In the trucking industry, efforts have been made in that area. Although natural gas helps reduce greenhouse gas emissions, it is not a zero-emission technology. So it does not help reach that goal. What is more, as far as I understand the trucking industry's experience, natural gas leads to other problems, including in terms of engine maintenance.
At first glance, it is an attractive solution, but, in practice, the zero-emission energy objective is not being reached, and the use of natural gas leads to other difficulties in terms of maintenance.