Environmental Issues

In two or three sentences, describe the key differences between power and energy. (5 marks)

The dictionary defines energy as the capacity of a physical system to do work while power as the rate at which work is done, expressed as the amount of work per unit time and commonly measured in units such as the watt and horsepower. Power  Energy  Time. The unit of measurement for energy is joule while for power, it is joule  time or watt.

In two or three sentences, describe the meaning of standby (also called vampire) electricity. One type of source of standby electricity is any remote-controlled device, which consumes electricity waiting for a signal from a remote control. Briefly describe two other types of standby electricity. (5 marks)

The Grinning Planet (2007) defines vampire power as the wasted standby power in home appliances. When an appliance is turned off but is plugged to an outlet, it still consumes electricity. Very common examples of these are a power adapter (no switch onoff mode) and digital clocks.

Examine and describe the differences in energy ratio (i.e., the energy input compared to the energy output) between corn-based ethanol and cellulosic ethanol. Provide citations for your discussions. (5marks)

Montenegro (2006) said that in todays world where climate change is a big issue, it is very important to shift to renewable sources of energy and at this current time, corn is a major source. Corn ethanol has been used as biofuel and the industry has surged and collapsed in recent years but researchers discovered that corn ethanol can lead to an even more promising source of biodegradable energy cellulosic ethanol which has very little production rate today (University of Tennessee). According to Mack (2009), the U.S. Department of Energy says cellulosic ethanol provides 54 percent more energy than corn-based ethanol in comparison to the amount of energy required for production. Additionally, cellulosic ethanol is considerably cleaner than corn ethanol. Mack (2009) said that corn ethanol emits 10-20 less carbon than gasoline while cellulosic ethanol is essentially carbon-free. According to the University of Tennessee, energy ratio for corn ethanol is 1.6 while cellulosic ethanol energy ratio ranges from 5 to 10, depending upon source of biomass.