Бурение грунтовых зондов, установка энергетических колодцев

Any fast growing grass can be used to produce cellulosic ethanol. These varieties of grasses can be divided into two groups depend­ing on the growing season as warm season and cold season grasses. Grasses are generally high yielding and rapidly growing plants. For example, once established, switchgrass fields yield from 5.2 to 11.1 metric tons of grass bales per hectare, depending on rainfall, according to USDA plant scientist Ken Vogel [119]. This type of grass that only needs to be planted once would deliver an aver­age of 13.1 mega joules of energy as ethanol for every mega joule of petroleum consumed in the form of nitrogen fertilizers or diesel for tractors used in growing them. Furthermore, USDA scientists are confident that switchgrass ethanol delivers 540 percent of the energy used to produce it. In comparison, roughly 25 percent more energy returned by corn-based ethanol according to the most opti­mistic studies [119].

It has been suggested that grasses growing on farmland margins such as switchgrass or grass mixtures in the Midwest region of the United States, can also be harvested. This may allow for land to be devoted to growing native grasses, which also provide habitat for native wildlife species. However, the harvesting of grasses, espe­cially native prairie grasses, may eliminate or disturb habitat for wildlife, or may interfere with biological or ecological processes such as nesting times for birds. Also, devoting farmland margins to biofuel feedstock production may undermine goals for land to be set aside for conservation of habitat in areas such as those rec­ognized under the U. S. Department of Agriculture’s Conservation Reserve Program (CRP).

Switchgrass and Miscanthus are major varieties of warm-sea­son grasses, and these grasses are high in cellulose, especially Miscanthus. A comparison of some warm-season and cool-season grasses in their cellulose, hemicellulose, and lignin contents is shown in Table 3.11.

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