The Links page on Communication Standards now includes a section on link shortening services. But when should you use them? That's a whole other question.
On websites, you should almost always embed your links. Your users won't see the URL you're linking to and the length of your URL won't matter.
If you're creating publications, exhibits, or other printed materials that have URLs on them, you will probably want to use a marketing URL. (See the section on Energy.gov URLs.) This allows you to have a permanent, official, EERE URL for your materials.
So when should you use a link shortening service? Simple: When you can't embed a link online. That means you'll probably only need them on social media websites such as Twitter.
As always, if you have any questions, you can ask here in the blog comments or send an email to the Communication Standards webmaster. We're always glad to answer your questions!