Feasibility Study into the Potential for Gasification Plant in the New Zealand Wood Processing Industry

The purpose of this research was to investigate the feasibility of installing gasification based combined heat and power plants in the New Zealand wood processing industry. This is in accordance with Objective Four of the BIGAS Consortium. This thesis builds on previous work on Objective Four (Rutherford, 2006) where integration into MDF (Medium Density Fibreboard) was investigated. The previous research identified the most suitable form of combined heat and power was a BIG-GE (Biomass Integrated Gasification Gas Engine) process, due to both lower capital investment and overall breakeven electricity production cost. This technology has therefore been adopted, and the investigation has been carried further in this research to incorporate integration into sawmills and LVL (Laminated Veneer Lumber) plants. It is recognised, however, especially when reviewing overseas successes and failures, that the base economics are only one factor in the feasibility of a plant. The research, therefore, has moved further to investigate New Zealand policy, the power market, lower capital alternatives and novel methods of integration. The conclusion of the study is gasification based combined heat and power plants in the New Zealand wood processing industry can be equal or better in economic terms than other forms of renewable generation, however, the application is very niche. Lower capital cost alternatives, stable and low priced biomass feed and a favourable power market in regards to distributed generation is key to the viability of such a plant. Government policy is favourable towards biomass gasification due to the target of 90% electrical generation by renewable resources by 2025. Distributed generation is also encouraged in the Government’s forward strategy. However, the technology has advanced further overseas due to capital grants and a premium paid for ‘green’ electricity. While the technology may be economic in its own right, active government support would lower the perceived risk increasing the likelihood of an investor taking interest in an initial project

Comparison of the performance of washcoating variations for Fisher-Tropsch synthesis in a microchannel reactor

Interest in biomass based Fischer-Tropsch fuels is currently heightened due to a global focus on the need for biofuels. While Fischer-Tropsch technology could be considered mature with significant worldwide production based on natural gas or coal, the challenge now is to develop Fischer-Tropsch processes that are economic at the smaller scale necessitated by the limitations of a biomass supply chain. The reactor is one aspect of this process and is the focus of this research. A microchannel reactor has been constructed and the performance compared against a more traditional fixed bed reactor. The microchannel reactor is constructed by wire cutting of 0.2 mm 316ss shim to yield channel dimensions of 0.2 × 0.3 × 37 mm with 50 channels per shim. The reactor was washcoated with unsupported cobalt, cobalt on titania, and a combustion synthesis cobalt deposition method. Comparison was made to a simple cobalt on titania catalyst in a fixed bed reactor. The catalysts were compared at 210, 225 and 240°C. The simple unsupported cobalt washcoat catalyst had slightly higher productivity per unit catalyst of all catalysts tested in the microchannel reactor and was 32 to 40 times more effective than the fixed bed reactor over the temperature range tested and also more effective than similar catalyst in a batch slurry reactor. This shows the microchannel reactor system to have significant advantages in terms of catalyst utilization compared to traditional reactors

Fischer-Tropsch Based Biomass to Liquid Fuel Plants in the New Zealand Wood Processing Industry Based on Microchannel Reactor Technology

This research forms part of a programme of work at the University of Canterbury investigating the production of liquid fuels from biomass. The drivers for this research are the plentiful supply of woody biomass in New Zealand as well as the necessity for a reduction in the use of fossil fuels. Fischer-Tropsch synthesis has been chosen as the base conversion method for syngas to liquid fuels. While Fischer-Tropsch plants are traditionally very large, the low geographical density of the biomass feedstock necessitates a shift from a traditional economies of scale approach. In this research a sawmill integrated polygeneration scenario is proposed that recognises the synergy between the heat and electrical requirements of a mill and the Fischer-Tropsch process that can supply both as well as liquid fuels. Techno-economic modelling of variations to this polygeneration arrangement were performed using a traditional Fischer-Tropsch slurry reactor as the basis. The breakeven price of syncrude produced in the process based on a 30 year plant life and 10% discount factor was as low as $US 167 per barrel. This arrangement is coupled with development of and experimentation with a microchannel reactor in a further attempt to overcome economies of scale disadvantages. The lab scale microchannel reactor consisted of a shim with 50 channels of 37mm length with 0.2mm height and 0.3mm width. The microchannel reactor was tested with shorter run periods to compare different catalyst washcoats consisting of neat cobalt, cobalt on titania and a combustion synthesis method over a temperature range of 210-240°C at 20 bar. Comparison was also made to a lab scale fixed bed reactor with a powdered cobalt on titania catalyst. The neat cobalt washcoat proved to have the best performance per unit mass of catalyst of the three washcoats. The performance of the microchannel reactor was 32-40 times better per unit catalyst mass than the fixed bed reactor. From data based on the shorter runs the neat cobalt washcoat and the cobalt on titania washcoat were selected for further analysis over longer runs at a range of pressures from 2-20 bar and temperatures from 210-240°C. These runs were each approximately 70 hours long and provided a better analysis of the narrowed catalyst choice. The productivity results of the catalysts were fitted to established kinetic equations from literature with an excellent correlation. More accurate Anderson-Schultz-Flory selectivity values were also obtained ranging between 0.72 to 0.82. This is certainly an area that would warrant further attention as a higher selectivity has a very positive affect on plant economics. Establishment of the kinetic equations for the catalyst performance allowed modelling of reactors with greater volume along with investigation of mass transfer limitations to assist in scale up of the technology. It was found that under 4-5mm hydraulic diameter channel dimensions the mass transfer limitation from the bulk gas phase to the catalyst interface is negligible. A scaled up microchannel reactor concept design is proposed utilising stainless steel mesh folded into 2mm channels to increase catalyst surface area compared to straight shim. A costing correlation was produced per unit of reactor volume to allow a full scale cost of the microchannel reactor to be estimated for inclusion into the techno-economic model. The revised techno-economic model was optimised through pressure variation to give a breakeven syncrude value of$US118 per barrel at Fischer-Tropsch reaction conditions of 10 bar and 240°C. This brings the value well within historical crude price trends

Feasibility study into the potential for gasification plant in the New Zealand wood processing industry

The purpose of this paper is to investigate the feasibility of installing gasification-based energy plants in the New Zealand wood processing industry. The study compared energy plants supplying the thermal and electrical energy in sawmills, laminated veneer lumber (LVL) plants and medium density fibreboard (MDF) mills. The breakeven electricity price for the MDF and LVL scenarios ranged from 4-8.9 c/kWh while the sawmill scenario was 11.6 c/kWh. The conclusion of the study is that while the economics are comparable with other renewable energy generation methods such as hydro and wind the location of the plant is critical to overall feasibility due mainly to biomass availability and power price both now and in light of expected future trends. The technology is complementary to the government's forward strategy which encourages both distributed generation and renewable energy.Combined heat and power Wood gasification Economic feasibility