Sweden’s second-largest peatland lies in Saltmyran, south of Arvidsjaur. The area comprises nearly 500 hectares and SCA has been harvesting peat there since 2000.
“Peat harvesting is very dependent on the weather, so you can’t afford to be of a nervous disposition. We had a fantastic summer this year so the production results will be excellent,” says Rainer Holmberg, site manager for Saltmyran.
Grey clouds are hanging low over Saltmyran when SCA's magazine Inside comes to visit in mid-August. The area is huge, and you can drive nearly three kilometres from the office and workshop before reaching the end of the peatland.
“Rainer Holmberg holds a handful of milled peat, a kind of powder, while Lars Södersten shows sod peat.SCA doesn’t own the peatland, but we have a concession right to harvest peat until the end of 2020. Then we have to apply for a new concession,” says Lars Södersten,
SCA Norrbränslen’s Marketing Manager in Västerbotten and Norrbotten. SCA also harvests peat at Docksmyran and Långmarksflon in Jämtland.
Peat consists of marshland vegetation – mainly bog moss and sedge – that is inhibited from decaying fully by acidic and anaerobic conditions. Peat has formed when land areas become marsh or lakes grow over.
Mills thin layers
Before harvesting a new area, the water is drained and all vegetation is taken away. Then the top layer of soil is removed to expose the peat. SCA produces both sod peat and milled peat.
“We make sod peat by lifting the peat from the ground and passing it through special nozzles to produce 10-20 cm long sausage-like sods. The sods are left on the ground and turned occasionally until we think they are dry enough. Then they are scraped into strips, and when the strips are long enough, they are loaded onto peat wagons and driven to large stacks that are covered with plastic,” says Lars.
Rainer shows milled peat that has been scraped into long strips. After drying, it is placed in large stacks. Peat does not absorb water readily when it is dry, so only the surface becomes moist in rainy weather. “Milled peat, on the other hand, is like a powder. You start by milling the top centimetres of the peatland. Then the peat is turned on the ground a few times to speed up the drying process and scraped together into a strip. This is repeated several times until the strip is long enough, about 1.5 metres wide and 1 metre high. Then we load the peat and drive it to the large stacks that are packed by a piste machine outdoors. They must be packed properly because we want as little oxygen in the piles as possible, to reduce the risk of fire. The biggest milled peat stack we’ve had was about 48,000m3,” says Rainer.
Worst enemies
The worst enemies of peat harvesting are weather and fire risk. “We need fine, dry weather to harvest peat, otherwise it all turns into black muck. If it rains for a few days, we have to wait another couple of days before we can start working again. It rained so much last year that we produced less than 48,000 cubic metres here at Saltmyran. The weather has been good this year so production started as early as May and volumes will be excellent. June, July and August are the top months for peat harvesting and sometimes we work around the clock in three shifts,” says Rainer.
Since peat is such a dry material, there is a major risk for fires. The dust from peat can get into tractor engines, which means that embers can fall down onto piles.
The machinery used for production at Saltmyran is owned by SCA. However, 15 tractors, piste machines and some other machines are owned by the contractors who handle the harvesting. One of the many stacks of milled peat can be seen in the background. “A peat fire is very difficult to extinguish, so all machinery has fire-fighting equipment. The most effective weapon against fire is a bucket. If you smell or see smoke, you put the smouldering pile in the bucket and take it to a ditch where it can be sprayed with water. Windy weather is not good for harvesting either, because if a fire starts it can spread fast,” says Rainer.
Alone in the winter
Rainer has worked at Saltmyran for 29 years and knows nearly everything there is to know about peat. In the summer, he is joined by the contracting firm that handles the actual harvesting, but in the winter he is mostly alone.
“There can be up to 20 people here in the summer. I work with planning, checking the moisture content of the peat, taking water samples from nearby creeks and quite a few other things. In the winter, I clear snow and load the trucks that transport the peat and deliver it to customers. There might be 20 trucks a day here sometimes.”
Varying moisture content
The moisture content of sod and milled peat varies, which means they have different energy contents per ton.
"But last season, we sold everything we had produced and some more on top of that. One of the benefits of peat is that it can be stored for a few years."
“When peat is removed from the pile, the moisture content is 70%. Dry sod peat has a moisture content of 36-40% and a heating value of around 3 MW per ton, while milled peat is slightly higher with a moisture content of 45-50% and an energy value of about 2.1 MWh per ton,” says Lars. “We sell more milled peat because it works best in large boiler installations.”
Peat is primarily used in thermal power stations and large boiler installations, where it is usually mixed with other biofuels.
“The benefit of co-incineration is that the boilers are cleaner on the inside, which reduces the risk of operational problems,” says Lars. “Our customers are mainly here in Norrbotten and Västerbotten, otherwise transport would be too expensive. One customer in Arjeplog uses our peat to make an emulsifying agent, as peat absorbs oil very efficiently.”
Demand for peat is largely driven by supply and demand for other biofuels.
“Peat is only classed as a partially renewable material. That means that peat is subject to a price mark-up through emissions trading and may be more expensive than other biofuels depending on the current price of emission rights. But last season, we sold everything we had produced and some more on top of that. One of the benefits of peat is that it can be stored for a few years,” says Lars.
Peat does not currently constitute a major portion of Norrbränslen’s energy supplies. It represents 100 GWh of the 3.6 TWh that Norrbränslen supplies per year.
“But there is a potential for growth,” says Lars. “Less than 1% of Swedish peatlands are harvested today. Here at Saltmyran, we can probably harvest peat for at least another 15 years.”
Misan Lindqvist Image Per-Anders Sjöquist Source SCA Inside Forest Products 4/2011