I have several posts I am working on for the future that will require big query service account keys. So rather than repeating this in the posts this will give the posts a reference to what to do.
First setup an account for Google, activating an account will require a payment card, and a Google account may cost so keep an eye on costs so you don’t get hit with an unexpected bill.
Service account
to create a service account go to the IAM & admin menu item an open service account.

click on the Create Service Account option.

put a meaningful name into the serviceaccountname and a good description.
create and continue and put the least required level of permission.

And complete the creation by clicking DONE the service account will appear in the service account list.
in the service account options click the menu item Manage Keys

add a key by selecting Create new key, the options of JSON or P12 can be chosen. I chose JSON. Click create. A file will be created. This needs to be kept in a secure place. As your project can be accessed with it.
