Overview of CO Bioconversion into Third-Generation (3G) Bioethanol—a Patent-Based Scenario

The transport sector is responsible for 25% of greenhouse gas emissions, mainly carbon dioxide (CO). Its emissions are the main driver of the worsening global climate change scenario. Finding feasible options to sequester this greenhouse gas is a great challenge for scientists, governments, and industry. Carbon capture, utilization, and storage (CCUS) are technologies that capture CO directly or indirectly by transforming it into other products of interest. In this context, biological CO conversion can be performed by photosynthetic microorganisms, such as microalgae and cyanobacteria, producing a wide variety of bio-based added-value products, such as third-generation (3G) bioethanol. However, the main obstacle to the spread of 3G bioethanol is economical, as it is still a recent and little-explored technology, lacking technical and scientific development for its production to become economically viable. Within this perspective, this work presents a patent-based mapping of current technological trends in 3G bioethanol production, which revealed that it is an emerging field with 171 patent deposits since 1979, with a tendency of at least 10 patents published per year in the last 15 years. The main drawbacks industries are focused on remain those from 2G bioethanol production, such as biomass hydrolysis. Therefore, with extensive cooperation between governments, scientists, and industries, it may be a matter of time before 3G bioethanol production becomes a reality. The presented data are expected to contribute to technical knowledge of 3G ethanol production, including the knowledge transfer from the academy to the industrial sector.