Plug-ins In Winter

By Bill Moore

Posted: 01 Oct 2009

There are two Montréals: the one above ground of glass office towers, majestic cathedrals and public parks. Then there's the one below ground where it is possible to go to work, shop, dine out and find entertaining diversions and never go outside, especially during Montréal's long, bitter cold winters that can last from November through to May. The underground Montréal is linked by their subway system.

The fact that winter is so long and so cold in Canada, which Canadian's take a certain perverse pride in, also raises questions about how will plug-in electric cars perform under these demanding conditions? It's a question that was discussed during a panel I sat in on during the first day of the PHEV '09 conference here.

At least two universities in different parts of Canada have, over the last couple years, been studying the problem and reached similar conclusions: battery performance drops significantly along with the thermometer, requiring more fuel to be burned to compensate and to provide cabin heat. One study comparing a conventional, non-hybrid Corolla, a standard Toyota Prius, and a Hymotion-converted Prius demonstrated that the plug-in Prius showed the most pronounced increase in fuel consumption, which is pretty much what you'd expect, really.

Without having access to the presenter's slides, I can't quote you precise numbers but from my notes, one study indicated fuel consumption increased five fold in the PHEV. The bottom line is that in those climates where winters are long and cold, the IC engines in plug-in cars are going to run more often, though with this caveat: all of the test vehicles were equipped with first generation plug-in kits that operate only in electric mode when the car is kept below 35 mph. None of the tests were conducted with what I call second generation kits that enable the car to operate at higher speeds in electric mode. What impact winter cold will have on vehicles engineered specifically as plug-in hybrids is not presently known, but in correspondence with me today, GM's Rob Peterson indicated that the company will shortly be releasing its data on the Volt in cold weather testing conditions.

The only exception to the rule that the colder it gets, the more fuel gets used, appears to be in the case of hybrid buses and here -- if I understood the study's conclusion correctly -- statistically, at least, it doesn't seem to have as pronounced an impact.

Curiously, from the perspective of HydroQuebec, when it comes to providing electric power to all those future electric cars, the colder, the better.

By sheer coincidence, I sat down for lunch with three of their executives the first day of the conference. I asked them what impact, if any, the introduction someday of tens of thousands and eventually millions of PHEVs and BEVs would have on their power system, 97-98% of which is powered by hydroelectricity, which Canada, unlike America, considers a renewable energy resource. They smiled and said, none.

Unlike utilities south of the 49th Parallel that are designed to handle peak summer air conditioning loads, utilities in Canada like HydroQuebec have been engineered to handle peak winter heating loads, most of it from radiant baseboard heaters in people's homes. Where companies like Duke Energy in the U.S.A installed 25kVA transformers for neighborhood power distribution, HydroQuebec went with 127kVA units. According to my luncheon companions, Duke and its U.S. counterparts rely on night-time temperatures gradually cooling down their heat-stressed transformers in summer, so having hundreds and eventually thousands of electric cars plugging in and recharging over night doesn't give the transformers time to cool down. This is a big concern for U.S. utilities, the HydroQuebec executives explained.

By contrast, the colder it gets in Quebec, the better because those monster 127kVA transformers can actually tolerate loads up to 150kVA when its -40C outside. Additionally, most Canadians already plug-in their cars to power block heaters and battery warmers during the winter to make sure their vehicles start after siting hours in sub-zero temperatures. Canada's grid has been scaled to accommodate this seasonal load. The introduction of plug-in electric vehicles doesn't represent that large a paradigm shift for our Canadian neighbors.

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