Biodiesel: The Ultimate Solution to Emission of Greenhouse Gases in Ship Engines
Ships are among the biggest climate sinners. Polluting the atmosphere with millions of tons of combusted marine diesel. The shipping industry emits about one billion metric tons of carbon dioxide worldwide per year.
According to new research led by the University of Washington, the first to measure this phenomenon’s effect over years and at a regional scale. Satellite data from a shipping lane in the South Atlantic suggest that ships alter clouds to block an additional 2 watts of solar energy on average from reaching near the shipping lane per square meter of the ocean surface.
A previous study reported that shipping emissions are responsible globally for about 400,000 lung cancer and cardiovascular disease premature deaths and 14 million cases of childhood asthma per year. One of the numerous possible ways on the reduction of greenhouse gas (GHG) emissions from ships is to use biodiesel or biofuel blends.
Challenges of Biofuel
If condensed water accumulates biodiesel fuel, bacteria and mould can develop. Microbial production contributes to excessive sludge formation, clogged filters and piping. The Microbial growth can be reduced or mitigated due to frequent tank drainage and the application of biocide in the tanks.
2. Oxygen degradation
Biodiesel can degrade over time, forming contaminants of polymers, and other insoluble. Deposits in piping and engines could form, compromising operational performance. In advanced phases, this could lead to increased in advanced phases, the acidity of the gasoline which may cause corrosion in the fuel system and accumulation of deposits in pumps and injectors.
Therefore, it is recommended not to bunker the fuel for long-term storage before use but to treat the fuel as fresh products and to use it within a relatively short period of time. At an early stage, adding antioxidants to the fuel can boost a fuel’s ability. A slightly longer storage time without degradation.
3. Low temperature
The higher biodiesel concentration typically has a higher cloud point (depending on feedstock) than diesel. This leads to weak flow properties and clogging of filters at low temperature. It is therefore important to know the product’s cold flow properties. It will help to keep the storage and transfer temperatures above the cloud point.
This is the most important for higher concentrations of biodiesel (B80-B100). Some types of hoses and gaskets can degrade resulting in loss of integrity and contact with certain metal materials, such as copper, brass, lead, tin, Using zinc, etc. This could also contribute to increased deposit formation. It is, therefore, necessary to verify that these components are robust in the fuel system and can be used along with biofuel.
5. Possible degeneration of rubber sealings, gaskets and hoses
It is important to verify that these components in the fuel system are endurable and can be used together with biofuel.
Biodiesel has proven to have a solvent property. So it is anticipated that deposits in the fuel system would be flushed when converting from diesel to biofuel, clogging fuel filters. During this time, it is recommended to flush the system and/or control the filters.
Insufficient logistic support at ports for fuels not compatible with diesel type fuels.
Lack of long-term fuel test data to guarantee the safety and continued reliability of the selected fuel.
Alternate fuel for marine sector
More than 330 million tons of fuel per year is consumed by the shipping industry. Marine fuels are mainly derived from crude oil with the primary fuels used being Heavy Fuel Oil (HFO) and Marine Diesel Oil (MDO). In Emission control areas ( ECAs), higher quality distillate fuels are mainly used and are known as ULSD (Ultra Low Sulfur Diesel).
In North America and Europe, emission control areas have been established in coastal areas. These areas impose stringent limits on emissions of SOX, NOX, and particulate matter. To satisfy these requirements, ULSD or other low-polluting fuel substitutes or exhaust gas cleaning systems within ECAs must be used.
The following are alternatives to marine transport fuels that can play a key role in decarbonizing the shipping industry and eventually lead to the objectives of climate change.
1.Ultra-low-sulphur Diesel (ULSD) Fuel
ULSDs are very low sulphur content (15ppm mass basis) diesel fuels. Low sulphur residual fuel (LSRF) are diesel fuels that contain up to 500 ppm of sulphur at most.
The shipping industry and public agencies are exploring the potential for renewable bio-based fuels to be used to achieve their long-term sustainability objectives. In the event of a spill, biofuels produced from plants or organisms biodegrade rapidly, posing much less danger to the aquatic environment. It is versatile as they can be combined with traditional fossil fuels to power or serve as a substitute for conventional internal combustion engines.
a) Methanol and Biomethanol
By reforming the gas with steam, and then refining and distilling the resulting synthesized gas mixture to create pure methanol, methanol is primarily derived from natural gas. The result is a clear, liquid, organic chemical that is water-soluble and readily biodegradable.Biomethanol can also be made from black liquor in pulp and paper mills as a biofuel.
b) Dimethyl Ether – DME
DME (di-methyl ether) is a safe, high-density liquid fuel that can be used in power generation, transportation, heating, marine, and a wide range of other applications as a direct substitute for diesel fuel. It is non-carcinogenic, degrades rapidly in the atmosphere and is not a global warming agent. It does not sink to the water table and is not consumed by the soil. Accidental spills do not poison water.
c) Biodiesel or FAME
Methyl aster fatty acid (FAME) is produced by transesterification from vegetable oils, animal fats or waste cooking oils. Different oils (triglycerides) are converted into methyl esters. This is the industry’s most commonly available form of biodiesel and is often blended with standard marine diesel.
d) Hydrogen Derived Renewable Diesel – HDRD or HVO (hydrotreated vegetable oil)
Hydrogenation derived from renewable diesel (HDRD) or HVO is the product of blended fats or vegetable oils, alone or blended with petroleum refined through a method of hydrotreatment known as fatty acids-to-hydrocarbon hydrotreatment. To distinguish it from biodiesel, diesel-generated using this process is called renewable diesel.
e) Algae Biofuel
Algae diesel fuels are as safe as petroleum diesel fuel, but they have slightly lower heating values than fossil equivalents. These disadvantages are negated by mixing with petroleum diesel. So, the efficiency of the blended fuel compares favourably with petroleum diesel. Blending also decreases the standard diesel’s sulphur content to be diluted proportionally. There is almost no sulphur in algae fuel, so the SOx exhaust emissions are virtually zero. It must meet the petroleum diesel F-76 specifications when blended with 50% petroleum diesel. In terms of compatibility with the fuel system and engine components, it is considered to be a drop‐in fuel.
3. Gaseous Fuels
Not only are natural gaseous fuels very low in sulphur content but their combustion results in considerably lower NOx, PM and CO2 emissions compared to their liquid counterparts. The cost is usually generally 70% less than residual fuel and 85% less than distillate fuel.
It is possible to transport natural gas in a compressed state known as compressed natural gas ( CNG) or in a liquid state known as liquefied natural gas ( LNG).
a) Liquefied Propane Gas (LPG)
The general opinion around the world seems to be that LPG is a luxury commodity. Therefore, it is priced accordingly and relative to other alternative fuel options is too costly.
b) Biomethane – Bio LNG
Biomethane, which is biomass-generated methane, is an interesting fuel to promote the transition from fossil fuels to renewables and to fulfil the goals of reducing greenhouse gas emissions. There is a rising interest in using it in the shipping sector because it is chemically similar to fossil LNG. Also, it can benefit from the growing LNG infrastructure.
The most CO2-friendly fuel of all is commonly considered to be biomethane. Bio-LNG is of better quality than fossil LNG. It can be generated by upgrading biogas or by converting lignocellulosic biomass or other types of biomass thermo-chemically into bio-SNG.
Electrification, particularly for ship types with frequent load variations, has created strong interest. The shore-based electricity challenge for powering ships is linked to the energy density of batteries and other storage solutions, restricting the vessel’s range. In shipping, electrification can take two different forms: as a hybrid propulsion system or as a pure electric propulsion system.
5. Pyrolysis oil
Pyrolysis oil is a dark-brown liquid formed by a thermochemical process called fast pyrolysis from biomass. The biomass particles are heated, vaporized, and condensed into liquid in the absence of oxygen. The method is often referred to as flash pyrolysis as biomass is heated at about 500 ° C in the absence of oxygen with a very short retention time of usually less than 2 seconds.
Usually, 65-70% liquid bio-oil (dry feed base), 15-20% char (a black charcoal-like powder), and non-condensable gases are produced by the method. Pyrolysis-derived fuels have not yet been approved for use in marine diesel engines. But in other applications such as pulp mills, stationary diesel engines, power plants and industrial boilers, they may potentially replace residual oil, light fuel oil or natural gas.
6. Hydrogen and Fuel Cells
Hydrogen is the smallest and lightest of all gas molecules, providing the highest energy to weight storage ratio of all fuels. In principle, internal combustion engines and turbines can also be used for combustion of hydrogen. Commercial engines for combustion of hydrogen are unavailable. The focus is primarily directed towards pilot projects including fuel cells which have superior fuel to electricity conversion efficiency. Hydrogen as fuel, however, can be difficult and expensive to manufacture, transport and store. The most widely used devices for turning hydrogen’s chemical energy into electricity are fuel cells.
Compatibility of Diesel and Petrol Engine with alternate fuel
1.Diesel engines: The air is so compressed that the fuel is heated and ignited by it. Different fuels with different temperatures for auto-ignition need various types of engines.
The following fuels work in Diesel engines:
- Biodiesel (FAME), vegetable oil, DME (dimethyl ether), BTL (biomass-to-liquid), GTL (gas-to-liquid), and HVO (vegetable oil hydrotreated)
2. Otto Engine: Before a spark is produced, the fuel-air mixture will not ignite. Compared with 1:20 for compression ignition (Diesel), the compression ratio is much lower (typically 1:11)
The following fuels work in Otto engines :
- Gasoline, ethanol, methanol, natural gas
- Biomethane (In compressed (CNG) as well as in liquid (LNG) form)
Most frequently asked questions:
1.What is Biodiesel?
Biodiesel is the alternative fuel made of soybean oil and other vegetable oils or recycled cooking oil-processed for diesel engines.
2.How do I use Biodiesel?
Biodiesel is sold at stores and fuel docks in 5-gallon containers so that it can be directly poured into your fuel tank (it mixes easily with standard petroleum diesel) to produce blends of up to 20 %. For every 20 gallons of standard diesel fuel, add 5 gallons of biodiesel. To decrease moisture condensation, tanks should be kept full, particularly in winter. Biocides are suggested to prevent bacterial growth. Industrial biocides can be found in local marine supply shops. Follow directions for their use carefully.
3.What do I expect from using Biodiesel or its blends?
Biodiesel will restore the lubricity properties of diesel with a 5% blend. There would be a substantial decrease in smoke, soot and burnt diesel odour from the exhaust of the engine at 20%.
4. What additional modifications may I expect from the use of biodiesel?
In addition to reducing exhaust odour, the amount of soot accumulated on the hull of the boats can also be decreased by higher concentrations of biodiesel. Your diesel engine, especially at low rpm’s, should run smoother, and it can start easier. Biodiesel itself burns cleanly and further increases the combustion of petroleum fuel as an oxygenated fuel with no crude oil pollutants.
5.Do I have to change my engine in order for my boat to use biodiesel?
No, Biodiesel mixes with your regular diesel fuel as a blend and should require no changes to your engine in blends up to 20%. Biodiesel can damage old rubber fuel lines (in high concentrations) and even clean the inside of old fuel tanks, causing fuel filters to clog the released sediment.