Determining True Sustainability

ASTM International activity in transportation and energy has many other facets, with a number of developing technologies showing great promise in moving the aviation industry toward a greener profile — one that would replace traditional petroleum-derived fuels with alternatives that rely to varying degrees on renewable, biomass-derived feedstocks.
For example, hydroprocessed esters and fatty acids synthetic paraffinic kerosene (HEFA-SPK, annex A2 of D7566) is a specific type of renewable fuel produced by deoxygenation and hydroprocessing of natural oils derived from algae or oil seed plants such as jatropha and camelina. Catalytic hydrothermolysis jet (CHJ) fuel uses a different method to convert oil from sources like algae, tallows, and other waste oils to a jet fuel product.
But how does one determine the relative sustainability of alternative fuels?
The committee on bioenergy and industrial chemicals from biomass (E48) is responsible for two key standards designed to facilitate evaluation of the relative sustainability of options when at least one option contains products derived from renewable resources.
The practice for evaluating relative sustainability involving energy or chemicals from biomass (E3066), first approved in 2016, was updated last year. And, because an iterative process of measurement and evaluation is recommended to identify opportunities for improving sustainability, the point of comparison becomes a critical factor. Therefore, science-based practices and document-reference scenarios are needed when evaluating sustainability of bioproducts. The new standard practice for reference scenarios when evaluating the relative sustainability of bioproducts (E3256) addresses this need.
“E3256 is a more fundamental standard, developed to be a companion to E3066,” says Charles Corr, an industry consultant, D02 member, and technical adviser to E48. “To improve sustainability in the real world, we need to carefully compare options. To do this, the test scenario must be compared against what would have happened in the absence of the test scenario or a ‘business as usual’ scenario. E3256 was developed to provide standard guidelines and criteria for selecting the reference scenario.”
Keith Kline, a scientist at Oak Ridge National Laboratory, picks up the thread. “The goal is to help users apply clearly defined methods that support transparent, replicable, and fair comparisons. When dealing with complex biological systems involving forests or croplands, this is a challenge. Yet it is important to analyze and document the most probable alternative uses for land, crops, or residues. Cascading use and ultimate disposition of biomass in each scenario need to be defined. It is critical to clearly document data sources and assumptions for each scenario when assessing the impacts of a biobased product system. For example, how would land management, emissions, and landscape ecosystem services differ if one didn’t use specific crops or residues for energy products,” he asks.
Kline describes the challenge of identifying more sustainable options in a world of imperfect knowledge. “It is essential to include stakeholders in a systematic process to evaluate and test options that provide incremental improvements toward achieving defined goals and objectives. Adaptive management is required as circumstances change or new information becomes available. And context matters. The best options for producing clean, renewable jet fuels in Chicago today are likely to be distinct from those in Miami or Los Angeles, and the options will be different 20 years from now,” he says.
That’s where the new standards come in. Given how complicated reference scenarios become in any biological system, a standardized way to document them is valuable.
“The E48 effort approaches sustainability as a system for improvement,” states Corr. “Sustainability is not a steady state. We have developed standards to encourage a consistent and transparent approach to facilitate an equivalent comparison of options. The comparison can be between proposed refinements to a process or optional products from a feedstock. More traditionally, you might think of the comparison of a bioproduct against what would be used in the absence of the bioproduct, the traditional source.”
Changing out “traditional” sources for more sustainable ones is, Corr emphasizes, an ongoing process. And it’s a process with a long way to go. The organization Circle Economy estimates that today only 8.6% of the world economy can be considered circular, but it is hoped that the ASTM standards discussed here will help improve that percentage.