Hydrothermal Carbonization (HTC) of Green Waste: An Environmental and Economic Assessment of HTC Coal in the Metropolitan Region of Berlin, Germany

Abstract

Standard-Nutzungsbedingungen:Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden.Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen.Sofern die Verfasser die Dokumente unter Open-Content-Lizenzen (insbesondere CC-Lizenzen) zur Verfügung gestellt haben sollten, gelten abweichend von diesen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. Terms of use: Documents in EconStor may AbstractBased on a life-cycle sustainability assessment and the calculation of carbon abatement costs, we quantify the greenhouse-gas emission reductions and costs if green waste in the metropolitan region of Berlin, Germany, is diverted from composting into the production of hydrothermally carbonized coal (HTC coal) that is used as a substitute for hard coal in the generation of electricity and heat. Depending on the geographical origin of the green waste, we specify an urban scenario, a rural-urban scenario, and a rural scenario. Approximately 302 kilogram (kg) of carbon-dioxide equivalents (CO2e) can be saved per megagram (Mg) of fresh-matter (FM) input in the urban scenario, 298 kg CO2e/Mg FM input in the rural-urban scenario, and 316 kg CO2e/Mg FM input in the rural scenario. All three scenarios combined can mitigate a total of 70,511 Mg CO2e per year. This corresponds to about 1.6% of Berlin's annual greenhouse-gas reduction targets over the 2005-2020 period. If only private costs are considered, the HTC scenarios are less profitable than their reference cases. However, the inclusion of emissionrelated damage costs has the potential to render them socially preferable. The respective thresholds for social desirability coincide with the carbon abatement costs, about 163 €/Mg CO2e in the urban scenario, 74 €/Mg CO2e in the rural-urban scenario, and 75 €/Mg CO2e in the rural scenario. The lower abatement costs in the latter two scenarios are due to HTC-coal co-firing in an existing power plant rather than mono-firing it in a newly built biomass power plant. This shows that a comparatively favorable use of HTC coal might be as a bridging technology. 1) IntroductionThe German government aims to cut the country's annual greenhouse-gas (GHG) emissions by 40% by 2020, 55% by 2030, 70% by 2040, and 80-95% by 2050, relative to the 1990 level (BMWi and BMU 2010). One of the main mechanisms to reach these targets is to substitute fossil fuels with renewable sources of energy, such as wind, solar energy, and biomass. In the power sector, for example, Germany has the objective to raise the share of renewable energy sources in gross electricity consumption to 40-45% by 2025, 55-60% by 2035, and at least 80% by 2050 ( § 1 EEG 2017 as published in Bundesgesetzblatt 2016). 4 However, Germany largely relies on fluctuating renewables, especially wind and photovoltaics (Neuhoff et al. 2016). 5 In order to deal with the fluctuat...

Challenges and opportunities of hydrothermal carbonisation in the UK; case study in Chirnside

“…Thus, it could be more feasible in terms of process economics and in terms of potential energy supply to implement a HTC-CHP process capable of processing a larger quantity of organic waste. However, a life cycle analysis conducted in 2017 by Medick et al 108 that investigated the coupling of HTC both with a new BCHP plant and an existing CHP plant for the conversion of 55 000 t per year of green waste in Germany deemed all modelled scenarios as economically unfeasible at that time. That being said, it could be the case that a small-scale HTC plant coupled with an existing CHP plant as an alternative means for sewage and food waste disposal in a small town is more feasible than the large-scale HTC plants assessed in their study.…”

Fate of Nitrogen, Phosphate, and Potassium during Hydrothermal Carbonization and the Potential for Nutrient Recovery

“…Hydrothermal carbonization (HTC) is a thermochemical process to convert wet biomass at moderate temperatures and pressure to a coallike product, known as hydrochar (HC), a liquid product, known as process water (PW), and a gas product. 1,2 HTC is economically and environmentally promising, 3 the use of water as a solvent is a key factor for the environmental performance of HTC; water is a good medium for heat transfer as increasing its temperature enhances its solvent properties by reducing its solvent polarity and decreasing its viscosity. 4 Water facilitates the permeation for porous media and thus it promotes the decomposition of biomass.…”

“…HTC is economically and environmentally promising, the use of water as a solvent is a key factor for the environmental performance of HTC; water is a good medium for heat transfer as increasing its temperature enhances its solvent properties by reducing its solvent polarity and decreasing its viscosity . Water facilitates the permeation for porous media and thus it promotes the decomposition of biomass .…”

Fermentative α-Humulene Production from Homogenized Grass Clippings as a Growth Medium

“…Green waste is defined as garden and park waste, as well as cuttings from roadside greenery, consisting predominantly of grass clippings and other plant biomass with low lignin content. In major cities, large quantities of potential substrates occur, e.g., in Berlin (3.7 million residents) more than 120,000 tons of herbaceous fresh matter are generated annually [1]. The waste material is mostly composted or applied in biogas plants, although these current methods are not particularly profitable.…”