On February 2006, President George W. Bush said, "All of a sudden, you know, we may be in the energy business by being able to grow grass on the ranch and have it harvested and converted into energy." Analyze and compare two of the following options:

1. Surveying the technical literature on the topic, we find an article by Schmer et al. [20]. According to this article, the net energy yield of switchgrass grown over 5 years on marginal crop land on farms in the mid-continental United States was \(60 \mathrm{GJ} /\) ha. This is equivalent to about \(0.2 \mathrm{~W} / \mathrm{m}^{2}\), about 10 times the bioethanol from corn in the United States, and represents a potential source of ethanol sometime in the future.

2. Bioethanol can also be produced from sugarcane in climates such as in Brazil. For sugarcane, the production is 80 ton/ha.

3. Ethanol from corn using technology of 2009.