(35f) Assessing Sustainability By Life Cycle Assessment Versus Techno-Ecological Synergy: A Case Study for Biofuel Production

Authors: 
Liu, X., The Ohio State University
Bakshi, B. R., The Ohio State University
Limitations on resource availability and the increasing consumption patterns have necessitated the quest for sustainable development. Many methods and tools have been developed to assess and design for sustainability. Attempts have been made to improve process efficiency to reduce resource consumption and waste generation. Paradoxically, even though the environmental impacts associated with per unit product have been reduced significantly, our ecosystem has been degraded further. This is mainly due to the following two reasons, 1) problems may shift outside the selected boundary, and 2) the role of ecosystem goods and services for supporting human activities is largely ignored despite their essential role in sustaining human activities. Therefore, for a methodology to claim its contribution to guiding sustainable decision making, both of these aspects need to be accounted for.

The most widely used sustainability assessment method is Life Cycle Assessment (LCA). It is used to estimate and assess the environmental impacts of resources used and emissions created during the main stages of a product's life cycle. Even though this method can potentially expand the system boundary to include the upstream and downstream effects, it largely ignores the role of ecological goods and services. LCA encourages decisions that do â??less badâ?. Thus, the results from LCA are comparative in nature. The alternative that has the lowest environmental impacts is considered sustainable. This can potentially lead to misleading results and perverse decisions [1].

Techno-Ecological Synergy (TES) framework aims to assess and encourage synergies between systems in technological and ecological spheres [1]. The methodology considers systems at multiple spatial scales. Technological systems, ranging from individual processes to supply chains and life cycles can be evaluated along with their relevant supporting ecological systems. The key concept for TES is that resource uses and emissions are permitted but must stay in line with the capacity of relevant ecosystems. The necessary but not sufficient condition to be satisfied for reaching the goal of sustainability is to maintain the demand for ecosystem services within the supply at the largest ecological scale. By directly considering the role of ecosystem services, different insights and novel ecological solutions can be obtained.

The potential benefits achievable with TES methodology are illustrated by an application to a biofuel life cycle, including the production of selected direct inputs into farming, the farming phase and the ethanol manufacturing. Three ecosystem services have been considered to imply the general applicability of TES, namely carbon sequestration, air regulation and water provisioning. From this multi-scale and multi-objective analysis, we can identify processes that demand more from nature than can be supplied. This insight can be used to understand trade-offs and synergies between various ecosystem services, and identify opportunities for technological improvements and ecological restoration. Thus, by using TES approach, we not only have the option to reduce resource inputs and emissions as with the LCA approach, but also the option of increasing the supply of ecosystem services that can be achieved by proper land use. This solution might be potentially more cost-effective and environmentally friendlier than solutions developed by traditional methods such as LCA.

References:

[1] Bakshi, Bhavik, Guy Ziv, and Michael Lepech. "Techno-ecological synergy: A framework for sustainable engineering." Environmental Science & Technology 49.3 (2015): 1752-1760.