The development of an integrated environmental techno-economic assessment framework. How to assess the potential of microalgal-based biorefineries

During the development of a new technology, three main questions need to be answered: 1) “Is the process technologically feasible?”; 2) “Is the process economically profitable?”; 3) “Is the process environmentally sustainable?”. The answers on these questions are currently provided by different assessment methodologies at different moments of technology development. This leads to differing system boundaries and a large variation in results. An example of such a new technology is the concept of microalgal-based biorefineries. Microalgae are small photosynthetic organisms with a large productivity which can grow on degraded lands. They can accumulate large amounts of valuable components. Currently, most algal-related research focusses on the development of energy applications. However, this concept is currently not economically viable and the environmental impact is uncertain as well. Microalgal-based biorefineries can provide a solution as multiple products are valorized from a microalgae feedstock. This corresponds to increased revenues and a decreased environmental impact per product. However, the results of the economic and environmental assessment of this concept vary as well. This can be explained by the large variation in methodological assumptions and the lack of an integrated assessment methodology. Based on a review of economic and environmental assessment of microalgal-based biorefineries, four recommendations were identified for the development of such an assessment methodology. First, a clear framework with predefined steps is required. Second, the methodology should be adaptable to the appropriate level of technology development. Third, the methodological assumptions should be clearly stated. Fourth, the technological assessment needs to be integrated to create a dynamic model, where a change in one parameter is automatically translated in a change in all output parameters. Based on these four recommendations, the Environmental Techno-Economic Assessment (ETEA) methodology was proposed, which integrates the Life Cycle Assessment (LCA) methodology in the Techno-Economic Assessment (TEA) methodology. The development of this methodology was initiated by developing a TEA case study on microalgae biorefineries. Four scenarios were constructed, ranging from a basic scenario, including conventional technologies, to an intermediate scenario, with the inclusion of a medium recycling step, towards an advanced scenario, where more state-of-the art technologies were included. An alternative microalgae biorefinery scenario, with the cultivation of an alternative algae species for an alternative end product was included as well. The inclusion of a membrane for medium recycling proved to be important for an economically viable process. The most important process parameters were the carotenoid content and price. Afterwards, the LCA methodology was integrated in this model to develop the ETEA methodology. This methodology consists of five steps: 1) market study; 2) process flow diagram and mass and energy balance; 3) economic analysis; 4) environmental analysis; 5) interpretation. The case study consists of three scenarios, based on the basic, intermediate and advanced scenario of the TEA model. An alternative geographical location, being India, was included for each scenario to enable a geographical comparison. According to the results of the ETEA model, the algae biorefinery in India has higher profits, while the algae biorefinery in Belgium has a lower environmental impact. The ETEA methodology can be used to assess the technological, economic and environmental potential of a new technology. However, in reality multiple technology options are possible. Instead of analyzing each possible scenario, a superstructure containing all possible options was constructed. The ETEA methodology was extended with a multi-objective optimization to identify the optimal microalgal-based biorefinery scenario taking both economic and environmental objectives in account. From an economic perspective, the optimal algal-based biorefinery produces feed for aquaculture. The environmentally optimal scenarios produce a combination of carotenoids, fertilizer and energy products. The ETEA methodology provides a framework to assess a new technology over the entire product lifecycle at each stage of technology development. By providing insights on how a new technology can be improved for multiple objectives, the time-to-market for this new technology can be shortened.

Jaar van publicatie:2018

Toegankelijkheid:Open