... konulu sunumlar: "Alternative Fuels Biofuels, Natural Gas and Electricity."— Sunum transkripti:
Alternative Fuels Biofuels, Natural Gas and Electricity
First Generation Biofuels First-generation biofuels derive from edible biomass, primarily corn and soybeans in the United States and sugar cane in places like Brazil. They are the low-hanging fruits in a forest of possible biofuels, given that the technology to convert these feedstocks into fuels already exists.
Ethanol Ethanol (C 2 H 5 OH)is also known as grain alcohol. It is made by fermenting corn kernels—a biological process similar to the one that gives us beer and wine. Here is the recipe: 1.Chop the corn and mix with lots of water; 2.Cook to convert the starches to sugars; 3.Add yeast which eats the sugars in the corn, producing ethanol and water.
Ethanol Ethanol is most commonly used to increase octane and improve the emissions quality of gasoline. Today more than 40 percent of the gasoline sold in the U.S. contains ethanol—typically premixed with gasoline to make a blend called E10 that is 90 percent gasoline, 10 percent ethanol. In Illinois, a blend that is 85 percent ethanol (E85) is also sold for use in vehicles that have so-called flex-fuel engines.
Advantages of Ethanol Ethanol is a clean-burning fuel, potentially providing more horsepower than gasoline. Ethanol has a higher octane rating (over 100) and burns cooler than gasoline Ethanol can degrade quickly in water, therefore, posing less environmental harm than oil in the case of a spill. Ethanol production can support agricultural communities like central Illinois!!!
Ethanol and Food Supply Corn has worked its way into much of our foods –high fructose corn syrup –cow feed –corn oil for cooking Twenty two pounds of corn are needed to produce just one gallon of ethanol. Ethanol production can supplant actual food production, driving up price of food
Other Concerns About Ethanol Farming corn requires fossil fuels. We put more energy into Ethanol agriculture than we get out –Corn requires 29 percent more fossil fuel energy than the biofuel produced Ethanol process requites lots of water. –It takes between four and five gallons of water to produce a gallon of ethanol at a biofuel plant. –Usually this water is taken from the local surface or groundwater supply.
Quantitative Ethanol In addition this would require a lot of land to grow the corn. Let’s calculate how much land we need to replace oil/gasoline –an Illinois cornfield is 1.5% efficient at turning incident sunlight into stored chemical energy –the conversion to ethanol is 17% efficient assuming 1.2:1 ratio, and using corn ethanol to power farm equipment and ethanol production itself –growing season is only part of year (say 50%) –net is 0.13% efficient (1.5% 17% 50%) –need 40% of 10 20 J per year = 4 10 19 J/yr to replace petroleum –this is 1.3 10 12 W: thus need 10 15 W input (at 0.13%) –at 200 W/m 2 insolation, need 5 10 12 m 2, or (2,200 km) 2 of land that’s a square of 2,200 km on a side!!!!
What does this amount of land look like? We don’t have this much arable land! And where do we grow our food?
Generation 1 Biofuels: Biodiesel Biodiesel is a domestically produced, renewable fuel that can be manufactured from vegetable oils (mainly soybean), animal fats, or recycled restaurant greases. Biodiesel is safe, biodegradable, and reduces serious air pollutants such as particulates, carbon monoxide, hydrocarbons, and air toxics. Biodiesel can also be used in its pure form but it may require certain engine modifications to avoid maintenance and performance problems and may not be suitable for wintertime use.
Disadvantages of Biodiesel Pure biodiesel, B100, costs roughly a dollar more per gallon than petrodiesel. Biodiesel is less suitable for use in low temperatures, than petrodiesel. Need to heat storage tanks in colder climates to prevent the fuel from gelling The energy content per gallon of biodiesel is approximately 11 percent lower than that of petroleum diesel. Vehicles running on biodiesel are therefore expected to achieve about 10% fewer miles per gallon of fuel than petrodiesel.
Second Generation Biofuels: Celluluse Cellulose is the fiber contained in leaves, stems, and stalks of plants and trees – the most abundant organic compound on earth. –In nature, cellulose supports a plant’s vertical growth (stalks) and stubbornly resist biological breakdown. Unlike corn and sugar – the plants now used to make most ethanol – cellulose is not used for food, and it can be grown in all parts of the world.
Sources of Celluluse Cellulose ethanol can be made many sources including: 1. wood residues such as sawdust and construction debris 2. agricultural residues such as cornstalks and wheat straw 3. “energy crops” such as switchgrass and other fast growing grasses and woody materials
Second Generation Biofuels: Celluluse Ethanol can be made from cellulose much as it is today from corn once the very tightly bound sugars in the plant fiber are broken down by enzymes found in yeasts and bacteria. Accomplishing this task at low cost has been the principal obstacle to commercial development.
Third-Generation Biofuel: Algae During photosynthesis, photosynthetic microbes such as algae and cyanobacteria (sometimes referred to as blue-green algae) capture carbon dioxide and sunlight and convert it into oxygen, biomass, and fat. Photosynthetic microbes also store plenty of fat, which forms the basis for biofuel. They also grow quickly—some forms double in just 12 hours, whereas grasses and other large plants can take weeks or months to do so.
Advantages of Algal Biofuels Algae can be grown using land and water unsuitable for plant or food production Algae requiring only sunlight, water and carbon dioxide. Bio-oil produced by photosynthetic algae and the resultant biofuel will have molecular structures that are similar to the petroleum and refined products we use today. Algae have the potential to yield greater volumes of biofuel per acre of production than other biofuel sources.
Complications with Algal Biofuels Trying to grow concentrations of the algae is difficult in an open pond. –The water needs to be just the right temperature for algae to proliferate, and even then open ponds can become choked with invasive species. Most companies pursuing algae as a source of biofuels are pumping nutrient- laden water through plastic tubes that are exposed to sunlight, called photobioreactors or PBR.
Complications with Algal Biofuels The chemicals and energy to release the oils from algae is very expensive at the moment. The combined cost of the photobioreactors, energy, and chemicals required to produce biodeisel from algae makes it not economically viable even at $150 bbl crude, yet. $$$$
Natural Gas Vehicles (NGV) Natural gas commonly occurs with crude oil in petroleum traps. Natural gas consists primarily of methane and other simple hydrocarbon gases such as butane, ethane and propane. Most natural gas consumption in the U.S. is used for generating electricity and for industrial uses. But less than 1 percent of current natural gas consumption is being applied for vehicles.
Natural Gas Vehicles (NGV) The Honda Civic GX is the only NGV commercially available in the US market however you can convert any gasoline or diesel engine to a natural gas engine
Natural Gas Vehicles (NGV) Because of the gaseous nature of this fuel, it must be stored onboard a vehicle in either a compressed natural gas (CNG), a replacement for gasoline, or a liquefied natural gas (LNG), a replacement for diesel fuel. The natural gas is be stored in high pressure cylinders usually located in the vehicle's trunk.
Advantages of NGVs Natural gas costs are lower than gasoline. On average, natural gas costs one-third less than gasoline at the pump. Per unit of energy, natural gas contains less carbon than any other fossil fuel, and thus produces lower carbon dioxide (CO2) emissions per vehicle mile traveled. Air Pollution such as carbon monoxide, nitrogen oxides (NOx), and volatile organic compounds (VOCs) pollutants from a typical NGV are much lower than those from gasoline-powered vehicles.
Advantages of NGVs The United States has natural gas reserves across the country so our dependence on forgiven oil would decrease. A well-established pipeline infrastructure exists in the United States to deliver natural gas to almost every urban area and most suburban areas. NGVs have lower maintenance costs. Because natural gas burns so cleanly, it results in less wear and tear on the engine and extends the time between tune-ups and oil changes.
Disadvantages of NGVs One of the biggest complaints about NGVs is that they aren't as roomy as gasoline cars. This is because NGVs have to give up cargo and trunk space to accommodate the fuel storage cylinders. Not only that, these cylinders can be expensive to design and build -- a contributing factor to the higher overall costs of a NGV compared to a gasoline-powered car. NGVs tend to cost $3500 to $6000 more than gasoline powered ones
Disadvantages of NGVs Another drawback is the limited driving range of NGVs, which is typically about half that of a gasoline-powered vehicle. There are only about 1,300 NGV fueling stations in the United States and they are located in only certain parts of the U.S. If a dedicated NGV ran out of fuel on the road, it would have to be towed to the owner's home or to a local natural gas refueling station, which might be harder to find than a "regular" gas station.
Disadvantages of NGVs Ultimately natural gas, like gasoline, is a fossil fuel and cannot be considered a renewable resource. While natural gas reserves in the United States are still considerable, they are not inexhaustible. Some predict that there are enough natural gas reserves remaining to last another 67.1 years, assuming that the 2003 level of production continues.
Electric Vehicles (EV) Electricity can be used as a transportation fuel to power battery electric vehicles (EV). When used to power electric vehicles, electricity is stored in an energy storage device such as a battery.
Electric Vehicles (EV) EVs are not a new technology. They were first introduced in the early 1900’s. EVs eventually faded away due to the lack of available electricity and the cheaper, faster gasoline powered vehicles
Advantages of EVs EVs have lower "fuel" and maintenance costs than gasoline-powered vehicles. EVs require no warm-up and have excellent performance up to the limit of their range. EVs are cheap to "refuel." At the average price of 10 cents per kwh, it costs around 2 cents per mile. No more Oil Changes!!!! EVs are 100% emission-free, having no polluting byproducts HOWEVER…….
Pollution and EVs The electricity used to recharge EV batteries is generated mainly by burning fossil fuels. According to the Electric Vehicle Association of Canada, even EVs recharged from coal-powered electric generators cut carbon emission roughly in half. EVs recharged from cleaner forms of electrical power generation, such as nuclear plants, can reduce carbon emissions to less than one percent of those currently produced by internal combustion engines.
Disadvantages of EVs EV batteries have a limited storage capacity and their electricity must be replenished by plugging the vehicle into an electrical source. Recharging of batteries often takes about 3 hours A battery pack of an average EV can weigh up to a 1,000 pounds. This weight puts pressure on batteries and they drain out faster. Also, the acceleration of an EV is compromised by it’s weight
Disadvantages of EVs EV still have limited range, typically no more than 100 to 120 miles. They are expensive!!!! Batteries that power these cars are a costly affair. –The promising and long-lasting lithium-ion batteries cost about US$10,000 each, which for the most part make these cars expensive. –And if the batteries last only about 4 years, they could add to the maintenance costs.
The Future of Electric Vehicles (EV) The Nissan Leaf goes on sale at the end of 2010 in some markets, with a cost of around $21K in California and Georgia after government incentives. However the battery warranty is unknown.
Hybrid Electric Vehicles (HEV) The term most commonly refers to hybrid electric vehicles (HEVs), which combine an internal combustion engine (ICE) and one or more electric motors. Modern HEVs utilize regenerative braking, which converts the vehicle's kinetic energy into battery- replenishing electric energy, rather than wasting it as heat energy as conventional brakes do. This means that unlike EVs, HEVs do not actually need to be charged from your home electric outlet
Hybrid Electric Vehicles (HEV) Some varieties of HEVs use their internal combustion engine to generate electricity by spinning an electrical generator (this combination is known as a motor-generator), to either recharge their batteries or to directly power the electric drive motors. Many HEVs reduce idle emissions by shutting down the ICE at idle and restarting it when needed; this is known as a start-stop system.
Advantages of HEVs HEVs saves gasoline. Combining the cleaner energy of an electric motor with the long range capacity of a gasoline engine allows a hybrid car to save as much as 30 miles a gallon. In a HEV, the ICE is shut off automatically when the car stops, thus saving fuel. The gasoline engine is automatically turned on when the accelerator pedal is stepped on.
Advantages of HEVs EEVs emit lower toxic emissions compared to conventional gasoline- powered cars due to less gasoline being burned. The gasoline engine installed in these cars is smaller and less polluting. It helps reduce the air emissions of smog-forming pollutants by up to 90% and also cut down carbon dioxide emissions by half.
Drawbacks of HEVs HEVs have much higher price tag as comparative to other conventional cars and the reason being the costly batteries and two separate engines which adds up to the efficiency of these cars. Another factor associated with the cost is that in the replacement parts for these vehicles will also be expensive. Plus, not every garage will work on HEVs.
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