Facilitating access to the algal economy: Mapping waste resources to identify suitable locations for algal farms in Queensland

• Abundant waste nitrogen (N), phosphorus (P) and CO2 are co-located in many regions in Queensland, Australia.
• Waste N, P and CO2 are located in regions that are climatically suitable for growing algae.
• When considering the use of waste streams, nitrogen (N) is typically limiting.
• N can potentially be fixed from the atmosphere, thereby making waste phosphorus (P), a non-renewable resource, limiting.

Algae offer a multiple-benefit opportunity as the products that can result from algal cultivation are numerous and diverse. However, commercial production of algal-derived materials is scarce and in Queensland Australia is virtually non-existent, partly due to challenges around readily available resources. In this work, the potential to regionally recycle waste nitrogen (N), phosphorus (P) and CO2 to support algal production is considered. A feature of the work is mapping the availability of the three resources for algal cultivation (N, P and CO2) together with climatic and land use considerations. Mapping resolution is defined by the boundaries of Queensland's (Australia) regional authorities. Layering the maps enables identification of regional hotspots for growing algae. Waste resources are shown to be most abundant in Mackay, Burdekin, Toowoomba, Cassowary and Bundaberg; regions which also have favourable eco-climatic conditions. Waste nitrogen is the limiting waste stream, in these and most other regions however additional requirements can be fixed atmospherically, whereas waste CO2 is shown to be abundant relative to waste nutrients. It is found that, based on the availability of waste phosphorus, the top 5 most suitable regions have sufficient resources to produce around 1.1 million t/y of algal biomass. This could potentially produce 309 ML of biodiesel which is 5% of Queensland's 2011 diesel oil sales. The outcomes of this work highlight new opportunities for industrial ecology in non-urban regions.