The research article I have chosen is an experimental
study of a diesel engine running on blends of diesel and pentanoli.
It has been recognized that non-renewable fossil fuel reserves are constantly
in demand and are becoming exhausted. Additionally, the use of these
non-renewable fuels generates various environmental problems, the major being
global warming. Countries have demonstrated interest in developing alternative
energy resources that are renewable, cost-effective, and clean. Amongst the numerous
renewable energy alternatives, bioalcohols could serve as an appropriate
resource for diesel engines. Alcohols such as methanol (CH3OH),
ethanol (C2H5OH), propanol (CH7OH), and
butanol (C4H9OH) have been utilized due to the reduction
of emissions and use of fossil fuels but have limitations including low cetane
numbers, calorific value, and higher latent heat of evaporation. Thus
1-pentanol (C5H11OH), which has better fuel
characteristics, be produced from natural fermentation of biomass, can be
easily blended with diesel, better cetane number, and latent heat of
evaporation is being investigated as a new type of bioalcohol. For the study,
fuel blends of 5% (D95Pen5), 10% (D90Pen10), 20% (D80Pen20), 25% (D75Pen25),
and 35% (D65Pen35) by volume of 1-pentanol were added into diesel and tested
under 4 engine loads. The exhaust emissions were measured with a gas analyzer,
returning measurements of hydrocarbons (HC), carbon monoxide (CO), oxygen (O2),
and nitrogen oxide (NO). The results were that the blends produced higher CO
emissions due to the higher latent heat of evaporation of pentanol (except
D95Pen5), produced higher HC emissions, and increased NOx emissions
(except D95Pen5 and D65Pen35). It was concluded that D95Pen5 could be utilized
as an alternative fuel as it decreased exhaust gas temperature, CO and NOx
emissions at the expense of increasing HC emissions.
Diesel engine have become a major topic on air quality
due to the amount of toxic and harmful emissions they produce. Originally,
diesel engines were promoted as a more environmentally friendly alternative to
petrol engines; producing a fifth less carbon dioxide (CO2)ii.
Diesel engines use less fuel for the same performance as a petrol engine; on
average, diesel engines will emit 120 g-CO2/kilometer compared to
200 g-CO2/kilometer for petrol enginesiii.
In the United States, although heavy diesel engine vehicles such as trucks and
buses represent only 2% of all motor vehicles, they produce approximately 20%
of all NOx emissions from all sources. The demand for renewable,
cleaner, and safe fuel alternatives to diesel has become an important research subject.
The results of the study are interesting in the fact
that overall, there was an increase in emissions due to the nature of pentanol.
While pentanol has a number of advantages over other alcohols such as being
easily blendable with diesel, safe usage in diesel engines without any engine
modifications or additives, and better cetane number and latent heat of
evaporation, it increased HC, NOx, and CO emissions when compared to
diesel fuel. Other studies have shown pentanol’s potential as a future
generation fuel and additive; for example, it improved the fuel properties
(high viscosity and cold flow properties) of diesel-biodiesel blends and
reduced NOx emissionsiv.
The research points to further investigate the D95Pen5 blend as it decreased
the exhaust gas temperature, CO and NOx emissions but increased HC
emissions. Future implications may point to researching pentanol not as a
stand-alone blend with diesel, but as an additive fuel to improve fuel
properties. Butanol has also gained research interest because of its higher
cetane number and energy density. Similar to pentanol, it is easily blendable
and can be produced naturally. Additionally, it is seen to result in a
reduction of soot and NOx emissionsv.
As such, a future direction that could be studied is optimizing a blend of
diesel-butanol-pentanol as seen in Li, L., et al. study (2015)4.
Personally, I believe the article gives significant results.
Pentanol blends are a newer technology and by investigating the potential
future of this blend, it may prove to become a better additive compared to the
current alcohols of methane, ethane, and butane. While the results have shown
that the blends actually increase the emissions, it is still significant
research which can be used to further study this blend type – potentially changing
the experimental conditions by using different engine technologies or other
Clearly the aim of introducing blends of biofuels is
to decrease various harmful emissions and at the same time, give the same
performance compared to diesel fuel but the results of using blends may not always
be a net positive. As seen with the study, the blends of pentanol increased the
HC, CO, and NOx emissions compared to the base diesel fuel. While
pentanol may be easier to blend with other potential alcohols and is a
renewable resource, this is still counterproductive as it generates more
emissions compared to simply using diesel fuel, according to this study. This
trade-off becomes a complex optimization problem: the objective is to decrease
the overall greenhouse gas emissions (i.e. look at the entire lifecycle) while
implementing as much renewable fuel in a blend as possible without losing
vehicle performance. An important factor to consider in the optimization is the
process of producing these alcohols compared to diesel fuel. Extracting crude
oil, to produce diesel fuel, is generally a dirty process: involving a lot of
wastewater generation and utilization of hazardous chemicals which cause
negative effects on the environmentvi.
Properly treating the wastewater and the processing of crude oil requires the
use of energy, usually fossil fuels, and thus produces another source of
emissions. Similarly, processing biofuels requires the use of energy and
produces emissions: such as through fertilizers, harvesting crops, and
processing and converting bio-waste. Thus, it is important to consider and
optimize the entire lifecycle of a renewable fuel compared to the lifecycle of
a fossil fuel to decrease the overall effect of global warming.
In Canada, the government has imposed a fuel
regulation called the Renewable Fuel Regulations. These regulations require
fuel producers and importers to include an average renewable fuel content of 5%
and 2% in gasoline and diesel, by volume, respectivelyvii.
According to the performance report, GHG emission reductions of approximately
7.0 megatonnes (Mt) of CO2 equivalent were accrued in the first two
years of the Regulations (~3.7 Mt/year). As of 2017, the Clean Fuel Standard regulatory
framework was developed with the objective to achieve 30 Mt of annual
reductions in GHG emissions by 2030viii.
Looking specifically at the renewable fuel blends, the short-term decision was
that the current volumetric requirements be kept the same. In the future, the
required renewable fuel content will most likely be increased in order to reach
the annual reductions goal of 30 Mt. As more blends are developed, the existing
requirements will be raised. If the government potentially provided further
incentives, such as lowering taxes on renewable fuel resources, it will help during
future industrial practices as a drive to use more renewable fuels in gasoline
and diesel content.
In conclusion, the
study points to further research in developing cleaner blends as they are not
only a renewable source, they will produce less GHG emissions and increase the
air quality. Additionally, if the vehicle performance is maintained and the
fuel is cost-effective, it will drive the industry to shift towards more
renewable sources. With a joint-relationship between the research and
regulations: through new updated regulations (as seen with the newest Clean
Fuel Standard) and ongoing maintenance of the requirements as appropriate, I
believe biofuels will have a bright future as a renewable resource.