Peat

Peat has many uses in agriculture, industry, and energy generation because of its organic chemical content and combustion properties. Although abundant in the middle latitudes of the Northern Hemisphere, it has been exploited as fuel primarily in northwestern Europe.

Where Found

Peat is developed by the compression of dead organisms in bogs, swamps, and other wet areas. The main US producers are Florida, New York, Minnesota, and Michigan; in addition, Alaska contains vast peatlands. Worldwide, the major producing nations are, from greatest to least, Finland, Ireland, Belarus, Estonia, Sweden, Russia, Latvia, Canada, the United States, Moldova, Ukraine, and Lithuania.

Primary Uses

Most applications of peat are in agriculture, horticulture, and soil management. Peat is used in earthworm culture media, golf course construction, nurseries, potting soils, mixed fertilizers, mushroom cultures, packings for seedlings and starter plants, and general soil improvement. It is sold as reed-sedge peat, sphagnum moss, humus, and hypnum moss.

Technical Definition

Like crude oil and coal, peat is composed of the remains of dead organisms compressed in wet ground or water. It is akin to fossil fuels in that it is a partially carbonized form of organic matter—requiring hundreds or thousands of years to form—whereas other fossil fuels are later stages of carbonized matter, having developed over much longer periods of time.

Description, Distribution, and Forms

Peat forms in bogs, fens, sedge meadows, and some swamps as the debris of peat mosses (sphagnum), grasses, and sedges falls to the wet earth and becomes water-soaked. In the absence of oxygen underwater, the plant matter and microorganisms compact without completely decomposing, forming soft, usually fibrous soils that are tan to black in color. The organic component, which includes cellulose, lignin, and some humus, is always greater than 20 percent, and in most peat soils plant fragments are visible; the ash content is less than 50 percent, usually as low as 10 percent. Although the rate varies widely, in general a peat field increases in depth about three centimeters yearly. The bottoms of large peat fields are typically about ten thousand years old and can be as much as 50 meters below the surface, although 3-meter to 6-meter fields are common.

Most deposits of peat lie between 40° and 65° latitude of the Northern Hemisphere. Worldwide, of peat are comparable to those of other fossil fuels. For example, according to some estimates, resources in the United States surpass the combined potential energy yield of the nation’s petroleum and natural gas. According to the USGS, total world peat resources were estimated at 13,000,000 thousand metric tons in 2023. That year, the top producers of peat were the United States, Belarus, and Canada. In the United States, Alaska contains most of the reserves, but peat is also available in Minnesota, Washington, Michigan, Wisconsin, Maine, New York, North Carolina, Florida, and Louisiana. Some countries well below the fortieth meridian have exploitable peat reserves, especially Indonesia, Cuba, and Israel.

History

Historically, particularly in northern Europe, peat has fueled fires since the Stone Age. It provides one-half to two-thirds as much energy as coal, or about 3.8 megajoules per dry kilogram, yet gives off far fewer pollutants, such as sulfur and ash. It can be converted into coke, charcoal, or a synthetic natural gas. During the Industrial Revolution, with the increase in the use of fossil fuels for heating and other energy needs, these sources became more important worldwide, although peat continues to play a role in energy production in some countries.

Obtaining Peat

Peat is cut, or harvested, in blocks from the peatlands where it has formed, then sent on to processing plants for its various applications. According to the US Geological Survey’s Mineral Commodities Summaries, peat is a renewable resource, and it continues to accumulate on 60 percent of the world’s peatlands. However, encroaching development and the rate of regeneration—peat fields, once harvested, regenerate only after thousands of years—mean that peat is not a renewable resource in a practical sense. Intensive peat “mining” has caused concern among environmentalists, who worry that the rapid exploitation of peat fields, especially in Ireland and the United Kingdom, may permanently destroy bogs and fens and thereby threaten the many animals and birds dependent upon those wetland habitats. Climate scientists also worry that mining peatlands will result in the release of additional greenhouse gases, accelerating the progression of global climate change.

Uses of Peat

Peat can be burned in home stoves and fireplaces or in factories and public power plants. In Ireland, Russia, Finland, Estonia, Latvia, Lithuania, and Sweden peat is employed primarily as a fuel, where it is a traditional domestic resource. Dried and pressed into briquettes, peat burns easily in fireplaces, stoves, and braziers. These four nations have burned increasing amounts of peat to generate electricity. Because Ireland has historically had limited wood and resources, it has consumed considerably more peat for power generation than for domestic heating, whereas the other countries primarily rely on coal for the latter purpose.

Whereas peat has been used as fuel for heating and power generation in countries where other sources are scarce or require supplementation, in the United States and Canada, as well as some European countries, peat is used mostly for potting soils, lawn dressings, and soil conditioners. Because they are much lighter and fluffier than soils, peat preparations let water and oxygen penetrate easily and increase water retention, and so can be useful in soil supplements or mulch. Throughout the United States, commercial nurseries and homeowners apply such products to gardens and tree beds. Farmers have raised grasses, clover, wild rice, cranberries, blueberries, strawberries, Christmas trees, and root and leafy vegetables on peat fields, and ranchers have used them for hay and grazing. However, peat fields are difficult to drain and clear, often remain wet, promoting rot and disease, and can be low in nutrients.

During the energy crisis of the 1970s, researchers investigated peat and other organic substances as alternative sources of fuel. However, few of the efforts resulted in commercial products because oil again became cheaper than peat during the 1980s.

Peat also yields such mineral and organic substances as dyes, paraffin, naphtha, ammonium sulfate, acetic acid, ethyl and methyl alcohol, waxes, and phenols. Combined with clay, it forms lightweight blocks for construction. It can remove heavy metals from industrial waste and can be turned into coke for iron processing or into charcoal for purifying water. With its mildly antibiotic properties, peat served as a lightweight surgical dressing during World War I.

Another of peat’s well-known functions—and one of its oldest—is giving the smoky flavor to Scotch and Irish whiskeys as their malts slowly dry over open peat fires.

Peatlands may play a substantial role in slowing the onset of global climate change. Roughly 15 percent of global peatlands worldwide have been drained for land development and agriculture. Environmental scientists estimate that peatland restoration projects could prevent the release of up to 394 million tons of carbon dioxide equivalent each year. Additionally, many environmental scientists recommend against disturbing untouched peatlands, as doing so might reduce their greenhouse gas reduction.

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