06. Jul 2020

Natural refrigeration - for sure

The European Union wants to push back climate-damaging refrigerants. Within ten years their use is to be drastically reduced. There are still some reservations about the climate-friendly alternatives. But the change is becoming more and more attractive.

Natural refrigeration - for sure


Just a few years ago, when Lothar Serwas wanted to convince a customer of a refrigeration system that operates with a natural refrigerant, he needed very good arguments. Almost all customers had reservations. "There were actually no exceptions," remembers Serwas. The customers wanted to see application examples because the systems are very complex. They doubted that enough engineers, site managers and service technicians were available to install and operate the refrigeration systems in large numbers. They were worried that the high operating pressure when using the refrigerant carbon dioxide (CO2) could become a danger to personnel.

That's what almost every sales pitch was about. But with time, that changed. Lothar Serwas has experienced this development in different functions. He has worked for Carrier Kältetechnik Deutschland GmbH in Cologne since 1995. The refrigeration system manufacturer equips food retailers with everything they need to cool food. Over the past 24 years, the market has seen a turnaround. "It has taken a lot of effort to convince people that natural refrigerants can be handled," says Serwas. But the effort has been worth it.

The vast majority of freezers and refrigerated counters in German supermarkets are still operated with conventional refrigerants. But when Carrier Commercial Refrigeration equips a store with new refrigeration systems today, natural refrigerants almost always flow in the systems. "That's gotten into people's heads," says Serwas.

Lothar Serwas - Carrier Kältetechnik Deutschland GmbH
Lothar Serwas - Carrier Kältetechnik Deutschland GmbH
Lothar Serwas - Carrier Kältetechnik Deutschland GmbH

"It has entered our minds that natural refrigerants can be controlled."

Carrier uses carbon dioxide (CO2) and propane (R290) in its products for so-called plug-in refrigerated display cases. Other natural refrigerants are ammonia, air, water and hydrocarbons such as isobutane. All these substances have the advantage that when they escape from refrigeration systems they neither damage the ozone layer nor have a negative impact on the climate - in contrast to synthetic refrigerants such as fully halogenated hydrocarbons (CFCs), which have been banned in new appliances for almost 30 years now. Fluorinated greenhouse gases (F-gases) have been used as a substitute since the 1990s. Although these do not attack the ozone layer, they contribute to global warming. For this reason, the EU wants to reduce their use by 70 percent by 2030 (compared to 1990).

The Federal Environment Ministry warns on the website kaeltemittel-info.de of supply bottlenecks and sales bans for particularly climate-damaging agents. The future costs are difficult to estimate. This brings with it many uncertainties. Natural refrigerants on the other hand promise investment security. But they are not a perfect solution either, because there is no such thing as a perfect solution. CO2, for example, the refrigerant used by Carrier in supermarket refrigeration systems, requires a high operating pressure. The components must therefore be extremely stable, which makes them somewhat more expensive - although the increasing demand is slowly making up for this disadvantage.

In addition, CO2 is odorless, and it displaces the lighter oxygen. If it spreads unnoticed in the room, people can suffocate in the worst case. This places high demands on safety. For example, refrigerant detectors must be installed in all engine rooms, which give a visual and acoustic alarm as soon as a certain CO2 concentration is reached. If a CO2 refrigeration system is located in a closed engine room, ventilation must be provided to transport escaping gas directly to the outside.

In addition, there is a whole host of rules and regulations. Many of these also apply to conventional systems. With natural refrigerants, however, there are still some specific properties to be considered. "Essentially, you have to make sure that the refrigerant displaces the air, is more or less toxic and, when mixed with air, can be flammable under certain conditions," says Rainer Brinkmann, Technical Support Industrial Refrigeration at Johnson Controls System & Service GmbH in Mannheim.

Ammonia, for example, is toxic and also flame-retardant, but its pungent smell is a kind of built-in warning system. A gas warning system is only mandatory for larger systems. The requirements are high, but in Brinkmann's opinion they can be easily met. "This is no witchcraft", he says.

Natural refrigerants are a climate-friendly alternative.

In some industries natural refrigerants have always been important.

"Ammonia has never disappeared from industrial refrigeration because it is so energy efficient," says Monika Witt, Managing Director of TH. WITT Kältemaschinenfabrik GmbH in Aachen and deputy chairwoman of eurammon e.V., Frankfurt, which promotes the use of natural refrigerants.

The energy balance is an important argument. "The entire influence of refrigeration systems on global warming is due to 80 percent of energy consumption," says Monika Witt. "With climate-friendly refrigerants, which are also energy-efficient, we protect the climate twice over". In addition, the initial disadvantage that the systems are still somewhat expensive to buy turns into a cost advantage in the long run.

Witt considers many reservations about natural refrigerants to be irrational. "The thought of a few grams of propane in a car air conditioner gives us shivers. But 50 to 70 liters of flammable liquid in the tank compartment does not worry us," she says. Thousands of filling stations in Europe are proof that it is possible to handle flammable and explosive substances safely, she says. And unlike petrol stations, no untrained users are concerned about the operation of the refrigeration systems. After all, they are well trained specialists.

Monika Witt - TH. WITT Kältemaschinenfabrik GmbH
Monika Witt - TH. WITT Kältemaschinenfabrik GmbH
Monika Witt - TH. WITT Kältemaschinenfabrik GmbH

"With refrigerants that are climate-friendly and energy efficient, we protect the climate twice over."

In numbers

50 times

hhigher than the ignition energy of natural gas is that of ammonia, which does not burn without a supporting flame.

up to 80%

of the influence of refrigeration systems on global warming are due to energy consumption.