How can I read the system power management settings

The power management settings are stored here.

/Library/Preferences/SystemConfiguration/
com.apple.PowerManagement.plist

 But how do I read them with the preferences API?

I tried this, but the returned list was null
CFStringRef app_id =
         CFStringCreateWithCStringNoCopy(kCFAllocatorDefault,
         "com.apple.PowerManagement", kCFStringEncodingUTF8,
         kCFAllocatorNull );


     CFArrayRef list = CFPreferencesCopyKeyList (
             app_id,
             kCFPreferencesAnyUser,
             kCFPreferencesAnyHost
             );