Analysis of Hybrid Hydrogen Systems: Final Report

Abstract

Executive SummaryThis project examined biomass pathways for hydrogen production and how they can be hybridized to support renewable electricity generation. The project considered many potential hybrid systems before narrowing the focus to two. The systems were studied in detail for process feasibility and economic performance. The best-performing system was estimated to produce hydrogen at a cost ($1.67/kg) within range of the Department of Energy target for central biomass-derived hydrogen production, while also providing value-added energy services to the electric grid.Of the domestic resources available for hydrogen production, biomass shows significant promise. Recent assessments have shown that more than 400 million tons of biomass currently is available annually in the United States (Milbrandt 2005). This could be converted to roughly 30 million tons of hydrogen by thermochemical processing. Thermochemical plants provide many opportunities for system integration.The project team generated a matrix considering the combination of biomass-processing technologies and how they could be hybridized with other technologies. The matrix contained more than 100 potential binary combinations. These were ranked based on criteria such as resource availability, technology maturity, and hybridization benefits. Some of the top concepts are listed below.Combined wind power and biomass gasification for co-production of fuel and power Combined electrolysis and biomass gasification for co-production of fuel and power Combined coal and biomass/bio-oil gasification systems for co-production of fuel and power with carbon sequestration for both processesCo-location and thermal integration using steam from a nuclear reactor to feed bio-oil reforming to produce fuel These results were further ranked using a decision matrix. Direct wind and wind-electrolyzer combinations with biomass gasification rose to the top of the decision matrix due to several factors. These selections provide renewable fuel and power, supplement grid demand, and also can take up excess electricity. The two concepts chosen for further analysis in this project can be summarized as follows.Direct grid leveling of intermittent wind power with an indirectly heated biomass gasification plant. The plant will produce both electricity and hydrogen.Using an electrolyzer in place of an air separation unit (ASU) with a directly heated fluidized-bed biomass gasifier for co-production of fuel and power.Both of the concepts chosen for further analysis share the basic idea of combining windgenerated electricity with a biomass gasification plant. Wind availability significantly overlaps biomass resource availability, making the use of locally produced wind electricity for gasification feasible. The proposed hybrid systems attempt to do one of two things:iv Fill wind energy shortfalls and feed a natural gas turbine that would be used for this peaking purpose; or Absorb excess renewable power during low-demand hours.The indirect gasification concepts studied could be cost compet...

Techno-economic analysis of autotrophic microalgae for fuel production

“…These two steps together were assumed to achieve 90% extraction efficiency. The oil/ solvent phase is separated from the water and spent biomass material using disk stack centrifuges (private vendor discussion), and the spent biomass plus water is sent to anaerobic digestion to produce biogas for power production [30][31][32][33]. Beyond the 10% extraction efficiency loss, an additional 5% of the extracted oil was assumed to be lost through entrainment in the water phase.…”

“…All capital costs for algal oil production were estimated based on vendor quotes, prior literature studies, or standard engineering estimates [5,20,21,32,33,39,40]. Capital costs for the hydrotreater facility were based on a report by Larson et al [41].…”

System Analysis of Thermochemical-Based Biorefineries for Coproduction of Hydrogen and Electricity

“…Previous work in system analyses of hydrogen production from biomass gasification includes that of Larson et al [1], Spath et al [2], Williams et al [3], Corradetti and Desideri [4], and Dean et al [5,6]. Both Spath et al and Corradetti and Desideri focused on indirectly heated atmospheric pressure biomass gasification systems, yet the technologies, unit operations, and economics given in these works are directly relevant to the present effort.…”

“…Establishment of optimal biorefinery size is often carried out etnploying biofuel supply chain models and due to refinery cost scaling parameters, such models typically recommend the maximum allowable plant size based on resource availability [18,19]. Plant capacity in this effort was guided by geographic information system (GIS) data from a previous study by Dean et al [5], which recomtnend a 2000 tPD refinery size. Assuming an 80 km (50 mile) collection radius, there are multiple locations throughout the country that could support this level of wood requirement.…”

“…Assuming an 80 km (50 mile) collection radius, there are multiple locations throughout the country that could support this level of wood requirement. At scales larger than 2000 tPD, the number of possible plant locations in the United States becomes substantially limited [5,15]. Additionally, at these large plant sizes, economy-of-scales are more favorable in terms of minimizing unit production costs.…”