Beyond Daylight: Leveraging Nocturnal Carbon-Fixing Plants for Sustainable, Thrivable Societies

Fossil feedstocks are usually linked to the climate change crisis, while some biorenewables prove equally problematic. Switching from fossil to renewable feedstocks, for bioproducts and bioenergy, is vital for sustainability and thrivability. However, meeting the UN 2030 renewable targets appears unfeasible. Current efforts focus on classic photosynthesisers capturing carbon during daylight. This severely limits circular economy potential since over half of Earth is always dark. Leveraging carbon capture through plants like opuntia, sisal, agave and pitaya that fix carbon nocturnally could maximise biomass productivity worldwide. This could also improve health, prosperity, climate resilience and ecosystem restoration for thrivable societies. These plants capture carbon nocturnally via the Crassulacean Acid Metabolism (CAMPs) and excel in invasiveness, stress tolerance and productivity. Opuntia can yield 600 tonnes per hectare annually, outcompeting microalgae and sugarcane. Therefore, CAMPs could help fill the daily gap left by diurnal carbon absorbers. The large-scale ethanol production from opuntia in agrobiorefineries exemplifies this potential. Four agrobiorefineries configurations were evaluated: 1) the classical, using fossil fertilisers and chemical pretreatment, proved environmentally unsustainable and energy-inefficient; 2) organic fertilisers with chemical pretreatment improved environmental impact but remained energy-inefficient; 3) organic fertilisers with unrecycled ionic liquids were environmentally unsustainable but energy-efficient; 4) organic fertilisers with recycled ionic liquids proved cleanest and most efficient, achieving global warming and human toxicity potentials of 1.5 kg eq CO2 and 0.167 kg eq C₆H₄Cl₂. This redesigned system was three times more energy-efficient than traditional biorefineries, consuming 0.33 MJ per MJ of ethanol produced. The opuntia model generates 2400-3000 $USD profits per hectare annually for farmers (six times greater than producing corn and beans on the same land). The appropriate use of nocturnal carbon-capturing biomasses could enhance sustainable and thrivable solutions to carbon neutrality, green energy and chemicals to address climate change and advance sustainable development goals.