Survival outside the comfort zone: a fresh look at energy conservation

In his short story To Build a Fire Jack London sets up the agonizing scenario that will soon unfold, by describing his main character’s lack of appreciation for the basic thermodynamic reality in which we all live. The story takes place on an extremely cold day during the Yukon Gold Rush in the late 1800s, and the main character is en route, by foot, to meet with some associates. The problem with this character, says London,

We humans spend all of our lives inside a temperature comfort zone. We are either in it or we are not, and if we are not we will get into it or die trying. Literally.

We humans spend all of our lives inside a temperature comfort zone. We are either in it or we are not, and if we are not we will get into it or die trying. Literally.

… was that he was not able to imagine. He was quick and ready in the things of life, but only in the things, and not in their meanings. Fifty degrees [Fahrenheit] below zero meant 80 degrees of frost. Such facts told him that it was cold and uncomfortable, and that was all. It did not lead him to consider his weaknesses as a creature affected by temperature. Nor did he think about man’s general weakness, able to live only within narrow limits of heat and cold. From there, it did not lead him to thoughts of heaven and the meaning of a man’s life. 50 degrees below zero meant a bite of frost that hurt and that must be guarded against by the use of mittens, ear coverings, warm moccasins, and thick socks. 50 degrees below zero was to him nothing more than 50 degrees below zero. That it should be more important than that was a thought that never entered his head.

The story does not end well (you can read the whole thing here; and it is a classic). Though it is a pretty dramatic and extreme example of exposure to the elements, if you apply just a smidgen of the imagination the main character lacks, you can see that something similar could easily play out on any below-zero day anywhere. You don’t have to be in the Yukon on a minus-50 day to die of cold.

We are, as London says, creatures affected by temperature, “able to live only within narrow limits of heat and cold.” Those narrow limits comprise a temperature range of about 5 degrees Celsius—from about 18°C at the low end, to 23°C at the high end. That’s it. How often are outdoor temperatures inside that range? Very rarely, actually. This is why we have artificial heating, air conditioning, humidification, dehumidification, and air movement. Even when the outdoor temperature is within that very narrow 18° to 23° band, add water to the equation, either as vapour or liquid soaking our clothing, and we need devices that perform at least some of the functions just mentioned.

Imagine you are outside on a day where the outdoor temperature is 15° C (forget about the minus-50 in To Build a Fire). It’s raining. You are only three celsius degrees below the bottom end of the comfort zone. But unless you have good rain gear or are doing physical work, you will have to get shelter then warm up. If you are in the city, there is not much of a problem: get inside somewhere and dry off.

If you’re in the wilderness it’s different ball game. Read To Build a Fire, bearing in mind that though it is a dramatized example of what you have to do if you get wet, the main character’s crisis is not much different from what we would all almost immediately be dealing with if the electric grid went down on a cold winter day. It’s serious, in many cases life-or-death serious. In the outdoors, we have to get into the comfort zone. We will either get there, or die trying.

London’s imagination-challenged protagonist needs power, as in joules per second, and lots of it, so that he can evaporate the water that soaks his foot and thereby avoid, at the very least, frostbite and amputation. If his foot absorbed a quarter liter (just over a cup) of water, and that absorbed water is in the process of freezing, he will need a fifth of a kilowatt-hour of heat to evaporate it:

Because it is minus 50, the rate at which he puts that one-fifth of a kWh into the water is critical. He cannot afford to sit there for even a minute unless he is next to a heat source that is bathing him with enough heat to overcome the minus-50 and bring him at least into the low end of the human comfort zone, i.e. to at least 18°C.

If he wants that water evaporated in say 12 minutes, he needs a kilowatt of power. But that is just for the water. It’s minus-50 outside; he has to keep his whole body warm.

He needs about ten kilowatts of power, for as long as it takes to evaporate the water.

Hence the title of the story.

Now, just as you don’t have to be in the Yukon on a minus-50 day to die of cold, you also don’t have to be even in minus temperatures to be uncomfortable. The ambient temperature where you are could be a modest fifteen degrees, three degrees below the low end of the comfort zone, and if you are not moving, or if you are wet, then you could begin shivering (which is the body’s natural attempt to maintain its internal temperature of 37°C). It doesn’t take many degrees below 18 for us to need warmer clothing, even when we are dry. If we are outdoors and our clothing is wet, then we need some way of drying it off. This need becomes critical very quickly.

We don’t notice this when we are in the city. That is because artificial energy is widely available. Get wet and cold even on a warm summer day, and we can just go home and change into dry clothes, even take a warm shower. Home is nice and dry, those wet clothes can go into the dryer, and warm water is a staple of our urban energy diet.

That doesn’t happen by magic. Something at home keeps it dry; that something is enough energy to get into the water that is on your wet clothes and change it from liquid to gas. Because time is of the essence—we cannot wait for months for the water in our clothes to evaporate—we need power, i.e., energy divided by time. That power comes by way of countless machines and devices, most of which run on some form of heat, all of which get hot.

The self-styled conservationists
There are people who spend entire careers telling us to minimize energy usage. They harangue us to cut consumption, as if the comfort zone is not a matter of existential survival. This is all for the purpose of shaving a joule here and there off our overall consumption. Their motive appears to be helping us cut fossil fuel consumption, so as to reduce the amount of carbon dioxide (CO2) we put into the air.

What nonsense. We all of us spend our lives trying to stay inside the comfort zone; if we are not there now we will spend 100 percent of our time to get there. We will get there or die trying.

In the context of the climate change debate, we will get into the comfort zone using fossil fuels if we have to.

But we do not have to. We can use electric resistance heating. If the electricity is carbon-free, like nuclear, then we can have electricity that is 100 percent carbon free, and space heating that is 100 percent carbon free.

This does not require some technological breakthrough. We know how to build nuclear plants: my home province of Ontario starting about fifty years ago built an entire fleet of nuclear plants; the last one came online twenty-three years later. We know exactly how to build these plants.

As for electric resistance heating, electric heaters are everywhere. The technology was invented more than a century ago.

The Ontario Comfort Zone: how we stay there today, and how we could stay there in five years
To stay inside the comfort zone on cold days, people who run buildings in Ontario created in 2012 nearly 29 million tons of CO2.

Those 29 million tons represent about 152 billion kilowatt-hours of heat. Interestingly, that is roughly the same amount of energy that was in the gasoline that powered gasoline cars in Ontario in 2012. It is also about the same amount of energy that went into Ontario’s electrical grid in 2012.

Annual Energy production in Ontario
Energy typebillion kWhCO2, million tonsCIPK, grams
Space heating15228.6189

The 29 million tons of CO2 from space heating could easily have been zero—we could have gotten the 152 billion kWh of heat from electrical resistance instead of by burning combustible fuels. We would not have had to sacrifice a single kWh of the energy we needed to keep warm and dry. Those 29 million tons should have been zero.

We can create our own comfort zone, with zero carbon emissions. We just need to choose zero carbon sources for making our electricity.

Our problem is, we are not able to imagine.

For another article on energy conservation, see “Energy, affluence, and poverty: the cruel 21st Century disparity

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8 years ago

Sufficiently dense areas could have gotten the heat directly from nuclear fission, without the conversion to electricity and back.  This would yield about 3x as much useful heat per unit of fuel (possibly more if well-understood heat pump techniques were used).

It should not be all that difficult to design a core for something like the NuScale which takes CANDU-sized bundles.  This way, LEU fuel in the city-sited CHP units could be recycled as DUPIC in the CANDU units, thereafter going to disposal on a two-stage, once-through fuel cycle.  Using thorium, the fuel cycle could be completely closed and run with a breeding ratio greater than 1.

8 years ago

Don’t forget the potential electric output which can be achieved by dropping the steam temp from ~275°C at the SG outlet to ~150-200°C for the distribution system.  You get a two-fer there.

8 years ago
Reply to  Engineer-Poet

I love the idea of district heating. I also love the idea of distilling seawater if it could still be hot enough. Not too sure where California puts it’s power plants. Best guess is not near a giant coastal fault line.

8 years ago
Reply to  Kyle

The other Fukushima plants rode out the shakes well enough. But I wonder how many chemical and gas facilities perch on fault lines totally without a curious peep from the 4th estate…

James Greenidge
Queens NY

8 years ago

I love the idea of district heating.

It works nicely wherever the density is high enough.  Outside such areas you can still use electric heat.

I also love the idea of distilling seawater if it could still be hot enough.

The steam temperatures used for flash distillation (~115°C) are much lower than what’s distributed in NYC (~200°C).