When you get a Heap Space error when building with maven you can increase this heap space by setting MAVEN_OPTS.

On windows this is done by creating a mavenrc_pre.bat file in your %HOME% directory with this content:

set MAVEN_OPTS=-Xmx512m -XX:MaxPermSize=128m

Similar there is a mavenrc_post.bat for everything you want to be executed after the build.