窝 here is very very informal use of Chinese language, which is hard understood by non-Chinese speakers. This character means to hide resulting waste in this context. 窝藏 Would be a relatively complete expression for this character here but not exactly the same meaning...

There are some really good explanations in Baidu zhidao, links below.

It's pretty hard to translate as a phrase, but in a sentence there are a few ways to do it:
http://energy.people.com.cn/GB/15034895.html
内蒙古目前窝煤窝电的现象有望成为历史
...Inner Mongolia's problems with inefficient distribution and consumption of energy could be history.
...could mean the end of the bottlenecks that have bedeviled Inner Mongolia's energy resources.
Inner Mongolia has always had plenty of coal and electricity, but no way to get them to consumers. Now that could be a thing of the past, due to...

窝囊气 wō nang qì =pent up frustration petty annoyances
窝煤窝电=frustration and incapability in terms of coal transportation and electricity transmission

窝 means nested, or trapped in its nest and unable to leave,
It can also be interpreted as locked and unable to leave its current location.
煤 means coal
电 means electricity

Read this news from http://finance.sina.com.cn/china/dfjj/20110630/005610069054.... and it will be self explanatory.

Summary of this news, in case you do not want to read this news:
Inner Mongolia has vast reserves of coal. However, there is no way yet to transport it out of Inner Mongolia to the Eastern region of China. The same applies to the excess electricity generated there. The news announces plans to build a highway to transport coal and other ways to channel out electricity to the Eastern region. Before this, due to insufficient resources of Inner Mongolia, the coal and electricity have been locked in there.