Miljödugga 3 ENGELSKA
19. What are four sources of unburned hydrocarbon emissions?
(unburned hydro carbons) UHC potentially arise from four sources: rich zones, where the oxygen deficit impedes the oxidation process; zones too lean for complete oxidation; cold zones, for example near walls; and unburned fuel from the sac volume of the injector.
What CO2-equivalence does methane gas have?
21
What CO2-equivalence does methane gas have?
25
How much have the NOx and PM emissions of trucks dropped between 1988 and 2010?
98% reduction of PM and 97% reduction of NOx (according to El Gustavo) 96% reduction of PM and 94% reduction of NOx (according to M16 Drive)
Why aren't all biological materials bio fuels?
A 3000 year old tree can not necessarily be classified as a bio fuel since it will take another 3000 years for the circle to be closed (benne översättning). which is not enviromentally viable. Also, fossil fuels are biological and bio fuels are by definition renewable:^)
Why do alcohols produce less soot than other fuels?
Alcohol fuels offer reduced probability for soot emissions due to the oxygen present in the fuel. Together with the reduced combustion temperature, alcohols offer an attractive way to operate CI engines with reduced emissions of both NOx and soot compared to regular diesel fuel
14. Cargo ships and tankers have negative impacts on the environment locally and globally. What are those impacts? What percentage of the global trade volume is transported with these ships?
Although entirely necessary for the efficient functioning of the world's economy, these transport activities are a source of pollution. Ballast water discharges, wildlife collisions, marine debris or oil spills negatively affect the environment and human health. According to UNCTAD, around 80% of the global trade by volume and over 70% of the global trade by value are carried by sea and being handled by ports worldwide.
How does the amount of thermal NOx change with temperature?
At a certain temperature NOx formation starts increasing exponentionally
If two SI and CI engines of similar size are to produce the same power, which one needs to have a boosted induction system?
CI engines generally produce less power than SI engines, which is why many of them are supercharged
20. High cylinder temperatures typically allow CO to be oxidized to CO2 what is one cause for CO emissions even when high cylinder temperatures prevail?
CO mainly becomes problematic when the final combustion stages have not been completed before the bulk temperature in the cylinder drops below approximately 1500 K during the expansion stroke. The oxidation step from CO to CO2 then cannot be completed [16]. At higher temperatures, CO remains high in pockets richer than stoichiometric
What substances does a hydrocarbon produce with complete combustion?
Carbon dioxide and steam
What emissions contribute to the greenhouse effect? What emissions are dangerous for our health?
Carbon dioxide, Methane, N20 (Nitrous oxide), CFCs, Hydrofluorocarbons, Water Vapour Carbon monoxide, PM, NOx
What substances are formed with incomplete combustion?
Carbon monoxide and Carbon
Why is carbon monoxide (CO) so dangerous?
Carbon monoxide has no smell, taste, or color and is therefore very hard to detect. Carbon monoxide prevents hemoglobin from absorbing and transporting oxygen. Carbon monoxide is not very harmful to nature.
When the emission requirements tightened for cars and heavy trucks, what two types of emissions proved the biggest challenges to reduce? (one for trucks and one for cars)
Cars: PM Trucks: NOx
What ways are there to reduce the NOx emissions of an otto engines?
Catalyst. Uses plates made from materials that react with the passing gas
What are the current problems of fossil fuels?
Combustion engines running on fossil fuels are used in both power production and transportation and are major contributors to global GHG emissions. According to the 2014 IPPC report, GHG emissions from transportation have increased at a faster rate than those from any other energy end-use sector alone and contributed 23% of the global CO2 emissions in 2010 [3]. CO2 is the main GHG from transportation, but nitrogen oxides (NOx), methane (CH4), volatile organic compounds (VOCs), sulfur dioxide (SO2), carbon monoxide (CO), F- gases, and black carbon (soot) are also emitted.
What is the difference between CNG and SNG?
Compressed natural gas, CNG, is with more than 20 million dedicated vehicles currently the most common alternative fuel to diesel fuel and gasoline and consists mainly of methane, CH4. Even when from fossil origin, due to its high H/C ratio, it can theoretically provide a reduction of 25% CO2 during vehicle operation compared to fossil diesel fuel or gasoline. Instead of extracting natural gas from gas wells, synthetic natural gas, SNG, can be produced by a number of processes from coal or other sources and has essentially the same properties as CNG. By liquefying the natural gas at -162 ̊ C and 0.25 bar over-pressure to LNG, the energy density can be increased 2.4 times compared to CNG.
What causes the combustion of DME to not produce a lot of soot?
DME has no carbon-carbon bindings which makes it hard to transform it into soot. It also contains oxygen which furtherly prevents soot from forming
Why is DME a suitable fuel for a DICI-engine?
DME is an oxygenated gaseous fuel that can be handled as a liquid when pressurized above 5 bar. Due to its high cetane number, it is suitable as a diesel engine (DICI) fuel but unsuitable for SI operation. For DICI operation, the fueling system needs to be designed for higher fuel flows compared to diesel fuel operation, due to the comparably low energy content in DME, and the fuel tank pressurized. Viscosity, as well as modulus of compressibility, is much lower than for diesel fuel, so fuel pumps need to be designed accordingly.
4. Biomass energy value chain can be optimized using two kinds of models. What is the major difference between them?
Deterministic models: Tools to find optimal value chains. Should include economical, social and enviromental factors Stochastic models: These parameters include quality of materials and delivery, market situation, price and return of investment
Why is the diesel engine dominant for trucks, while both the diesel and otto engines are common in cars?
Diesel engines provide higher torque which helps when pulling heavy loads. Otto engines are cheaper to manufacture and often gives the vehicle better driving abilities
12. Name the drawbacks of using gaseous fuels in transportation sector.
Drawbacks for gaseous fuels - renewable methane (or biogas) being the major option - are the lacking distribution infrastructure, vehicle fleet and, to some extent, the limited feedstock potential (in particular for biogas from anaerobic digestion).
What property makes gaseous fuels (bio gas and natural gas) especially suitable as fuels for otto engines?
Due to the low volumetric energy density of gaseous fuels both the onboard fuel storage and fuel injection systems differ from those used with liquid fuels. Gaseous fuels are typically compressed or liquefied to allow a reasonable driving range. Gaseous fuels such as methane- rich gases (natural gas or biogas) and propane or butane-rich gases (LPG) have very high RON ratings and are therefore well suited to SI operation and have actually been used historically longer than gasoline. RON rating = octance number An octane rating, or octane number, is a standard measure of the performance of an engine or aviation fuel. The higher the octane number, the more compression the fuel can withstand before detonating (igniting).
6. There are different drivers for increased use of bioenergy. What policies in EU and Sweden can lead towards an increased use of renewable fuels in transport sector?
EU policies such as the obligation for all member states to fulfill the target of minimum of 10% renewable energy in the transport sector for 2020 (European Parliament and Council, 2009) as well as policies in individual countries like the ambition of the Swedish Government for a vehicle fleet independent of fossil fuels by 2030 and a Sweden without any net greenhouse gas emissions by 2050 (indicating an entire transportation sector without fossil fuels), are policies that drives towards an increased use of renewable fuels for transport, most likely dominated by biofuels.
What are the problems of using alcohols as fuel?
Engine operation with alcohols is associated with a couple of other challenges. Alcohols are more corrosive than either gasoline or diesel. Methanol containing water is the most aggressive while higher alcohols are increasingly less so [21]. Alcohol engines use steel and certain plastics throughout the fueling system to avoid corrosion. In the case of methanol with water, stainless steel, and Teflon is recommended. Metals like lead, zinc, copper, aluminum and magnesium as well as some elastomers, plastics and rubber should not be used in contact with alcohols. The low lubricity of alcohols requires additives in the fuel to avoid problems with diesel type fuel pumps and injectors - unless alcohol tolerant units are used. Alcohols are solvents and can also form acids during combustion which could lead to higher demands on lubricant additives and possibly more frequent oil changes. Unlike gasoline or diesel fuel, neat alcohols are single- component fuels with single specific vapor pressures and boiling points that make for more challenging low-temperature cold starts. It can be difficult to vaporize enough fuel to reach an ignitable mixture.
What other fuel is added to gasoline (up to 10%) in Europe and the USA
Ethanol is also used as a drop-in fuel up to 10% in gasoline on several markets, including the European Union and the United States.
Why are high NOx emissions from diesel engines more problematic compared to the NOx emissions of otto engines?
Exhaust aftertreatment is not as elegantly handled in the CI engine as in the SI engine, and it might require several separate catalytic converters and particulate filters for the CI engine to comply with the more stringent emissions regulations.
What is FAME, RME, and SME? What differentiates them from fossil diesel?
Fatty acid methyl ester (FAME) is a group of fuels originating from vegetable oils and animal fats commonly known as biodiesel. In Europe, this is typically rapeseed methyl ester (RME) while in the US it is more commonly soy methyl ester (SME). Since essentially any vegetable oil or animal fat can be transesterified to biodiesel there is a substantial number of different fuel feedstocks. For instance, oils from algae, palm, coconut, jojoba, mustard, pongamia, tallow, lard, chicken fat, brain oil and many others. Several properties of FAME are similar to that of fossil diesel fuel, and they can, therefore, be used in diesel engines with little or no modifications. FAME has a similar or slightly higher viscosity compared to diesel fuel and for that reason works well in DICI fuel injection systems. FAME contains roughly 10% less energy than diesel fuel, leading to a corresponding increase in fuel consumption since engine efficiency is similar.
3. For every traffic fatality, approximately how many people are seriously injured? Annually, how many people are seriously injured? What is the demographic of people who suffer the majority of fatalities?
For every fatality, 10 people are seriously injured. Annually, an estimated 1.24 million people are killed in road traffic accidents. Out of the 1.24 million people killed annually from road traffic accidents, 92% occur in low- and middle- income countries. Young adults and therefore income earners form the majority of victims - while vulnerable road users such as pedestrians and cyclists are at highest risk of fatality.
11. To what is climate impact of fuels related and how do biofuels compare to the conventional diesel in that sense? (?)
For example, climate impact of different fuels is related to the CO2 equivalent well-to-wheel emissions for conventional diesel. Accounting for different feedstock and production alternatives for the respective fuel a best and worst case scenario is used for a number of categories. Most are better than diesel. Ethanol worse.
7. How high is Swedish bioenergy potential estimated to be in the near future as well as in the long run, i.e. over the periods of 10-30 and 30-50 years from now?
From a Swedish perspective Ecotraffic (2013) estimates a technical biofuel potential of 85 TWh/yr expressed in TWh final biofuels (in lower heating value) by 2030-2050. Börjesson et al. (2013) estimate that about 50-70 TWh/year of biomass could be used for bioenergy purposes in addition to today's biomass use from forest and farmland without directly competing with other agricultural or forestry cultivation. In the long run (30 to 50 years from now) this potential is estimated to increase to 80-100 TWh/year. Accounting for conversion losses in biomass to biofuel processes this still could contribute considerably to the transport sector energy demand lying in the range of 120 TWh/year for 2011 including about 30 TWh for international transport (aviation and marine transport) and a biofuel end use of 7 TWh (Energimyndigheten 2013a)
Two fuels have cetan numbers of 52 and 55 respectively. What fuel will ignite first?
Higher cetan number <=> More easily ignited
Name the five mechanisms of hydrocarbon emissions
Hydrocarbon emissions occur when the flame in an engine can't reach and ignite all the fuel. The five most common reasons are: Small cracks Fuel gathering close to walls, often by installations Oil films on the cylinder walls Extremely rich or poor combustion leading to misfire Direct short circuiting from inlet to exhaust system during gas exchange
What are the advantages of using hydrogen gas in a combustion engine? Why isn't it used to a greater extent?
Hydrogen is considered an excellent engine fuel, especially in SI engines, and has the obvious advantage of not yielding CO, CO2, and HC emissions. It has not become more widely used due to the difficulty of economic distribution and production. The energy content in relation to volume is very small for this, the smallest known molecule, making storage and transportation expensive. Hydrogen has fairly unusual and sometimes contradictory properties. For example, its research octane rating (RON) is very high while its motor octane rating (MON) is low. This indicates that hydrogen has a very low resistance to knock, which can be explained by its low ignition energy and extremely high flame speed. In a mixture, however, hydrogen acts in the opposite way by increasing the overall knock resistance.
17. Out of the global partnerships listed in goal 17, which one do you feel is the most aggressive? The most broad? Give a short motivation for each.
I don't palla läsa igenom them all
13. In 2010, in terms of all energy related CO2 emissions, for what percentage was transport sector responsible?
In 2010, the transport sector was responsible for approximately 23% of total energy-related CO2 emissions.
15. Delaying fuel injection is a very effective method for reducing NOx production because the peak in-cylinder temperatures are significantly lower. What drawbacks does this late injection strategy create?
Injecting the fuel later during the cycle reduces the combustion temperature due to the expanding motion of the piston. This method is associated with two negative side effects. The first is a lower effective expansion ratio, leading to reduced thermodynamic efficiency and, hence, higher fuel consumption. The second is increased emissions of PM. These arise because there is less time available to oxidize the soot formed, but also because the lower combustion temperatures inhibit efficient oxidation of the soot.
What is HVO?
Instead of using esterification to form FAME, vegetable oils and animal fats can be hydrotreated to form what is known as Hydrotreated Vegetable Oil (HVO). The hydrotreatment removes the double bonds and oxygen that leads to stability issues in FAME and thus gives HVO improved storage properties as well as reduced risk of oil contamination. To further improve the low-temperature properties, isomerization, the addition of flow improvers, control of reaction temperature or co-processing with petroleum-derivates are employed [50]. Final fuel properties are almost independent of original feedstock.
16. Border crossings enhance the trade between bordering nations, but how can it also affect their own national security?
International transport corridors play an important role. Border zones are a common conflict trigger. Hence, cross-border collaborative trade and transport solutions are required such as alignment of toll charges, border control procedures or harmonized security measures for transport operations. Transport is essential for stabilization missions in the quest to access and rebuild post-conflict states. On the other hand, transport corridors can facilitate insecurity and the activities of insurgents.
For what reason does the SI engine work with a stochiometric fuel/air mixture?
It can be run very cleanly by using stoichiometric operation and a three-way catalytic converter aftertreatment system (TWC). It lends itself very well to either liquid or gaseous fuel operation, with either lean-burn or stoichiometric operation.
What is "knack" and what can be done to prevent it from happening?
Knack is when the fuel/air mixture of the outer parts(?) of an otto engine cylinder ignite before they come in contact with the spark plug flame. Modern engines are fitted with a sensor that dectects if knack occurs. PALLAR INTE ÖVERSÄTTA RESTEN Om knackning detekteras minskar motorstyrningen förtändningen hos den cylinder som knackar. På detta sätt minskas flamutbredningstiden (som ju är maximalt den tid det tar för kolven att röra sig från tändpunkten till övre dödläget
Why is LNG produced? Why is LNG very uncommon as a fuel in vehicles?
LNG (Liquified Natural Gas) is formed by cooling Natural gas to low temperatures. It is not posionous and very energy dense compared to the gas, but hard to transport and handle due to its low boiling point
What fuel-engine combination gives the lowest soot emissions and the highest BTE? What combination gives the highest soot emissions?
Low soot and high BTE emissions - SI engine running on hydrogen gas High soot emissions - POMDME/DICI
What methods are there to reduce carbon dioxide emissions?
More effective combustion of fuel, renewable energy sources and chemical processes like catalysts
NOx includes both NO and NO2. Which one of those occur naturally in our body? Which one contributes to photochemical smog?
NO occurs naturally in our body. NO2 contributes to the photochemical smog. When NO gets to the atmosphere it quickly forms NO2
2. What emissions are the most problematic for a diesel engine?
One major disadvantage of the CI engine is its comparatively complex and expensive high pressure fuel injection system. Another important problem is the great amount of NOx and soot produced by CI combustion.
How does the fuel/air mixture affect the NOx emission levels of an otto engines. When are they at their highest/lowest?
One of the most sensitive parameters is the air/fuel ratio. With a stoichiometric mixture, high flame temperature is reached and there is still oxygen available. The expected trends were found. Low NOx is found with rich or lean mixtures and the peak is at slightly lean mixtures. It can be noted that it is about one order of magnitude difference in NOx if the engine is operated stoichiometric or extremely lean, λ>1.7. The highest at lambda=1.2, and lower at lower/higher lambdas
How is the engine load controlled in diesel and otto engines?
Otto-motor: Engine load is controlled by a throttle in the induction channel, thus controlling the total amount of fuel and air that enters the cylinder. Diesel-motor The load is controlled by the amount of fuel injected rather than by using a throttle that increases the pumping losses.
What does PM consist of and from where do these (two) originate?
PM consists of av complex mixture of non-gaseous emissions (either solid or liquid particles). The liquid parts are soluble organic materials and sulfuric acids. The solid parts are soot and ashes from lubrication and engine parts
Why does the PPC engine have low HC+CO emissions?
PPC = partially premixed combustion PPC can be seen as a concept combining principles from both DICI and HCCI. Typically, PPC is associated with a separation of the direct injection event and the auto-ignition combustion. By injecting the fuel at some point during the compression, combined with air dilution and high amounts of residual gases and a fuel with some resistance to auto- ignition, fully premixed or fully heterogeneous conditions can be avoided. This leads to low emissions of soot, NOx, HC and CO together with very high efficiency.
Why are NOx emissions so low in RCCI and PPC engines?
RCCI and PPC are low-temperature combustion (LTC) concepts designed for low NOx, which is also achieved according to the results in figures 6 and 7.
What trade-off happens when the nozzle diameter is reduced?
Reducing diameter size increases the mixing potential of fuel and oxygen at the injection stage. The smallest possible diameter is regulated by injection speed at full PATTE.
15. What are three ways the landscape is impacted by the expansion of roadways and railways?
Road and rail expansion and construction have a severe impact on the landscape, and can result in the destruction of the surrounding ecosystems and interactions, in land take or land degradation. The need for construction materials and the development of land-based transportation has led to deforestation, degradation of wetlands and reduction in biodiversity.
1. What three engine concepts are the most common i vehicles today? Which one has the highest efficiency and why?
Spark ignition, direct injection spark ignition and direct injection compression ignition. The one with the best effiency is injection compression ignition. The diesel or direct injection compression ignition (DICI) engine is, due to its high efficiency, the most common type of engine for commercial vehicles and marine applications.
What is the process of producing synthetic diesel and gasoline called? What is the major advantages these fuels have over their fossil equivalents?
Synthetic gasoline and diesel fuel may have several different feedstocks and names but are in general produced by the Fisher- Tropsch process. They typically exhibit slightly better emissions performance compared to their fossil equivalent. Sulfur is much lower than in fossil gasoline and diesel fuel where it can be very high and problematic on some markets. One obvious advantage with synthetic diesel fuel or gasoline is that no engine modifications are required.
3. How can energy systems be modelled and which important aspects should be taken into consideration? (?)
Systems analysis of biofuel production basically covers the whole chain from biomass resource extraction via processing and distribution to end-use. The definition of the systems boundaries can, in addition, have a large impact on the actual value of the different criteria. Thus, a very important aspect for enabling a transparent comparison between different studies is the proper definition of systems boundaries and how cogenerated by-products are valued.
8. In Africa, how many indirect jobs are created as a result of every job directly involved in the transport sector?
The African example illustrates that every direct job in the transport service sector usually results in 2 to 2.5 indirect jobs in other sectors
9. How can land use be defined in general and to what do direct and indirect land use change refer?
The IPCC defined land use in general (both direct and indirect) as "the total of arrangements, activities and inputs undertaken in a certain land cover type" or in other words as "the social and economic purposes for which land is managed (e.g. grazing, timber extraction and conservation)". Whenever land is transformed from one use to another land use change occurs with potential consequences at the overall systems level in economic, environmental and social terms. To properly account for land use change effects, in relation to biofuel production value chains, is difficult and controversially discussed. The difference between direct and indirect land use change (dLUC and iLUC) is basically that dLUC refers to effects directly linked to the land area that has a new use, whereas iLUC effects are impacts at another place and level. A simple example for dLUC would for example be deforestation for growing biomass energy crops. Indirect land use change could for example take place in case biomass energy crops (crop A) are grown on land that is used for another crop (crop B). In case the demand for crop B remains constant, land somewhere else might be used for growing that crop in order to satisfy the demand. This will lead to land use change somewhere else, but initiated by the biomass energy crop (crop A) and therefore is accounted as iLUC effect of growing that crop (crop A) in the life cycle assessment.
How big were the changes between the Euro-levels generally?
The allowed emissions are generally halved with each new level
23. What is the difference between "engine-out emissions" and "tailpipe emissions"?
The benchmarked regulated emissions are engine-out emissions and not tailpipe emissions. It can be argued that tailpipe emissions are more relevant since those would show the overall engine system emissions, including any emission after-treatment system (EATS). But in reality it is difficult to benchmark tailpipe emissions since the combined engine-EATS are tailored to specific emissions regulations that vary substantially for different applications and regions, and in certain cases do not require any EATS at all. Another issue is that few of the emerging fuels and engine concepts have been investigated with any EATS. Finally, engine-out emissions are possibly the most interesting since they indicate both the true potential of any fuel-engine combination and some of the requirements for EATS. Tailpipe emissions = det som kommer ut ur avgasröret, engine-out emissions = det som motorn producerar innan alla reningsprocesser (tror jag)
10. Which are the major challenges related to biofuel-induced land use change effects and which measures can be introduced for avoiding iLUC effects?
The difficulty of quantifying land use change effects is also highlighted by Höglund et al. (2013) who, from another perspective, identify the following major challenges related to biofuel-induced land use change effects (both direct and indirect): Deforestation, forest management, and climate change Degradation of biodiversity Nutrient leakage and removal Contribution to rising food prices and poverty Other socioeconomic aspects such as job creation, ways of life and recreational values. Among the key measures proposed in the report are: Stimulation of increased productivity and resource efficiency in the agricultural sector Supporting production on currently underutilized land Promotion of land zoning that strives for a richness in biodiversity and conservation of ecosystems Intensification of forest maintenance and management
What is EGR (Exhaust Gas Recirculation) and why is it used in otto engines?
The exhausts are lead back to the intake and functions as an inert gas during combustion. This heavily reduces the amount of NOx formed.
What emissions are regulated by the EU?
The following emissions are regulated by the EU: NOx emissions Total hydrocarbons (THC 420 blaze it) Non-methane hydrocarbons (NMHC) Carbon monoxide (CO) Particles (PM)
What is the octane number for alcohols (methanol, ethanol etc.) compared to gasoline? What is the advantage of this?
The high octane ratings of alcohols make them less prone to engine knock or pre-ignition, and they are therefore well suited as SI engine fuels. The reduced knock tendencies can be exploited with an increase in compression ratio leading to both higher efficiency and higher power output compared to gasoline operation. The high octane ratings of alcohols do also mean that they are not naturally suited to CI operation.
What differentiates HCCI from PPC?
The homogenous charge compression ignition (HCCI) principle is a comparatively new concept that has yet to find commercial success. The working principle is similar to that of the SI engine, in that the fuel and air are mixed before being induced into the cylinder. The HCCI engine does not use any specific device to ignite the in-cylinder charge. Combustion starts simultaneously throughout the cylinder through auto-ignition by compressing the charge to sufficiently high pressures and temperatures. PPC can be seen as a concept combining principles from both DICI and HCCI. Typically, PPC is associated with a separation of the direct injection event and the auto-ignition combustion. By injecting the fuel at some point during the compression, combined with air dilution and high amounts of residual gases and a fuel with some resistance to auto- ignition, fully premixed or fully heterogeneous conditions can be avoided. This leads to low emissions of soot, NOx, HC and CO together with very high efficiency.
4. In low-income countries, how could an improved transport sector increase the number of children attending school?
The provision of equal access to safe and reliable transport can promote equality and equitable educational opportunities for all. In many parts of the world, pro-male school enrolment still prevails. Actions have to be designed for increased accessibility of education facilities for female students Children's widespread role as transporters (e.g. head loaders for water supply) may constrain their access to education due to reduced time available to attend school7. Improved goods transport options (including water) can enhance education opportunities - particularly for girls. The availability of safe, affordable and accessible transport options promotes access to education for people with disabilities.
2. Rapid growth of biofuel production can help reduce net greenhouse gas emissions, but what may suffer as a result?
The rapid growth in biofuel production can affect food security through its impact on food prices and income.
What affects the NOx emissions of a CI engine more, the global lambda or reaction zone lambda?
The reaction zone lambda
12. What is often responsible for farmers not being able to expand their harvesting operations?
The shortage of reliable rural transport services has been quoted repeatedly as being responsible for food crops not reaching the market at all and holding back farmers to expand food production for the market. In other cases the poor quality of transport services accounts for waste happening during transport to the market.
What harmful effects does NOx emissions bring?
The very acidic nitric acid is formed when NOx reacts with water. It creates a lot of problems such as low PH levels in lakes. It is also bad for the human health and can cause heart problems.
Which three mechanisms produce NOx when combustion occurs? Explain them!
Thermal NOx: Forms at high temperatures. Oxygen and Nitrogen from the air forms NOx. The reaction is heavily affected by temperature. Prompt NOx: Summation of a more complex process not only containing air but fuel and all the 10000 steps of transforming fuel to CO2 and water. Fuel NOx: If the fuel contains Nitrogen it is prone (****ing pronne baby) to form NOx. The amount of fuel NOx depends on how much fuel is injected.
The benchmarking in the article has been done with the supposition of maximal possible efficiency for every individual concept. Why is this a problem?
This paper focuses on peak efficiencies although in practice engines may operate at lower efficiencies since engine efficiency varies with engine load (figure 1) and engine speed. Regulated emissions, particulate matter, NOx, HC, and CO vary substantially with fuel composition and operating conditions and are little correlated with engine efficiency.
What year did the emissions regulations close the gap between SI and CI engines? Which two tailpipe emissions were the least similar between the two engine types before this?
This was done in 2014 when Euro6 closed the gap between SI and CI. The least similar emissions were NOx and PM
18. What are the fundamental differences in the way SCRs and LNTs reduce the tailpipe-out NOx emissions? Why can't a 3-way catalyst be used on a CI engine?
Three-way catalytic converters used on stoichiometric SI engines since the mid-1980's do not function at oxygen levels in excess of one percent and, instead, one of two major catalytic technologies are used in current CI engines. One of the technologies is called selective catalytic reduction (SCR). It removes NOx from the exhausts by reducing it into nitrogen (N2) and water (H2O) over a catalytic surface. A reductant must be added to the exhausts upstream of the catalyst. An alternative technology is the so called NOx trap, or lean NOx trap (LNT). It uses a zeolite (an adsorbing material) to trap NOx in the material under lean conditions. Once the trap is full, it can be purged under fuel-rich conditions. Injecting diesel into the exhaust stream or running the engine rich will introduce hydrocarbons into the trap and NOx (which are oxidants) will react with them to produce H2O and N2.
Describe how liquid fuel turns to soot
Through a complicated chemical process involving dissolution and oxidation of fuel, growth of polyaromatic hydrocarbons(PAHs), coagulation of these in to primary particles. These are then lumped together into larger paricles
1. In which four types can biofuel feedstock be grouped according to its origin? Examples?
Todays primary bio fuels like ethanol, FAME, HVO, biogas etc. Conventional (primary) bio fuels in development like FT-diesel, methanol, DME, SNG etc. Non conventional bio fuels in develompent like buthanol, furans etc. Future bio fuels that are yet to be considered for primary use like algae-based fuels or electro fuels.
10. Why is it that affordable public transport can reduce the amount of poverty in a country?
Transport can provide affordable access to jobs, markets, schools and essential services
11. The role of transport infrastructure is not just to enable efficient transport of people and goods on a daily basis. What is another vital role of this infrastructure?
Transport ensures access to services, goods and opportunities. Compact city planning can reduce the need to travel. When combined with an inclusive and efficient public transport system including more attractive and safer options for active mobility, namely walking and cycling, integrated land- use and transport planning can improve accessibility and contribute to environmental sustainability.
6. In what ways could improved roads both help sustain and potentially harm local water ecosystems?
Transport ensures physical access to water; transport emissions can impact on freshwater sources. Transport emissions, transport-related waste or infrastructure works can impact on water quality
5. In rural parts of countries where women traditionally have duties around the home, how could an improved transport infrastructure help the women as individuals? How could it help the society?
Transport is a key enabler for women to access opportunities such as health services, education facilities, jobs or for participation in politics and social activities. Hence, safe, reliable and sustainable transport interventions can make a big difference in increasing women's education, productivity, health and promote gender equality. Actions should be taken to increase the proportion of female employees in the transportation sector, which is traditionally a male-dominated field. Women may have less access to funds and means of personal transport and rely more on public transport and NMT. The promotion of these modes can therefore empower women. Ensuring personal safety and security in regard of transportation is one major step towards gender equality. Women - often relying on public transport or walking - are particularly vulnerable in terms of crime, e.g. sexual harassment or theft. Taking action towards improved safety of women, and ensuring crime and violence free mobility
1. Mention two ways where improving the road quality can help reduce poverty
Transport is a necessary prerequisite that enables inclusive economic growth, poverty reduction, social progress and an overall improved quality of life. For instance, in Ethiopia, access to all- weather roads in 15 villages has helped to reduce the incidence of poverty by 6.7%. Transport is inextricably linked to socio-economic development. Transport offers the means for all to reach ameliorative opportunities while providing job opportunities. Transport provides accessibility while ensuring inclusiveness and social equality - with the cost of transport being the determining factor. Lowers cost and enhancing opportunities.
7. Of all the oil consumed every year, how much is not for the transport sector (as in not used or propulsion)?
Transportation accounts for approximately 25% of the world's energy demand and for about 61.5% of all the oil used each year. Which means that 38.5 % is not for the transport sector #quickmaths
9. During the hurricane Katrina disaster, which type of transport did not allow for efficient evacuation of the city?
Transportation infrastructure has to be made efficient, equitable and resilient. The example of hurricane Katrina illustrates that Katrina's evacuation plan functioned relatively well for motorists but failed to serve people who depend on public transit. It has to be noted that public transport (i.e. buses) has the potential to evacuate a city much faster than private transport.
Why can bio gas sometimes be considered positive for the greenhouse effect?
Varför kan man ibland anse att biogas ger ett negativt bidrag till växthuseffekten? With biogas, the CO2 emissions are typically reduced more than 90% and can sometimes even be considered to provide negative greenhouse gas emissions since the otherwise emitted methane is a stronger greenhouse gas than the CO2 produced by combusting the methane.
8. What are possible positive and negative effects of increased bioenergy production on water availability and management?
Water demand for bioenergy production might place an additional burden on water availability worldwide and induce increased competition over water resources in an increasing number of regions. However, bioenergy demand also leads to new opportunities since a number of crops that are suitable for bioenergy production are drought tolerant, relatively water efficient and grown under multi-year rotations3. By adopting such crops farmers may better cope with a change in precipitation patterns. In many cases an increased bioenergy production can be positive.
17. Explain why, in the soot-NOx tradeoff, lowering NOx emissions tends to increase soot emissions.
With sufficient EGR levels the NOx emissions may be reduced by a factor of 10 but, since EGR decreases the temperature during expansion, PM will increase due to less efficient soot oxidation. The opposite temperature dependencies of the NOx formation and soot oxidation rates leads to a dilemma called the soot-NOx tradeoff. It arises from the fact that most methods for reducing NOx emissions will increase the PM emissions, and vice versa.
2. What are the three types of biofuel processing and to which feedstock are they applicable?
sugar-based feedstock, e.g. sugar cane or sugar beet starch-based feedstock, e.g. corn, wheat and other cereals oil-based feedstock, e.g. rapeseed, palm oil, tall oil from pulping industry, animal fats from e.g. slaughtering lignocellulosic feedstock, e.g. wood, forest residues, straw, or bagasse. The major components in a feedstock basically determine the type of processing that is most adequate for biofuel production. Three major process platforms for biofuel processing exist: thermochemical conversion, basically biomass gasification, in particular suitable for lignocellulosic material, biochemical conversion processes (e.g. fermentation, anaerobic digestion) mainly applied to sugar- and starch-based feedstock and hydrogenation/esterification processes for conversion of oil-based materials, such as vegetable oils or animal fats, to fuels (mainly FAME and HVO).
