Effect of Biodiesel in ignition delay and levels of NOx emitted

Biodiesels have generally been found to exhibit a shorter duration of ignition delay (the interval between fuel injection and autoignition).

An increase in the fatty acid ester alcohol moiety alkyl chain length can reduce the duration of ignition delay, while the presence of carbon chain branches in the alcohol moiety can increase the duration ignition.

However, the impact of the alcohol moiety on ignition delay is less than the fatty acid moiety, and so where a specific ignition delay of a biodiesel is required, this is best achieved through modification of the fatty acid profile.

In direct injection common rail compression ignition combustion, the primary influence of the biodiesel composition on the levels of NOx emitted is through the duration of ignition delay.

Longer ignition delays result in a larger premixed burn fraction and peak heat release rates, which increase the rates of thermal NOx production.

In mechanically actuated fuel injection, biodiesel bulk modulus, which increases with alkyl chain length and degree of unsaturation, has a significant influence on the time at which fuel injection commences and thus the residence time of in-cylinder gases at elevated temperatures at which NOx formation occurs.

Therefore, it be may be advantageous to utilize different biodiesels of compositions optimized for lower NOx emissions in common rail and mechanical fuel systems respectively.

Making biodiesel with used cooking oil and a microwave

Using a microwave and catalyst-coated beads, scientists have devised a new way to convert waste cooking oil into biodiesel that could make it more affordable. They report how they did it in ACS' journal Energy & Fuels.

Biodiesel has many advantages over traditional fuels. It is renewable, biodegradable and emits less carbon dioxide. It can also easily take the place of conventional diesel without the need for carmakers to modify engines. However, producing biodiesel at a low cost remains a challenge. Waste cooking oil is currently the most appealing source because it doesn't compete with the demand for virgin cooking oil. However, the process to convert it to fuel is complicated and expensive.

The researchers developed silica beads coated with a catalyst and added them to waste cooking oil. Then, they zapped the mixture with a modified microwave oven to spur the reaction of the beads with cooking oil. In just 10 seconds, nearly 100 percent of the oil was converted to fuel. The researchers could also easily recover the beads and reuse them at least 10 times with similar results.

MacroFuels – Third Generation Biofuels from Seaweed

In the last decade, seaweed has received increasing interest worldwide as potential source of advanced biofuels production, which has resulted in a considerable attention from research, industry and policy makers. However, no large-scale, commercial algae-to-biofuels facilities had yet been implemented by the end of 2015.  Over the next four years experts from six European countries will concert their efforts to achieve breakthroughs towards the commercially viable production of third-generation biofuels from seaweed or macro-algae. In their efforts they will be financially supported by the European Commission who funds the MacroFuels project with 6 million Euros from their Research and Innovation programme ‘Horizon 2020’.

While current biofuels compete for scarce cropland, fresh water, and fertilizers, seaweed does not need fresh water, arable land or fertilizers to grow. In addition, seaweed beds can serve as a significant CO2 sink resulting in environmental benefits of seaweed derived biofuels and high value co-products.For improved cultivation MacroFuels will use 2D substrates based on advanced textiles to facilitate open sea cultivation. These patented and award winning substrates have been developed in the previous project (funded by the European Union under FP7) with the participation of several MacroFuels partners, and yield 3-5 times more biomass than state of the art 1D rope based systems. A rotating crops technology in combination with advanced textiles will further increase the biomass per area yield.

MacroFuels will achieve the following urgently needed technological and process-oriented breakthroughs which will make it possible for seaweed-derived biofuels to eventually compete favourably with fossil or older generation equivalent fuels.

·    Improve the efficiency of the seaweed-to-biofuels conversion technologies, which are currently in their infancy.

·   Vital breakthroughs in terms of pre-treatment and bioconversion of algae sugar to ethanol and butanol as well as thermal chemical conversion to furanics based biofuels. Significant efficiency improvements will be made by reducing the water through chemical and enzyme usage in the pre-treatment steps. Water reduction of more than 50% and total elimination of process steps will be achieved.

·      Quadruple the output on the same amount of substrate while decreasing the production cost of the seaweed raw material by a factor 10.

·  Creation of about 15,000 jobs based on the EU target of 2.5% biofuels which corresponds to 5000 km of cultivated seaweed area.

Hazards associated with biodiesel production

Regardless of the scale of operation of a biodiesel plant the hazards are the same: a combination of flammable, toxic and corrosion hazards depending on the stage of the process. In particular:

Methanol

This is a highly flammable and toxic liquid. It will freely burn in the open air or explode if confined in a vessel or room and ignited. Whilst all precautions should be taken to avoid leaks of flammable vapors into the workroom, leaks and spillages may still occur and it is necessary to take further precautions to reduce the likelihood of their ignition. In areas where such materials are handled, companies are required to identify the areas where flam­mable atmospheres may exist, for example due to a leak, and determine their likely extent. Such areas are classed as hazardous and should be classified into zones, depending upon the likelihood of their occurrence. In such areas ignition sources such as naked flames should be excluded and only suitably protected electrical equipment should be used. It should be noted that the presence of metha­nol can also render the product and any waste materials flammable, depending upon the way the biodiesel is manufactured.

The catalyst

Most of the catalysts used for biodiesel production are corrosive and some of them are violently water reactive, toxic, explosive and highly corrosive.

Feedstock oil

If clean and pure it should not be a health problem. However, if the source is unknown or of doubtful quality, then it should be treated as contaminated. Oils are a serious slipping hazard if spillage or contamination outside sealed vessels occurs. Oils can seep into lagging and many can self-combust following a period of chemical degradation. All oils are combustible and will add fuel to any developing fire.

Glycerol

This material is combustible (with a flash-point of 160°C). However, it may be contaminated with methanol and caustic, with their associated hazards, including a potential reduction in flash-point. Unless the initial by-product quality is reliably monitored, then prudence dictates that it should be regarded as contaminated until it has been suitably purified.

Biodiesel

If certified to EN 14241 : 2003  it may be regarded as combustible (its flash-point is approximately 150°C). It has rather unusual solvent properties, and will attack some common engineering polymers, including polyvinyl, natural rubber, some gasket and hose materials and metals, including copper, tin and zinc5. The effect can increase with heating and ageing of the biodiesel. It is also hygroscopic, and can absorb up to 1500 ppm water from the air. If even slightly contaminated with acid or alkali, biodiesel may be hydrolyzed to fatty acids and methanol. This reaction also occurs more slowly in the absence of water, so material stored for more than a couple of weeks may show evidence of a different flash­point than anticipated (which may be significantly lower). Unless this can be reliably prevented, then the product should be used as quickly as possible after production, or reclas­sified and stored and handled accordingly.

Wash water

This may be contaminated with acid, alkali and methanol. It should be treated as corrosive, toxic and flammable unless tests determine otherwise.

Reaction hazards

The main reaction hazards identified are in the preparation of the base catalyst, which can be by one or more of the following methods:

- The direct addition of sodium or potassium to methanol: this reaction is very exothermic and should be the subject of a rigorous risk assessment, particularly as molten sodium is spontaneously combustible in air and the reaction produces hydrogen as a by-product. Fortunately this route is not generally available to smaller/domestic producers.

- The addition of dried hydroxide or methoxide to methanol which is also very exother­mic (heat of dilution)

A much gentler heat of reaction is produced if the catalyst is supplied in methanol solution (although this has to be manufactured safely elsewhere), and further diluted to the required strength on plant. This is normally the preferred option for smaller companies.

A further reaction hazard occurs when concentrated mineral acid is mixed with water. Addition of water to acids often results in violent boiling and ejection of the acid from vessels. Acids should be added slowly to water with cooling and agitation.

  

General hazards

These include:

- Corrosion of processing equipment, building fabric, and supporting structures through exposure to caustic and acids leading to premature weakening and catastrophic failure. A by-product of the corrosion process is hydrogen,

- Biodiesel can soften and dissolve a variety of polymers commonly used in safety equipment, such as plastic aprons and rubber boots, causing premature failure.

Sodium Methylate as a catalyst for biodiesel industry

Growth in the biodiesel market is spurring two small companies to invest in U.S. production of sodium methylate, a catalyst used to convert fats and oils into the renewable fuel. These Davids will be going up against two biodiesel catalyst Goliaths, the German chemical makers BASF and Evonik Industries.

New Heaven Chemicals is starting up a plant in Manly, Iowa, that will make 18,000 metric tons per year of sodium methylate for biodiesel industry customers. Prasad Devineni, the firm’s director, says the plant is being commissioned and should be running in the next few weeks.

Although New Heaven will be new to U.S. production, its parent company, India’s TSS Group, has been importing sodium methylate from Saudi Arabia since 2006, Devineni notes. New Heaven anticipates building a second, similarly sized, sodium methylate plant in Houston.

Meanwhile, Interstate Chemical is advancing plans to produce sodium methylate in Erie, Pa., to serve customers such as the nearby firm Hero BX, which calls itself the largest biodiesel maker east of the Mississippi.

Interstate says it will spend $60 million to build plants for sodium methylate and methanol, the latter of which is reacted with sodium hydroxide to make the catalyst. Interstate has been producing sodium methylate for close to 10 years using an older process that starts with sodium metal. The firm’s plan to invest in the newer route follows DuPont’s decision to close its sodium facility in Niagara Falls, N.Y.

U.S. biodiesel consumption has enjoyed a meteoric rise from less than 100 million L in 2004 to almost 8 billion L in 2015, according to the National Biodiesel Board. During those years, Evonik erected sodium methylate plants in Alabama and Argentina. BASF built in Argentina and Brazil.

However, the years ahead may not be as heady for the catalyst newcomers. U.S. imports of biodiesel are on the increase. And a growing portion of biodiesel is so-called renewable diesel, which is made via a hydrotreating process that doesn’t require sodium methylate.

Algae biomass in EU

Meanwhile, 100 EU algae stakeholders are preparing to release a white paper, “European Roadmap for an Algae-Based Industry”, after a meeting co-organised by the European Algae Biomass Association, Miracles, FUEL4ME, Splash and the Algae Cluster (InteSusAl, BIOFAT and All-gas).

The White Paper will note:

• Further developments should be product driven. The development of marketable algae-based products is important for industrialization of the area.

• Algal strains should be further industrialized as sustainable green cell factories via strain improvement programs, allowing both GMO and non-GMO strategies.

• Advances in regulatory and standardization issues have been developed but still barriers remain for final applications of microalgae based products.

• More demonstration projects for specific markets at a production size of approximately 5 ha should be developed to push the field.

• Technological bottlenecks such as fouling and culture contamination need to be solved.

• Harmonisation is needed in terms of measurements and unit expression.

• Collaboration between algal and other industries should be enabled.

• Industrial and academic collaboration, education, communication to a wider audience about sustainability of the technology, consumers’ acceptance and legislation about products with algae inside need to be stimulated.

The EU partners also noted that developments of the last years in the algal field have been significant. Operational pilot and demonstration scale production facilities of up to 1 ha have been realized. The knowledge on fundamental biology develops rapidly, the technology for production matures and biorefineries that process algal biomass into multiple high quality products have been implemented.

The continued interest in advanced algae has produced numerous exciting technical advances on the laboratory, pilot and demonstration scales. However, attempts to translate these small scale successes into commercial technologies have been less successful. It is easy to blame lower oil and natural gas prices and opposition from special interest groups. However, nearly all commercialization projects have yet to produce significant quantities of algae on a continuing basis.

Algae needs a lot of water to live in and to make biomass with, but overwhelmingly its the habitat requirement that drives up the costs. If a 30-centimeter deep pond is producing 25 grams of algae per day, the algae are living inside 333 kilos of water.

Mainstream strategies to enhance agitation efficiency during transesterification process

Conventionally, biodiesel is produced through the agitation of the reagents, i.e., oil, alcohol (mainly methanol), and catalyst at about 60 ^oC (just below the boiling point of methanol i.e. 64.7 ^oC) for about 1 h.

Currently, the majority of industrial biodiesel production practices worldwide are batch or continuous processes with mechanical agitation. However, since oil and alcohol are not well miscible, mixing efficiency is therefore the main challenge faced.

The most efficient mixing is achieved when the alcohol–oil interfacial area is maximized by decreasing the droplet size of the reactants i.e. alcohol and oil as much as possible. Theoretically, this could be as low as the sizes of the molecules involved in the reaction. Therefore, both the agitation and temperature are indispensable elements required to accomplish a successful transesterification reaction.

Numerous attempts have been made to enhance agitation efficiency including chemical and/or mechanical strategies:

- Chemical strategies used to enhance agitation efficiency, involve the use of a co-solvent in order to achieve a single phase of alcohol-oil. The co-solvents used should:

1) be completely miscible in both the alcohol and oil and

2) have a boiling point close to that of the alcohol used e.g., methanol so that they could be easily , co-distilled and recovered/recycled upon the termination of the reaction. Cyclic ethers such as tetrahydrofuran (THF), 1,4-dioxane, diethyl ether, methyl tertiary butyl ether, and diisopropyl ether, owing to their hydrophilic oxygen atom capable of forming hydrogen bonds with alcohols, and their hydrophobic hydrocarbon portion capable of solubilizing oils, meet the first condition required for an ideal co-solvent. Having included the second condition, THF (boiling point: 66 oC) is regarded as the most ideal co-solvent especially if methanol is used in the transesterification reaction.

- Mechanical strategies used to enhance agitation efficiency fall into three different categories:

1) Improving the conventional impeller agitation systems.

2) Application of non-impeller novel agitation systems in which highly efficient mechanical energy is provided for mixing and initiating the transesterification reaction. These include ultrasound-based agitation systems, e.g., ultrasonic cavitation reactor, high frequency magnetic impulse cavitation reactor, static mixers, oscillatory flow reactors, and spinning tube in tube reactors.

3) application of novel systems in which no agitation is applied but conditions required for a successful transesterification are provided. These include microwave reactors which utilize microwave irradiation to transfer energy directly into reactants and consequently accelerate the rate of reaction and membrane reactors. In fact, the latter integrates reaction and membrane-based separation into a single process and increase the rate of equilibrium-limited transesterification reaction by constantly removing the products i.e. biodiesel from the reactants stream via membranes.

It is worth quoting that the final characteristics of biodiesel could be influenced by the procedure through which the fuel has been produced.