Contra Costa County in Northern California estimates savings of $30,000 annually once its 150-vehicle diesel fleet switches to biodiesel, according to the Contra Costa Times. After a three-month trial period with B20 (20 percent biodiesel), the county hopes to switch to B100, or pure biodiesel. The report sites the advantages of biodiesel: because it is domestically produced, it reduces our dependence on foreign oil; there is a 48 percent reduction in carbon monoxide, 47 percent less particulate matter and no sulfates; it is easy to convert diesel engines from petroleum-based fuel to biodiesel with little or no modification. Biodiesel costs about the same as conventional diesel now, although it becomes cheaper or more expensive by a few cents per gallon with the fluctuation of crude oil prices, the report says.