in this way would produce cheap, low carbon, zero-emission cryogenic 'fuel' to provide distributed cold and power for vehicles and buildings. Technologies are already being developed that could exploit large amounts of LNG waste cold. A liquid air zero-emission transport refrigeration unit to displace the highly polluting secondary diesel engines used on trucks and trailers is now in commercial trials with Sainsbury's in the UK. A projected global trade of 500mtpa LNG in 2025 could produce enough liquid air to cool almost 4 million fleet-average refrigerated trucks - equal to the entire global TRU fleet today. Other applications in development including data centre cooling.
Obviously it is all about economics. But analysis shows the liquid air could generate revenues worth more that 10% of the value of LNG at current market prices. Equally important are the environmental benefits. A diesel transport refrigeration unit consumes up to 20% of a refrigerated vehicle's diesel. Replacing a diesel TRU would slash the vehicle's total emissions of NOX by over 70% and of PM by over 90%, as well as reducing its CO2.
It is vital that the world's rapidly expanding cooling infrastructure should be clean. And it is only logical we stop wasting the 'packaging' of LNG and start to exploit the economic and environmental benefits of this waste cold.