Renewable fuels

From Phyco.org

Alternative fuels are chemical substances developed without the use of petroleum that can be used to power reactions within an engine or process. When fuels are produced by a process that adds energy into a system, rather than reducing that overall amount of energy, that system is considered renewable. Autotrophs such as algae or other plants are important for renewable fuels because they produce more complex molecules (i.e. sugars or oils) from simpler ones such as carbon dioxide and water using sunlight. It is believed that these fuels can be most efficiently produced by microorganisms such as algae or bacteria.

1 Biodiesel
2 SVO
3 Ethanol
4 Methane
5 Glycerol
6 Hydrogen
7 Crude Oil
8 External Links

[edit] Biodiesel

A viable replacement for petroleum-derived diesel fuel, undiluted biodiesel can be used in a diesel engine with very little modification to the vehicle.

[edit] SVO

Most of the oils that can be used to make biodiesel, can be used directly in slightly modified diesels. Such use is called SVO or Straight Vegetable Oil. It may be a lower cost solution than biodiesel.

[edit] Ethanol

Used to supplement gasoline, it is often mixed with gasoline in mixtures containing up to 85% ethanol by volume as fuel for flexible-fuel vehicles.

Ethanol can be obtained from algae in a few ways.

Cellulose Hydrolysis - The carbohydrate cell walls protecting certain algae can be broken down into ethanol.
Glucose & Pentose Fermentation - Cells produce sugars which can be extracted and fermented.
As a byproduct of cellular processes - Ethanol can be a waste product of certain algae under certain conditions.

[edit] Methane

Methane is the primary constituent of natural gas. Most useful in industrial processes, if natural gas can be created using algae, many parts of existing energy infrastructure can be retained.

Methane can be produced from bacterial digestion of algae much as 'swamp gas' is produced.

[edit] Glycerol

A by-product of the transesterification process used to create biodiesel, this can be fermented to create ethanol, which can then be used to create more biodiesel, or used to create E85 gasoline. Glycerol is also produced as a byproduct of some algal cellular processes.

[edit] Hydrogen

Often touted as the "fuel of the future," hydrogen can be created from certain algae. The culture reverts to a primordial state and begins to split water into hydrogen and oxygen using an enzyme known as hydrogenase, which, ironically, works only in the absence of oxygen. It is necessary to starve the culture of certain nutrients, such as sulfur, to activate an alternative metabolic pathway, which causes the algae to release large amounts of hydrogen gas. [1]

[edit] Crude Oil

Using gasification techniques such as the Fischer-Tropps process or other methods such as Thermal Depolymerization, it is possible to create hydrocarbons from biomass. A great deal of energy is lost during this process, however.

These biomass conversion processes are an important step to integrating algae into our current fossil fuel infrastructure.