Thistles form the basis for the Compost Bag. This organic material gives our bags their most important characteristic: they are 100% compostable. But cardoon thistles have many other ecological and economic advantages. In spring, cardoon thistles produce large purple flowers, which are fertilised by bees. Once they have finished flowering, a seed ball remains, filled with seeds rich in vegetable oil. This oil is not suitable for food production, but it is the ideal raw material for bioplastics.
Easy to grow
Cardoon thistles are actually very easy plants: they bloom smoothly every summer for about seven years on the most arid soils. Because the roots penetrate very deep into the soil, they always find water and additional irrigation is not necessary. The dry and rocky soils in Sardinia – where the thistles grow – are a disaster for food cultivation, but the ideal soil for these plants. The soil does not need to be fertilised either: the remains of the thistles that remain after harvesting die off in winter and then feed the soil sufficiently to allow new plants to flourish.
Nothing is lost
To turn a thistle into a Compost Bag, a special harvesting machine is used that cuts the plant at two different heights. First she harvests the well-filled seed bulbs. Then the machine mows the dry stems further down to about 30 cm above the ground. With the stems energy is generated which drives a biorefinery. The installation extracts oil from the seeds with which bioplastics are eventually made.
What remains of the plant – the 30 cm stem – dies off and feeds the soil for a new cycle. Residual products released during the conversion of oil to bioplastics are also reused, for example in cosmetics or biological herbicides. In this way, each thistle is fully used.
Booming local economy
Cardoon thistles are not only a good thing from an ecological point of view, they also give the economy in poor Northern Sardinia a strong boost. An industry was built in the region decades ago to process oil from the Middle East, but that plan never got off the ground. The result? Fallow land, derelict industrial sites and unemployment.
Today, the harvesting and processing of cardoon thistles provides work for 250 Italians and the biorefineries are running at full speed. Fields that had not been worked for years are now full of thistles. What’s more, the flowers attract a lot of bees in spring. The honey they make provides an extra income for many local farmers. The remnants of the pressed seeds are also returned to the farmers as concentrates for their goats. and that makes for stronger animals that offer quality milk, cheese and meat.