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To unlock the full potential of the Food—Water—Energy nexus with respect to decentralised microgrids, a fully integrated approach focuses not only on energy (microgrid) and food (aquaponics) but also on utilising the local water cycle. The integration of various water systems (such as rainwater collection, storage and wastewater treatment) within aquaponic-integrated microgrids yields the biggest potential for efficiency, resilience and circularity. The concept of a fully integrated and decentralised Food—Water—Energy microgrid will from now on be referred to as a Smarthood (smart neighbourhood) and is depicted in Fig. 15.2.
The benefit of implementing aquaponics into the Smarthoods concept is its potential to contribute to optimise integrated nutrient, energy and water flows (Fig. 15.1). This integration potential goes well beyond the already-mentioned
The Food−Water−Energy Nexus
30% of global energy demand is used for agriculture 70% of global freshwater demand is used for agriculture
Fig. 15.1 The Food—Water—Energy nexus shows the interplay between energy, water and food production (based on IRENA 2015)
img src="media/image-20201002190013698.png" alt="Decoupled Aquaponics Systems in a Smarthood" style="zoom:67%;" /
Fig. 15.2 The integration of decoupled aquaponics systems (as described in Chap. 8) in a decentralised local environment as designed for the Smarthoods concept. The green arrows show to what extent an aquaponics system can interact with the overall system. The red arrows represent heat flows, the blue arrows water flows and the yellow arrows power flows
crossovers between the energy and food systems. For instance, occurring biodegradable waste streams can be treated in anaerobic reactors (e.g. UASBs) and generate both biogas and bio-fertiliser (Goddek et al. 2018). Even the demineralized waste sludge can be utilised as liquid manure on conventional cropland.
img src="https://cdn.aquaponics.ai/thumbnails/f2cdbb3a-7dbf-4352-b468-af02021d0f64.jpg" style="zoom:75%;" /
Fig. 15.3 Illustrated photo of De Ceuvel (source: Metabolic — www.metabolic.nl)
An early example of an urban integrated aquaponic microgrid development is De Ceuvel, a previously abandoned shipyard in Amsterdam-North that has been converted into a self-sufficient office space and recreational hub. De Ceuvel serves as a testbed for new technologies and policies aimed at creating a circular economy. It features an all-electric microgrid including solar PV, heat pumps and peer-to-peer energy trading over the blockchain using their own energy token: the Jouliette[^1]. A small aquaponic facility produces herbs and vegetables for the on-site restaurant. The same restaurant utilises biogas extracted from locally produced organic waste for their cooking activities as well as space heating. In addition, there is a lab present that is used for testing the water quality and extracting phosphates and nitrates.
Although De Ceuvel is currently not actively using the aquaponics facility to increase the flexibility of its microgrid, sensors are being installed to monitor the energy and nutrient flows in order to assess its performance. This data will be used to aid in the development of newer and smarter urban integrated aquaponics microgrids, such as the Smarthoods concept proposed in this chapter. Early use cases found in urban living labs like De Ceuvel are essential to the successful development of the Smarthoods concept (Fig. 15.3).
Although a holistic approach to urban FWE systems such as the Smarthoods concepts yields many benefits, the integration of aquaponics systems within microgrids remains very case-dependent. Aquaponic food production systems are characterised by a higher yield and a lower water, nutrient and energy footprint than conventional agricultural systems; however, they are also more costly to build. They are therefore best suited in locations that require high yields due to, for instance, space limitations. In dense urban areas, there may not always be sufficient space to build an aquaponics facility, whereas for rural areas the cost of land may be too low to warrant building a state-of-the-art aquaponics facility; a standard agricultural facility with lower financing costs and yield will be more suited in such cases. The most optimal use case for an integrated aquaponic facility is one where sufficient space is available, and a high yield per area is required to offset the cost of land use. Suburban neighbourhoods and other urban areas (e.g. an abandoned warehouse) are therefore most likely to see the first implementation of microgrids integrated with an aquaponic facility (see Example 15.1).