It is timely that Engineering should devote a special issue to the topic of clean energy.The authors of the research articles and the views and comments cover much of what is a very diverse and con-troversial field.Responses to this topic cover a spectrum ranging from those that argue for emergency action to prevent the extinc-tion of the human race to those that deny the existence of climate change.Before dismissing any group,it is informative for engineers and technologists to note that there is a fairly even distribution across this spectrum[1]as shown in Fig.1.