In a daylong, and at times biting, confirmation hearing before the Senate Armed Services Committee yesterday, Defense secretary nominee Chuck Hagel refused to be pinned down on his positions on specific military energy programs. The former Nebraska senator and decorated Vietnam War veteran had already endorsed the administration's approach to certifying its fleets on alternative fuels in written testimony made public Wednesday but said he would need to "examine the value" of more aggressive efforts, such as the Navy's $170 million stake in an interagency program to build commercial-scale biofuel refineries.