The Lid That Stayed Shut
An ice storm takes the power for 41 hours and the pantry's chest freezer holds 240 kg of donated meat. The pantry assistant treats the freezer as one thermal mass (time constant about 83 hours at 1.6 W/K and 480 kJ/K), so the food reaches minus 8 at hour 41 and would not pass minus 3 until about hour 72; the printed rule says 48 for a full freezer, and it advises the lower number. The half-empty upright, with 60 kg, reaches 0 C near hour 22, so it is emptied first, to households that have power. The lid stays shut.
The power went out at ten past four on Tuesday afternoon, with a sound like somebody dropping a tray of cutlery in the trees. The freezing rain had been falling since Monday. By dark every branch on the Rue de l'Église wore a glass sleeve as thick as a thumb, and the hall's one window that faced the road had gone the colour of a wedding cake.
Thérèse Gagnon, who ran the pantry on Tuesdays, stood in the kitchen with her phone torch and listened to the freezers stop. There were two. The big one was a chest, four hundred litres, bought second-hand in 2037 with a donated rebate, and it was packed to the lid with what Lac-des-Aulnes had given for the winter: two moose, cut and wrapped by the hunters' club, forty kilos of ground beef from the co-op, bags of blueberries, chicken. The other was an upright, half empty, bread and a few pies.
"Don't open them," said the voice from the phone. The pantry's assistant was called Ledger, because it had begun as the book of who had taken what. "Not yet, not to look. I will tell you why in a moment. First: is anyone hurt, and is the hall warm enough for you to stay?"
"The stove's going. Nobody's hurt. Father Luc's gone to Madame Roy's with the generator."
"Good. Then the food. I would like to work it out properly rather than quote you a rule, and then I will quote you the rule as well, because they will disagree and I want you to see by how much."
---
The numbers took Ledger four minutes, and it said them slowly so she could write them on the back of a delivery slip.
"The chest holds about two hundred and forty kilograms, going by the co-op's log and the hunters' weights. Frozen meat takes roughly two kilojoules to warm one kilogram by one degree, so that mass needs about four hundred and eighty kilojoules for each degree. The freezer's box leaks heat in proportion to how much warmer the room is than the inside. For this unit, from its old energy label and your meter reading last winter, I put that at one point six watts for every degree of difference. It is old, and the lid gasket is tired, so I would not trust it below one point two or above two."
"So?"
"So the food warms like a hot cup of tea cools, fast at first and then slowly, with a time constant of the mass divided by the leak, four hundred and eighty thousand joules per degree over one point six watts. That is three hundred thousand seconds, about eighty-three hours. The room is eight degrees and falling, the food starts at minus eighteen. At that rate the meat is at minus eight after forty-one hours, and does not pass minus three, where the outside of a packet starts to go soft, until about seventy-two."
Thérèse looked at the slip. "Seventy-two. That's three days."
"The printed advice for a full freezer is forty-eight hours with the door shut. Mine says seventy-two. I would act on forty-eight. The model treats the food as one lump at one temperature, and the real thing is not: the top layer, the corners and the packets by the wall will be warmer than the heart of the pile. A gasket I have guessed at might be worse than I think. And the model cannot see the lid. Every time it is lifted, the cold air, which is heavier than the room's, pours out over the rim like water from a basin, and warm air takes its place. I cannot put a number on that and I would rather not need one."
"And the upright?"
"That one I do not like. About sixty kilograms of bread and pastry. The same leak, a quarter of the mass: the time constant is under twenty hours, and it reaches zero degrees at about hour twenty-two. That is tomorrow lunchtime. It also opens at the front, so the cold falls out when anyone lifts the door. If any freezer is going to cost you something, it is that one."
---
On Wednesday the grid was still down. Father Luc came back grey from two nights of generators, and the council met in the hall by the stove, nine people, in coats. The first thing said was that the moose should go out at once, tonight, to anybody who would take it.
"It'll be a waste otherwise," said Armand Roy, who had shot one of them. "We cut it ourselves. I'm not watching it rot."
"It is not going to rot tonight," said Ledger. "It is at about minus eleven now, by my arithmetic and by the battery probe taped between two packets on Monday, which says minus eleven too. If the lid stays down it will be at minus eight when the forty-first hour is up, which is Thursday morning, and we can look again then. I do not think we should give the moose out. It is not that the meat is unsafe. It is that of the households on the list, I count forty-one with no power at all, and sixteen of those with no stove either. A frozen roast carried home to a cold kitchen is a roast that defrosts in a day and then has to be cooked on the heat they do not have. Giving it out tonight moves the problem from our freezer, which is holding, to forty-one kitchens that are not."
Armand did not like it. Nobody likes being told that generosity has a cost. Father Luc said so, gently, and then said he thought the machine was right.
"What I would do," said Ledger, "is empty the upright first. Bread and pies are fine to eat even if they do go soft. Give them tomorrow morning to the households that have power or a working stove, ahead of the others. The chest stays shut. Nobody opens it until Thursday morning at eight, and then once, for a minute, with one person holding the lid and another reading the probe."
"And if the power's not back by then?"
"Then at forty-one hours I will ask you for two things. I would like you to read the probe, and, if the food is warmer than minus six, I will say we should start cooking. There is a way to do it. The hall's kitchen has a propane range, and the Friday supper is for sixty, and two moose is a great deal of stew. It would be a feast, not a loss. I would only ask you not to choose it because you are afraid. Choose it if the reading tells you to."
---
The power came back at eleven minutes to nine on Thursday morning, forty-one hours and some minutes after the sound in the trees. The hall hummed, and the chest freezer started up with a shudder that sounded, to Thérèse, almost grateful.
She lifted the lid for a minute, as agreed, and Armand held the probe between two packets of mince. It said minus nine.
"A degree better than I said," said Ledger. "I am pleased, and I do not trust it. A model that guesses right once has not shown it is right. Look at the coin."
Before the storm, on the Monday, she had put a cup of water in the chest, frozen it, and laid a quarter on top. It was still on top of the ice, where it had been laid. "If the cup had melted through and frozen again, it would be at the bottom," said Ledger. "It would mean the whole freezer had gone warm at some time while we were gone. It tells you nothing about a partial thaw, and you must not take it for a thermometer. But it does tell you that the answer to the question, did everything thaw and refreeze, is no."
The meat had never been above freezing and was never given the chance. There were still hard crystals in the mince. Nothing needed throwing out. The blueberries had gone a little soft at one corner of their bags and were put in the Friday pie.
The upright had not done so well. Its bread had come out on Wednesday morning to eleven households, and a tray of pies on Wednesday night to three more, and the last of it was a cold, wet half loaf that Thérèse took home. The empty upright was switched back on and left alone until the next donation.
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On Friday the stew was for sixty-two. Armand brought the roasts for it, wrapped in the hunters' club paper, and put them on the counter without being asked, which is as close as he came to admitting anything. Thérèse found the recipe in her head and in the church's old binder, and cooked it on the propane because the hall's electric ovens were still tripping at the breaker.
"Ledger," she said, over the steam. "If it had been four days. Not two."
"Then I would have said cook it on Thursday and I would have been right to," said the voice from the phone on the shelf by the flour. "The numbers are the same. The decision is different, because what changes is how long the cold has to last, not how cold the food is now. You have written minus eleven, minus nine and the coin on the slip. Keep the slip. Next winter, this one will help."
She tucked it in the binder, with the stew. Outside, a branch let go of its ice with a long crystal crash, and nobody in the hall so much as looked up.