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--- algae:biogas_biofuels [2026-08-05 22:02] – [Biogas and Biofuels] robert
+++ algae:biogas_biofuels [2026-09-13 17:30] (current) – Mostly rename EURlex robert
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 Algal bioremediation may also be used to treat the liquid fraction of AD digestate. The approach is relevant in situations where a high nutrient dilution rate represents a logistical or agrotechnical obstacle to distributing AD digestate for agricultural use. These approaches are also relevant in nitrogen-limited zones where the nitrogen content of the AD is non-local and cannot be returned to agricultural use in the area.
-Even in cases of AD of erobic wastewater sludge, when the liquid digestate is returned to the WWTP secondary stage, the algal pretreatment of the liquid phase of AD digestate can decrease the nitrogen load significantly.
+Even in cases of AD of aerobic wastewater sludge, when the liquid digestate is returned to the WWTP secondary stage, the algal pretreatment of the liquid phase of AD digestate can decrease the nitrogen load significantly.
 AD digestate may also represent an efficient and low-cost nutrient source for algal cultivation for certain algal products. When biogas is used in CHP, the exhaust can be used as the CO<sub>2</sub> source for algal cultivation. Finally, in these cases there is often a supply of heat (from cooling exhaust or from cooling of the biogas-operated engine) that may be used to heat (or even to cool - via absorption chillers) the algal cultivation media.
+This chapter is focused mainly on use of algae as bioguels and biogas substrate. Regulatory aspects of digestate bioremediation and other topics are covered in the chapter [[algae:waste_wastewater_nutrient_recovery|Waste, wastewater and nutrient recovery]].
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 The __BioGrace calculation tool__ (developed under a European project and freely available) provides a spreadsheet-based methodology for calculating GHG savings in compliance with RED II requirements. It is widely used by biofuel producers and their certification bodies.
-The GHG savings from algae-derived biofuels can be high in principle (algae require no agricultural land and can capture CO₂) but the calculation depends critically on the energy input to cultivation (lighting for closed systems, aeration, pumping). High energy consumption in cultivation can significantly reduce the net GHG saving calculation, and in some cultivation scenarios may fail the sustainability threshold. Producers developing algae-to-bioenergy pathways should model their specific system's GHG footprint before assuming eligibility.
+The GHG savings from algae-derived biofuels can be high in principle (algae require no agricultural land and can capture CO₂) but the calculation depends critically on the energy input to cultivation (lighting for closed systems, CO<sub>2</sub> supply - bubbling, pumping). High energy consumption in cultivation can significantly reduce the net GHG saving calculation, and in some cultivation scenarios may fail the sustainability threshold. Producers developing algae-to-bioenergy pathways should model their specific system's GHG footprint before assuming eligibility.
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 ==== CO₂ Capture and Storage ====
-Directive 2009/31/EC of the European Parliament and of the Council of 23 April 2009 on the geological storage of carbon dioxide, OJ L 140, 5.6.2009, p. 114. [[https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A02009L0031-20181224|EUR-Lex]]
+Directive 2009/31/EC of the European Parliament and of the Council of 23 April 2009 on the geological storage of carbon dioxide, OJ L 140, 5.6.2009, p. 114. [[https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A02009L0031-20181224|EURlex]]
 __Relevance to algae:__ Algae are studied as a biological carbon capture mechanism, particularly in the context of CO₂ utilisation in algae cultivation. CO₂ from industrial flue gases is increasingly used as a nutrient input for photosynthetic microalgae, and the resulting biomass sequesters carbon in organic form. This is not "geological storage" for the purposes of the CCS Directive (which governs capture and geological injection of CO₂), but it is increasingly relevant in the context of the EU Carbon Removal Certification Framework (see [[algae:greenhouse_gases_climate|Greenhouse Gases and Climate]]).