Abstracts - VGB PowerTech Journal 10/2018

Biomass ash: Challenges and opportunities

Nicolai Bech

2018 the EU has set a new target 32 % of renewable energy to be reached by 2030 in the hope to further reduce carbon dioxide emissions. The EU Commission has also issued recommendations on sustainability criteria for biomass. These recommendations are meant to apply to energy installations of at least 1 MW thermal heat or electrical power. [more...]

Biomass ash and options for utilisation

Angelo Sarabèr and Hans-Joachim Feuerborn

Biomass is increasingly used for power and heat production in a number of EU member states. The situation in the member states differs for fuel and combustion technology and also for the utilisation options of the resulting ashes. Bio­mass ash is produced by combustion by a wide variety of biomass types in different types of boilers for energy and heat production of different size. That leads to biomass ashes of different properties which are decisive for their (potential) use in the different applications. A survey has been performed of potential applications of biomass ashes. Only limited applications are implemented on a large scale and in specific countries due to different regulations. Biomass ashes are used in forestry, agriculture, building materials and civil engineering. Applications are addressed in some fertiliser acts (mostly coarse fraction of wood ashes) and in aggregate standards. Beside the requirements in the acts and standards they also have to meet environmental criteria. Main conclusion is that on EU scale, utilisation of biomass ashes is at the beginning of the transformation process from waste into a useful product.

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The H2020 Biofficiency project – A holistic approach towards ash-related problems in case of combined heat and power generation from biomass

Sebastian Fendt, Lynn Hansen, Thorben de Riese, Flemming Jappe Frandsen, Frans van Dijen and Hartmut Spliethoff

Heating and cooling account for about half of the EU’s final energy demand, while biomass currently accounts for more than 90 % of all renewable heat. Combined Heat and Power (CHP) plants using biomass represent a promising technology for increasing the share of renewables in the EU. However, the main problems arising from the use of biomass are ash-related problems caused by the ash composition, which limits steam temperatures and consequently the efficiency of the plant. The Biofficiency project aims to enable secure and almost carbon-neutral heat and power generation at the highest possible efficiencies while reducing environmental risks and paving the way for a sustainable development in ash utilisation. This article provides an overview of the project goals, the approach as well as some basics and first results towards a better understanding and more sophisticated handling of ash-related problems for the next generation of highly-efficient and sustainable CHP plants.

The use of wood ash for forest fertilisation – national and future European regulation – STRUBIAS

Rainer Schrägle

In Germany, the forced increase of the energetic use of wood for the future energy production leads to higher amounts of wood ash which need to be utilised or disposed. In forests and short rotation plantations the wood harvest leads potentially to a depletion of essential nutrients. The use of wood ash as fertiliser or for soil beneficiation is principally useful. In Baden-Württemberg, this use is established via a RAL quality scheme. With this quality scheme wood ash can be qualified as fertiliser or fertiliser component. Two levels of quality control systems for wood ash are established in Germany: The control of wood ash and a Dolomite-wood ash mixture, particularly designed for the use in forests, performed by the forest administration of Baden-Württemberg in co-operation with limestone plants and the free RAL quality mark which is organised by the Federal Quality Association for Wood Ash (Bundesgütegemeinschaft Holzasche). The use of the ashes is based on the German fertiliser act. It is subject to potential revision with the upcoming revision of the European fertiliser law. A subgroup of the fertilisers working group of the European Commission, the STRUBIAS (STRUvit, BIocoal and Ash) working group is working on product criteria.

The sustainable biomass program: Promoting sustainable sourcing solutions

Carsten Huljus

The uptake of renewable energy has increased significantly over recent years as national governments and energy companies alike focus their attention on reducing carbon emissions. Sustainable biomass has an important role to play in contributing to the portfolio of renewable energy technologies today and in years to come. Woody biomass is a valuable resource, all stakeholders need assurance that those involved in the biomass supply chain are acting responsibly. The Sustainable Biomass Program (SBP) has a central role to play in that regard. SBP manages a voluntary certification system designed for woody biomass used in energy production..

Wood ash brings nutrients back to the forest

Lisbeth Sevel and Rasmus Willumsen

HedeDanmark manages, develops, runs and maintains more than 120,000 hectares of forest in Denmark. It supplies approx. 1.6 million cubic metres of piled/stacked wood chip to the Danish energy sector. In view of a sustainable forest management, HedeDanmark has developed the Flisaske concept where the nutrient cycle is closed between wood-fired district heating plants and the forest. To close the circuit and ensure that the nutrients are recycled the ash is brought back to the forest where the nutrients in the ash contributes to more sustainable wood production and ensures the cultivation base in the forest. The concept is based on extensive research work.

Recycling of nutrients from residues of thermo-chemical processing of sugarcane bagasse and straw – handling of produced fertilisers based on biomass ash

Esther Stahl, Martin Meiller, Philipp Danz, Vitalij Dombinov and Hannes Herzel

In Brazil, approximately 2 until 10 million tons of ash are generated each year during sugarcane bagasse incineration. The ashes contain varying amounts of minerals essential for plant nutrition that could be used for fertilizing the plants. The project ASHES is a collaborative research between 7 partners from Germany and 4 partners from Brazil and deals with “recycling of nutrients from residues of thermochemical processing of sugarcane bagasse and straw”. The aim of the project is to develop optimised pathways for thermochemical utilisation of residues from sugar and bioethanol production, and to produce bagasse ash based fertiliser for major crops in Brazil.

Description of the fuel transport in the feeding area of waste incineration plants
Part 1: fuel and influence of fuel variations

Martin H. Zwiellehner, Florian Grafmans and Ragnar Warnecke

Basically the publication is divided into 2 parts. The present part 1 is dealing especially with the fuel properties and its influences on the feeding process. The 2nd part is focusing on a physical-mechanical approach for deriving a mass flow formula which makes it possible to pre-calculate the actual fuel mass flow in consideration of several effects and parameters. The most significant problem for combustion control systems which are implemented in waste incineration plants is the lack of knowledge about the actual calorific value (CV) of the fuel which is fed into the combustion chamber. Actual fuel inventory on the grate is also not known. Lots of studies do exist for „standard fuels” like coal and natural gas. For the inhomogeneous fuels which is dealt with in this publication (MSW , solid biomass, RDF ) there is no such literature available. The design of thermal treatment facilities respectively their furnace is done empirically – like in other incineration plants – by applying parameters of the fuels and the throughput capacity.

Wind Energy in Germany and Europe
Status, potentials and challenges for baseload application
Part 2: European Situation in 2017

Thomas Linnemann and Guido S. Vallana

One essential physical property of wind energy is its large spatiotemporal variation due to wind speed fluctuations. From a meteorological point of view, the electrical power output of wind turbines is determined by weather conditions with typical cor-relation lengths of several hundred kilometres. As a result, the total wind fleet output of 18 European countries extending over several thousand kilometres in north-south and east-west direction is highly volatile and exhibits a strong intermittent character. An intuitively expectable significant smoothing of this wind fleet output to an amount, which would allow a reduction of backup power plant capacity, however, does not occur. In contrast, a highly intermittent wind fleet power output showing significant peaks and minima is observed not only for a single country, but also for the whole of the 18 European countries. Between 2015 and 2017 the European wind fleet’s power utilisation factor resulted in annual mean values between 22 to 24 % and continuously available (secured) annual minima between theoretically 4 and 5% of its nameplate capacity despite tens of thousands of wind turbines distributed throughout Europe. Wind energy therefore requires a practically 100 % backup as long as the wind fleet’s nameplate capacity has not exceeded the cumulative load of these 18 countries considered, plus reserves. As the, also combined, capacities of all known storage technologies are and increasingly will be insignificant in comparison to the required demand, backup must be provided by conventional power plants, with their business cases fundamentally being impaired in the absence of capacity markets.

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(For more information about the VGB Wind Study - Part 1 see here!)