Biomass Waste EFW
Overview
Biomass is a feedstock for energy from waste processes. It is used in several different forms to produce energy and this effects the amount of power generated due to differences in variables like Moisture Content and Calorific Value. The different forms of biomass used in EfW processes are outlined below in the table.
| Waste | Overview | Tonnage (mt) '16-'17 |
|---|---|---|
| Waste Wood | Wood recycled | 1.63 |
| Meat and Bone Meal | (product of animal rendering/food processing industry) | 0.18 |
| Agricultural | (including straw and poultry litter) | 1.37 |
| Sewage Sludge | (exclusively as part of waste water integrated treatment process) | 0.10 |
| Process Residues | (including kernels and chaff) | 0.09 |
| Liquid Biomass | (including vegetable oils and tallow) | xxxx |
| Virgin Wood & Energy Crops | (including virgin wood and energy crops) | 2.36 |
Additionally, the details of the generating facility can affect the power output, for example the scale, technology used, or its ability to cogenerate heat and power.[1]
EfW plants that operate using only biomass as a feedstock can be considered as producing renewable energy. [2] Biomass can be considered a renewable fuel because the growth of biomass removes carbon dioxide from the atmosphere and stores it in components of biomass such as soil, plants and trees, acting as temporary carbon storage.[3] Biomass is the largest source of renewable energy in the UK.[3]
Biomass EfW
In 2017, there were 39 operational biomass EfW facilities in the UK with an electrical output exceeding 2.5 MW; the total biomass capacity of these plants is 5.73 Mt (excluding fuel imported by Drax), and these plants combined produced 4,226 GWh of power. The biomass capacity of UK EfW plants is generally increasing. From 2016-2017 the amount of biomass being processed by UK facilities increased by 6.9%.[1]
An example of a biomass EfW facility in the UK is Welland Bio Power in Northamptonshire, accepting 72,000 tonnes of waste wood per year, and producing 10.6 MWe (gross) of low carbon electricity. Welland Bio Power utilises Nexterra Gasification technology and was developed by CoGen Limited.[4]
Residual Waste EfW
Energy from Waste plants that use Waste Derived Fuel (WDF) but do not exclusively accept biomass will still have a portion of biomass in their feedstock. Often this is quantified as the amount of the C-14 isotope in the fuel compared to total carbon in the feedstock. This is an important parameter as the heat/electricity produced from an EfW plant that can be classified as renewable (and therefore eligible for subsidies e.g. ROC, RHI) is derived from the biogenic portion of the feedstock. Moreover, the amount of biogenic content relates to landfill cost saved by diverting this waste away from landfill[5]. This quantity of biomass in the feedstock also forms the basis of the Renewable Qualifying Multiplier (RQM) to calculate the quantity of payments made to a generator in line with the Contract for Difference (CfD) scheme.[6]
The non-biomass portion of waste feedstock (e.g. plastics) produce a similar product gas to biomass-derived gas. Additionally, they both have similar fuel characteristics, like high volatile matter content and low fixed carbon content. Subsequently, this enables similar processing conditions and gas cleaning techniques to be used in waste and biomass EfW facilities. However, significant differences do still exist between these two feedstocks, for example, generally higher ash content and higher content of other contaminants in a mixed waste feedstock and these warrant specific changes in the EfW process.[7]
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From Tolvik report – could include but only sites “included in this report” – not Drax, at least 2.5 MW
References
- ↑ 1.0 1.1 Tolvik Consulting Ltd, 2017. UK Dedicated Biomass Statistics - 2017. [online] [Accessed 13 Nov. 2019].
- ↑ Defra, 2014. Energy from waste A guide to the debate February 2014 (revised edition). London.
- ↑ 3.0 3.1 Office for National Statistics, 2019. A burning issue: biomass is the biggest source of renewable energy consumed in the UK - Office for National Statistics. [online] Office for National Statistics. [Accessed 14 Nov. 2019].
- ↑ CoGen, 2019. Projects — CoGen. [online CoGen.] [Accessed 14 Nov. 2019].
- ↑ WRAP, 2019. A Classification Scheme to Define the Quantity of Waste Derived Fuels. Wrap.org.uk. [online] [Accessed 1 Nov. 2019]
- ↑ LCCC, 2019. Contracts for Difference Generator Guide. Low Carbon Contracts Company. London.
- ↑ Waldheim, 2018. Gasification of waste for energy carriers. A review. IEA Bioenergy, [online] ISBN 978-1-910154-56-4. p.16. [Accessed 14 Nov. 2019].