Renewable fuels

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Renewable fuels are fuels produced from renewable resources. Examples include: biofuels (e.g. Vegetable oil used as fuel, ethanol, methanol from clean energy and carbon dioxide [1] or biomass, and biodiesel), Hydrogen fuel (when produced with renewable processes), and fully synthetic fuel (also known as electrofuel) produced from ambient carbon dioxide and water. This is in contrast to non-renewable fuels such as natural gas, LPG (propane), petroleum and other fossil fuels and nuclear energy. Renewable fuels can include fuels that are synthesized from renewable energy sources, such as wind and solar. Renewable fuels have gained in popularity due to their sustainability, low contributions to the carbon cycle, and in some cases lower amounts of greenhouse gases. The geo-political ramifications of these fuels are also of interest, particularly to industrialized economies which desire independence from Middle Eastern oil.

Contents

Rationale for renewable fuels

The International Energy Agency's World Energy Outlook 2006 concludes that rising oil demand, if left unchecked, would accentuate the consuming countries' vulnerability to a severe supply disruption and resulting price shock. Renewable biofuels for transport represent a key source of diversification from petroleum products. Biofuels from grain and beet in temperate regions have a part to play, but they are relatively expensive and their energy efficiency and CO2 savings benefits, are variable. Biofuels from sugar cane and other highly productive tropical crops are much more competitive and beneficial. But all first generation biofuels ultimately compete with food production for land, water, and other resources. Greater efforts are required to develop and commercialize second generation biofuel technologies, such as biorefineries and ligno-cellulosics, enabling the flexible production of biofuels and other products from non-edible plant materials. [2]

Hubbert's peak oil theory suggests that petroleum is a finite resource that is rapidly depleting. Of the worldwide total remaining petroleum reserves of approximately 1,277,702,000,000 barrels (203.1384 km3) (about one half of the original virgin reserves) and a worldwide usage rate of 25,000,000,000 barrels (4.0 km3) per year, only about 50 years worth of petroleum is predicted to remain at the current depletion rate. Petroleum is imperative for the following industries: fuel (home heating, jet fuel, gasoline, diesel, etc.) transportation, agriculture, pharmaceutical, plastics/resins, man-made fibers, synthetic rubber, and explosives. If the modern world remains reliant on petroleum as a source of energy, the price of crude oil could increase markedly, destabilizing economies worldwide. Consequently, renewable fuel drivers include: high oil prices, imbalance of trade, instability in oil exporting regions of the world, the Energy Policy Act of 2005, the potential for windfall profits for American farmers and industries, avoidance of economic depression, avoidance of scarcity of products due to a volatile ‘peak oil’ scenario expected to begin as early as 2021, [3] (though peak oil is not a new idea) and a slowing of global warming that may usher in unprecedented climate change.

Furthermore, the conclusion that anthropogenic greenhouse gas emissions are causing climate change, along with regional geopolitical instabilities have challenged nations to act to develop both alternative and carbon-neutral sources of energy. Renewable fuels are therefore becoming attractive to many governments, who are beginning to see sustainable energy independence as a valuable asset.

On December 19, 2007, President Bush signed into law the Energy Independence and Security Act, establishing a requirement that at least 36 billion US gallons (140,000,000 m3) of renewable fuel be used in the marketplace by 2022. [4]

According to the International Energy Agency (IEA), cellulosic ethanol commercialization could allow ethanol fuels to play a much larger role in the future than previously thought. [5] Cellulosic ethanol can be made from plant matter composed primarily of inedible cellulose fibers that form the stems and branches of most plants. Dedicated energy crops, such as switchgrass, are also promising cellulose sources that can be produced in many regions of the United States. [6]

Biofuel

Information on pump regarding ethanol fuel blend up to 10%, California EthanolPetrol.jpg
Information on pump regarding ethanol fuel blend up to 10%, California
A bus fueled by biodiesel Soybeanbus.jpg
A bus fueled by biodiesel

Biofuel is a type of fuel whose energy is derived from biological carbon fixation. Biofuels include fuels derived from biomass conversion, as well as solid biomass, liquid fuels and various biogases. [7] Although fossil fuels have their origin in ancient carbon fixation, they are not considered biofuels by the generally accepted definition because they contain carbon that has been "out" of the carbon cycle for a very long time. Biofuels are gaining increased public and scientific attention, driven by factors such as oil price spikes, the need for increased energy security, concern over greenhouse gas emissions from fossil fuels, and support from government subsidies.

Bioethanol is an alcohol made by fermentation, mostly from carbohydrates produced in sugar or starch crops such as corn or sugar cane. Cellulosic biomass, derived from non-food sources such as trees and grasses, is also being developed as a feedstock for ethanol production. Ethanol can be used as a fuel for vehicles in its pure form, but it is usually used as a gasoline additive to increase octane and improve vehicle emissions. Bioethanol is widely used in the USA and in Brazil. Current plant design does not provide for converting the lignin portion of plant raw materials to fuel components by fermentation.

Biodiesel is made from vegetable oils and animal fats. Biodiesel can be used as a fuel for vehicles in its pure form, but it is usually used as a diesel additive to reduce levels of particulates, carbon monoxide, and hydrocarbons from diesel-powered vehicles. Biodiesel is produced from oils or fats using transesterification and is the most common biofuel in Europe.

In 2010 worldwide biofuel production reached 105 billion liters (28 billion gallons US), up 17% from 2009, and biofuels provided 2.7% of the world's fuels for road transport, a contribution largely made up of ethanol and biodiesel. [8] Global ethanol fuel production reached 86 billion liters (23 billion gallons US) in 2010, with the United States and Brazil as the world's top producers, accounting together for 90% of global production. The world's largest biodiesel producer is the European Union, accounting for 53% of all biodiesel production in 2010. [8] As of 2011, mandates for blending biofuels exist in 31 countries at the national level and in 29 states/provinces. [9] According to the International Energy Agency, biofuels have the potential to meet more than a quarter of world demand for transportation fuels by 2050. [10]

Pyrolysis oil is another type of fuel derived from the lignocellulosic fraction of biomass. By rapidly heating biomass in the absence of oxygen (pyrolysis), a liquid crude can be formed that can be further processed into a usable bio-oil. As opposed to other biofuels, pyrolysis oils use the non-edible fraction of biomass and can occur on the order of milliseconds and without the need for large fermentation reactors. [11]

Hydrogen fuel

Hydrogen fuel requires the development of a specific infrastructure for processing, transport and storage. Photo praxair plant.hydrogen.infrastructure.jpg
Hydrogen fuel requires the development of a specific infrastructure for processing, transport and storage.

Hydrogen fuel refers to the use of hydrogen gas (H2) as an energy carrier. Broadly speaking, the production of renewable hydrogen fuel can be divided into two general categories: biologically derived production, and chemical production. [12] This is an area of current research, and new developments and technologies are causing this field to evolve rapidly.

The biological production of hydrogen fuel has been a topic of research since at least the 1970s. Hydrogen gas can be produced from biomass sources like agricultural and forest residues, consumer waste, and other specific agricultural crops. [12] Specifically, hydrogen fuel is produced by a process called gasification, where biomass is processed into combustible gas and then burned, or by pyrolysis, a related process which can lead to hydrogen gas suitable for fuel-cell applications. One continuing subject of research regards the production of unwanted co-products in both of these processes. The presence of other contaminant gases often depends on the specific composition of the biomass source, which can be difficult to control. [12] Another source for biological production of hydrogen fuel is algae. In the late 1990s, it was discovered that if algae are deprived of sulfur they will switch from the production of oxygen, as in normal photosynthesis, to the production of hydrogen. [13] Experimental algae farms are attempting to make algae an economically feasible energy source. [14]

There are also several physico-chemical methods for producing hydrogen; most of these methods require electrolysis of water. When this process draws its power from renewable energy sources like wind turbines or photovoltaic cells, the production requires little consumption of non-renewable resources. Hydrogen fuel, when produced by renewable sources of energy like wind or solar power, is a renewable fuel [12] known as green hydrogen.

Synthetic fuel (electrofuel)

Electrofuels, also known as e-fuels or synthetic fuels, are a type of drop-in replacement fuel. They are manufactured using captured carbon dioxide or carbon monoxide, together with hydrogen obtained from sustainable electricity sources such as wind, solar and nuclear power.

The process uses carbon dioxide in manufacturing and releases around the same amount of carbon dioxide into the air when the fuel is burned, for an overall low carbon footprint. Electrofuels are thus an option for reducing greenhouse gas emissions from transport, particularly for long-distance freight, marine, and air transport. Several emerging companies are developing products in this space, including British company Zero, which is building a development production plant at Bicester Heritage near Oxford.

Processed engineered fuel

Processed engineered fuel (PEF)[ clarification needed ] is a partial replacement for fossil fuels in cement kilns. It has significant calorific value and can be used as a fuel substitute for coal and gas in high-combustion facilities. PEF facilities typically divert waste from landfill, reducing demand for non-renewable coal and reducing waste to landfill.[ citation needed ]

See also

Related Research Articles

<span class="mw-page-title-main">Biofuel</span> Type of biological fuel

Biofuel is a fuel that is produced over a short time span from biomass, rather than by the very slow natural processes involved in the formation of fossil fuels such as oil. Biofuel can be produced from plants or from agricultural, domestic or industrial biowaste. Biofuels are mostly used for transportation, but can also be used for heating and electricity. Biofuels are regarded as a renewable energy source. The use of biofuel has been subject to criticism regarding the "food vs fuel" debate, varied assessments of their sustainability, and possible deforestation and biodiversity loss as a result of biofuel production.

<span class="mw-page-title-main">Biodiesel</span> Fuel made from vegetable oils or animal fats

Biodiesel is a renewable biofuel, a form of diesel fuel, derived from biological sources like vegetable oils, animal fats, or recycled greases, and consisting of long-chain fatty acid esters. It is typically made from fats.

<span class="mw-page-title-main">Ethanol fuel</span> Type of biofuel

Ethanol fuel is fuel containing ethyl alcohol, the same type of alcohol as found in alcoholic beverages. It is most often used as a motor fuel, mainly as a biofuel additive for gasoline.

<span class="mw-page-title-main">Alternative fuel</span> Fuels from sources other than fossil fuels

Alternative fuels, also known as non-conventional and advanced fuels, are fuels derived from sources other than petroleum. Alternative fuels include gaseous fossil fuels like propane, natural gas, methane, and ammonia; biofuels like biodiesel, bioalcohol, and refuse-derived fuel; and other renewable fuels like hydrogen and electricity.

Cellulosic ethanol is ethanol produced from cellulose rather than from the plant's seeds or fruit. It can be produced from grasses, wood, algae, or other plants. It is generally discussed for use as a biofuel. The carbon dioxide that plants absorb as they grow offsets some of the carbon dioxide emitted when ethanol made from them is burned, so cellulosic ethanol fuel has the potential to have a lower carbon footprint than fossil fuels.

<span class="mw-page-title-main">Bioenergy</span> Renewable energy made from biomass

Bioenergy is a type of renewable energy that is derived from plants and animal waste. The biomass that is used as input materials consists of recently living organisms, mainly plants. Thus, fossil fuels are not regarded as biomass under this definition. Types of biomass commonly used for bioenergy include wood, food crops such as corn, energy crops and waste from forests, yards, or farms.

<span class="mw-page-title-main">Synthetic fuel</span> Fuel from carbon monoxide and hydrogen

Synthetic fuel or synfuel is a liquid fuel, or sometimes gaseous fuel, obtained from syngas, a mixture of carbon monoxide and hydrogen, in which the syngas was derived from gasification of solid feedstocks such as coal or biomass or by reforming of natural gas.

<span class="mw-page-title-main">Biomass to liquid</span>

Biomass to liquid is a multi-step process of producing synthetic hydrocarbon fuels made from biomass via a thermochemical route.

Pyrolysis oil, sometimes also known as biocrude or bio-oil, is a synthetic fuel with few industrial application and under investigation as substitute for petroleum. It is obtained by heating dried biomass without oxygen in a reactor at a temperature of about 500 °C (900 °F) with subsequent cooling, separation from the aqueous phase and other processes. Pyrolysis oil is a kind of tar and normally contains levels of oxygen too high to be considered a pure hydrocarbon. This high oxygen content results in non-volatility, corrosiveness, partial miscibility with fossil fuels, thermal instability, and a tendency to polymerize when exposed to air. As such, it is distinctly different from petroleum products. Removing oxygen from bio-oil or nitrogen from algal bio-oil is known as upgrading.

The United States produces mainly biodiesel and ethanol fuel, which uses corn as the main feedstock. The US is the world's largest producer of ethanol, having produced nearly 16 billion gallons in 2017 alone. The United States, together with Brazil accounted for 85 percent of all ethanol production, with total world production of 27.05 billion gallons. Biodiesel is commercially available in most oilseed-producing states. As of 2005, it was somewhat more expensive than fossil diesel, though it is still commonly produced in relatively small quantities, in comparison to petroleum products and ethanol fuel.

Biofuel is fuel that is produced from organic matter (biomass), including plant materials and animal waste. It is considered a renewable source of energy that can assist in reducing carbon emissions. The two main types of biofuel currently being produced in Australia are biodiesel and bioethanol, used as replacements for diesel and petrol (gasoline) respectively. As of 2017 Australia is a relatively small producer of biofuels, accounting for 0.2% of world bioethanol production and 0.1% of world biodiesel production.

Second-generation biofuels, also known as advanced biofuels, are fuels that can be manufactured from various types of non-food biomass. Biomass in this context means plant materials and animal waste used especially as a source of fuel.

<span class="mw-page-title-main">Algae fuel</span> Use of algae as a source of energy-rich oils

Algae fuel, algal biofuel, or algal oil is an alternative to liquid fossil fuels that uses algae as its source of energy-rich oils. Also, algae fuels are an alternative to commonly known biofuel sources, such as corn and sugarcane. When made from seaweed (macroalgae) it can be known as seaweed fuel or seaweed oil.

Biogasoline is a type of gasoline produced from biomass such as algae. Like traditionally produced gasoline, it is made up of hydrocarbons with 6 (hexane) to 12 (dodecane) carbon atoms per molecule and can be used in internal combustion engines. However, unlike traditional gasoline/petroleum based fuels, which are mainly composed from oil, biogasolines are made from plants such as beets and sugarcane or cellulosic biomass- substances normally referred to as plant waste.

<span class="mw-page-title-main">Aviation biofuel</span> Sustainable fuel used to power aircraft

An aviation biofuel is a biofuel used to power aircraft and is a sustainable aviation fuel (SAF). The International Air Transport Association (IATA) considers it a key element in reducing the environmental impact of aviation. Aviation biofuel is used to decarbonize medium and long-haul air travel. These types of travel generate the most emissions, and could extend the life of older aircraft types by lowering their carbon footprint. Synthetic paraffinic kerosene (SPK) refers to any non-petroleum-based fuel designed to replace kerosene jet fuel, which is often, but not always, made from biomass.

<span class="mw-page-title-main">Biofuels by region</span> Use of biofuel as energy source across the world

The use of biofuels varies by region. The world leaders in biofuel development and use are Brazil, United States, France, Sweden and Germany.

United States policy in regard to biofuels, such as ethanol fuel and biodiesel, began in the early 1990s as the government began looking more intensely at biofuels as a way to reduce dependence on foreign oil and increase the nation's overall sustainability. Since then, biofuel policies have been refined, focused on getting the most efficient fuels commercially available, creating fuels that can compete with petroleum-based fuels, and ensuring that the agricultural industry can support and sustain the use of biofuels.

<span class="mw-page-title-main">Electrofuel</span> Carbon-neutral drop-in replacement fuel

Electrofuels, also known as e-fuels, a class of synthetic fuels, are a type of drop-in replacement fuel. They are manufactured using captured carbon dioxide or carbon monoxide, together with hydrogen obtained from water split by low-carbon electricity sources such as wind, solar and nuclear power.

Carbon-neutral fuel is fuel which produces no net-greenhouse gas emissions or carbon footprint. In practice, this usually means fuels that are made using carbon dioxide (CO2) as a feedstock. Proposed carbon-neutral fuels can broadly be grouped into synthetic fuels, which are made by chemically hydrogenating carbon dioxide, and biofuels, which are produced using natural CO2-consuming processes like photosynthesis.

References

  1. ↑ "Technology". Carbon Recycling International. 2011. Archived from the original on 2013-06-17. Retrieved 2012-07-11.
  2. ↑ Contribution of Renewables to Energy Security
  3. ↑ Biomass for biofuel isn't worth it
  4. ↑ Issue Update: Renewable Fuels Retailer Liability
  5. ↑ International Energy Agency (2006). World Energy Outlook 2006 Archived 2007-09-28 at the Wayback Machine p. 8.
  6. ↑ Biotechnology Industry Organization (2007). Industrial Biotechnology Is Revolutionizing the Production of Ethanol Transportation Fuel Archived 2006-02-12 at the Wayback Machine pp. 3-4.
  7. ↑ Demirbas, A. . (2009). "Political, economic and environmental impacts of biofuels: A review". Applied Energy. 86: S108–S117. doi:10.1016/j.apenergy.2009.04.036.
  8. 1 2 "Biofuels Make a Comeback Despite Tough Economy". Worldwatch Institute. 2011-08-31. Retrieved 2011-08-31.
  9. ↑ REN21 (2011). "Renewables 2011: Global Status Report" (PDF). pp. 13–14.{{cite web}}: CS1 maint: numeric names: authors list (link)
  10. ↑ "IEA says biofuels can displace 27% of transportation fuels by 2050 Washington". Platts. 20 April 2011.
  11. ↑ Huber, George (2007). "Breaking the Chemical and Engineering Barriers to Lignocellulosic Biofuels: Next Generation Hydrocarbon Biorefineries".{{cite journal}}: Cite journal requires |journal= (help)
  12. 1 2 3 4 New Horizons for Hydrogen (PDF), National Renewable Energy Laboratory, 2003, archived from the original (PDF) on 2016-03-04
  13. ↑ Wired, It Came from the Swamp: Reengineering Algae To Fuel The Hydrogen Economy, accessed September 17, 2007.
  14. ↑ The Register, Pond life: the future of energy, accessed September 17, 2007.
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