Natural Refrigerants are Efficient

Longer read warning!

Scroll on, or dig in if you are up for a little perspective on natural refrigerants and efficiency.

Yes, I know I had to much time on my hand yesterday evening writing this up ??

The intention is to inspire and make you reflect on natural refrigerants. So experience over the years in terms of energy efficiency and choice of refrigerant (working fluid) I here want to share.

Sometimes when commercial interest gets mixed up with technology insights and thermodynamic laws, some may spread what they believe to be true without truly understanding what they talk about. (It may also be they do know but put a different story forward in the interest of their share/stake holders)

I have been fortunate to work with natural refrigerants over the last many years in different positions from component development in terms of valves and electronics to the other end of business development and trying to make solutions working with natural refrigerants more competitive than those with chemical refrigerants.

Often have I been accused of wanting to use CO2 (R744) as refrigerant for everything. It has always been about understanding where natural refrigerants can be used in a efficient manner while making it a good solution for the customer and the environment.

Note that many are much cleverer than I in looking at a given application and then deciding what is the right refrigerant for the job. Over the years I have learned a little tagging along clever people working on both sides and in between these refrigerants. I hope this write up will nuance this well while also not hide that I will always be a natural refrigerant first kind of guy!

CO2, Propane, Ammonia, Air, Water and other natural refrigerants are not less efficient than the chemical refrigerants. What most get wrong is that the right technology needs to be chosen to work with a specific working fluid in a given application (Temperature demands, Ambient conditions, safety, oil management, serviceability in a certain geographical area etc.)

A few examples for context and inspiration:

#1

Recently I saw a video from the UK on heat pumps. During the interview touching natural refrigerants, the person interviewed made a clever move to mention CO2 in supermarket refrigeration while the topic was on domestic heat pumps with R32 and R290 (propane). This company did not yet publicly have a propane heat pump solution…The person then went on to claim that CO2 was horrible in terms of efficiency… on the contrary CO2 in supermarket refrigeration is very efficient. Especially in the UK climate. Second the heat generated while cooling and freezing is in a CO2 system of high value. Hence the larger banners in the UK have heat recovery and are also able of running their refrigeration systems as heat pumps, (They have what’s called a false load on the gas cooler) in case the heat generated from keeping product at temperature is not sufficient in terms of heat demand. This Normal in newer installs as supermarkets are becoming very efficient with doors and lids on cabinets. On another note in terms of hot water production (DHW if you like) most should realize that not many technologies will match the CO2 eco-cute in terms of efficiency.

2#

Recently I was requested to quote a CO2 chiller (below 500 kW) for climate control purposes. End customer consultant engineer had this as demand. Looking at it, considering the other demands on site, ambient conditions, no desire of heat recovery etc. I ended up recommending, in the initial talk, a propane chiller instead in terms of efficiency and first cost. Customer insisted to have a CO2 chiller quoted for this (for me) special location. We ended up not being able to quote in this case due to dimensional requirements as well. But it goes to show that from and end customer point of view I see a dramatic demand for natural refrigerant solutions and an awareness of what they want and for what purpose. However it is important I find, always to get around the alternatives because I guarantee you it is not a given just because a large engineering company is behind the request that they have good insight in what may be the best solution for customer, the electricity grid, usage of waste heat etc.

The two examples above, however far from each other, demonstrates that there is significant “noise” around refrigerants and selecting the right technology for the job at hand.

Often we then come to the GWP (Global Warming Potential) discussion. The GWP is a measure of the CO2 equivalent in our atmosphere, which is good to know in case the refrigerant gets out of the system. Looking at it combined with energy usage of a system we will see it referred to as TEWI (Total Equivalent Warming Impact). This is a sum of Direct and Indirect impact. Direct if the refrigerant escapes to the atmosphere and indirect in terms of carbon emissions related to electricity production to run the equipment.

One shall always look carefully at this and hence chose the refrigerant that does the least harm for sure. In my book that’s always a natural refrigerant. Among Hydrocarbons R290 (propane) and R600a (Isobutane) like in your fridge at home the GWP is around 3. In terms of Ammonia R717 we have a GWP of 0 and CO2 R744 we have 1. Try and look up the GWPs of the refrigerants you work with!

As innovation takes time, potentially longer in this mechanical industry, I request the reader to reflect that those companies not offering natural refrigerant solutions may have other reasons than they should not be efficient. Wested interest in production facilities, access to technology and so forth is playing a big role in my view.

I do not want here to claim that one single natural refrigerant is always the best, as it is not the case. But I will claim that for 99% of applications in terms of volume a natural refrigerant will always be able of matching a chemical one in terms of efficiency and hence overall TEWI.

It may then be that in more areas this comes with a higher Capex (investment) still. But that is to change I am sure and confident. Look for the small positive signs (early indicators) like the Midea R290 air to air split going to market, or the VW group bringing economy of scale to CO2 (R744) thermal management of electrical Vehicles, just to mention two examples. The technologies, components and skills are there. The rest is companies not having the right compressors etc. in their portfolio, fear of flammability (rightly so) and so on.

This write up may be provocative to some. If you feel provoked, I ask you kindly to reflect on how you contribute to a better future for all, and what good the products you bring forward does and do you actually understand the impact they have?

I fully recognize to be in a privileged situation, and some may not have the luxury of deciding on a natural refrigerant. Even I own a R32 air to air heat pump in my summer house and Drive a Volvo Diesel… and that is for sure a 1st world problem I recognize that fully.

I hope you get inspired to look for a natural alternative next time looking at your choise of working fluid for your solution, and I am always open to learn from facts and scientific evidence! Have a wonderful Friday out there!