In a country with minimal energy resources, peat offered Ireland an indigenous source of fuel that, at one time, provided heat and power to a large portion of the nation.
What is Peat?
Peat is partially decomposed plant material that has formed over thousands of years in bogs, ferns, mangroves, and various other wetlands. At first glance, it appears as no more than a muddy deposit of soil, what's different however, is that it can be mined and burned for energy.
How are Peatlands Formed?
Peat is formed in environments that lack the oxygen needed by decomposers to breakdown dead plant material. Thus, instead of plant debris being converted to energy and carbon dioxide, the plant (and its carbon) remains locked in its solid form.
Over thousands of years, the accumulation of this partially decomposed plant debris becomes compressed and forms a carbon-dense material known as peat. Often, these conditions have existed for long periods of time – leading to peat deposits being up to several meters thick.
Why are Peatlands Important?
Peatlands store more than twice as much carbon as all of the world's forests
Across the world, this accumulation of non-decomposed organic material stores massive amounts of carbon underground.
In fact, peatlands are flat out the largest terrestrial store of carbon – storing more than all other vegetation types combined (upwards of 550 GT) and more than twice as much as the world’s forests.
Where are Peatlands?
Peatlands occur on all continents, in all regions, and at all altitudes. Tropical peatlands exist in locations such as Indonesia, the Congo Basin and the Amazon Basin, however peatlands are most common in high northern latitudes, such as in Canada, Russia, and Europe.
Peatland degradation occurs when these areas are harvested for fuel. In order to harvest peat, the wetland's standing water must first be drained and the earth's surface must be ripped up to access the peat underground.
A side effect of this invasive process is that it exposes thousands of years of non-decomposed organic matter to the oxygen needed by decomposers to break it down – releasing its stored carbon into the atmosphere. As a result, degraded peatlands are hot spots for greenhouse gas emissions.
They are so carbon-dense that degraded peatlands make up just 0.3% of the Earth's land area, yet are responsible for a disproportionate 5.6% of global anthropogenic CO2 emissions – accounting for an estimated 1.3 GT of CO2 annually – greater than aviation and marine transportation emissions combined.
The good news is peatland restoration is relatively easy and cost-effective to implement compared to other carbon reducing technologies. Restoration involves blocking the water drains and re-wetting the bog to create the water-logged, nutrient-poor conditions that peatlands are known for, and then letting nature do the rest. These projects also help to reestablish the natural ecosystem benefits of peatlands, including improving water quality and biodiversity.
On the downside however, if significant levels of degradation have occurred, peatland restoration is not always possible.
Ireland's characteristic wet climate has made peatlands one of its most prominent natural features – covering 15.8% of the country's landscape.
Peat, also known in Ireland as "turf," has been harvested from these locations for centuries.
Without much in the way of forestland or traditional fossil fuel resources, peat became an important source of fuel for the country during the Industrial Age. Indigenous peat extraction also helped the nation buffer disruptions in coal supplies during the world wars and reduced Ireland's dependence on foreign oil.
Nowadays, peat is mostly used in residential heating and electricity generation, however it is also used in horticulture, glass/ceramic crafting, and even to smoke whiskeys.
Irish Peatland Degradation
Over the last 400 years that peat has been harvested, a substantial amount of damage has been done across Ireland. All together, the original extent of Irish peatlands has been reduced by over 47% – with less than 20% being considered worthy of conservation today.
Over the past two decades, Ireland has taken larger and larger steps towards phasing down extraction and restoring damaged peatlands.
The semi-state-owned company, Bord na Móna, who manages peat extraction in Ireland announced the closing of all its remaining operations earlier this year. The company will now be focused on rehabilitating harvested peatlands.
Surely a great announcement, however much work is still left to be done as these areas emit an annual 1.25 Mt of carbon.
As of 2019, peat accounts for 6.4% of Ireland's total residential energy consumption and 1.5% of its total energy production – down 33% from 2005.
While these are small percentages, due to the high emissions associated with peat combustion, the carbon intensity of Ireland's electricity remains one of the highest in the EU. To get an idea of how impactful, in 2020, peat and coal generated just 8% of the country's electricity, but accounted for 29% of its electricity-related emissions.
Phasing down peat energy and putting a cap on degraded peatlands has become a large impediment for Ireland in reaching its clean energy goals, despite the progress it has made on building out its renewable energy capacity. In 2019, 41% of Ireland's electricity came from renewable resources, predominately wind power.
Today Ireland seeks to continue restoring its harvested peatlands and has plans of sourcing 70% of its electricity from renewable sources by 2030.
There was a time in Ireland's history when peat served it well. It provided a domestic fuel source that heated, powered, and employed a large portion of the nation. However, its days have finally come to an end.
Peat varies greatly in character depending on its state of decomposition and moisture content, with its moisture content often being the limiting factor in its effectiveness as a fuel source. The natural water content of peat ranges from 50 to 70% by weight, but can be as high as 90%. Therefore, it is necessary for peat to be at least partially dried before being used for fuel.
The three types of commercial peat and their moisture contents are:
- milled peat: 40-50%
- air-dried sod peat: 30-40%
- peat briquettes: 10-20%
While the IPCC does not classify peat as a fossil fuel, it is considered by some to be the youngest type of fossil fuel because its formation is the first geological step in the coalification process.
Percent Carbon by Weight:
- Coal: 76-87%
- Peat: 50-60%
- Wood: 48-55%
The greater the percentage of carbon, the more heat given off when burned.
- Milled peat (wet peat): 10.5 MJ/kg
- Peat briquettes (dry peat): 17 MJ/kg
- Anthracite (pure coal): 29.3 MJ/kg
- Oil: 40 MJ/kg
This means peat emits ~1.23 times more carbon per unit of energy than coal.