Professor Richard A. Williams, Principal and Vice Chancellor, Heriot-Watt University and Professor Toby Peters, Visiting Professor in Transformational Innovation for Sustainability, Heriot-Watt University share new thinking on how to meet the global demand for cooling – while reducing emissions and energy use – and call for global working groups from R&D institutes to accelerate delivery.
Cold is a pillar of modern society and demand is booming worldwide to deliver air conditioning, data centre cooling and transport refrigeration, particularly in emerging economies. Although our cooling technologies are becoming increasingly sophisticated, they are, in equal measure, energy intensive. The IPCC projects that, by the end of this century, air conditioning alone will consume almost half the electricity that we generate worldwide today.
Cold is also highly polluting, emitting 10% of the world’s CO2 emissions, which is three times more than aviation and shipping combined. Large amounts of toxic NOx and particulate materials are also released.
While we pollute, we are equally wasteful, throwing away huge quantities of cold during the re-gasification of liquid natural gas (LNG) at import terminals. But what if we could recycle this wastage, simultaneously providing cold and power? Could this dramatically reduce the environmental impact and spiralling costs?
The global trade in LNG has increased significantly in recent years and is vital to the energy security of a growing number of countries. LNG is natural gas that has been refrigerated to -162°C to make it compact enough to transport by tanker, but this cold energy is normally discarded during the re-gasification process. Research suggests that recycling this waste cold could generate more than $50 per tonne in economic and social benefits. With a projected global LNG trade of 500 million tonnes, this new “waste recycling” market could be worth $25 billion per year by 2025.
Economic modelling and case studies developed in Britain, Spain, Singapore and India suggest that in ‘developed economies’, LNG waste cold could form the foundations of an entirely new economy – the ‘cold economy.’
Energy would be stored and moved as cold rather than converted into electricity and then converted again to provide cooling. The Cold Economy is less about individual clean cold technologies – although these are vital – and more about the efficient integration of cooling with waste and renewable resources, and with the wider energy system.
The Cold Economy approach is powerful because it recognises that there is no demand for cold per se, but for services that depend on it. For the first time we are asking ourselves ‘what is the energy service we require, and how can we provide it in the least damaging way’, rather than ‘how much electricity do I need to generate?’
If the service required is cooling, current approaches such as burning diesel, which produces power and heat, or electric-powered air conditioners that expel heat into their immediate environment, are suboptimal.
Only 23 of the 111 LNG import terminals worldwide currently attempt any form of cold recovery and this is usually limited to the industrial plants close to the terminals themselves and at times when LNG is being re-gasified. The amount recycled could be raised by converting it into novel energy vectors that store and transport it for use on demand, such as liquid air or liquid nitrogen. Recycling waste cold in this way would produce cheap, low carbon, zero-emission cryogenic ‘fuel.’
Britain is currently developing two main energy technologies that could exploit large amounts of LNG waste cold: liquid air energy storage (LAES), which provides large-scale electricity storage for balancing the electricity grid and cryogenic expansion engines (CEE) that are driven by liquid air or nitrogen.
Due to the current grid regulations in the UK and elsewhere, the business case for new investment in LAES is challenging but the financial potential of CEE applications is more positive.
The first application of a CEE system is a zero-emission transport refrigeration unit to displace the highly polluting secondary diesel engines used on trucks and trailers today. Developed by the Dearman Engine Company, it is now in commercial trials with Sainsbury’s. Other Dearman engine applications include a back-up electricity and cooling generator for data and food distribution centres, and a ‘heat hybrid’ engine for trucks and buses that reduces diesel consumption by over 25%.
It is estimated that projected global trade of 500mtpa LNG in 2025 could produce enough liquid air to cool almost four million fleet-average refrigerated trucks – equal to the entire global transport refrigeration units fleet today.
While waste cold of LNG re-gasification is a huge resource, there are also significant barriers to overcome: air liquefiers are capital intensive, plant operators are naturally risk averse, and any such project would require an entirely new business model. Barriers aside, modelling shows that recycling LNG waste cold as distributed cold and power would be profitable once demonstrated and produce significant and measurable environmental benefits.
Given the urgency to meet global cooling demand growth, there is a clear need for government, industry and research institutes to convene global working groups to accelerate delivery of the cold economy with an in-depth feasibility study. This will maximise the business case through an in-depth analysis of the economic, environmental, and energy resilience aspects of this approach, comparing its costs and benefits with alternative strategies for greening cooling.
Heriot-Watt University Energy Academy is a pan-university initiative supported by all Schools at the Edinburgh and Orkney campuses. The Energy Academy has two principal objectives; to consolidate energy research activities and facilitate interdisciplinary programmes, both within the university and with other HEIs; and to ensure external parties can easily gain an appreciation of our vision, skills-base and active research projects. R&D activities at Heriot-Watt University are designed to be demand-driven and in line with current priority industry and government objectives. For more information, please visit http://www.energy.hw.ac.uk/research.html