The Kyoto Protocol, adopted in 1997, involved debate among nations about measures to halt global warming, and since then each nation has embarked on initiatives aimed at reducing their greenhouse gas emissions. The protocol required Japan to reduce its greenhouse gas emissions to 6% below 1990 levels between 2008 and 2012. In this context, in 2003, the city of Hamamatsu in Shizuoka Prefecture, an environmentally conscious city, drew up a plan to prevent global warming, and proactively tackled the task of reducing CO₂ emissions from the city’s various operations.

Of the facilities in Hamamatsu, those that were using the most energy were the sewage treatment facilities. In fact, the largest of these facilities, the Chubu Sewage Treatment Center, was emitting some 9.2% of the entire CO₂ emissions generated by all of the city-run facilities, and something needed to be done urgently. That is why, in 2005, Hamamatsu installed a Kubota circulating fluidized-bed incinerator. This circulating fluidized-bed incinerator system had three excellent environmental features. The first was the fact that the incinerator inhibited the amount of dioxins^* generated. The second was that because the system was energy saving and highly efficient, there were fewer CO₂ emissions. And the third was that this system made it possible to dramatically reduce emissions of N₂O (nitrous oxide), which has approximately 300 times more of a greenhouse effect than CO₂. What is more, in addition to these environmental features, this circulating fluidized-bed incinerator was compact, highly fuel efficient, and it was possible to recycle the ash generated by the incinerator as a material to be used in cement. Therefore, in 2008, not only was there a significant reduction in N₂O, but a 9.19% reduction in CO₂ emissions, compared to when it was installed in 2005, was also achieved.

However, in 2008, just as Hamamatsu was striving to achieve a further reduction in CO₂ emissions, crude oil prices jumped to USD 140 dollars a barrel, and the price of the kerosene used in the incinerator system also rose sharply. For Hamamatsu, necessity dictated that costs had to be reduced, and so Kubota received a request from Hamamatsu to change the fuel used in the circulating fluidized-bed incinerator to natural gas. We immediately began assessing the technology, cost, and construction time required. There was no precedent whereby a fuel conversion works project had been carried out on an incinerator system whilst it was still in operation, and what those involved feared the most was the incinerator stopping running. In order to prevent this, engineers from both Hamamatsu and Kubota conducted extensive testing and managed to achieve their objectives by installing gas burners while leaving the kerosene burners in operation. This made it possible to switch fuels within a limited period of time while continuing to operate the system, at the same time achieving a significant reduction in CO₂ and running costs. As we tackled environmental challenges in the 2000s, this particular challenge was one great step for Kubota, contributing in part to the creation of a sound material-cycle society.