Regenerative gasification systems operating on farm-waste and bioenergy-crop feedstocks

This work investigates the feasibility of using an advanced gasifier to convert dairy-farm animal wastes and biomass willow wood into fuel gas that could be utilized for power production. In our energy conversion scheme, a high-temperature air-blown, regenerative gasification system is used to convert the biomass to synthetic fuel gas. The preheated gasification air is supplied by a ceramic heater. The syngas produced by the gasifier can be utilized on the farm for generating electricity or for other energy needs, thus helping to reduce the operating cost of the farm. Microturbines, modified to operate on low-BTU gas, are used to generate electrical power. For the manure-fueled gasifier, preliminary calculations indicate gasification conversion efficiencies of 65 to 85 percent could be achieved, depending on the gasifier operating configuration. Implementation of a gasification system on the dairy farm provides both economic and environmental benefits. In a case study, using information collected from an upstate New York dairy farm, the results showed that gasification of dairy animal wastes would allow this particular farm to exceed energy self-sufficiency by over two times its requirement. Gasification also provides an economical means of disposing excess animal wastes. The disposal/utilization of excess animal wastes is a serious problem facing the dairy industry. Willow wood, a dedicated bioenergy crop, makes an excellent fuel for ash-rejection gasifiers because of its low ash content and high ash-softening temperature. Although there has been success in cofiring willow with coal in utility power plants, gasification offers another method of converting willow biomass to energy. The predicted gasification efficiency of the willow-fueled gasifier is about 85 percent Adopting a method to cogasifying willow biomass with various amounts of farm wastes can be an excellent way to reduce the overall fuel cost. In addition, this will assist in addressing the problem of seasonal variations in the supply of willow biomass.