Encode a string in UTF-8

I want to encode a string into UTF8 in PowerShell.

This is what I tried:

$consumer_key ="xvz1evFS4wEEPTGEFPHBog"$enc_consumer_key = System.Text.UTF8Encoding($consumer_key)

But I get an error:

System.Text.UTF8Encoding in not recognize as the name of cmdlet