Historians used to tell us that the growth of human civilization was broken into three stages: the Stone Age, the Bronze Age, and and Iron Age. Nowadays we know these distinctions to be over-simplified. Nonetheless the emergence of iron and steel in human history was a major turning point.

Bronze is an alloy of copper and tin. Both of these metals have been known since antiquity. The natural ores for both copper and tin are easy to smelt. Temperatures in the 250 to 350 Celsius range (600 Fahrenheit) can be obtained in fireplaces and thus early peoples could work these materials.

Iron is another story. The separation of iron from its ore requires a lot of heat energy. Charcoal is needed to smelt iron ore and more specialized furnaces are required. Temperatures have to be in the 1250 Celsius (2300 Fahrenheit) range. Thus it is reasonable that iron (and steel) emerged later in human history.

One of the key moments in the so-called Industrial Revolution was the invention of the modern blast furnace. Steel is iron that contains small amounts of carbon. Controlling the carbon content changes the brittle pig iron and wrought iron into the tougher and more malleable steel. The blast furnace made the conversion of iron to steel cheaper and more efficient and gave more control over the quality of the final product.

Today steel is made with coke which is a charcoal made from coal, not wood. The demand for “met” (metallurgical) or coking coal is growing even as the demand for thermal coal is declining. The production of virgin steel needs a lot of coke. Recycled scrap steel is worked in an electric arc furnace which does not need coke. Most electric arc furnaces are powered by natural gas which provides the energy for the electric current generation. Steel melts at about 1500 Celsius (2700 Fahrenheit) so you can see that the energy needs are still very high. Recycling of scrap steel is a well-established industry and the energy savings from virgin steel production are significant. Most manufactured steel is recycled as scrap when its lifespan is reached. Think of all the auto junkyards—those are scrap metal stockpiles.

World demand for steel is of course on the increase. As countries like China and India, the two most populous in the world, improve their standards of living they will build more modern-style buildings and consume more modern devices like vehicles and tools. Energy consumption is the true measure of wealth. Americans consume more energy per capita than everyone else. It is only natural that poorer nations will seek to emulate American economic gains and attempt to deliver a better life for their citizens. That means they will consume greater quantities of primary energy sources (coal, oil, natural gas, nuclear fuel) and seek to build more energy generating technologies (solar panels, hydroelectric dams, wind turbines). Demand for all the natural resources will accelerate in the coming decades. This is an inescapable fact of economic growth! Economic growth is the Holy Grail of Western societies and the obvious benefits are plain to all. The rest of the world wants what we take for granted.

But economic growth comes with environmental costs. This is another inescapable fact of modern life. Can we get there without polluting our world to the point of making it un-inhabitable? Yes, but it will take a lot of creative people working together. And we will have to revisit our notions of wealth and freedom and reevaluate our needs regarding comfort, leisure, and consumer goods.

Here’s a graph that shows the significance of iron processing and steel manufacturing in the overall industrial sector:

The most important rule of all is “you can’t get something for nothing.” Whatever we want, whatever we do, comes at a cost. What’s it worth to us?