The line, “There are problems in the bigger picture of carbon consumption and emission,” deplores

Directions: Read the given passage and answer the following question.

Combustion engines contribute to greenhouse gas accumulation in the atmosphere and are responsible for climate changes. A sane, sober revision of vehicle use is long overdue. While ethanol has been championed as an alternative to petroleum fuels, it mainly helps to reduce dependency on oil producing countries. Ethanol or methanol can be blended with petrol to reduce petroleum dependency. Petrol engines can use up to 10% ethanol without modification. New "flex" engines can use higher percentages of ethanol up to 100%. Hybrid flex-fuel vehicles are optimised to run on a maximum blend of 15% petrol with 85% ethanol (E85 fuel). The production of flex engine vehicles has increased, but the supply of flex fuel is limited.
There are problems in the bigger picture of carbon consumption and emission. When ethanol is made from corn, a lot of energy value must be spent on its production. While innovations in production technologies continue, there will be an ongoing requirement to invent new methods of production. Investment in new technologies will require government policy changes, subsidies and research grants. This will give rise to new competition between ethanol plants and food production.
If you are an optimist, you might argue that improved technologies will save the day --- corn yields per acre have been increasing mostly because of genetic engineering, so that food and ethanol production need not compete in the future. The ethanol industry uses only the carbohydrate fraction of the corn; the protein and oil fractions are used as animal feed to be consumed by humans as dairy products, eggs and meat. If you are a pessimist, you might point to the recurrent droughts in recent years and predict more crop failures in years to come. Other non-food vegetable sources of carbon will become alternative sources of raw materials.