You just need to know the number of accounts the query returns? Why not use getNearbyTech.size()? No need to use an aggregate expression.
edited to add getNearbyTech is declared as a list, so getNearbyTech.size() will get you the number of elements in the list. The ".size()" method call takes no parameters. You can read more about list methods here
To reference the size in a visualforce page, you'd need to declare getter/setter methods in your controller class:
public Integer NumAccts {get; set;}
and set the value at some point (usually in the constructor)
NumAccts = getNearbyTech.Size();
Then you can reference the count in a Visualforce page like this:
{!NumAccts}
The only think I'm unclear about is whether the "@future" affects whether the size will be available when the constructor runs. If not, there may be an extra hoop to jump through to refresh the page when the query actually complete. Perhaps someone else here will let us know.