You have 100 'energy slaves'

I haven’t been posting much in the last month or so because I am in the home stretch of finishing a textbook on climate risk1. I plan to post chapters in the spring, but I thought I would post this section on embedded energy now. Read it and appreciate how much our modern energy system does for us.

What is embedded energy?

Consider an iPhone. Its constituents were once sand and ore, transformed through energy-intensive manufacturing into glass, metal, silicon, and countless other advanced materials.

The total energy required to create an iPhone is what we call its “embedded energy.” This includes the energy consumed in extracting raw materials, manufacturing components, transporting goods, maintaining infrastructure, and eventually disposing of or recycling products at the end of their useful life. It includes the energy consumed in writing the software and running the cloud services that the phone relies on.

Embedded energy is everywhere. A steel beam embodies the energy used to mine iron ore, smelt it into steel, and transport it to a construction site. A hospital building represents not just the energy used in construction, but the ongoing energy required to heat, cool, light, and operate it.

Every good (road, building, vehicle) or service (a university lecture, an hour of tax preparation) requires energy without which that good or service would not exist.

Example: a Big Mac

Consider the humble Big Mac. The bread requires energy to grow the wheat, mill it into flour, bake it, store it, and ship it across supply chains. The hamburger patty requires energy to grow the grain that feeds cattle, as well as the energy to slaughter, process, refrigerate, and cook it. Even small ingredients like pickles and onions contribute.

When everything is added up, a single Big Mac embodies around 10 megajoules (MJ) of energy. To provide context for this number, know that an adult doing sustained, hard physical work might produce about 100 joules per second of useful power.

How big is 100 J/s? A joule of energy is about the same energy it takes to lift an apple from the floor to a nearby table. Thus, 100 joules per second is the same as lifting 100 apples (about 20 lb) from the floor to a table every second. As I said, that’s hard physical labor.

It would therefore take a human roughly 10⁵ seconds2 ≈ 24 hours ...