The modern world is cold. From air conditioning to temperature-controlled pharmaceuticals production to data center cooling to the vast global “cold chain” of refrigerated food transportation and storage, the ability to create low temperatures at will has become a hallmark of advanced societies.
And the demand for cold is on the rise. Urbanization is dramatically transforming economies around the world, resulting in a booming middle class that wants the convenience and utility of refrigeration and air conditioning. Currently in the developing world, an estimated 30 percent to 40 percent of food is lost before it can even make it to market. With an expanded cold chain, farmers can earn more money by transporting their crops in refrigerated trucks, and families will be able to buy better-preserved foods at grocery stores. Many stand to benefit from increased access to cooling systems.
But keeping things cold also places a heavy burden on the environment, most importantly because it’s energy intensive. Experts say that more attention needs to be paid to improving efficiency of cooling systems, especially in the cold chain for food — by far the most significant user of cooling, accounting for an estimated 15 percent of all electricity consumed worldwide.
“The most important impact of refrigeration for the climate is energy consumption of the systems,” says Didier Coulomb, director of the International Institute of Refrigeration. From cold storage on farms to refrigerated shipping to cold displays in retail outlets to refrigerators in homes, it’s estimated that about 70 percent of the food in the U.S. travels through the cold chain. Countries such as China and India are expected to reach similar numbers in coming years, and most of these systems still depend largely on diesel fuel.
In the UK, the Dearman engine company is focusing on reducing the energy required by a critical and growing link in that cold chain: refrigerated trucks. There are roughly 2 million refrigerated trucks worldwide today, according to Tim Fox, Dearman’s international ambassador. By 2025, that number could be close to 10 million, according to a report from the company, each truck using up to 20 percent of its fuel powering refrigerator units.
“If we continue to provide that transport refrigeration based on the business-as-usual diesel solution, the environmental degradation in terms of air quality and the subsequent impact on health in the middle of rapidly urbanizing areas is going to become quite substantial,” Fox says.
Dearman has developed a new engine for truck refrigerators that uses liquid nitrogen and produces zero greenhouse gas emissions. A field trial is underway and Dearman expects to have some engines on UK grocery trucks in 2016. With a company factory able to produce at least 10,000 engines annually by 2018, Fox expects to see them in all developed countries by the early 2020s, and growth by then in places still building out their cold chains, such as China, India and Malaysia.
Beyond food, people will also increasingly look for ways to keep themselves cool in a warming world. The UN Intergovernmental Panel on Climate Change projects that demand for air conditioning in emerging-market economies will have a significant impact on energy use worldwide, jumping from about 300 terawatt-hours in the year 2000 to more than 10,000 in 2100.
New building designs that incorporate passive cooling can cut down some of that demand, but the hot and humid parts of the developing world will likely rely on energy-intensive cooling, meaning that systems requiring less energy can have an enormous impact.
“We have to improve the quality of energy efficient systems and the development of adaptive systems for developing countries,” Coulomb says.
With that in mind and with more than half of the world’s best-selling drugs expected to require cold chain protection by 2016, companies like Pelican BioThermal are developing reusable temperature-controlled shipping containers with recyclable vacuum-insulated panels that reduce global warming potential by 75 percent and post-consumer waste by 95 percent. And, there’s even a community-based health services organization in Africa that began using solar-powered cooler units mounted on camels to deliver medical supplies to remote communities in Kenya and Ethiopia.
Meanwhile, refrigerants, the actual substances used to create cold and sub-zero temperatures, are known as super greenhouse gases for their exceptionally high global warming potential and propensity to leak into the atmosphere. Dichlorodifluoromethane, once one of the most widespread refrigerants, had a measured global warming potential of 10,900 relative to carbon dioxide, and was eventually phased out of use. One of the most common refrigerants today, chlorodifluoromethane, has a GWP of 1,810, and is also being phased out worldwide.
“It’s a bit of a conundrum,” says Douglas Reindl, a refrigeration expert and professor of engineering at the University of Wisconsin–Madison. “Some of the refrigerants that we’ve already phased out are tremendously efficient, and they’re tremendously effective. That’s the good news. The bad news is that when they escape from these systems they can cause significant damage to the environment.”
Depending on the system, up to 30 percent of a refrigerant’s volume leaks annually, expelling vast amounts of greenhouse gases into the atmosphere where they can persist for decades or centuries. Commercial refrigeration, such as the food coolers inside grocery stores, accounts for roughly 40 percent of annual refrigerant emissions worldwide, according to the UN IPCC. In 2012, the National Institute of Standards and Technology — part of the U.S. Department of Commerce — performed a study of more than 56,000 chemicals and compounds to find refrigerants with the lowest global warming potential. Only about 60 were found to be compatible with common equipment. Reindl says researchers are trying to develop newer and better refrigerants to reduce the environmental impact, but no perfect solution exists.
The Milwaukee-based Astronautics Corporation of America is hoping it has come up with one solution. The company developed a novel heat pump that uses a magnetic system to cool a water-based liquid, replacing harmful gas refrigerants and showing major improvements in energy efficiency compared with traditional compressor technology.
The growing cold economy is a complex issue, further complicated by a growing and warming world. Like many problems we face today, it will take some combination of doing things better and discovering new, high- and low-tech solutions to provide all people with the benefits only a portion of the world’s population has seen to date.
Posted on July 22, 2015
by Edwin Kalischnig