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Mirror Imaging Hides the Customer

When thinking about the energy transition, or any other of life’s many challenges, I try to guard against mirror imaging.  The way I define mirror imaging is to assume other people live, think and act like I do.  Mirror imaging allows one to believe that there is an easy solution or a single solution to many challenges just because you have implemented that solution and it worked for you.  Of course we know that we all live very differently, but mirror imaging can make a very complicated and messy world easier to comprehend and rationalize.  It is convenient and therefore enticing. 


This worked for me. Do the same. Job done. 


This illusion gets shattered when we travel and we are faced with the reality of other people’s differences.  This was recently the case during a recent 3 week trip to Japan where my wife and I experienced big city and small village accommodations in both hotels and private residences.  Since I work in the area of energy and climate change mitigation, I observe how people live; from transportation to eating, heating homes to laundry.  It is safe to say that finding people who lived the same way as I do in Canada was difficult. 


While certainly not a robust scientific census, I did note a few things that got me thinking.  In every private residence we stayed in, space heating was via a heat pump.  These were always minisplit systems where individual rooms where heated rather than the entire home.  You may have heard about heat pumps as they are one of the key heating technologies required during the transition away from fossil fuel combustion to electrification.  In summer, heat pumps become air conditioners which I understand is required during Japan’s hot and humid months.  So in terms of decarbonizing space heating, they appear to have a solution in hand.


Hot water for washing and bathing, on the other hand, was always produced by instantaneous gas fired hot water heaters in the places we stayed.  In the cities, most of the units I saw were fed from the main gas grid which I assume was natural gas but in smaller villages, LPG/Propane was supplied using swappable cylinders delivered by truck.  The instantaneous water heaters were mounted either inside the house with the flue gas chimney vented outside or the entire heater was mounted outside with only cold water supply and hot water return lines going through the wall. 


The power used to heat water is an important consideration.  Heating water is typically a high power demand application.  For example, a typical shower requires 17 kW (58,000 BTU/hr) of power!  That is a lot of power and is one reason you don’t see electric instantaneous hot water heaters very often. 


As we described in a previous article, hybridization using heat pumps with natural gas to meet peak heating loads during cold days is an effective way of providing space heating without overtaxing the electrical grid in cold climate countries like Canada.  But while travelling in Japan I wondered what are they going to do about decarbonizing hot water? 


The easy answer is to electrify hot water.  I already have an electric resistance hot water tank in my home and it works just fine.  If we want to increase efficiency, we can add a heat pump to heat the hot water tank.    In places like the UK, the radiant heating system and hot water system are integrated so you can use a heat pump to do both.  The common element in all of these systems is that they heat a tank of hot water over a period of time so the heat provided from the resistance heater or the heat pump is decoupled from the demand.   So Japanese households will simply transition to hot water tanks heated with heat pumps or resistance heaters for hot water.  Job done.


To see if this the right answer, it helps to understand how the hot water is used in a typical Japanese household.  The first crack in the mirror is that Japanese people prefer to bath in the evening.  After a long hard day at work and long commute, a good way to end the day before going to bed is a relaxing soak.  This is different than in North America where we tend to shower in the morning before work.  But there is another twist which adds more cracks.  Instead of filling up the tub and hopping in, Japanese people shower beforehand; thoroughly washing with shampoo and soap and rinsing completely before going into the tub.  As everyone is clean before entering the bath, bath water is shared by family members.   So everyone in the household showers AND they then they share a bath.  About 33% of total residential energy use in Japan is for hot water whereas in Canada it is about 19%.


The other thing to note is that Japanese homes are significantly smaller than a typical North American home.  According to Statistica, the average Japanese home is ~1000 sq ft whereas the average home in the US is ~2500 sq ft.    Furthermore, in my Japanese travels I did not see a mechanical/laundry room or basement in the homes I visited. 


Understanding the customer first before developing the solution is one of IBET’s core tenants.  So knowing the above, it is relatively easy to understand why Japanese households typically use instantaneous gas fired hot water heaters.  They use a significant amount of hot water in the evenings but have limited space in which to install a hot water tank.  They can’t use electricity directly as the power demand is too high.  So that leaves them with burning a chemical fuel like natural gas or propane to supply hot water instantly as required.


To use clean electricity to heat hot water, Japanese households will need to incorporate some kind of storage into their homes or move to a district hot water system.  A quick search shows that some OEMs have heat pump water heaters for the Japanese market and in 2022 approximately 700,000 such units were sold.   It is important to note that all of these systems include a hot water tank indicating that they are not a direct replacement for an instantaneous water heater. These systems are also sold predominantly in the new build market segment as the allocation for space for a hot water tank is easier. 


Alternatively, Japanese households could also store electricity in batteries and use that to power instantaneous resistance or heat pump electric water heaters.  Both storage options will add significant upfront capital costs and may result in loss of space inside existing homes. 


The other option is to use a chemical fuel that will result in low GHG emissions when burned in an instantaneous hot water heater.  The options here are biogas, renewable natural gas (RNG), synthetic LP gas or clean hydrogen.    Upfront capital costs will be about the same as current instantaneous units but these fuels will increase ongoing operating costs as they will be significantly more expensive than current fossil based natural gas or LPG.  However, they will not reduce usable space in the homes so functionally they are identical to current hot water systems.


The solution is therefore not so straightforward.  What may work in North America may not work elsewhere.  Once you throw away your mirror and understand the customer’s needs, you can really begin to find solutions to our climate problems that work for everyone and not just you.


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