Organic wastes and residues have been the main biomass sources so far, but energy crops are gaining in importance and market share. Residues, wastes, and begasse are primarily used for heat and power generation.
Sugar, starch and oil crops are primarily used for biofuel production.
Biomass is mainly used to produce energy in three ways: direct-burning, fuel blending as in co-firing, and gasification.
Co-firing systems simply replace parts of the coal burnt in existing power plant furnaces with biomass. It has the advantage of emitting less toxic and greenhouse emissions than coal. Gasification is the most efficient way of using biomass.
Fuel blending involves co-firing wood with coal, or mixing ethanol (as practiced in US and Brazil and the EU) or biodiesel ( as in Malaysia ) with conventional petroleum based fuels.
Bio-ethanol is an excellent biofuel substitute for gasoline as the main car fuel. The world leaders in biofuel development and use are Brazil, United States, France, Sweden and Germany.
US and Brazil are the top world producer of ethanol, together they produce 70% of the world’s total ethanol. But Brazil is the largest exporter of ethanol while US is a net importer.
Top Biofuel Feed Stocks
Globally, biofuels are most commonly used to generate energy to run vehicles and generate heat for homes and for cooking. Biofuel industries are gaining enthusiasm due to their cleaner and renewable nature as source of energy, amidst a concerted global effort to combat climate change. There are three categories of feedstock, namely the first, second and third generations feedstock. Traditional or first generation feedstock are coincidentally food crops like maize, corn, sugarcane, oil palm and rapeseed/canola.
There are two common methodologies. One involves the yeast-aided fermentation of feedstock high in sugar or starch (sugar cane, maize, corn, sweet sorghum or starch ) to produce ethanol.
The second is to extract oil from oil crops ( oil palm, soybean, algae, jatropha), reduce their viscosity by heat and burned directly in a diesel engine, or they can be chemically processed via transesterification (with sodium hydroxide as catalyst ) to produce fuels such as biodiesel. Biodiesel is the most common biofuel in Europe.
Sugar Cane
Major cultivation region: Brazil
Brazil is the leader in sugarcane ethanol fuel and the largest exporter of ethanol. Ethanol is an excellent substitute for gasoline, the main car fuel used around the globe. Most of Brazil’s sugarcane plantations are on pasture lands, and rain-fed, making it the world’s most efficient producer of sugarcane. Energy from sugarcane ethanol generates 8.3 times more energy per hectare than corn ethanol. A report released by Oxfam in 2008 concluded Brazilian sugarcane ethanol though “far from perfect” is the most favorable biofuel in the world in term of cost and GHG emissions.
Corn, which is the biggest ethanol crop in the United States, is not considered very efficient, because the energy gain from producing corn-based ethanol is relatively low. By comparison, crops like sugar cane, jatropha, and palm oil are considered more efficient in terms of net energy gain.
The search for a more viable feedstock to produce feedstock with higher sugar content is going on fervently so as to increase the viability of the biofuel projects.
The University of Illinois has succeeded in identifying and trial planting a type of tropical maize. It is very lush, tall and full of sugar in its stems. Trials also show that tropical maize requires much less nitrogen fertilizer than conventional corn, and that the stalks actually accumulate more sugar when less nitrogen is available. Nitrogen fertilizer is one of major costs of growing corn. The release of nitrous oxide from its usage will cause global warming effect as it is one of the greenhouse gases.
Tropical maize grows taller than traditional corn and requires less nitrogen fertilizer.
Photo Origin: Marilyn Upah-Bant/University of Illinois
Earless Corn could have enormous impact on US ethanol
Rapeseed / Canola
Major cultivation regions are EU, China, Canada and India. In Europe, rapeseed accounts for 80% of biofuel production. Though not a food crop, cultivation needs fertilizers and good soils. Concerns of rapeseed as biofuel producing up to 70% more greenhouse gas than fossil fuels were raised. Findings by the University of Edinburgh show increased levels of nitrous oxide emissions from use of fertilizers. It also illustrated the importance of ensuring that measures designed to reduce greenhouse gas emissions were assessed thoroughly before being hailed as a solution feedstock
Major cultivation regions: Indonesia, Malaysia.
Palm oil has a relatively high energy output. Palm oil based biofuel provides a high quality fuel blend with fossil fuels such as petroleum to help meet the growing renewable energy demand from developed countries like the European Union.
The residual biomass are normally recycled to fuel extraction process. Use of palm oil as biofuel will unavoidably increase its price as a staple food in Southeast Asia.
Once a favorite in the Netherlands as a source of biofuel, but there is currently a call to review the clean development mechanism (CDM) project assessments related to its use.
Scientists studied activities at palm plantations in Indonesia and Malaysia discovered extensive deforestation and excessive use of chemical fertilizers due to increase in demand for palm oil. Lands for the expanding palm plantations was often created by draining and burning peat land, which sent huge amounts of carbon emissions into the atmosphere. They doubt that, in the quest for greater agriculture output, if there is definite greenhouse gas reduction benefits along the entire life cycle of the feedstock.
Advantages of biofuel over fossil fuel:
- It comes from a renewable resource against a finite resource.
- Raw materials, the crops, can be grown easily and thus easily obtainable.
- The fuel crops absorb the carbon dioxide in the air, thus reducing the net carbon dioxide emitted during the ethanol combustion on road use.
- Blending ethanol with gasoline helps to ease pressure on the ever depleting gasoline supplies and ensure greater energy security, avoiding heavy reliance on oil producing nations.
- Bioethanol is biodegradable and far less toxic than fossil fuels.
- Need of energy crops may help to boost the agriculture industries provided no deforestation is involved.
- By blending ethanol with gasoline, the fuel mixture combust more completely and reduces polluting emissions, improving vehicle performance.
Environmental Impacts and Drawbacks of Bioethanol as Biofuel
A study by Nobel Prize winner Paul Crutzen found ethanol produced from corn, and sugarcane had a “net climate warming” effect. Two researches published in early 2008, from the University of Minnesota, and the Princeton University, found that biofuels produced by fermenting plant-derived sugars to ethanol (termed First Generation Biofuel) have many limitations:
- The most significant being such production may actually produce more carbon dioxide emissions than they save. Clearing forests, peat lands, and grasslands for biofuel crops will release carbon back to the atmosphere to cause greenhouse warming as these plants are nature’s means of carbon capture.
- Since fermentation requires food crops such as sugar cane, corn, maize, wheat, sugar beet, chances of food shortage and food security will rise.
- Food crop cultivation involves energy-intensive sowing, harvesting, fertilizing and distributing and generates almost as much carbon dioxide as is being saved, and affecting water resource.
- They are not cost competitive relative to fossil fuels after the spike in food prices in 2007 – 2008 and the subsequent crude oil price plunge.
Environmentalist P. Jensen voiced his opinion of the proper production of biofuels which depends very much on the types of plants and how they’re grown and processed. You can end up with a 90% reduction compared to fossil fuels — or a 20% increase. “It’s important to take a life-cycle view,” and not to “just see what the effects are here in Europe.”
Until recently, European governments had sought to lead the rest of the world in the use of biofuels, aiming to derive 10% of Europe’s transportation fuels from biofuels by 2020. But the allure has dimmed amid growing evidence that the kind of goals proposed by the European Union are contributing to deforestation, which speeds climate change, and helping force up food prices.
Britain, one of the biggest proponents of increased biofuel use, will adopt a more cautious approach and slow down the introduction of biofuels, until the evidence is clearer on environmental and social effects of biofuels, said Ruth Kelly, the British transport minister. (NYTimes July 2008)
Meanwhile, advocates of biofuel look forward to Second-Generation Biofuel for long term success. Scientists are developing technology to use inedible cellulose fibers. Currently the cost to produce cellulosic ethanol is too high to be viable.
The director of the Lawrence Berkeley National Laboratory and a 1997 co-recipient of the Nobel Prize in Physics, Steven Chu, has strongly advocated research into solar power and advanced biomass, in particular biofuels made from grasses which won’t compete for space with farmland. Chu has criticized corn-based ethanol. Chu is now President Obama’s secretary of energy.