Use of my batch geocoder requires a mapquest application key. The key is free! The steps for obtaining a key are as follows:
1. Go to the MapQuest Developers Page.

2. Fill in the information requested. Make sure to check the box saying you agree with the terms of use.

3. Click on CREATE NEW ACCOUNT.

4. Wait for email from mapquest. When it arrives, click on the link in the email.

5. Go to https://developer.mapquest.com/user

6. Click on KEYS AND REPORTING.

7. Click on MY APPLICATION.

8. You will now see a page that lists your CONSUMER SECRET (not important) and your CONSUMER KEY (important). The latter is your application key