UCSD Sustainability Solutions Institute

During the past year, an investigation has been initiated regarding how future climate changes may impact the hydrology of the Tijuana River Watershed – a binational watershed. The study has used gridded observed daily precipitation and temperatures and downscaled daily precipitation and temperature projections from three global climate models (GCM) to drive the VIC macroscale hydrologic model. Sensitivity analysis using VIC suggests about 2% reduction of runoff for each 1% reduction in precipitation. A 1oC increase in average temperature produces about 3% reduction of runoff. All three GCM simulations yield annual warming, with end-of-century temperature increases from approximately +1oC under a lower emission scenario in the less responsive PCM1 to +3oC in a higher emission scenario with the more responsive GFDL model. Climate projections suggest greater warming in the spring and summer months ranging between 2oC to 3oC under the higher emission scenario. Two of the three GCM simulations yield more frequent summer drying as gauged by VIC simulated soil moisture in the twenty-first century under the higher emission scenario. Summer soil moisture declines most, and most rapidly, in the later part of the twenty-first century. This initial evaluation provides perhaps the first direct estimates of the climate change impacts on the Tijuana River Watershed. However, transforming these results into a more useable projections and impacts will be a task for the future and will require collaboration and interaction between local stakeholders and the researchers.

This project was developed into two avenues aiming at assessing levels of metals in kelp and salt marsh plants in the San Diego area. This information was then used to address whether metals levels found in kelp and salt marsh plants reflect bioavailable metals in the environment, which could help their use in environmental monitoring.

An economic and technical analysis of the use of separated wood biomass as a feedstock for gasification for a 3 MW power plant was conducted for the Miramar Landfill, located in San Diego County, CA. The method to generate combustible gas from the biomass is based on a dual-fluidized bed gasification process which operates at atmospheric pressure with air and produces a high quality producer gas with little nitrogen. The objective of the study was to determine the economic feasibility of the proposed biomass power system in terms of the potential revenue streams and costs. Major economic considerations in the analysis include feedstock, capital, and operating costs. Regulatory issues, inclusive of production credits, renewable energy incentives, and feed-in tariffs are addressed as significant economic inputs. The Miramar landfill, in San Diego County, CA is representative of a typical existing urban landfill, with corresponding feedstock and some market for separated wood biomass. The economic analysis of the proposed 3MW gasification power plant indicates that it would not have a net positive NPV under the current urban scenario. More likely successful candidates are landfill sites in more rural areas or urban sites, where new landfills are being developed or where the landfill is no longer operational but has become a transfer station. In all cases waste heat sales are a critical element in determining economic viability.

This report examines the economic and technical feasibility of using separated biomass feedstock from the Miramar Landfill, located in San Diego County, to generate 3 MW of power. The process will utilize gasification technology provided by West Biofuels, LLC. The objective of the study is to determine the economics of the proposed biomass power system in terms of the potential revenue streams and operational costs. The goal of this study is to determine whether this project has a positive net present value (NPV) based on the site specific parameters associated with the Miramar Landfill.