The South African National Energy Development Institute (SANEDI), in partnership with the DSI/NRF/CSIR South African Research Chair in Waste and Climate Change at the University of KwaZulu-Natal, has developed a Waste-to-Energy Roadmap for South Africa to contribute to the country’s Just Energy Transition with the aim to map the potential for insertion of waste to energy technology in South African municipalities. The South African Waste-to-Energy Roadmap identifies relevant technologies for the effective recovery of waste into biogas and energy, while mapping barriers and drivers for potential uptake at local level (Nell and Trois, 2022). One important element of the WtE Roadmap is a WtE Policy Review document (including institutional barriers and drivers) and detailed mapping of the policy and regulatory frameworks pertaining available WtE technologies for the treatment and valorisation of MSW in South Africa. The development of a WtE Roadmap supports the South African Government in delivering an economic recovery from the COVID-19 pandemic that is green, clean, resilient and inclusive based on the following research question:“How can South Africa transition to a sustainable smart energy system, implementing WtE as a resource, and how can different WtE solutions co-exist with other renewable energy technologies in a renewable South African energy system?”.There is global outreach to implement mitigation measures to reduce the amount of greenhouse gasses (GHG) emitted into the atmosphere and stabilize the impacts of climate change. Waste management in the South African context is an emerging sector with increasing emphasis placed on the development and application of integrated waste management strategies (Trois and Jagath, 2011). South Africa has recently adopted the Waste Hierarchy, through the National Waste Management Strategy and is progressively implementing policies aimed at maximizing the valorisation of waste as a resources, such as the Extended Producer Responsibility EPR and the Carbon Tax (Trois et al, 2022 (Task 36 Report); Roberts (Task 36 Report)) The National Waste Management Strategy (DFFE, 2018) drives the diversion of waste from landfills, the valorisation of waste as a resource, and assists South African municipalities in dealing with landfill airspace constraints. Over 70% of South Africa’s waste goes to landfill resulting in loss of resources to the economy (DFFE, 2018), and social (human health) and environmental impacts, however, Municipalities face challenges in delivering services and diverting waste from landfills (Kissoon and Trois, 2022). In the absence of full cost accounting, alternative waste treatment typically appears more expensive than landfilling thus creating a lock in.At the same time, South Africa is seeing a large-scale shift to low-carbon energy supplies and solutions with associated changes in infrastructure requirements and the way utilities provide energy services while continuing the drive for universal energy access for all South Africans with a particular focus on energy poverty and poverty alleviation initiatives in the country. The waste sector in South Africa contributes to >4.3% of the national GHG emissions (NIR, 2017). However, the nexus waste, climate change and renewable energy provision is not explicitly explored or addressed in current policies at national and/or local level, thus delaying the achievement of the nationally determined contributions (NDCs) in matter of implementing and rolling out projects towards the adaptation and mitigation of climate change from the waste sector.There is a need to investigate how different WtE solutions can be integrated in the South African energy system and play together with a national sustainable energy transition that not 3only reduces greenhouse gas emissions, but also improves security of supply and assists in an overall sustainable development for South Africa and similar emerging economies. The South African Waste to Energy Roadmap explores the following aspects of WtE development:1) The current state of the art for WtE technologies (including considerations on their appropriateness for the South African context), and their potential role in the energy system;2) The development of an energy system analysis and how it can assist in providing a renewable and secure energy supply for the country;3) Key contributions to the sustainable development of the South African energy system and WtE sector, with particular focus on policy and institutional frameworks; 4) The development of an implementation plan and policy/institutional framework for the insertion of WtE technologies in South African Municipalities.There is a need to develop decision-making tools for Municipalities to decide on the best Waste to Energy strategy that would achieve sustained waste reduction, resource recovery, carbon emissions reduction and job-creation. On the other hand, it is also necessary to facilitate the insertion and localisation of these WtE Technologies by analysing sustainable renewable energy systems on an hourly basis, by ensuring energy balance and assessing security of supply. These elements are crucial both in a South African context but also on a wider global level. Thus, in the development of the SA WtE Roadmap, the SARChI Chair Waste and Climate Change engaged with Task 36 of the IEA Bioenergy to compile a comprehensive Policy Review Report that compares barriers and drivers relevant to South Africa, with the policy frameworks and lessons learnt from the other member-countries of Task 36 (United States of America, Germany, Ireland, Sweden, Italy and Norway).

Renewable natural gas deployments in the United States have increased significantly in recent years. As of 3/31/2020, there are 119 operational projects with a further 88 under construction. Renewable natural gas upgrading is a mature technology that processes biogas into high purity methane. Historically, amine, membrane, water scrubbing, or pressure-swing adsorption technologies have been used to perform this gas upgrading through the separation of carbon dioxide and methane. The process of biomethanation instead converts the carbon dioxide into additional methane through the addition of hydrogen.In addition to increased yields of methane compared to incumbent separations approaches, biomethanation offers potential as a grid-scale energy storage technology by utilizing otherwise curtailed low-carbon electricity to produce the hydrogen needed by the organisms. Being a biological process, the hydrogen and carbon dioxide conversion is quickly ‘rampable’. There have been several pilot- and demonstration-scale installations of the technology andthis case study explores some of the economic and environmental considerations

Discussions about the climate changes and actions to counter the adverse effects of the massive historic and ongoing emissions have reached far beyond the scientific conferences. Climate activists like Greta Thunberg have gotten attention and recognition. This has also made the public more aware about the issue than before. Together with the strong scientific advice presented by IPCC around the urgency in taking action to reach the 1.5°C target, things are starting to happen. 

EU had set a goal of reducing the greenhouse gas emissions with 20% until 2020, which was reached ahead of time. The added knowledge developed during that time also have raised the awareness that the transition to a low carbon economy needs to be accelerated. In 2019 EU presented the green deal where it was stated that the EU would transform to become the first carbon neutral continent by 2050 (this is also in line with the IPPC estimation on when the world needs to become carbon neutral to achieve the 1,5°C target). Originally the EU set a part-target to reduce the emissions with 40% until 2030, this has since been revised to increase the ambition and the new target is 55% to 2030. To achieve these targets there has been several different packages developed. The green deal contains a multitude of actions, both on energy aspects like energy efficiency and replacing fossil energy sources, but also actions on circular economy to decrease the emissions driven by mass-consumption and in practice by the economic development. As one of the goals, the decoupling of resource use from the economic growth is mentioned. Amid the hunting after greenhouse gas emissions, it can be easy to ignore other sustainability aspects, however they are also part of the green deal. Bioenergy is mentioned but it will be connected with demands on the sustainability and coupled to aspects like biodiversity. On top of the measures EU also have identified the finance sector as a driver in the transformation, to guide the sector on what should be considered as sustainable actions, a Taxonomy is being developed.

Sweden has been early in the transformation away from fossil fuels. This is especially true when it comes to the heating sector where district heating has made it possible to replace fossil fuels with bioenergy in a large scale. This has also been the case with the utilization of Waste-to-Energy where today, close to 50% of the MSW is treated in WtE facilities. With the increased demands on carbon neutrality these also face demands on reducing their fossil emissions. A multitude of actions to succeed with this is investigated, including measures to increase the separation of plastics from the residual waste, exchanging support fuels to bio-oils, and BECCS/CCS. 

Hydrothemal Carbonization (HTC) technology has demonstrated to successfully convert biowaste and sludge – which are input feedstocks - into high quality hydrochar, sometimes considered to be a more valuable product than biochar materials. Several HTC industrial plants operate in Europe. Ingelia, an HTC technology developer, operates its own industrial HTC plant in Valencia (Spain) since 2010, CPL Industries Ltd operates an HTC Plant in the UK which was commissioned in 2018 and a third plant is under construction in Belgium, expected to start operations in 2021. Ingelia HTC technology has been proven at commercial scale, reaching TRL9. The HTC process acts as an acceleration of the natural coal formation process, working at moderate pressure and temperature (20 bar and 210 ºC for the Ingelia process), allowing the dehydration of the organic matter and increasing the C-content up to 60 wt.%. By means of HTC, feedstock with high moisture content converts into a coal-like product called hydrochar. The Ingelia HTC technology includesseparation equipment for impurities that are present in the waste such as sands, stones, pieces of metals or glass. However, there are some inorganic components in the carbon structure, such as Ca, K, or P, that can be reduced by specific washing and chemical post-treatment steps. As a result of the HTC process, most of the carbon content of different wet organic waste streams is concentrated and retained within the obtained hydrochar. HTC process represents a solution for the valorisation of biowaste streams, while generating a carbonbased solid fraction, hydrochar, that can be used as an energy source, a soil ameliorant, or as a feedstock to produce bioproducts. The hydrochar is chemically stable and storable, preventing the emission of methane if the feedstock would be landfilled. The moisture present in the feedstock condensates after the HTC process, and solubilises elements like N, P, K, etc. These elements represent a liquid biofertilizer that potentially can be used as a substitution of chemical fertilizers. The HTC process provides a source of renewable carbon whose properties can be adapted to its final application. The hydrochar can undergo specific post-treatment to reduce the content of specific nutrients to the limits accepted in the industry and energy sector, or to modify moisture content and density (by palletisation or briquetting) with the aim of delivering a product that can be sold as a natural resource for fossil coal substitution.A life cycle assessment was carried out to determine the potential environmental impacts (global warming, freshwater eutrophication, and terrestrial acidification) of a large-scale HTC plant processing 78 000 ton of wet biowaste and sludge per year in Italy. The analysis highlighted three major contributors to overall environmental impacts; electricity and thermal energy used in the process, CO2 produced in the process, and the organic content in the waste streams impacting the environment when applied to land. The analysis shows that there is potential for improving the environmental performance of the HTC process by optimising energy use and using greener sources of energy.

Projektets syfte är att bidra till en mer rättvisande bild av de direkta utsläppen från fossilt innehåll i avfall som eldas i avfallsenergianläggningar. Detta genom att vidareutveckla modellen från det tidigare projektet Modellering av referensvärde pMC i avfall som går till energiåtervinning (förbränning). Målen i projektet har varit att: 1. Tydligare definiera de avfallstyper som ingår i de underkategorier som används i befintlig modell 2. Fastställa hur stora andelar av underkategorierna som eldas i de 15 största avfallsenergianläggningarna som ingår i EU:s handelssystem för CO2 (ETS, eg. de anläggningar som enligt ETS har utsläpp på minst 50 000 ton CO2 under 2019) samt för tre anläggningar som ligger relativt nära brytpunkten 50 000 ton CO2. 3. Fastställa hur stora variationer det finns inom olika underkategorier mellan anläggningarna samt mellan åren (2017–2019). Undersöka skillnader i referensvärde för 100 procent biogent avfall beroende på variationerna över tid och mellan anläggningarna. 4. Ta fram uppdaterade fördelningar mellan biogent/fossilt på olika avfallskategorier samt undersökt hur stor inverkan dessa har på referensvärdet. 5. Uppdatera modellen enligt slutsatserna från målen 1–4 ovan. Utifrån resultatet från ovanstående genomförandemål rekommenderar projektet att ett nationellt referensvärde (pMCref) används vid beräkning av fossila koldioxidutsläpp från svenska avfallsenergianläggningar. Projektet rekommenderar också att anläggningar som eldar huvudsakligen olika blandade avfallsströmmar (som exempelvis hushållsavfall, RDF mm) ligger till grund för den nationella schablonen. Av denna anledning har projektet exkluderat en anläggning eftersom den i huvudsak eldar träavfall och därmed kraftigt skiljer sig ifrån övriga 12 anläggningar vad gäller mottaget avfall. Det nationella referensvärdet för 2020 respektive 2021 hamnar baserat på ovanstående rekommendation på 107,2 respektive 107,0. Eftersom det redan är överenskommet ett referensvärde för 2020 rekommenderas att det nya referensvärdet används från 2021. Ett möjligt undantag från användning av ett nationellt referensvärde är anläggningar som huvudsakligen eldar träavfall eller exempelvis en blandning av träavfall och gummi. För det förstnämnda fallet skulle då en kombination av den nationella schablonen och en för träavfall bli aktuell. Över de tre åren data samlades in utgjorde Träavfall och träfraktionen i Stödbränsle totalt sett omkring 3 procent av totalt förbrända mängder. Projektet har finansierats av Naturvårdsverket och Avfall Sverige.

Det finns driftparametrar som påverkar reaktiviteten på flygaskan från avfallseldade CFB-pannor. Det finns också goda skäl att tänka ett par varv extra kring säkerhetsfrågor i miljöer där dessa askor kommer i kontakt med, eller har kommit i kontakt med, vatten! Det är tidigare känt att askor från avfallseldade CFB-pannor kan bilda vätgas när de kommer i kontakt med vatten. Det övergripande syftet med projektet har varit att minska de vätgasrelaterade arbetsmiljöriskerna förknippade med dessa flygaskor samt att öka kunskapsnivån kring de vätgasrelaterade riskerna generellt. Projektet har undersökt vilka driftparametrar och mekanismer som kan påverka vätgasbildningen både sett till mängd och hastighet, undersökt mängden metalliskt aluminium i askor/beläggningar i pannan samt att genomfört en grovriskanalys för en tänkt logistikkedja med båt. Undersökningarna har fokuserats till P14 och P15 vid E.ON:s Händelöverk. Resultaten visade bland annat att det i litteraturen finns väldigt lite information direkt relaterad till frågeställningen i CFB-pannor. Istället får slutsatser och teorier byggas kring litteratur som hanterar närliggande frågeställningar i andra miljöer. De experimentella resultaten indikerar att det finns en skillnad i reaktivitet i flygaskan mellan de båda pannorna och att val av bäddmaterial är en driftparameter som tycks kunna påverka reaktiviteten. Vid inblandning av ilmenit i bäddmaterialet tycktes den maximala vätgasbildningen sjunka och/eller bli mer fördröjd i tiden. De övriga driftfall som studerades var: dellast, varierande tillsats av ammoniak i SNCR systemet samt lagring/åldring av aska i NID-filtret (rökgasreningen) när en del av filtret är ur drift. Det finns indikationer på att dessa driftfall också kan ha påverkan, men dataunderlaget är för litet för att med säkerhet fastslå något. Det tycks dock svårt att förutom med bäddmaterial påverka reaktiviteten med bibehållen funktion i driften i övrigt. Ask/beläggningsprover från olika delar av pannorna visade att halten metalliskt aluminium i ekonomiser är fullt jämförbar med de efter NID-filtret och därmed är det stor risk för vätgasbildning vid våt rengöring av dessa delar. God ventilation och utbildningsinsatser för att öka medvetenheten är viktiga rekommendationer för att minska/hantera risken. Slutsatserna från grovriskanalysen logistikkedjan lyfter faran med att generalisera vätgasbildningen från askorna eftersom den varierar så kraftigt. Det är också viktigt att ta hänsyn till att vätgasbildningen kan vara fördröjd och inte initieras förrän askan utsätts för mekanisk bearbetning. Den mekaniska bearbetningen utgör också en risk utifrån att den kan initiera gnistbildning. Denna gnistbildning kan i sin tur agera som tändkälla för bildad gas.

There are operating parameters that affect the hydrogen formation from APC-residues generated in waste fired CFB-boilers. There are also reasons to be careful and take extra consideration to safety aspects in environments where the APC-residue has been exposed to water. It is well known that if the APC-residues generated from waste fired CFB-boilers are exposed to water; hydrogen gas is formed. The overall aim of the project has been to decrease the work environment hazards related to hydrogen formation from these APC-residues. Another aim has also been to increase the general knowledge related to these hydrogen related hazards. This has been accomplished by exploring which operating parameters and general mechanisms that affect the hydrogen formation from the APC-residues. Both total amount of gas formed as well as the velocity of the gas formation has been of interest. The APC-residues used in this project have been from P14 and P15 at the waste-to-energy plant Händelöverket, owned and operated by E.ON. In literature there are almost no publications on the hydrogen gas formation from APC residues generated by waste fired CFB boilers. There are some related to waste fired grate boilers though. Conclusions and theories from literature data must be put together from results regarding similar materials in totally different environments. The experimental results indicate a difference in the hydrogen formation from APCresidues originating from P14 and P15. The bed material used in the boilers is also one of the operational parameters that seems to affect the reactivity of the APCresidue. The introduction of a share of Ilmenite in the bed material seems to have lowered the amount of hydrogen gas formed, alternatively it delayed the formation. Other operational conditions that was considered was a decreased thermal load, lowered amount of ammonia added to reduce NOx, and storage/aging of ash in the NID-reactor while it was not running on full capacity. There are indications that these conditions also affect the reactivity, however there are too few data available to make specific conclusions. In general, it seems difficult to control the reactivity of the APC-residue while keeping normal production in the plant. In fouling samples, from different parts of the boilers, levels of metallic aluminium fully comparable to those in the APC-residue were detected. Thus, there is a significant risk of hydrogen formation when using wet cleaning methods during maintenance stops. Proper ventilation and education are two of the recommendations to mitigate the risks. A potential logistic chain for APC-residues, based on ship transports, was risk assessed. Since the hydrogen formation differs greatly between different ash deliveries, an important conclusion was that it is hazardous to generalise the results, especially by using average hydrogen formation rates. Another conclusion was that consideration must be made for the fact that the hydrogen formation might be delayed and might not arise until the APC-residue is treated mechanically

IEA bioenergy Task 36 “Material and energy valorisation of waste in a circular economy” prepared this report about trends in waste management for the example of municipal solid waste (MSW). Within the waste hierarchy, recycling is given preference over recovery, and waste-to-energy (WtE) conversion is given preference over landfilling. MSW is non-hazardous household and commercial waste, of which more than one third typically is biogenic in origin. Incineration represents the state-of-the-art WtE technology; alternative thermal treatment technologies such as gasification and pyrolysis have had far fewer applications to MSW due to economic factors and relatively low technology readiness. This is a situation that is currently changing. Specifically in the European Union (EU) technologies develop and new pathways are sought. Major trends in the EU are driven by legislation and implementation goals, some of which are country specific:

• banning of landfilling in combination with limited social acceptance and, in some countries, legal restrictions for additional incineration capacity

• increasing waste generated or imported in combination with limited incineration capacities have led to increased waste treatment cost (gate fees) and waste exports

• recycling rates that are lower than EU and national Circular Economy objectives

• global demand for sustainable routes for waste processing, particularly with regards to reducing greenhouse gas (GHG) emissions, and

• heightened social awareness and concerns about environmental impacts including climate change and marine littering.

Key opportunities driven by these trends are related to the adoption of non-incineration thermal technologies

• for energy recovery as a response to decreasing public acceptance for direct waste incineration, and

• as a pathway to chemical recycling of waste, which accelerates the transition to a Circular Economy. This involves co-processing of biomass and waste to improve the economies of scale associated with biomass conversion plants.

The upcoming report discusses both trends impacting solid waste management systems within EU countries as well as selected alternative thermal treatment technologies. Aspects concerning technology readiness and affordability are highlighted in this report as well as the need to combine mechanical waste pretreatment and sorting with thermochemical treatment in order to increase recycling rates and to improve economics.