How firewood became a pellet

If you asked what fuel humanity has used the longest, the answer is probably wood. From fires in caves to hearths in thatched huts, for hundreds of thousands of years people have burned wood to warm themselves and cook their food. Wood is, in that sense, humanity's oldest companion of a fuel.

And yet this oldest of fuels carried, along with it, an old inconvenience.

The oldest fuel, yet a troublesome one

Picture a log of firewood. First, it is bulky. It takes up much room to haul and to stack. And it demands constant attention: someone must stand by and feed in fresh logs so the fire does not die. Damp wood scarcely catches, and burns with acrid smoke. On top of that, each log differs in thickness and length, so it is hard to guess how long it will last.

For a single small stove, one might let it pass. But imagine a vast power plant running on such a fuel. If people had to pick and feed logs every moment, check whether they were wet, and fret over when the fire might die, steady electricity would be impossible. Wood was a good fuel, but in its natural shape it could hardly carry the great household of the modern age.

An invention born of crisis

In truth, the idea of pressing wood into small pellets to burn was not so new. As early as the 1800s, a German engineer is said to have fired a steam engine with pellets pressed from wood. That unwieldy wood becomes far more usable when packed small and hard — people had sensed this, dimly, even then.

This idea truly gained the power of machinery in the early twentieth century. Yet at first that machine was used not for fuel, but somewhere quite unexpected: making animal feed. In the early 1900s an American company called California Pellet Mill introduced a machine that pressed grain powder into pellets, and in the 1930s its engineer Edgar Thomas Meakin perfected the ring die method still used today. Since pressing powdered feed into pellets shrank its bulk, made it easy to carry, and easy for animals to eat, this "pellet mill" became a trusted workhorse of the feed mill.

Then came the fateful year of 1973. When conflict in the Middle East led oil-producing nations to shut off their oil, the price leapt fourfold almost overnight. Oil that had cost three dollars a barrel became twelve within months. At filling stations the sign "No Gas Today" went up, and cars lined up long to refuel. Prices rose several times a day. Only then did the whole world realize, to the bone, how bound it was to a single drop of oil.

People urgently sought something to replace oil, and their eyes turned naturally to the oldest companion — wood. And they took the tool that happened to be at hand, the very pellet mill that had pressed animal feed, and applied it to wood. Finely crushed wood, pressed under high pressure into small, hard pellets. And so the dim idea of the 1800s and the feed machine of the twentieth century met before the oil crisis, and were at last reborn as the wood pellet we know.

Once it became a small pellet, the troubles of firewood melted away as if by magic. Pressed tight, its bulk shrank and its heat grew concentrated. Being uniform in size, a machine could feed it in steadily, bit by bit, so no one had to stand guard. Bone-dry and even, it burned with little smoke and burned clean. The wood that had been so hard to handle became, at last, a predictable fuel.

The newest shape of an old fuel

The history of the pellet came, step by step, this far: from unwieldy firewood, from the trouble that demanded constant hands, to a small pellet at last easy to handle and easy to foresee. The oldest fuel, carried on for hundreds of thousands of years, was reborn — through people's long contriving — in its most manageable shape yet.