When the American adventurer and entrepreneur Clarence Birdseye discovered a way to freeze fish in the 1920s, little did he know that his invention would become a pillar of the modern economy.
The small multi-plate freezing device he developed ended up revolutionising agriculture, health and a host of other industries.
Without the ability to cool and freeze things, the modern economy could not function - the global supply of food, medical supplies and data would simply break down.
In the coming decades, demand for cooling is expected to exceed that for heating, boosted by global warming and the growth of middle-class consumers in the emerging world.
By 2050, the number of cooling appliances is forecast to more than triple to nearly 10 billion1.
The problem is that keeping things cold is an exceptionally energy intensive activity that contributes to climate change. Cooling is already responsible for 17 per cent of all electricity used worldwide, and 7 per cent of CO2 emissions, more than double that of aviation and shipping combined2. In about 30 years’ time, it is projected to consume 9,500 terawatt hours of energy – equivalent of all the electricity consumed in China and the US combined in 2012.
"Cooling underpins all aspects of our society from our food chain, comfort, health and data. But it’s the Cinderella of the global climate change debate. Until recently nobody considered it in the energy debate," says Toby Peters, Professor of Cold Economy at the University of Birmingham and a long-time advocate of energy innovation. "Socially and environmentally, meeting our cooling (demand) sustainably is the biggest challenge we face."
[1] Birmingham Energy Institute, 10.07.2018
[2] International Energy Agency, 2012
It is a challenge that he has been tackling head on. Six years ago he founded Dearman, a UK tech start-up, to help reduce the carbon footprint of the cold economy’s biggest polluter: refrigerated transport.
Mobile cooling – the provision of cooling for both vehicle air-conditioning equipment and transport refrigeration – accounts for 25 per cent of energy use and as much as 31 per cent of emissions within the cold economy.
Dearman’s team of engineers are developing a zero-diesel zero-emission cooling system for the refrigeration unit of delivery vans that generate both energy and cold storage at the same time.
A key feature of the technology is its innovative use of liquid air as an energy store. Dearman engines operate like steam engines, but powered by nitrogen which is liquefied at -196C. When nitrogen turns back to gas, it does so at room temperature and it expands by 700 times in the process. That expansion creates a force that drives the pistons of an engine and releases cold which can be used for cooling.
Dearman’s technology uses a heat exchange fluid which allows near-isothermal, or constant temperature, expansion of nitrogen, increasing the engine’s efficiency. The only emission from a Dearman engine is air – or nitrogen.
It’s an added advantage that liquid nitrogen is both cheap and easy to get hold of. That’s because industrial gas companies produce large quantities of the stuff as waste, so there’s no need to build new plants to produce chilled air.
“With liquid nitrogen, you don’t have a chicken and egg problem with infrastructure. And we have oversupply of nitrogen,” says Peters, who is now a Dearman non-executive board member.
The Carbon Trust estimates that liquid nitrogen can be supplied in the UK at 5-8 pence per litre, making it competitive with taxed diesel.
Dearman’s engines are already being trialled by British supermarkets Sainsbury’s and M&S as well as Anglo-Dutch firm Unilever. The firm plans to have 30 cooling trucks on the road by end-2018.
Cold chain is heating up
It’s important that technologies such as Dearman’s become commercially successful because demand for cold storage and transport is sure to grow rapidly.
That’s clearly the case in emerging economies, where the lack of a temperature-controlled integrated network of warehouses, packaging facilities and vehicles means that as much as 40 per cent of perishable food is lost before reaching the plate.
Building a cold chain in the developing world would not only reduce post-harvest loss, but would also enable farmers to sell their products in cities, where prices can be many times higher.
It would also allow farms to produce higher value-added products – dairy farmers producing yogurt or ice cream for example, Peters adds.
In India, just 4 per cent of fresh produce passes through this cold chain, compared with over 70 per cent in developed countries. China’s cold storage capacity stands at 3.7 cubic feet per capita, just a third of that in the US, even though it has grown 20 times since 2007.
More concerning, though, is that a lack of cold storage and transport hampers the effective distribution of vaccines which prevent infectious diseases. An estimated 2 million die in developing countries because of the lack of such medicines, according to the World Health Organization.
There is a conundrum in all this, however. If emerging economies use their growing resources to build a traditional cold chain, it could have dire consequences for the environment.
Refrigerated trucks are a particular problem as the diesel auxiliary engines they use for cooling emit 29 times more particulate matter and six times more nitrogen dioxide than their primary engines.
“If you deliver a cold chain that runs on diesel, you swap one problem with another – environmental catastrophe. As we build a new cold chain in a clean and sustainable fashion, we want to leapfrog the new technologies,” Peters says. “I look at a cold chain as an infrastructure that has a number of benefits – protect value, create new markets and enable rural communities to move up the value chain.”
