Carbon Footprint Reduction

© Pascal Chisom Okechukwu

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THE ROLE OF CHEMICAL ENGINEERS IN REDUCING THE CARBON

FOOTPRINT

BY

PASCAL CHISOM OKECHUKWU

REG. NO: 2011214087

SEMESTER PAPER SUBMITTED IN PARTIAL FULFILMENT OF THE

REQUIREMENT FOR ChE 591; ENVIRONMENTAL POLLUTION

ENGINEERING AND CONTROL

TO

DEPARTMENT OF CHEMICAL ENGINEERING

FACULTY OF ENGINEERING AND TECHNOLOGY

NNAMDI AZIKIWE UNIVERSITY, AWKA, NIGERIA

LECTURER-IN-CHARGE: PROF. P K IGBOKWE

JANUARY, 2016


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ABSTRACT

This work presents the issue of the Carbon Footprint and the causes; dangers of

Climate Change beside it. It went further to explain how complex the carbon

footprint is, in terms of calculating it both individually and on a larger scale.

More importantly, it focused on the efforts greatly contributed by Chemical

Engineers in curbing the Global Warming phenomenon and reducing the carbon

footprint, through technologies like the carbon offsetting alternatives, catalytic

converters, coal gasification, and CCS.


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1.0 INTRODUCTION

The Environment consists of all the external factors (living or non-living)

affecting an organism. And every minute change in any one factor in an

ecosystem can influence whether or not a particular plant or animal species will

be successful in its environment.

1.1 Global Warming and Our Future.

Within the last century, the amount of carbon di oxide in the atmosphere has

increased dramatically, largely because people burn vast amounts of fossil fuels-

coal and petroleum and its derivatives. Average global temperature also has

increased- by about 0.6 Celsius degree (1 Fahrenheit degree) within the past

century. Atmospheric scientists have found that at least half of that temperature

increase can be attributed to human activity. They predict that unless dramatic

action is taken, global temperature will continue to rise by 1.4 to 5.8 Celsius

degrees (2.5 to 10.4 Fahrenheit degrees) over the next century.

Shrinking Greenland Ice Sheet


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The consequences of such a modest increase in temperature may be

devastating. Already scientists have detected a 40 percent reduction in the

average thickness of Arctic ice. Other problems that may develop include a rise

in sea levels that will completely inundate a number of low-lying island nations

and flood many coastal cities, such as New York and Miami. Many plant and

animal species will probably be driven into extinction, agriculture will be

severely disrupted in many regions, and the frequency of severe hurricanes and

droughts will likely increase.

Following these findings and future predictions, there arose the need to

drastically reduce our carbon footprint.

1.2 The CARBON Menace

It is very much possible that Carbon related compounds (including the Oxides

and Methane) accounts for approximately 50 percent alone of the contributions

to global warming. The predominant form of carbon in the air is Carbon dioxide

(CO₂). It is usually considered nontoxic and innocuous, but increasing

atmospheric levels (about 0.5 percent per year) due to human activities appear

to be causing a global climate warning that may have disastrous effects on both

human and natural communities.

Anthropogenic (human-caused) CO₂ releases are difficult to quantify because

they spread across global scales. The best current estimate from the

Intergovernmental Panel on Climate Change (IPCC) is that between 7 and 8

billion tons of carbon (in the form of CO₂) are released each year by fossil fuel

combustion and that another 1 to 2 billion tons are released by forest and grass

fires, cement manufacturing, and other human activities. Typically, terrestrial


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ecosystems take up about 3 billion tons. This leaves an average of at least 3

billion tons to accumulate in the atmosphere.

Carbon Monoxide (CO) is a colourless, odourless, non-irritating but highly toxic

gas produced by incomplete combustion of fuel (coal, oil, charcoal, or gas),

incineration of biomass or solid waste, or partially anaerobic decomposition of

material. CO inhibits respiration in animals by binding irreversibly to

haemoglobin. About 1 billion metric tons of CO are released to the atmosphere

each year, half of that from human activities. In the United States, two-thirds of

the CO emissions are created by internal combustion engines in transportation.

Land-clearing fires and cooking fires also are major sources. About 90 percent of

the CO in the air is consumed in photochemical reactions that produce Ozone.


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2.0 The CARBON FOOTPRINT

According to timeforchange, a carbon footprint is defined as the total amount

of greenhouse gases produced to directly and indirectly support human

activities, usually expressed in equivalent tons of carbon dioxide (CO₂).

Calculating or checking for one’s carbon footprint is usually a cumbersome task.

Say: when you drive a car, the engine burns fuel which creates a certain amount

of CO₂, depending on its fuel consumption and the driving distance. When you

heat your house with oil, gas or coal, then you also generate CO₂. Even if you

heat your house with electricity, the generation of the electrical power may also

have emitted a certain amount of CO₂. When you buy food and goods, the

production of the food and goods also emitted some quantities of CO₂. So it

becomes quite inescapable for every individual on Earth, when it comes to

contributing to Global Warming.

Your carbon footprint is the sum of all emissions of CO₂, which were induced by

your activities in a given time frame. Usually it is calculated for the time period

of a year. And the best way is to calculate the carbon dioxide based on the fuel

consumption.

The carbon footprint is a very powerful tool to understand the impact of

personal behaviour on global warming. Most people are shocked when they see

the amount of CO2 their activities create! If you personally want to contribute

to stop global warming, the calculation and constant monitoring of your

personal carbon footprint is essential.

The table below shows the CO₂ emission for the most common fuels in the USA

and UK.

timeforchange.org


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Fuel Type Unit CO₂ Emitted Per Unit

Petrol 1 gallon (UK) 10.4 kg

Petrol 1 litre 2.3 kg

Gasoline 1 gallon (USA) 8.7 kg

Gasoline 1 litre 2.3 kg

Diesel 1 gallon (UK) 12.2 kg

Diesel 1 gallon (USA) 9.95 kg

Diesel 1 litre 2.7 kg

Oil (heating) 1 gallon (UK) 13.6 kg

Oil (heating) 1 gallon (USA) 11.26 kg

Oil (heating) 1 litre 3 kg

Table. Showing the CO₂ emission for common fuels in the USA and UK

For example, if your car consumes 7.5 litres diesel per 100 km, then a drive of

300 km distance consumes 3 x 7.5 = 22.5 litres diesel, which adds 22.5 x 2.7 kg =

60.75 kg CO₂ to your personal carbon footprint.

Now, each of the following activities add 1 kg of CO₂ to your personal carbon footprint:

Travel by public transportation (train or bus) a distance of 10 to 12 km (6.5 to 7 miles)

Drive with your car a distance of 6 km or 3.75 miles (assuming 7.3 litres petrol per 100 km or 39 mpg)

Fly with a plane a distance of 2.2 km or 1.375 miles.

Operate your computer for 32 hours (60 Watt consumption assumed)

Production of 5 plastic bags

Production of 2 plastic bottles

To calculate the above contributions to the carbon footprint, the current UK mix for electricity and trains was taken into account.


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3.0 The CARBON FOOTPRINT REDUCTION

Having known the consequences of releasing much CO₂ into the atmosphere, by

our everyday living, it has ever being an utmost concern for all parties involved

in the contribution to this ever-increasing carbon footprint; to find all possible

means of keeping it at and beyond bay. The most common way to administer

the solution is to Reduce, Reuse, Recycle, and Refuse. In manufacturing, this can

be done by recycling the packing materials, by selling obsolete inventories of

one industry to another looking to buy the unused items at a lesser price.

Also, reusable items such as thermoses, should be used for daily coffee or plastic

containers for consumables, rather than disposable ones. Disposable items,

when used however, should be properly recycled. It is estimated that some 1.2

tons of CO₂ is saved annually, when one household recycles at least half of their

household waste. Other means of reducing our carbon footprint involves driving

less, walking more or biking, using less air conditioning and heating in the house,

etc. These would all ensure burning less fuel and releasing fewer emissions into

the atmosphere.

On the larger scale, the huge leap in reducing carbon footprints is participated

in; and carried out by major industries and organizations. This is where Chemical

Engineering comes in to take the lead.


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4.0 The Role of CHEMICAL ENGINEERS

Chemical engineers play a leading role in the design and implementation of

effective technology-based solutions to control CO₂ emissions. Current projects

include

Advanced combustion systems that reduce the formation of CO2 and

other combustion-related Green House Gases;

Pollution-control systems engineered to capture CO2 emissions; and

Use of cleaner-burning alternative energy sources, such as biomass-

derived fuels and solar- and wind-generated power. Known as the Carbon

Offsetting Alternatives.

Already existing techniques involve the use of Catalytic Converters in

automobiles and other fossil fuel-driven engines; and Coal gasification. While

other efforts involve the development of mechanisms for sequestering CO2

emissions underground to prevent their accumulation in the atmosphere.

Sequestration, not yet practised on a commercial scale, involves the injection of

compressed CO2 into stable, subsurface geological reservoirs. This is known as

Carbon Capture and Storage (CCS).

For the confinement of this work, these designs and implementations would be

treated in little details.

4.1 CATALYTIC CONVERTERS

Chemical engineers, working with scientists and other engineers, have helped

devise ways to cost effectively reduce the amount of pollution produced by

petroleum-derived, fuel-burning engines.


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A catalytic converter is an emissions control device that converts toxic pollutants

in exhaust gas to less toxic pollutants by catalysing a redox reaction (oxidation

or reduction). Catalytic converters are used with internal combustion engines

fuelled by either petrol (gasoline) or diesel- including lean-burn engines as well

as kerosene heaters and stoves. The catalytic converter is considered one of the

most important contributions to the field of air-pollution control. It is now a

standard feature on vehicles everywhere. It destroys the three main pollutants

found in engine exhaust- namely: carbon monoxide, nitrogen oxide, and

unburnt hydrocarbons.

The converter consists of a porous honeycomb ceramic base material coated

with a precious metal catalyst. The honeycomb structure provides high catalyst

surface area, which minimizes the contact between the catalysts and the

pollutants in the exhaust gases.

Figure. Basic structure of the catalytic converter for automobile engines.


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When this novel structure was first invented, it featured two distinct chemical

engineering advantages:

It maximized the amount of catalyst-coated surface area to which the

engine exhaust may be exposed.

It minimized the amount of expensive precious-metal catalyst required.

To recognize how important catalytic converters are in environmental

protection, President George W. Bush awarded the its inventors, the chemical

engineer John Mooney and the chemist Carl Zeith, with the 2002 National

Medal of Technology, the highest honour given for innovation in the United

States.

4.2 COAL GASIFICATION

Coal remains the cheapest and most plentiful of all the fossil fuels. However, it

is also the most polluting. Chemical engineers have worked to perfect coal

gasification, a method to generate electricity and produce fuels from coal with

significantly less environmental impact. Now utilities can burn clean synthetic

gas made from coal and have considerably fewer emissions than with traditional

pulverized coal combustion.

Coal gasification electric power plants are now operating commercially in the

United States and in other nations, and many experts predict that coal

gasification will be at the heart of future generations of clean coal technology

plants. Rather than burning coal directly, gasification (a thermo-chemical

process) breaks down coal or virtually any carbon-based feedstock- into its basic

chemical constituents. In a modern gasifier, coal is typically exposed to steam

and carefully controlled amounts of air or oxygen under high temperatures and


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pressures. Under these conditions, molecules in coal break apart, initiating

chemical reactions that typically produce a mixture of carbon monoxide,

hydrogen and other gaseous compounds.

Coal gasification may offer a further environmental advantage in addressing

concerns over the atmospheric build-up of greenhouse gases, such as carbon

dioxide. If oxygen is used in a coal gasifier instead of air, carbon dioxide is

emitted as a concentrated gas stream in syngas at high pressure. In this form, it

can be captured and sequestered more easily and at lower costs. By contrast,

when coal burns or is reacted in air, 79 percent of which is nitrogen, the resulting

carbon dioxide is diluted and more costly to separate.

4.3 CARBON OFFSETTING ALTERNATIVES

Asides the Solar and Wind Energy alternatives that are in efficient use in most

technologically leading nations of the world, the option of Biomass Energy has

become a huge trend. Chemical engineers are helping reduce harmful emissions

through the development of technologies used to convert biomass into fuel.

Biomass is fuel that is developed from organic materials, a renewable and

sustainable source of energy used to create electricity or other forms of power.

Bioenergy is the most widely used renewable energy worldwide and can be

defined as “energy contained in living or recently living biological organisms”. It

can be differentiated into three distinct types.

Biofuels. Such as ethanol and biodiesel are fuels made from crop such as corn

and oil palms respectively.

Biogas. Is produced with waste products such as sewage and dung.


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Solid Biomass. Suh as wood has been used since ancient times for cooking and

heating purposes- and more recently to generate electricity.

Burning biomass to create clean electricity releases no new carbons back into

the atmosphere. Instead, it releases what would be released naturally as the

organic matter decomposed. It forms a closed cycle too, because the carbon that

is released when biomass is burned is re-absorbed by other plants in their

growing cycle.

The use of biomass will reduce the nation’s greenhouse gas emissions, thus

helping mitigate climate change (carbon footprint). Biodiesels and biogas are

now being speedily improved and are already replacing fossil fuels in most

countries.

4.4 CARBON CAPTURE and STORAGE (CCS)

Carbon capture and storage or sequestration prevents large amounts of carbon

dioxide from being released into the atmosphere. The technology involves

capturing CO2 produced by large industrial plants, compressing it for

transportation and then injecting it deep into a rock formation at a carefully

selected and safe site, where it is permanently stored.

Because CCS can achieve significant CO2 emission reductions, it is considered a

key option within the portfolio of approaches required to reduce greenhouse

gas emissions. The technology involves three major steps:

Capture. The separation of CO2 from other gases produced at large industrial

process facilities such as coal and natural gas power plants, steel mills and

cement plants. See the Figure below.


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Transport. Once separated, the CO2 is compressed and transported, usually via

pipelines, to a suitable site for geological storage.

Storage. CO2 is injected into deep underground rock formations, often at depths

of one kilometre or more.

The need for CCS stems from the fact that we need a very significant scale of

CO2 mitigation. CCS can contribute around 14% of total energy-related CO2

reductions by 2050, compared to a `do nothing’ approach (2014, IEA, Energy

Technology Perspectives).

Around 40% of CO2 emissions come from the power sector. Another 25% come

from large-scale industrial processes such as iron and steel production, cement

making, chemicals and refining. Demand for fossil fuels is likely to remain strong,

especially in developing countries, where a significant percentage of the

population currently has no access to electricity.

CCS is a viable option- in some cases, the only viable option- for significantly

reducing emissions from such large-scale emission sources.


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5.0 CONCLUSION

Reducing the carbon footprint on planet Earth has proven to be a realistic and

already working process. With chemical engineers taking the lead in designing

and developing astounding technological projects to not only ensure the end to

a net increase of CO2 emissions, but also to capture some of the already emitted

CO2 in the atmosphere and convert them into future useful energy once more.

The development of biomass energy technology and other carbon offsetting

alternatives has further ensured that future generations would have less to

worry about on the issue of carbon footprint and global warming. Major

companies like Shell are seriously improving on the development of the CCS

technology and other projects such as improving the production of Liquefied

Natural Gas (LNG), which has a very much lesser impact on the environment

compared to other fossil fuels.


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REFERENCES

Zimmerman, Michael. “Environment”. Microsoft ® Encarta ® 2009 [DVD].

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William P. Cunningham, Mary Ann Cunningham, Barbara Woodworth Saigo.

Environmental Science: A Global Concern. 8th Edition. The McGraw-Hill

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https://en.wikipedia.org/wiki/carbon_footprint

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https://en.wikipedia.org/wiki/catalytic_converter

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