I like to ask students in class what they had for dinner. I’m interested in their dietary habits, but mostly I’m characterizing “energy,” the quantity that moves and sustains us. Food is a good way to feel what that is.

On the back of food containers, bold text displays how many “Calories” (designated with a capital “C” as a unit for food) we’re taking in with a given serving size of chips or noodles or cookies. To me, this is food’s value, the reason we eat. It’s telling us what we gain in comparison to the 2,000 Calories of energy recommended each day.

I did a quick search for the price and energy content of an extraordinary food item, a can of chili. You can function on only four of those cans each day, so for about $8 you could live on the energy content of chili.

Please know that I’m not recommending this. There are problems, both with that particular diet and with taking nutrition advice from a physics teacher. But that intake of matter and energy grows and pulses what’s inside of you. Even if you’re pregnant and developing a new life within, that child will be assembled from the air you breathe and the contents of that chili. Our basic building blocks are pretty simple.

Energy stored in cans in your pantry is a good deal. It’s even better if you could harvest personal energy from electricity. Here in Utah, you’ll likely pay something like 10 cents for every 1,000 Calorie equivalent of electrical energy. At that rate, you’d be out less than a quarter for your body’s needs each day — if only you could plug yourself into an outlet like your phone. We don’t have such an adapter, though.

Similarly, you can’t plug your computer into a can of chili, even though there’s about four times as much energy in the chili can as there is stored in my laptop battery I’m writing on right now. My computer and myself each need energy, but we have different processes for using it, and at vastly different costs.

Asking students what they had for dinner will bring up that can of chili, a burrito or grilled cheese sandwich. These all trace energy back to plants, which receive energy from the sun. Noodles are processed from wheat, which at some point took to growing in a flood of sunlight. Cheese came from milk from a cow, who was eating alfalfa that also got energy radiated from our star. In turn, we eat those foods. We are indirectly, though quite literally, solar powered.

It’s no small feat, getting that energy into forms we can use, refined in ways that our digestive processes can make use of. This is why food is relatively expensive compared to the free energy just pouring through blue skies.

The electric company uses a wide array of energy sources, but these are still dominated by fossil fuels like coal or natural gas. There are inherent problems with these: They’re limited and have to be extracted from deep within Earth, not to mention that their burning changes the very nature of our atmosphere and climate, which creates an existential crisis for us and generations to come. Yet I’ll still marvel that even coal, a striking vein of which you can see in roadcuts along Highway 6 just this side of Price, is a massive storage of solar energy. Hundreds of millions of years ago, plants were taking in energy from the sun and, due to an absence of microbes, they did not decay the way plants would today. Not being “eaten” by other life forms, the sun’s energy of hundreds of millions of years ago is stored deep within rock layers.

Yet, as with an emergency cache of canned chili in my basement, coal and natural gas are one-time stores. We’re raiding a limited pantry supply and dumping its byproducts into our climate systems all at once. I’m enthusiastic about the prospects of getting energy directly from our solar source — onto the plants I eat or solar panels on a roof — leaving some chili on the shelf, some coal in the ground.

Adam Johnston is a professor of physics and director of the Center for Science and Mathematics Education at Weber State University, where he helps prepare future teachers and supports educators throughout Utah.

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