The evolution of waste into a resource: Examining innovation in technologies reusing coal combustion by-products using patent data

The reuse of waste begins with the development of new technologies for ways to use waste. Despite the critical role of innovation in waste reuse, innovation for waste reuse technologies has been largely overlooked in innovation studies. This paper presents the first patent study examining the innovation process for a specific waste reuse technology, to elucidate how waste evolves into a resource with a greater possibility of being used. This study specifically analyzes how innovation occurs, what drives it, and the consequences of this innovation. Coal combustion by-products (CCBs), which are solid residues generated from coal-fired utilities, are specifically examined as a test case because they have been promoted as a resource through century-long innovative efforts for use in construction, mining, and agricultural applications. Having examined more than 700 patents from the United States Patent and Trademark Office database, the results of this study show that innovation has primarily occurred: (1) to reuse CCBs, particularly fly ash, in various building, construction, and structural products; (2) by businesses, particularly those that need to use CCBs; and (3) since 1967, and the number of CCB-related patents peaked during the early 1980s and 1990s. For the drivers of innovation, this study identifies the impact of some market factors, such as cement and lime price, and institutional activities, such as the establishment of industrial associations that support CCB reuse, on patent filings. The role of regulation in innovation, however, is ambiguous with regard to CCB reuse. Although more CCBs have been used as more innovation occurs, the use of CCBs has increased with a lag, due to variation in the values of individual technologies and barriers to the implementation of technologies in the reuse market.