The effects of inter‐cutting interval on biomass yield, growth components and chemical composition of napiergrass (Pennisetum purpureum Schumach) as a source of bioenergy was investigated over 1 year in Thailand. Five cutting intervals (1‐, 2‐, 3‐, 6‐ and 12‐monthly) were examined on three napiergrass cultivars (Bana [hybrid with pearl millet], Common [normal type] and Muaklek [dwarf type]). Peak biomass yield occurred in all cultivars with 3‐month inter‐cutting interval, with a mean of 50.2 t dry matter (DM) ha−1 year−1 averaged across cultivars, while a 6‐month interval produced 46.2 t DM ha−1 year−1. Although cellulose concentration increased as inter‐cutting interval increased, energy concentration in the harvested material also peaked with 3‐monthly cutting. Both Common and Bana were superior to Muaklek in terms of DM production. Further studies are needed to refine harvesting frequency in different seasons to maximize biomass yields while ensuring cash flow and minimizing harvesting costs.

Eight cultivars of napiergrass (Pennisetum purpureum Schumach.), namely Dwarf, Muaklek, Bana, Taiwan A148, Common, Wruk wona, Tifton and Kampheng San, were grown in central Thailand in [2008][2009] and biomass yield, chemical composition and theoretical ethanol yield were measured. Harvests were made every 3 months. Biomass yield and cell wall compositions differed significantly (P < 0.05) among cultivars. Tifton produced the highest annual biomass yield at 58.3 t/ha followed by Wruk wona (52.1 t/ha), while the lowest yield of 27.1 t/ha was in Dwarf. Biomass yield varied with season with highest yields in May and lowest in February during the dry season. Cell wall concentrations were higher in the tall cultivars than in the short ones (Dwarf and Muaklek) (P < 0.05). Theoretical ethanol conversion efficiency ranged from 350 to 460 L/t DM among the cultivars following pretreatment with steam explosion. While a number of cultivars showed significant potential for use as biofuels in central Thailand, Tifton seemed to be the most promising.

Three newly introduced cultivar/lines of leucaena (Leucaena leucocephala (Lam.) de Wit.) from Australia (cultivar Tarramba) and Hawaii (lines KU19 and KU66) were compared with current leading cultivars Peru and Cunningham. In 2006–2008, leaf and woody stem production and plant chemical compounds were analyzed for forage and bioenergy utilization. The experiment was conducted at the Kasetsart University Farm, Pak Chong, Nakhon Ratchasima in central Thailand. The results indicated that newly introduced cultivar/lines have a greater dry matter yielding ability than the cultivars Peru and Cunningham. KU19 generated the highest levels of biomass, KU66 was second highest yielder, followed by Tarramba, Cunningham and Peru. Each of the new cultivar/lines produced a superior woody stem yield for biofuel production than Cunningham and Peru. Regarding plant chemical compositions, the new cultivar/lines were similar to Peru and Cunningham, exhibiting an energy value at 4.6–4.7 kcal g−1. The cost benefits for farmers to grow Tarramba would result in an increased income and subsequent profit when compared with the current cultivar Peru following this 2‐year study. We conclude that the new introduced cultivar/lines of Tarramba, KU19 and KU66 can be a more efficient and a productive energy supplying plant for gasification when compared with currently used cultivars Peru and Cunningham.