Why do we need alternatives for wood pellets? Isn’t burning wood pellets a clean and carbon neutral way to heat up industrial and non-industrial buildings? As it has recently been discovered, it is not. The issue is not only with the sustainability, but also practicality. Traditionally, wood pellets made from trees require 7 years to grow before they can be harvested – an uncompetitive figure compared to Arundo’s annual harvest. Read the article below, and find out what is the current viewpoint on burning pellets and the importance of non-wood alternatives.
The health risks of using wood pellets
Not only was the burning wood pellets declared a disaster for climate change in 2017, but now there is clear evidence that it can mean a threat to human health. The wood pellets industry claims that what they use are tree branches and waste wood, environmental groups, however, disagree, saying that vast amounts of valuable, untouched forest are being chopped down in states including North Carolina, Florida and Texas, to be then transported to Europe, replacing coal in power plants there.
Communities living on farmlands near the Texan, German-owned pellets manufacturing plant are now struggling with respiratory problems and asthma (some of them even needs emergency inhalers) and claim that the air is rather sooty, than fresh in the area. This one particular plant is capable of producing 578,000 tons of wood pellets a year, which are destined to cross the Atlantic to satisfy a vibrant market for the product there.
As William Schlesinger, a biogeochemist and member of the US Environmental Protection Agency advisory board said
“When you cut down existing trees and burn them, you immediately put carbon dioxide in the air” and that the problem with wood pellets is “none of the companies can guarantee they can regrow untouched forest to capture the same amount of carbon released.”
He even called the renewable forest industry a
“Hoax in terms of its benefit as climate mitigation.”
Europe’s say on wood pellets and non-wood pellets
Nowadays, pellets are one of the major transnationally dealt solid biomass produces used expressly for energy purposes. Regarding the traded volume, an estimated 4 million tonnes of pellets are exported, a figure that could compete with biodiesel or bioethanol. With this sudden upsurge of demands, however, the EU also had its say.
Contemporary aims were inserted in legislature – Directive for Renewable Energy Sources (RES) – thereby ensuring the fair contribution of all EU member states. The principle concern was the share of energy from renewable sources in the total consumption of energy in 2020, being set at 20%. Whilst it was argued by Sikkema et al. that the use of pellets in the Netherlands, Sweden, and Italy, correspondingly can mark a substantial amount of evaded GHG emissions. Approximately 12.6 million tonnes of CO2 emissions were avoided in 2008 in EU-27 countries plus Norway and Switzerland, founded on the utilisation of 8.2 million tonnes of wood pellets and the replacement of coal and heating oil.
As good as this may sound, wood pellets are not completely eco-friendly, they are most definitively not sustainable, and are growingly more expensive. Based on a 2010 study, the prices of most pellet types are increasing. Though the majority of the markets of non-industrial pellets are generally independent, industrial pellet markets depend on the import of wood pellets from outside the EU-27. Thus, industrial pellet markets are unstable, depending mainly on the establishment or the abolishment of public support schemes. Now, the EU has devoted its efforts to step up for its forests and sanctioning those that utilise unsustainable wood commodities – while encouraging the consumption of products from deforestation-free supply chains in Europe. Where will this lead? As the industrial pellet market depends heavily on legislator support and the European Union is currently preferring non-wood pellets, prices are set to increase. The demand for pellets are nevertheless predicted to grow in line with the sustainability goals, yet those are more likely to be cheaper, more sustainable and reliable non-wood pellets.
Non-wood pellets alternative: Arundo donax
Arundo donax (also known as giant reed or giant cane) has a wide range of applications and innumerable advantages compared to other energy crops. This non-invasive, perennial plant grows in different kinds of environments and adapts well to a variety of soils – even marginal lands – and growing conditions. It is an energy crop which requires low input and has low cost production, in contrast to wood.
Regarding the cultivation and harvesting for pelletising, Arundo holds both ecological and financial advantages over the traditional wood pellets. As mentioned above, the earliest a tree can be harvested for pelletising is after 7 years – whilst Arundo can be harvested for 25-30 years annually. This significantly improves the raw material supply that a pellet producer has, whilst saving huge amounts in production and operation costs. Once trees are cut down, the trunks have to be removed before new seedlings can be planted. This is both expensive and time consuming, in contrast to an Arundo plantation, which does not need annual removal and replanting. Regarding the ecological costs for wood-based pellets, trees impound as many nutrients from the soil as they can for growth – leaving a poorer quality soil behind. Unlike Arundo, which transfers all the mobile nutrients back to the soil at the end of the vegetative season on top of the leaves and the occasionally deteriorating rhizomes. Thus, the organic content of the soil improves with an Arundo plantation whilst only the valuable biomass, lignin and cellulose is collected – contrary to trees that exploit the soil.
As for the heating value of giant reed, it equals to that of wood, more precisely it is 17-18 MJ/kg (dry matter value), and as perennial crops tend to contain higher concentrations of ash, the ash content of the giant reed is 4-6 % is higher than wood’s, consequently meaning that minor modifications of the furnaces to handle larger ash quantities could be required. The leftover ash after burning giant reed pellets can be used on the plantation as a nutrient to contribute to even higher yields.
Arundo donax can be burned directly to produce heat, however it is more effective to chip or pulverize it before burning. In practice, the best is to convert the reed into thicker energy carriers, such as bio pellets or briquettes. Thanks to the relatively high melting temperature of giant reed (900-1000 ºC) its combustion is safe for furnaces.
As for the energy balance of this plant (energy output – energy input) it is 4654.4 GJ/hectare, which is higher than both Miscanthus (3025.3 GJ/hectare) and Switchgrass (1760.3 GJ/hectare). When combined with its carbon dioxide sequestration ability – which stands at 160.1 tons of CO2 per hectare per year, or 1.96 tons of CO2 per ton of Arundo – we are faced with a truly sustainable, green and profitable resource for non-wood pellet production.
For more information on non-wood pellets from Arundo, visit our website or get in touch with us at info@arundobioenergy.com!
