Different refrigerants for the car air conditioning system

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The widely used refrigerant r134a may no longer be used in new vehicles from the end of 2016 due to an EU directive on environmental protection. The new alternatives r1234yf and R744 (CO2) are more environmentally friendly, but also have their pitfalls. We tell you what to look out for

The "old" refrigerant r134a

The refrigerant r134a is colloquially called "the old refrigerant". Old, because their use in new cars will be banned from january 2017 due to their damaging effect on the climate.

The "new" refrigerant r1234yf

After it became clear that r134a would be banned, car manufacturers agreed on r1234yf as an alternative. The advantage is that only minor modifications are required to the existing air-conditioning systems, thus saving high development costs. However, the r1234yf costs about 140€ per kilo, while the r134a is only about 8€ per kilo. As a result, the price of the air-conditioning service rises sharply, which is often not understood by the customer.

Since 2012 the r1234yf is used in some cars. This liquefied, colorless gas has a faint inherent odor and is much more climate-friendly than r134a. However, it is classified as highly flammable and the auto-ignition temperature is 405°C.

The new alternative CO2 (R744)

Mercedes benz was not satisfied with r1234yf and therefore developed a new air conditioning system for CO2. From the end of 2016, the new S-Class (model 222) and the E-Class (model 213) will initially be equipped with this type of air conditioning system. Other carmakers are expected to follow suit and switch to CO2 air conditioning in the medium term.

The advantages of the CO2 (R744) refrigerant are obvious:

1430 times lower global warming potential than r134a
Non flammable
High cooling capacity
Attractive price with approx. 26€ per kilo

Is it allowed to fill a r1234yf air conditioner with r134a??

No, this is not allowed by law and mixing should be avoided at all costs. Through various service couplings and the use of an air conditioning service unit with a refrigerant analyzer, any possible mix-up of refrigerants is immediately detected. This avoids damage to the air conditioning system and thus consequential costs due to contamination.

How to ensure safe handling of refrigerants?

As with all chemicals, certain precautions should be followed to ensure safe handling. The recommendations for the workshop are:

At least one air change per hour in the entire workshop area
In pits, at least three air changes per hour
Exclusive use of suitable air-conditioning service equipment
Open fire and light as well as ignition sources such as the arc during welding must be kept away
For all refrigerants, protective equipment should be used when handling them, e.g.B. Long-sleeved work clothing to be worn.

In addition, air conditioning services must only be carried out by qualified personnel. Every employee who carries out activities in connection with air conditioning systems requires a training certificate in the form of a certificate of competence for air conditioning systems.

These air conditioning service units are required

To be equipped for each refrigerant, different air conditioning service units are needed. These must be labeled in such a way as to avoid confusion, as the different properties require different technical concepts and designs. In addition, the air conditioning service units for r134a and r1234yf have different service couplings.

For those who do not want to have two air-conditioning maintenance units, the texa konfort 780R bi-gas air-conditioning service unit is an alternative. This is as big as a "simple" air conditioning service unit, but both refrigerants can be used in the same unit.

In the medium term, workshops will have to add a CO2 R744 air conditioning service unit to their equipment in order to be equipped to service new cars fitted with it. the use of other air-conditioning service units is not possible, as five times higher pressures prevail in CO2 air-conditioning systems and therefore different requirements are placed on the air-conditioning service unit.

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Natural gas vehicles are seen by some as a bridge technology on the way to completely CO2-free transportation. But they are good as an environmentally friendly transitional solution until electric cars are suitable for everyday use? Senior researcher moritz mottschall answers the question and comes into contact with his personal history in the process.

Before living at the eco-institute, i was a cab driver in berlin. the company i drove for had a very special cab: on the side was a green sticker that said "TUT – a thousand environmental cabs for berlin". This "eco-taxi" had a modern bi-fuel drive with two tanks, one for compressed natural gas and one for gasoline.

These insights into reality gave me the decisive plus points in my interview: for example, i knew the (open) secret that many eco-taxis from a certain manufacturer ran on super gasoline instead of natural gas for a long time due to problems. The gasoline was even paid for by the manufacturer, to the delight of the contractors. The question of the environmental benefits of natural gas vehicles could not be answered clearly at the time. But how does it look today?

Today, natural gas vehicles are sometimes referred to as a possible bridge technology on the way to completely CO2-free transport, for example with electric cars with batteries or hydrogen fuel cells. The idea in the background: natural gas causes less direct CO2 emissions than gasoline. This is because natural gas has a better so-called C/H ratio. This means that for every carbon atom (C), there are a particularly large number of hydrogen atoms (H). That’s why natural gas causes fewer direct CO2 emissions than gasoline.

Gas as a source of electricity

a major argument for natural gas is that it could be replaced by biogas in the future, making the car almost CO2 neutral. Despite this, many millions of euros are currently being invested or planned in fossil natural gas infrastructure. For example, the northstream 2 pipeline or terminals for liquefied natural gas in northern germany.

In the long term, it is clear: even the cleanest gas can only be burned once! So we asked ourselves: aren’t there more sensible ways of using natural gas or biogas than burning it in a vehicle engine with very low efficiency and blowing more than two-thirds of the energy into the environment in the form of waste heat?? One possibility would be to use the gas in highly efficient gas and steam power plants to generate electricity. This electricity could be used where the bridge is supposed to go: in an electric car.

A comparison of e-cars and natural gas cars

So we did the math. A VW e-golf and a natural gas-powered VW golf TGI have been launched. For both, many users have entered real consumption data in the spritmonitor database.De entered, which we have taken into account. However, this is not a completely fair comparison. the two vehicles differ significantly in terms of performance: the e-golf’s output of 100 kilowatts is 23 percent higher than the natural gas vehicle’s 81 kilowatts. We therefore include a generic vehicle from the compact class in the race, which we have taken from our technology data base, the TEMPS model (transport emissions and policy scenarios) of the oko-Institut.

Final energy consumption of the electric and natural gas cars considered, source: oko-institut

In addition to the electricity consumed in the vehicle, part of the electrical energy is lost on the way to the battery: during electricity transport or during the charging process. Total losses of 16 percent are estimated here.

In our comparison, the burner uses the gas directly. The electric car uses electricity generated from natural gas in the power plant. In the european average (73.2 percent combined electricity and heat generation, 26.8 percent exclusively electricity generation), this results in 475 grams of CO2 equivalents per kilowatt hour (reuter, benjamin; hengstler, jasmin; whitehouse, simon; zeitzen, lena (2017): greenhouse gas intensity of natural gas. Final report. Hg. V. NGVA europe, last checked on 08.04.2019.). In a particularly efficient gas-fired power plant in germany, it is even only 423 grams of CO2 equivalent per kilowatt hour (ecoinvent v.3.5; electricity production, natural gas, combined cycle power plant).

When used as a fuel, emissions depend on the origin and composition of the natural gas, as the content of methane, ethane and propane in the natural gas can differ, for example. But the upstream emissions caused by the supply of natural gas, which are also referred to as emissions in the upstream chain, also differ. upstream emissions are caused by leakage and energy consumption in the extraction, processing and transport of the gas to germany.

These direct and upstream emissions can be related to the energy contained in the natural gas. In the calculation, we assume around 68 grams of CO2 equivalents per megajoule. Of this, about 18 percent is accounted for by upstream process steps and 82 percent by direct emissions in the vehicle.

Conclusion

For operation, the picture is clear: both for a particularly efficient natural gas power plant and the european mix of natural gas power plants, the electric car performs better than the natural gas burner. the fact that such a large difference arises even when taking into account the electricity losses during transmission and charging is due to the different efficiencies: modern gas-fired power plants have an electrical efficiency of well over 50 percent, in some cases up to 60 percent. Gasoline-powered internal combustion engines, on the other hand, can generally convert 20 to 30 percent of the energy into motion. Even if a particularly inefficient gas-fired power plant were assumed, operation of the electric car with the burner would result in comparable or lower emissions.

Specific greenhouse gas emissions from vehicle operation for natural gas-powered passenger cars and natural gas-powered electric cars for different types of power plants (including emissions from the upstream chain), source: oko-institut

However, a fair comparison must also take into account the costs of vehicle production. This is important because the production of electric cars leads to higher emissions, especially from batteries. Estimation of greenhouse gas emissions from battery production is currently subject to great uncertainty. Often outdated emission factors and wide ranges are used. Our estimate is based on the calculations of the ifeu institute, which they prepared for agora-verkehrswende.

Accordingly, an internal combustion engine in the compact class – gas-powered cars were not explicitly considered – has an emissions advantage of almost six metric tons. The electric car produces more than 13.2 metric tons of CO2 equivalents through production and disposal, while the internal combustion engine produces only around 7.4 metric tons.

Greenhouse gas emissions from operation, vehicle production and disposal of a compact class vehicle as a function of lifetime mileage, source: oko-institut

Depending on the emission factor used, the electric vehicle, taking into account production and disposal, has a lifetime mileage of about 82 kilometers.000 (efficient natural gas power plant in germany) or 93.000 kilometers (mix of natural gas power plants in the EU) a climate advantage over the gas car. With a typical lifetime mileage of 150.000 the greenhouse gas emissions of an electric car powered by natural gas are between three and five tons lower than those of a natural gas burner. This corresponds to a greenhouse gas reduction of between 12 and 17 percent.

In fact, this is just a game of arithmetic. Because in a balance sheet, it is best to also use the electricity mix in the respective network. And gas electricity tariffs are at least not known to me.

However, the great advantage of electromobility becomes apparent: the high energy efficiency at the vehicle level. Impressively, the double conversion of natural gas into electricity and then into kinetic energy is more efficient than the direct conversion of natural gas into kinetic energy in a gasoline engine.

Besides, the reality is more complicated: gas-fired power plants, for example, perform certain functions in the power grid to stabilize the grid. Due to their high flexibility, they can be operated in such a way as to compensate for fluctuations in power demand on the electricity grid.

On the other hand, greenhouse gas emissions from the transport sector, which are currently not traded, would be shifted to the energy sector, where emissions are already traded and capped.

Nevertheless, my comparative view can serve as a suggestion to use the available energy, be it natural gas, biogas or synthetic methane, where it can be used most efficiently. Natural gas cars are not. That’s why we shouldn’t focus on a supposed bridge, but rather tackle the goal of zero-emission driving head on.

Moritz mottschall is a senior researcher in the field of resources& mobility in berlin. One focus of our work is energy efficiency and alternative drive concepts in transportation.

if you want a clean car on sundays, you have to wash it on saturdays. Photo: dpa//christin klose

the operator of a gas station in schorndorf-haubersbronn is said to have violated the ban on car washing on sundays and holidays. The police were unable to detect any violations during checks. Nevertheless, a fine is now imminent.

Schorndorf – ralph lindacher is angry. He and his wife run a car wash in schorndorf, Germany. As is the case everywhere in Baden-Wurttemberg, their car wash must remain closed on Sundays and public holidays. But not everyone adhered to this rule, the two say.

In the fall of 2018, ralph lindacher says, he first heard from a customer that cars were also being washed on Sundays at a service station in the haubersbronn district of the city. "as a result, i drove by there a couple of times on sundays and the washing facility was in operation each time," says lindacher. "i think it’s simply not fair when some people abide by the rules and others don’t."

The management denies everything

That’s why he and his wife called and wrote to the gas station operator to ask him to comply with the legal ban on washing cars on Sundays and public holidays – without success, as ralph lindacher says. "i also asked our joint umbrella organization BTG in minden what we could do, because we really wanted to sort this out without any authorities," he says. "but after the operator did not react, we informed the city in the summer of 2019."

Nevertheless, the washing facility and the self-service boxes at the Haubersbronn service station were still in operation on Sundays until recently, says Lindacher. In response to a telephone inquiry from our newspaper, the management of the service station explains that they "do not wash cars on Sundays".

No complaint received for a long time

Jorn rieg, the acting head of the safety and order department of the city of schorndorf, confirms that in the past the city was "repeatedly informed that the car wash in haubersbronn would be operated illegally on Sundays and holidays". According to the "public holiday law" in force in Baden-Wurttemberg, the "operation of automatic vehicle washing facilities" – i.e. washing bays, washing lines, portal washing facilities, but also the use of high-pressure cleaners on pre-wash bays – is prohibited on Sundays and public holidays.

However, no charges were filed against the service station operator in Haubersbronn for a long time. "we have nevertheless taken the information as an opportunity and informed the operator of the car wash for the last time in a letter dated september 2020 of the ban on operating a car wash on sundays and public holidays," says rieg. "likewise, employees conducted another on-site visit in november 2020, during which the employee of the operator’s company was also made aware of the legal requirements. We were assured several times by the operator that they would adhere to the regulations."

e-mail with evidence photo sent to the police

Also, no violations of the car wash ban were found during random checks in january 2021. Nevertheless, the "tipsters have also been made aware that they are welcome to contact the police enforcement service directly in the event of further violations outside the reach of the police authority," explains rieg. A corresponding notice had been issued on 7. February 2021 also received. But even on this day, the police had not been able to detect any violations of the Sunday washing ban during several checks.

"therefore, no administrative offence proceedings were initiated on the part of the police enforcement service", explains Jorn rieg. However, on the same day, a complaint was filed with the city "with e-mail and with a photo as evidence" against the operator of the car wash and the wash boxes. "this administrative offense will be brought to a conclusion with the issuance of a fine notice," says the head of department.

Fines of between 250 and 1000 euros threatened

In this case, there is no legally stipulated "regular fine". "it is up to the responsible fine authority to determine the amount of the fine at its own discretion," says rieg. "in the case of violations, the range we set is between 250 euros and up to 1000 euros."

It is not known to our newspaper whether the operator concerned intends to appeal against the fine notice. The management would only like to emphasize that no cars are washed there on Sundays. "at least since the announcement of 7. february," says ralph lindacher, "the car wash actually stopped operating on sundays."