Definition
Biofuels are listed among renewable sources of energy. They are divided into solid, liquid and gaseous.
Fuel wood, woodchips, wood pellets, scobs, straw and hay are classified among solid biofuels. Gaseous biofuels are biogas (methane), wood gas and hydrogen made by fission process from hydrocarbon biofuel.
Liquid biofuels have found their application in transportation - they are mixed with standard fossile fuels - i.e. gasoline and diesel. In various EU countries they are added in various proportions. Bioethanol, ETBE, vegetable oils and biodiesel are commonly classified among liquid biofuels. The biofuels industry in the CEE region currently produces liquid biofuels of the so-called “first generation”, made of corn, sunflower and rapeseed, which are also called energycrops. In other parts of the world liquid biofuels of the first generation are typically made of sugar cane, soy oil or palm oil.
Nowadays there is development intechnologies for biofuels of the “second generation”, which are produced from cellulose, agricultural residues, or even from waste. However, biofuels of the second generation are not produced on a commercial scale yet, due to their high cost. In laboratories biofuels of the “third generation” have started to be examined, which can be made e.g. from algae. We are probably decades away from the commercial uptake of the second and third generation biofuels, as the research and commercial implementation of liquid biofuels of the first generation lasted almost 80 years.
Advantages of biofuels
- lower emissions of greenhouse gases in transportation
- they are notable renewable source of energy in the long-term
- they can be produced directly in our region, from our traditional crops, as opposed to crude oil and natural gas which have to be imported
- while crude oil is a depletable source of energy, crops for biofuels production are renewable and varied
Three generations
Biofuels of the first generation
They are produced by fermentation of sugars and starch, or by transesterification of oils and fats. Biofuels of the first generation can be produced from sugar crops (sugarbeet, sugarcane), from starch-containing crops (potatoes, cereals) and from oil crops and animal fats (rapeseed, soya, sunflower, oil palm, pork fat). Opponents of biofuels claim that the utilization of oilseeds and cereals for production of this generation of biofuels contributes to increasing food prices, however, as a matter of fact currently only 3% of agricultural land is used worldwide for the production of energy crops.
Biofuels of the second generation
The other group of inputs for the production of biofuels are the so-called lignocellulosic raw materials, more precisely timber, residues from woods, foliage, crust, straw. These crops can be processed by various technologies, from hydrolysis, to gasifying or cracking. Their advantage is that they do not compete for prime agricultural land with food crops, they can be grown on lower quality soils and another plus is also the fact, that the whole plant can be used, not only its part. The European Commission recently mandated that until 2020 the proportion of biofuels in fossile fuels should include up to 7% of the first generation biofuels and 0,5% of the second generation biofuels, although this is a non-binding target. Currently, biofuels of the second generation are still in the research stage and they will influence the market approximately in 10 years time.
Biofuels of the third generation
In the future it is likely that biofuels made of sea algae will be used. According to scientists their advantage will be a high degree of utility per unit of area used. Meaning that e.g. from an area of two parking places we may grow such an amount of biofuel, which could be compared to a soya field with the size of a football pitch. Algae are the fastest growing plants and are highly productive. In the future it will be grown in pools or specialized bioreactors.
Liquid Biofuels
Bioethanol
Bioethanol is one of the first fuels that was used in automobile engines ever. In a larger amount it was used during the Second World War in Germany, Brazil, Philippines and the United States. After the war crude oil products became more affordable, therefore bioethanol use declined. Thanks to a fluctuation of crude oil commodity prices the production of bioethanol has increased in the last decades. Bioethanol is pure alcohol made from renewable raw materials, that’s used as a propellant. It is produced through alcohol fermentation process from biomass, the key raw materials used are plants with a higher amount of starch content (corn, cereals, potatoes) and/or saccharides (sugarcane and sugarbeet). In the process a byproduct called dried distillers grains with solubles (DDGS) is also produced, which is used as a high-quality animal feed. Bioethanol or its derivatives are currently used as 5-10% additives in conventional fuels, resulting in decrease in costs of fuel production, increase of octane number and decrease of CO2 emissions.
Advantages
- there is a wide variety of input materials for its production
- it supports domestic farmers
- it enables higher effectiveness of combustion in engines
- it is chemically similar to gasoline and therefore it is usable in automobiles without any engine adjustment
- its usage decreases air pollution
- Energy safety - it decreases the dependence of a country on crude oil imports
ETBE
Ethyl-terc-butyl-ether (ETBE) is used as an oxidation admixture for gasoline, increasing its octane number (118 ETBE). This practially means an increase of engine combustion effectiveness. ETBE is made by reaction of ethanol with isobutene in the presence of acid catalyzer and higher temperature, it is a fuel made on the basis of bio-methanol.
Advantages
- Its usage reduces greenhouse gas emmisions
- it has a higher heating capacity and a lower steam pressure
- it is more easily mixed with gasoline
Vegetable Oils
They are produced from oil seeds, in our region mainly rapeseed or sunflower, but soya or oil palm can also be used. In the first phase oil seed is pressed, during this process approximately 20% of oil is pressed out. Then this oil is degummed (phosphorus is removed and washed in water), after physical refining, filtration and drying it is used as input for the production offatty acid methyl esther(FAME), commonly known as biodiesel.
Advantages
- vegetable oils belong to the cheapest biofuels
- oil crops have high value for the farmers in the regions where they are grownthey are a simple and accessible form of liquid fuels
Biodiesel
It is produced from 100% raw material of vegetable or animal origin, in its production no fossil elements were used. The basic raw material is vegetable oil – rapeseed, sunflower, soya, palm, as well as used cooking oil (used oil from households or restaurant facilities), or animal fat. The most frequent technological process for biodiesel production is transesterification of fatty acids, which are present in vegetable oils or animal fats.
Advantages
- in combustion process itis more effective, which decreases emissions
- it has high lubricating capability, which decreases the wear of engine
- it is easily storable and its possible leaking into water does not cause microbiological burden
- it quickly degrades in soil and does not cause soil pollution
