The Toyota Prius spurred a revolution in automobile design, causing the makers of mass-produced cars to invest in hybrid technology to increase the fuel efficiency of their model lineups. A compelling speech about the environment can be made about other factors that are often neglected when considering a car as environmentally friendly. Expand upon fuel economy and discuss the whole life cycle of the car from production to the junkyard. Consider aspects like plants that are "zero-landfill" such as those run by Subaru and also consider the amount of biodegradable materials used in cars. Fuel efficiency is one of many considerations when labeling a car as a "green vehicle."
The nuclear-versus-coal debate has been going on for decades, but in the midst of the Japanese earthquake, tsunami and nuclear disaster of 2011 the debate has heated up. Discuss the pros and cons of nuclear and coal power plants, but expand upon the existing pros and cons and consider ways to mitigate the negatives of each. Consider disaster management plans for nuclear reactors, or even base your whole speech around such a topic.
A compelling speech can be made about the discussion of developing nations. Consider the environmental conditions of the United States during the Industrial Revolution and compare those conditions and the pollutants produced to the conditions in developing countries such as China and India. Was America's economic infrastructure built around environmentally unsound practices? Discuss from a philosophical standpoint how this should shape the development of nations like China. Consider the morality of making a country live up to a higher standard than we were held to. To add depth to the topic you can also discuss the possibility that during the Industrial Revolution Americans did not know about coal mining's health impacts on the miners or about the soil contamination caused by mining, whereas these impacts are now known.
Consider the actual impact of the Cash for Clunkers program. Examine the fuel economy cutoffs required for a car to qualify for the credit on the trade-in and purchase end. There are a few important aspects to consider when analyzing the impact of this program. Beyond the increased fuel economy of the new cars placed on the road, you should also consider the emissions systems on the cars traded in and how they compare to modern emission controls systems. On the other hand it is also important to consider the space the traded-in cars will take up in landfills as well as the loss of junkyard parts for those still driving similar models because the Cash for Clunkers program required the salvage yard to destroy the engine, transmission and other drivetrain components of vehicles traded in under the program.