Chapter 3. What type of sink? Landfill or valorisation? Organics or energy?
viewed in France as a new opportunity for a waste-to-energy solution. The process involves recovering rejects from sorting centres or by-products from waste processing (such as woody waste from composting in Madagascar) to produce fuel. Only dry wastes are channelled into this process, which creates an obvious risk of competition with materials recovery activities. In Madagascar, production of these alternatives to wood-fuel yielded 300 tonnes in 2016, earning the recycling company, Madacompost, revenues equivalent to those it earned from compost sales. This also gives Madacompost access to carbon credits, as this valorisation helps to reduce methane emissions.
3. Gasification: at the end of utopia Other energy recovery methods are also being explored, such as gasification. In Surabaya, a contract was signed for a project to build a gasification power plant in 2018 (Cavé 2016), and solid waste recovery is under study, particularly in Lomé. Following similar trends, discussions are underway in several of Brazil’s southern states1 (notably Paraná) to integrate this technology into their regional waste management plans. Heated low-tech/high-tech debates are taking place around this technology, which is still mastered to a far lesser degree than incineration and used by only a few cities in rich countries (notably Japan) for MSW management.2 These still costly and globally underdeveloped technologies designed to recover energy mostly from recyclable or compostable wastes may come up against the same limits as incineration in Delhi. In the Indonesian case, the gasification project (still far from completion) is likely to compete with the organics recovery system currently in place (Cavé, 2016). Moreover, this technology, which is highly complex to implement in global North countries (only Japan has developed it on a large scale), is nowhere to be found in global South countries. The main brakes on this method of energy recovery are the types of waste (too wet to be burnt) and the maintenance of the infrastructure, which uses highly sensitive and costly technology. As a result, the risk of dysfunction is extremely high. In addition to the enormous long-term costs incurred, the main risk of an over-reliance on this type of technology is that it may enter into competition with the recovery of recyclables (as it requires the most easily combustible wastes). The example of Delhi shows that the two sectors inevitably experience tensions in the medium-term.
III.
The underestimated potential of organics recovery
Organic waste should be at the heart of public action as it represents at least 50% of household waste stocks – and in some cities as much as 80%. It thus constitutes the bulk of waste in municipal collection and landfills. Since bio-waste carries potential health risks, it is vital to encourage rigorous local waste management so as to prevent the concentration of pathogenic vectors. Several processing techniques may be envisaged. The first technique is the recovery (via composting or anaerobic digestion) of pre-sorted waste. This means collecting bio-waste at source, which poses many technical and financial hurdles (mainly transport-related), although various methods for composting raw waste are now
1
Solid waste management workshops organised in 2016 in Curitiba by Le Mans University together with Paranacidade. 2 www.bioenergyconsult.com/gasification-municipal-wastes/
72 | TECHNICAL REPORTS– No. 54 – OCTOBER 2020
