Exclusive interview with Alexander Cohr Pachai, Johnson Controls

 

Alexander Cohr Pachai: Until recently nobody has really been thinking about the heat that is emitted by a normal refrigeration system. The condenser side emits the cooling capacity in addition to which there is the power input you put into the compressor, all of which is lost as waste heat. In the past energy has been too cheap for people to bother about collecting this waste heat. Now with the new ammonia heat pump you can evaporate at 30°C – 40°C and then you can boost the heat up to a valuable temperature for cleaning processes, such as for in slaughter houses for example, where you need to clean very effectively using 90°C water to remove bacteria. You can produce this hot water to be used at night by running the ammonia heat pump during the day. 

 

We need to rethink the way we use energy now because the energy prises have risen dramatically. It is worth investing in heat pumps, and the payback time is relatively short in many cases if the alternative is a gas or oil boiler. It is good for business, and is not only a technology for being green. Heat pumps with ammonia can also produce warmer water than a lot of other alternatives as it doesn’t suffer from chemical breakdown – ammonia is very stable, making it appropriate for such purposes.

 

 

Alexander Cohr Pachai: We have been looking at different solutions to recover energy from gas process plants where for example hydrogen and other gases are dealt with. These plants produce quite a lot of heat over the year and could actually sell the heat if they raised the temperature to produce hot water. Using an ammonia heat pump such plants could boost temperatures to 70°C, which is high enough for the gas processing plant to sell the heat to a district heating installation. The gas plant would have payback period of about 0.9 years. This is a rough calculation as there are lots of factors you have to know and to take into consideration, such as loading and unloading, and the data we collected so far were not very detailed.

 

We are now looking into two projects in Denmark that could use ammonia heat pumps and feed the heat into a district heating system, and also into a few breweries in the Middle East, where a lot of hot water is used to clean bottles.

 

 

Alexander Cohr Pachai: In Denmark we had a systems using the sea water vapour as working fluid in Augustenborg, Denmark. I don’t know if it is still in operation. To my knowledge there are no others doing it in the same way as in Drammen, but in Denmark we have about 700 small district heating plants where an ammonia heat pump would fit very well because you can then take advantage of the low energy tariffs at certain times of day. There is a huge potential and we are starting to investigate the possibilities. We have tested the ammonia heat pump unit, so we know it works. We will launch the product  at the end of this year.

 

 

Alexander Cohr Pachai: District Cooling is already big in Finland and in Stockholm in Sweden, so we know how it works and have already supplied a lot of the equipment. With regard to the Middle East, we have yet to come across any interesting district heating/cooling projects that could benefit from an ammonia heat pump.

 

 

Alexander Cohr Pachai: A lot of breweries have cooling towers emitting a lot of heat and water, and this heat can of course be recovered and put into a heat pump. Water at 30°C is not very useful, which is why it is regarded as waste, but in the future it could be used as the energy source for heat pumps. This is particularly simple if the cooling load coincides with the heating load, otherwise you have to think more carefully about how collect the heat and combine it with needs.

 

 

Alexander Cohr Pachai: The biggest challenge is to convince the customer because many customers are sceptical of the short payback times and say ‘you’re pulling our leg’! Of course with better quality data we can improve the accuracy of our payback time calculations. However, we have well developed calculation models that people can use themselves. Perhaps they can use them to convince themselves that such installations are a good idea.

 

Psychology is still the biggest barrier facing the implementation of natural refrigerants.

 

 

Alexander Cohr Pachai: The biggest threat for natural refrigerants is accidents, and we need to avoid them by ensuring we have well trained personnel. Unfortunately accidents happen, but then again they also occur with fluorinated refrigerants. For example there was an incident in Korea not so long ago, so accidents can happen with any refrigerant.