New feed sources key to ambitious climate targets

Area of Science:

• Climate science
• Bioenergy
• Land use management

Background:

• Limited net carbon sinks pose challenges for climate change mitigation and ocean acidification.
• Land scarcity intensifies competition between food security and bioenergy production.
• The potential of microalgae for energy is recognized, but its land-sparing benefits for livestock feed are underexplored.

Purpose of the Study:

• To quantify emissions pathways using microalgae as a feedstock for livestock.
• To assess the land-sparing potential of alternative livestock feed sources.
• To evaluate the contribution of microalgae-enabled land use changes to climate change mitigation.

Main Methods:

• Utilized the FeliX model to simulate emissions pathways.
• Quantified land freed up by replacing conventional pasture and feed crops with microalgae.
• Modeled the establishment of forest plantations on freed land for energy production.

Main Results:

• Microalgae feedstock can free up to 2 billion hectares of land.
• Forest plantations on this land could supply 50% of global primary energy demand.
• This scenario offers emissions mitigation of up to 544 x 107 PgC from energy and LULUC sectors by 2100.

Conclusions:

• Microalgae as livestock feed offers a viable strategy for significant land sparing.
• Large-scale afforestation on freed land can substantially meet energy demands and mitigate emissions.
• Combined with carbon capture and sequestration, substantial reductions in atmospheric carbon are achievable, nearing preindustrial levels.