UN Sustainable Development Goal 2: End hunger, achieve food security and improved nutrition and promote sustainable agriculture
UN Sustainable Development Goal 15: Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reserve land degradation and halt biodiversity loss
How biogas contributes to the above goals:
- Increased crop yields: After digestion of the feedstock, the solid and liquid fractions left over can be used as an organic amendment/soil improver (digestate or composted digestate biofertiliser) on farms in place of energy intensive chemical fertilisers. Use of digestate biofertiliser has been demonstrated to increase crop yields (Consorzio Italiano Biogas e Gassificazione, 2015).
- Phosphorus recycling: Phosphorus is widely used in agriculture to promote the growth and maturity of plants. However, the world’s phosphorus supply is limited, becoming increasingly scarce and concentrated in only a few countries (most of the world’s reserves are owned or controlled by Morocco, China and the US) (Cordell, Drangert and White, 2009). Due to inefficiencies in use, phosphorus is lost to surface water bodies where it causes toxic algal blooms. Phosphorus recovered from dewatering liquors left over from the digestion of waste water can be sold and used as biological struvite on agricultural land.
- Soil degradation: Globally, 52% of the land used for agriculture is moderately or severely affected by soil degradation (United Nations Convention to Combat Desertification, 2014). By recycling the nutrients in the soil through the anaerobic digestion of primary, break and catch crops and organic wastes, and returning them to the soil in the form of digestate biofertiliser, desertification of land can be prevented and reversed. This is a vital step towards ensuring food security.
- Deforestation: 1.6 billion rural people around the world are to some extent dependent on forests for food, fuel or fodder needs. Overcutting of vegetation for use as wood fuel and charcoal in rural communities contributes to deforestation and degradation of forests (Chao, 2012). By digesting livestock manures, agricultural residues and biosolids to generate biogas which can be used as domestic fuel, land degradation and deforestation can be reduced.
- Nutrient recycling: In developed countries, where 40% of food waste occurs at retail and consumer levels, collection and treatment of food waste can ensure that the nutrients are returned to farmland in the form of digestate biofertiliser, rather than being lost in landfill or through incineration (FAO, 2011).
Farm on Po River Plain, Italy
- Digests animal manure, cover crops including nitrogen fixing plants, livestock effluents, perennials grown on set-aside land or land undergoing desertification, agricultural by- products and organic wastes.
- The biogas generated is used to power an electricity generation unit of 1MW.
- The digestate is applied back to the farm.
- The introduction of anaerobic digestion under the ‘Biogas done right’ regime has resulted in:
- Recirculation of nutrients and increase in harvest yield via use of digestate biofertilises
- Significantly increased carbon content of the soils
- Better soil coverage and reduced leaching and run-off due to cover crops
- Self-sufficiency in fertilisers
- Increased production of crop residues such as straw for the livestock.
Richgro Anaerobic Digestion Plant, Jandakot, Australia
- Digests solid and liquid wastes from nearby breweries, chicken farms, supermarkets and other food and beverage waste
- The digestate, which is rich in living micro-organisms and nutrients, is blended with other garden composting products to be sold as commercial biofertiliser.
- The biogas produced is used for 2MWe electricity generation which is utilised on-site and excess exported to the grid.
- The excess heat generated is channelled to the on-site hot houses where blueberries are grown.