Different kinds of bio-based waste streams can provide opportunities for sustainable use of bioenergy
Waste with potential for bioenergy use includes sewage sludge from waste water, manure from livestock, biowaste fraction of municipal solid waste, used cooking oil and other industrial food waste.
Nevertheless, several challenges are also related to the increasing use of bio-based waste for energy. Even if waste is bio-based, it doesn’t mean that it’s truly a renewable resource in a society where the overall aim is to reduce waste production. According to European waste legislation, priority should always be to first reduce waste as much as possible and then reuse and recycle materials The EU’s political agenda, which wants to build a circular economy where resources are rather reused than burned, and legislation to increase recycling, pushes these aims even further. Also, a big part of the resource is very scattered and not simple to collect for energy use.
In addition, much of these “waste” streams are already being used as low-value inputs for industrial and agricultural processes and cannot be diverted to bioenergy production without secondary impacts on downstream markets.
Some proportion of this “waste” plays a valuable environmental role in protecting soil quality through composting. For example, straw from agricultural production is also important for the soil and can be used for animal bedding and other uses in agriculture. Tall oil which is a side product of the pulp industry is already used as raw material for biobased chemicals- using it now for biofuels puts extra pressure on that feedstock and hence can force the use of alternatives such as fossil fuels.
Considering these limitations, the potential of waste resources for energy use is also fairly limited. Incentives to use ‘waste’ for bioenergy need to be carefully designed in order not to displace other uses or to hamper the need to enforce a circular economy.