Wheat ethanol
Wheat ethanol is a form of bioethanol produced primarily from wheat grain, and it serves as a renewable transportation fuel. In Europe, wheat is the most prevalent cereal utilized for bioethanol production, with the European Union (EU) witnessing a significant rise in its use for fuel applications over the past two decades. The production process involves several steps, including milling, fermentation, and distillation, ultimately yielding high-purity ethanol suitable for blending with gasoline or diesel. Wheat-based ethanol production not only contributes to energy security but also supports rural development through agriculture.
In terms of global production, the United States and Brazil are the leading bioethanol producers, with the EU also making considerable contributions, especially through starch and molasses from sugar beets. While Germany and France are the main consumers within the EU, there is a notable reliance on imports to meet demand, particularly from Brazil. The environmental impact of wheat ethanol production is a complex issue, influenced by factors such as fertilizer usage and land-use change, which can significantly affect greenhouse gas emissions. Despite these challenges, the ongoing push for renewable energy sources highlights the potential benefits of wheat ethanol in addressing energy needs while promoting sustainable agricultural practices.
Wheat ethanol
Summary: Bioethanol used as transportation fuel is produced from several feedstocks. Wheat is the most common cereal used for bioethanol production in Europe.
Bioethanol is an alcohol produced from the biodegradable fraction of products and residues from agriculture and forestry. In 2022, the United States was the world’s largest bioethanol producer, having produced more than 15 billion gallons, primarily from corn. The United States was followed by Brazil, which produced more than 7 billion gallons, primarily from sugarcane. In the European Union (EU), starch and molasses from sugar beets are the main feedstocks. There has been a sharp increase in starch-based ethanol, with wheat as the major feedstock. EU bioethanol fuel production in 2022 corresponded to nearly 1.46 billion gallons. In the past, production was mainly devoted to beverage, industrial, and technical applications. This trend was reversed in 2006, due to increasing demand for fuel purposes. Recent statistics show that European ethanol production for nonfuel applications has remained stable in recent years, whereas fuel applications are becoming considerably more significant, rising from 9.2 percent in 1998 to over 70 percent in 2009. The use of wheat-based ethanol is expected to increase substantially in the 2020s as India announced that it intended to ramp up to a 20 percent fuel blend.
The EU consumption of bioethanol fuel has been on a sharp rise, with annual rates greater than 30 percent between 2005 and 2010. Germany and France are the main consumers, accounting for more than 44 percent of total consumption. There is a gap between consumption and production levels in the EU, which is filled by bioethanol imports, more than 70 percent of which are from Brazil. Bioethanol is used as a transportation fuel in several blend compositions. The most common include (1) up to 5 volume-volume percent (v/v percent, and more recently 10 v/v percent is allowed) of bioethanol in gasoline for conventional vehicles; (2) up to 85 v/v percent bioethanol in gasoline for modified vehicles (flex-fuel vehicles); and (3) 95 v/v percent bioethanol in diesel fuel, used in captive fleets of Swedish buses.
Production of Bioethanol From Wheat
Wheat cultivation includes several steps, namely soil preparation (plowing), fertilization, sowing, weed control, and harvesting. After transportation to the processing plant, the raw material is washed to remove any debris, such as soil and stones. The grain goes through a grinding process in a hammer mill in order to increase the grain surface and maximize the efficiency of the subsequent steps. The milled grain is then mixed with preheated water and liquefaction enzymes, forming a mash and releasing the starch from the cell material. After cooling down, a mixture of amylase enzymes is added to break down the starch into simple sugars (saccharification). Sugars are fermented to ethanol using yeasts, in a process that releases carbon dioxide and yields a solution of 8 to 10 percent milligrams per milliliter alcohol. This alcohol concentration is increased up to 95–96 v/v percent by distillation. If ethanol is to be mixed with gasoline for transportation purposes, further dehydration of 99.7 v/v percent or more is required, which is usually achieved through molecular sieve technology. On average, 1 liter of ethanol is produced for each 2.84 kilograms of wheat processed. After fermentation and distillation, the leftover residue (whole stillage) is pressed and dried to form distiller’s dried grains with solubles (DDGS). Approximately 350 kilograms of DDGS are produced per ton of wheat. DDGS has both high protein and high fiber content and can be sold as feed for ruminants.
Energy and Environmental Issues
Several factors affect the energy and greenhouse gas (GHG) balance of ethanol production from wheat: production and application of fertilizers and pesticides, fossil energy inputs, soil emissions due to land use, and (direct and indirect) land-use change (LUC). According to the EU renewable energy directive 2009/28/EC, typical GHG emission savings of wheat-based ethanol over gasoline amount to 45 percent, although not including soil carbon emissions from LUC. Recent reviews of (wheat-based) ethanol studies show that the GHG balance over the life cycle (that is, from wheat cultivation to delivery of bioethanol to the end user) may vary significantly, and if lands with high stocks of carbon are converted to biofuel production, the total GHG balance may become critical. This aspect must be balanced against the recognized advantages of biofuels promotion, namely security of energy supply and rural development.
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