<?php
global $post;

if ( has_post_thumbnail() ) {
	// First retrive Image ID by Post ID from get_post_thumbnail_id()
	$attachment_id  = get_post_thumbnail_id($post->ID);
	// Image url
	$image_url    = wp_get_attachment_image_src($attachment_id,'full', false);
	// Alt text
	$image_alt = get_post_meta($attachment_id,'_wp_attachment_image_alt', true);
}