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Biofuels
A lot of energy is locked up in the
Corn, soy, sugarcane, and other food crops are rich in oils, starches, and sugars that can be easily converted to biofuels. The starch in corn kernels, for example, can be enzymatically broken down to glucose, which is fermented to ethanol by bacteria or yeast. However, growing food crops for biofuel production typically requires a lot of energy (in the form of fossil fuels) and it damages the environment. Making biofuels from other plant matter such as weeds or agricultural waste requires additional steps, because these materials contain a higher proportion of cellulose. Breaking down this tough carbohydrate to its glucose monomers adds cost to the biofuel product.
In 2006, David Tilman and his colleagues published the results of a 10-year study comparing the net energy output of various biofuels. The researchers made biofuel from a mixture of native perennial grasses grown without irrigation, fertilizer, pesticides, or herbicides, in sandy soil that was so depleted by intensive agriculture that it had been abandoned. The energy content of this biofuel and the energy it took to produce it were measured and compared with that of biofuels made from food crops (Figure 5.16).
Which of the three crops required the least amount of land to produce a given amount of biofuel energy?
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Biology Today and Tomorrow without Physiology (MindTap Course List)
- Biofuels A lot of energy is locked up in the chemical bonds of molecules made by plants. That energy can fuel consumers, as when an animal cell powers ATP synthesis by aerobic respiration. It can also fuel our cars, which run on energy released by burning biofuels or fossil fuels. Both processes are fundamentally the same: They release energy by breaking the bonds of organic molecules. Both use oxygen to break those bonds, and both produce carbon dioxide. Unlike fossil fuels, biofuels are a renewable source of energy: We can always make more of them simply by growing more plants. Also unlike fossil fuels, biofuels do not contribute to global climate change, because growing plant matter for fuel recycles carbon that is already in the atmosphere. Corn, soy, sugarcane, and other food crops are rich in oils, starches, and sugars that can be easily converted to biofuels. The starch in corn kernels, for example, can be enzymatically broken down to glucose, which is fermented to ethanol by bacteria or yeast. However, growing food crops for biofuel production typically requires a lot of energy (in the form of fossil fuels) and it damages the environment. Making biofuels from other plant matter such as weeds or agricultural waste requires additional steps, because these materials contain a higher proportion of cellulose. Breaking down this tough carbohydrate to its glucose monomers adds cost to the biofuel product. In 2006, David Tilman and his colleagues published the results of a 10-year study comparing the net energy output of various biofuels. The researchers made biofuel from a mixture of native perennial grasses grown without irrigation, fertilizer, pesticides, or herbicides, in sandy soil that was so depleted by intensive agriculture that it had been abandoned. The energy content of this biofuel and the energy it took to produce it were measured and compared with that of biofuels made from food crops (Figure 5.16). The production of which biofuel was most efficient (which had the highest ratio of energy output to energy input)?arrow_forwardBiofuels A lot of energy is locked up in the chemical bonds of molecules made by plants. That energy can fuel consumers, as when an animal cell powers ATP synthesis by aerobic respiration. It can also fuel our cars, which run on energy released by burning biofuels or fossil fuels. Both processes are fundamentally the same: They release energy by breaking the bonds of organic molecules. Both use oxygen to break those bonds, and both produce carbon dioxide. Unlike fossil fuels, biofuels are a renewable source of energy: We can always make more of them simply by growing more plants. Also unlike fossil fuels, biofuels do not contribute to global climate change, because growing plant matter for fuel recycles carbon that is already in the atmosphere. Corn, soy, sugarcane, and other food crops are rich in oils, starches, and sugars that can be easily converted to biofuels. The starch in corn kernels, for example, can be enzymatically broken down to glucose, which is fermented to ethanol by bacteria or yeast. However, growing food crops for biofuel production typically requires a lot of energy (in the form of fossil fuels) and it damages the environment. Making biofuels from other plant matter such as weeds or agricultural waste requires additional steps, because these materials contain a higher proportion of cellulose. Breaking down this tough carbohydrate to its glucose monomers adds cost to the biofuel product. In 2006, David Tilman and his colleagues published the results of a 10-year study comparing the net energy output of various biofuels. The researchers made biofuel from a mixture of native perennial grasses grown without irrigation, fertilizer, pesticides, or herbicides, in sandy soil that was so depleted by intensive agriculture that it had been abandoned. The energy content of this biofuel and the energy it took to produce it were measured and compared with that of biofuels made from food crops (Figure 5.16). About how much energy did ethanol produced from one hectare of corn yield? How much energy did it take to grow and produce that ethanol?arrow_forwardAs the sun shines on Earth, plants use its energy to complete the process of photosynthesis. Energy is transformed during the process into chemical energy in the form of sugars, such as carbohydrates. However, the energy available at top consumers is much less than that produced by autotrophs. Why is this so?arrow_forward
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- Chemical bond energy: Is the energy used by photosynthesis for the fixation of carbon Is generated as usable energy for the cell Is generated by processes in the chloroplast and mitochondria All of the abovearrow_forwardWhat happens to a molecule when it is oxidized? Electrons are gained Electrons are lost Electrons are converted into neutrons Electrons are converted into protons Electrons combine with a proton to produce a protoelectronarrow_forwardHello sir/miss, the question and answer are provided below. Is the answer to the question correct? Explain how the carbon cycle is related to energy flow in ecosystems. The carbon cycle is related to energy flow in ecosystems because they both involve photosynthesis. In the carbon cycle, carbon dioxide plays a role in plants and microorganisms using photosynthesis. The energy flow in ecosystems absorbs a small part of the Sun’s radiant energy (0.023%) by living organisms for photosynthesis.arrow_forward
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