| dc.description.abstract | Aquatic environments provide economic value in the form of ecosystem services (ES), such as jobs and food through fisheries, eco-tourism, flood buffering against storms, and nutrient capture (Turner et al., 2000). Globally, marine dead zones have doubled since the 1960s due to excessive nitrogen (N) and phosphorus (P) introduced by synthetic agricultural fertilizers, the burning of fossil fuels, and human and animal waste (Diaz & Rosenberg, 2008; Rabotyagov et al., 2014). There is a range of bioremediation or cleanup methods that can alleviate excess nutrients in waterways. The private firm Hydromentia LLC practices bioremediation through Algal Turf Scrubber (ATS) technology at a variety of sites to capture nutrients, sequester carbon (C), and produce algal biomass from point and non-point source nutrient dense waters. Harvested algal biomass has additional value as crop fertilizer, livestock feed, or as an input to biofuel generation in anaerobic digestion (AD) (Hydromentia, n.d.c). Studies looking at ATS systems’ costs and benefits through a comprehensive economic lens are currently lacking and there is opportunity to incorporate more nutrient trading and crediting into analyses (Pizarro et al., 2006; Higgins & Kendall, 2012). The objectives of my study were to evaluate the costs and benefits associated with an ATS-AD system, quantify the ES values an ATS-AD system provides, and provide economic justification to support policy makers in developing additional funding for a wider variety of global ATS-AD projects.
My research included both financial and economic appraisals for the Fall River ATS and ATS-AD site, located in Durham, North Carolina, USA, with a 20-year timeframe and based on Hydromentia’s 2017 Fall River Pilot Report. Hydromentia provided data on financial costs of construction, operations and energy use, and benefits of nutrients captured and dried algal biomass in pounds per year. First, I conducted two comparable financial appraisals, which include the ATS site with and without an AD component used to reduce the energy costs to operate the system. Second, I conducted three economic cost-benefit analyses (CBA), based on different scenarios of household populations, to assess the following questions:
• Do the bioremediation efforts of the ATS-AD system outweigh the costs?
• How much biofuel can be generated from algal biomass from the proposed site?
My research aimed to answer these questions and hypothesized that the economic CBA values are greater than that of both financial CBAs. Including the benefits of avoided eutrophication, nutrient capture, and algal biomass converted to biofuel in an economic CBA provided a more accurate representation than a traditional financial assessment from the business’ point of view.
The results of both financial analyses showed negative end values, suggesting the benefits of ATS technology do not outweigh the costs from a traditional business perspective even when AD is incorporated, although the AD component resulted in a smaller negative value. My economic analyses resulted in positive values for all three percentages (75%, 50% and 25%) that ES would be transferred to the Falls Lake Watershed case study population, suggesting that the ES benefits ATS systems provide outweigh the costs of the project. The results support my stated hypotheses and could influence policy makers and governments to further incentivize this bioremediation technology through grants, tax breaks, and subsidies. | |
