Power Up Your Waste
RENEWABLE ENERGY FROM WASTE
It is widely acknowledged that one of humanity’s greatest present challenges is the amount of waste we produce; less well understood is the value to society of these residual waste streams.
The plastic mountains are being harvested and turned into aviation fuel, and for a number of years now, methane emissions from landfill sites have been collected and used to generate electricity; without this technology, the unavoidable landfill gas emissions would be odorous and twenty-five times more harmful to the atmosphere than carbon dioxide. A large scale landfill site in the northern suburbs of Melbourne can generate sufficient electricity on a daily basis to power 14,000 homes!!
Agricultural countries such as Germany and the USA have, for over twenty years, been taking manure from intensive farming, by-products from the food processing industry, and energy crops such as maize, canola, rapeseed and bagasse from sugarcane, and directing these waste streams to biogas plants which anaerobically digest the waste and produce electricity or biomethane. Anaerobic digestion (AD) has been particularly successful in Europe where the level of energy market prices supports the purchase of electricity generated by such processes.
In Australia, although landfill gas to electricity systems have been in place for a number of years, there is still significant value in the waste streams generated by many large companies which is currently being lost.
The value in these waste streams can be identified in various ways. Particularly interesting are the conversion methods which mimic nature’s own way of recycling, AD being one such method, and one which can be used on a large or small scale to convert waste to electricity and fertilizer.
An example of one of the smaller scale uses for AD is in Africa, where the AD of waste streams such as animal manure, kitchen and garden waste, produces electricity to assist children to study and fertilizer to grow high energy, protein rich crops such as mushrooms. The sale of both of these outputs has lifted many out of the cycle of poverty by generating food, employment and income on a local basis, as well as reducing the amount of waste sent to landfill (and amount of methane in the atmosphere), thus demonstrating the significant value in these waste streams, socially, economically and environmentally.
