Biomass recycling: sustainable energy production and nutrient recovery for the future.

The sun provides most of the energy used on the Earth. If we think beyond solar panels for making electricity: biological energy, such as sugars produced by photosynthesis in plants, sustains just about all of life on Earth. In the process, carbon dioxide is used and oxygen is produced.

We need to change our thinking about waste as a product that is thrown away, to waste as actually being a resource that can be reused. We can recycle aluminum, glass and paper. Electronic goods such as computers contain copper, gold and other rare earth minerals. We dispose millions of tonnes of organic waste in landfill (about of 30% waste going to landfill is organic waste).

According to the Australian Government Department of the Environment and Energy’s National Waste Report 2013: 14 million tonnes (Mt) of organic waste was generated (excluding paper, cardboard and primary production); of which, 6.14 Mt  was recycled (44 per cent) and 1.24 Mt (9 per cent) used in energy recovery, and the remaining 6.63 Mt (47 per cent) going to landfill. (1)

According to Clean Up Australia, around “47% of household waste in Australia is made up of organic waste like food scraps and garden cuttings” (2)

In countries such as South Korea which has banned food waste from landfill from 2005. ‘Instead, food waste is now being turned into compost, livestock feed as well as biomass and biofuels. To promote recycling, the government has been providing financing for the expansion of public recycling facilities that transform food wastes into livestock feed, compost and biomass. The South Korean government has recently invested a total of 782.3 billion Korean Won (about AU$902 million) to build 17 biogas facilities and 4 sewage sludge drying fuel facilities that are estimated to turn 188,000 tonnes of organic waste into biofuels every year.’ (3)

The decomposing of organic material in anaerobic (lacking oxygen) environment allows microbes that produce methane from the decomposition process to thrive. (4)

Biomass is utilised in many developing and developed countries around the world; although not always for energy production. Germany is one of the leading developed countries utilising biomass. There are almost 9,000 plants operating in Germany: with 150 plants and 23 MW in electricity production added in 2015 {although mostly small manure based plants). The nearly 9,000 biomass plants in Germany provide over 4,000 MW power to about 8 million homes and has a storage capacity of 100 MW. (5)

The use of bioenergy in Germany in 2015 helped abate 61.3 million tonnes of CO2 equivalents. (6)

Coal fired power plants are highly polluting, producing nitrogen oxide, sulphur dioxide, mercury, particle matter and other toxins. “A 2004 report by the Clean Air Task Force estimated that soot pollution from power plants contributes to 24,000 premature deaths, 38,200 non-fatal heart attacks, and tens of thousands of hospital visits and asthma attacks each year.” (7)

Typically coal fired power plants are located far away from large population centres. Coal fired power plants are also highly inefficient, with over half of the energy being lost as heat. On the contrary, bi-generation can utilise this heat to also provide heating to nearby buildings and tri-generation plants can provide both heat and cooling to nearby buildings. It makes sense to have (smaller) biomass power plants located where the heat generated can be utilised. There have been reports of biomass generators being installed in pig farms and chicken producers: where the animal waste has being utilised to provide electricity for the farm as well as heating for the animals and earning money feeding excess electricity into the grid.

There has been a rapid expansion of the use of biomass to generate power and produce transport fuels. Between 2000 and 2010 transport fuel production had increased by 525%. Currently biofuels contribute 3% of global transport energy. The International Energy Agency predicts this will increase to 27% by 2050. Research has shown the benefits of incorporating plants (such as Acacia saligna (golden wreath wattle) in medium and high rainfall areas) into rotational cropping systems, where it’s fast growing and tolerance for environmental conditions: where the wood can be used as a biofuel; the litter and prunings can contribute significant nitrogen to the soil and lessen the need for fertiliser for future crops for up to three years: and, the deeper root system can recapture nutrients for shallower rooted annual crops and prevent nutrient leaching, reducing environmental impacts from traditional farming. (8)

Perhaps the most exciting discovery in methane production from biomass sources by UNSW led research is the use of crystals from a red synthetic dye that greatly increases methane production from food waste by up to 18 times. This will greatly improve the economics of biomass as a fuel source. The dye, called Neutral Red is a synthetic molecule used for more than 150 years as a textile dye. The needles-like crystals apparently assist methane producing microbes grow faster and thus produce more methane. (9)

According to Andrew Lang, World Bioenergy Association vice-president: “CSIRO research shows that about 9 per cent of our national electricity demand could be produced just from the economically available straw in our main cropping regions, much of which is free burned. Our unutilised biomass could produce about 30 per cent of our consumed energy, including more than 17 per cent of our power needs.” (10)

Not only can energy be produced, in the form of natural gas and electricity: modern biomass facilities can extract: nutrients such as phosphorus and nitrogen (replacing fossil fuel fertilisers), organic mulch and clean water from the process. (11)


(8) Integrating Food and Energy Systems, R Sudmeyer et al, Publication 13/099, 78 pages

(10)  Letters to the Editor, The Weekly Times, 13 December 2017 p. 19

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