sustainable energy

Biofuels

A Biofuel is a fuel that is sourced from non fossilized organisms or from by products of these organisms.

For example Biodiesel can be made from vegetable oils or animal fats.

Cattle or horse manure is another biofuel and it is the side product of recently living organisms.

What is biofuel?

The energy that we get from Biofuels originally came from the sun. This solar energy was captured through photosynthesis by the plants used as feedstocks (raw materials) for biofuel production, and stored in the plants' cells.

Many different plant materials can be used for biofuel: Sugar crops (such as sugar cane or sugar beet), or starch (like corn or

maize) can be fermented to produce ethanol, a liquid fuel commonly used for transportation.

Natural oils from plants like oil palm, soybean, or algae can be burned directly in a diesel engine or a furnace, or blended with petroleum, to produce fuels such as biodiesel.

Wood and its byproducts can be converted into liquid Biofuels, such as methanol or ethanol, or into woodgas.

Wood can also be burned as solid fuel, like the familiar firewood. Chipped waste biomass, such as the tops of trees discarded by logging operations, can be burned in specially designed furnaces.

Researchers are working to improve biofuel production processes. Before bioenergy can make a larger contribution to the energy economy, feedstocks, agricultural practices, and technologies that are efficient in their use of land, water and fossil fuel must be developed

How is it made?

May reduce U.S. reliance on oil imports and enable moderate reduction in emissions of greenhouse gases compared with oil.

Fosters the building of Biofuels infrastructure. Made from vegetable oils like soy and canola and animal fat, biodiesel provides 90% more energy than is

required to produce it. Compared with petroleum-based diesel fuel, biodiesel is estimated to cut greenhouse-gas emissions 40% to

80%. Sugar cane yields more ethanol per acre than corn, and it requires less energy to produce; hence, it is

regarded as greener than corn ethanol. Sugar isn't a food staple, so making ethanol from it hasn't driven up food prices as has the production of large

amounts of corn ethanol. Brazil makes nearly as much ethanol from sugar cane as the U.S. does from corn; cane provides nearly half of

Brazil's transportation fuel from plants grown using about 1% of its arable land. Made by breaking down wood chips, farm waste, and nonfood crops like grasses, cellulosic ethanol wouldn't

require diverting the use of cropland Scientists are making progress at breaking down plants' tough cellulose and lignin molecules, the key to

turning nonfood biomass into fuel The fastest-growing plants, algae theoretically can produce 30 times more energy per acre than other biofuel

options. A particularly rich mix of byproducts can be made in algal-Biofuels operations (everything from nutraceuticals

to feedstocks for making plastics), potentially abetting their cost-effectiveness. This is the Biofuels' dark horse.

Benefits

Ethanol is energy intensive to produce, and the recent boom has pushed corn prices to more than $5 a bushel (from $2 in 2006).

That is increasing the cost of everything from beef to soft drinks. The Biofuels craze is helping drive up grain prices worldwide as farmers devote more acres to corn

and less to other crops. Over 450 pounds of corn are needed to fill a 25-gallon tank with ethanol_ enough calories to feed a

person for a year. Like corn ethanol, biodiesel's production from food crops boosts "agflation.“ European demand has been blamed for inducing farmers in Southeast Asia to burn and replant the

rain forest with palm plantations, which has released large amounts of greenhouse gases. Production is limited at the moment_ just 250 million gallons in 2006 Growing sugar cane requires a warm, rainy climate, which limits its potential as a global fuel

source. Still costly and difficult to make, ethanol produced from nonfood plants is more energy intensive

than that made from corn and sugar cane. By one estimate, putting all the grassland in the U.S. into fuel production could replace only about

10% of petroleum. Unlike cellulosic ethanol, the biomass for making a lot of fuel from algae doesn't yet exist; it has to

be grown from scratch. Harvesting is still expensive. Cost-effectively producing algal Biofuels on a large scale may be

many years away.

Cons

A clean, efficient, fuel source

HYDROGEN

There are two processes that can be used to take hydrogen fuel and create useful work, combustion and in fuel cells. Combustion simply uses the hydrogen in an internal combustion engine or gas turbine instead of a hydrocarbon, like gasoline or jet fuel. A fuel cell is an electrochemical device and is a big reason hydrogen is seen a great potential fuel source.

Combustion Before going to hydrogen, conventional combustion with hydrocarbons will be discussed to give a comparison. Under ideal conditions the fuel burns fully on only reacts with the oxygen in the air. Below is the unbalanced

chemical equation. This was used instead of an exact equation because the results are the same, just in different quantities.

Hydrocarbon + O2 ==> CO2 + H2O This is a great, simply process that releases heat which can be converted to work, however this is the ideal

case. The actual process is a lot messier because of impurities, incomplete combustion, and because there are other molecules present during combustion, namely nitrogen. The air is mostly nitrogen, which is why some of it reacts.

Hydrocarbon + N2 + O2 ==> CO2 + H2O + CO + N2 + NOx + C + Hydrocarbon The fuel never completely burns, and other products are released. The products CO and NOx, while being

poisonous, contribute to creating smog. The C comes out of the engine as nasty black soot. The unburned hydrocarbons also contribute to health hazards, and represent waste. Even if the fuel does completely burn the result is carbon dioxide and water. CO2 emission is one of the largest concerns with combustion, since it is a greenhouse gas and may be contributing to global warming.

When hydrogen is combusted it does not release carbon dioxide, carbon monoxide, or soot, since there is no carbon in the fuel. This is a great advantage compared to fossil fuels. However, this does not remove the possibility of creating NOx, since nitrogen is still present during combustion. Below is the general chemical reaction.

H2 + N2 + O2 ==> H2O + N2 + NOx Using hydrogen as fuel cleans up the combustion process a lot, and it does not produce carbon dioxide.

However it not have any better efficiency than fossil fuels, about 25 to 30%. In liquid form hydrogen gas 3 times as much energy in combustion as gasoline, but to get the same amount of energy about 3 times the volume is needed. If liquid is going to be used it needs to be extremely cold ( less than -260°C or 435°F). This would need insulation to keep it cold, which would add to the bulk of the fuel tank.

How is hydrogen made

Hydrogen is environmental friendly, does not pollute, hydrogen only release water vapor and heat as its byproducts

Does not release CO2, which contribute to global warming. Hydrogen can quickly be refueled just like gasoline. Hydrogen is 100% renewable energy if hydrogen is obtained through

electrolysis. Hydrogen is abundant and can be produce around the world. Recharging hydrogen fuel cells in cars cost less than filling up with

gasoline. Hydrogen use in cars is 40%-60% more fuel efficient with electric motor

than gasoline cars. Reduce our dependent on foreign oil.

Benefits

Hydrogen is highly flammable and explosive. There are not enough hydrogen stations to refuel hydrogen cars Hydrogen cars can only be lease by Honda. Expensive to use on cars as because hydrogen fuel cell batteries

are expensive. It is expensive to transport, store and produce hydrogen power. It takes more energy to produce hydrogen than producing it. Cars run on hydrogen fuel cell do not travel farther than cars

running on regular gasoline. Hydrogen fuel use in cars use water to function, living in cold

climate will freeze the water causing problem.

Disadvantages

Biofuelswww.google.comhttp://

www.dec.ny.gov/energy/44157.html

http://money.cnn.com/galleries/2008/fortune/0804/gallery.green_biofuels.fortune/5.html

http://www.biofuelplanet.com/Biofuels/

www.google.comhttp://

www.facstaff.bucknell.edu/mvigeant/univ_270_03/john/hydrogen.htm

http://www.keyframe5.com/hydrogen-pros-and-cons/

Websites

hydrogen