I here argue that Corpus Linguistic (CL) investigations can show evidence that renewable energy has become increasingly important in the last 20 years as shown in the Brown Family corpus, a linguistic database of both British and American English whose diachronic data span from 1930s to 2000s. I use collocation analysis, a well-known CL technique, to discover collocates (accompanying words) that significantly associate with energy. The significance is statistically calculated using Log Likelihood (LL). No content word is found up to 1930s data. Some content words related to the categorization of energy are found in 1960s data. In 1990s data renewable is within top-3. In 2006 data, renewable is found to rank first, showing a very strong significance with energy.