Engineering impact exam

8/11/2019 Engineering impact exam

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Department of Mechanical and Aeronautical Engineering

IMPACT OF ENGINEERING ACTIVITY AND GROUPWORK

MIA 320

Exam

26 NOVEMBER 2013

Examiners

Mr Karl Grimsehl PrEng

INSTRUCTIONS

1. Time: 3hrs

2. Full marks: 120

3. Use side 1 of the answer sheet.

4. Closed book.

5. PLEASE ONLY MARK ONE ANSWER PER QUESTION.

Assessment Criteria Reference Yes No

Does the student show an understanding of the impact of technology

on Society? i.e.: Is the student able to reflect on the importance of

local and global projects on the progression of society?

Questions

15-18

Can the student use his/her knowledge of Occupational Health and

Public Safety and apply this knowledge to a realistic scenario/real life

situation? i.e.: Can the student apply the OHSA to a case study?

Questions

1-10

Is the student aware of the impact of Engineering Work on the Physical

Environment? i.e.: Is the student able to mitigate negative effects of

Engineering activity on the physical environment?

Questions

24-30

Can the student identify the interpersonal effect of Engineering

Activity on a personal, social and cultural level? i.e.: Can the student

identify possible conflicts within a workforce/local community due to

Engineering activity?

Questions

11-14

19-23

SATISFACTORY? YES NO


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General OHSA questions

Question 1

Youve recently been appointed manager of an abattoir in the Western Cape. In the abattoir there is a piece of

machinery that you think might be unsafe to operate.

If you considered the following points,

1)

The severity of the risk associated with the machine.

2) The state of knowledge reasonably available to you concerning removal or mitigation of the hazard.

3) If methods and means to remove the hazard is readily available.

4) The cost of removing the risk.

What, with respect to the OHSA, did you consider?

A. You considered the risk of the machine.

B. You considered the safety of the machine.

C. You considered if it was reasonably practical to remove the risk.

D.

You considered the standard of the machine.

Question 2

You come up with the brainwave to import protective eye equipment from China to sell at a discounted price to

mines in Mpumalanga.

Which statement is true?

A. It is your responsibility to ensure that the product is safe.

B. It is the mines responsibility to ensure that the product you sell to them is safe.

C.

It is the Chinese manufacturers responsibility to insure that the product is safe.D. It is Governments responsibility to insure that the product is safe.

Question 3

You are an OHSA Safety representative. In performing your duties as a Safety officer you noticed a blocked

emergency exit but failed to report it.

Which statement is true?

A. A civil case could be brought against you because you noticed the fault in performing your duties as

an OHSA representative.B. You can be held liable because you noticed the discrepancy in performing your duties as an OHSA

representative, however, if you would have noticed it after hours, you cant be held liable.

C. A civil suit cannot be brought against you.

D. It depends on the scenario.


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Question 4

You own a printing press. An incident occurred where hydrogen peroxide was spilled and two people were injured to

such an extent that they were unable to return to work for a period of two days. According to OHSA what should you

do?

A. Report the incident to an inspector.

B.

Aid the injured employees financially with their recovery.C. A and B.

D. No action is required.

Question 5

You were recently appointed as the OHSA representative for your office building. During a routine inspection of the

fire extinguisher in your bosssoffice you notice incriminating/indiscreet pictures of him and Susan from accounting

on his PC screen. If you dont want to jeopardise your position asthe OHSA representative, what should you do?

A.

Inform your bosss wife.B. Keep quiet because talking about it would be against OHSA.

C. Tell your colleagues.

D. Whichever you feel is the most ethical thing to do, OHSA has nothing to say about this.

Question 6

You own a software developing company, employing 15 people working in an open plan office environment. How

many safety officers should you have?

A. 0

B. 1

C. 2

D. 3

The next few questions refer to the General Safety regulations of 1986 of the OHSA.

Question 7

You own a spray painting company where you do custom paintwork on motor vehicles and motorcycles. In your

company you work with flammable liquids such as Acetone and Turpentine. You own a 1mx1mx1m spray cabinet for

spraying small components and a spraying room with ventilation slits on the side of the room to spray automobiles.

Which of the following statements are applicable to you?

1) You as employer shall provide every employee doing spray work with a respirator, mask or breathing

apparatus.

2) The minimum airflow in the spray room should not be less than 0.3m/s.

3) You can switch off your ventilation system at the close of business each day.

4) The airspeed in your spray cabinet should not be less than 1m/s.

5) You shall not permit any person to smoke in any place where flammable liquids are stored.


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A. 1 and 2

B. 1, 4 and 5

C. 1, 2, 4 and 5

D. All of them

Question 8

When should you give PPE to your employees?A. Always.

B. If there are unsafe conditions.

C. If there is an unsafe condition and it is not practicable to safeguard the condition without PPE.

D. It is the employees responsibility to make sure he has the necessary PPE.

Question 9

After five years in industry you realize that engineering is not for you. In an attempt to find a more relaxed job you

become a general cleaner for a company that produces chemicals. One of your duties as cleaner is to clean the inside

of a dangerous substance storage tank.

With respect to the General safety regulations of 1986, if the air cannot be tested or vented what precautions does

your employer need to take in order for you to clean the tank?

1) All the pipes entering the storage tank must be shut and locked.

2) You must wear an approved breathing apparatus.

3) You must be attached to a rope that reaches beyond the access of the confined space.

4) A person trained in resuscitation must be in attendance immediately outside the entrance.

A. 1

B.

1 and 2

C. 1,2,3 and 4

D. None of the above

Question 10

When is it permitted to fasten two ladders together in order to extend its reach?

A. Always.

B. If the reach of the ladders will not be extended by more than 3m.

C. Only with the approval of an inspector.

D.

Never.

Please read through the following case study and answer the questions

Experts, complex systems and Challenger

Much that has been written in the engineering community on the NASA Challenger accident (28 January 1986) has

focused on the question of engineering ethics.

Did Boisjoly and Thompson, engineers at Morton Thiokol Inc., manufacturers of the rocket boosters, argue strongly

enough that the temperature at the launch site was too cold for the O-rings? Should they have blown the whistle

when they were over-ruled?

Did the engineer-managers act unethically when they recommended a launch in spite of the dangers?In short, would a better appreciation of and adherence to engineering ethics have saved the lives of those seven

astronauts? While the direct answer to this question is probably yes, we would miss some important lessons about


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the nature of technology and the implications for a broader view of engineering ethics if we were to stop our

analysis there.

A closer look at the events and problems surrounding the accident indicates that many things were wrong. The

launching of a space shuttle involves the operation of a very complex system, a system that includes not only

complex hardware, but also a wide range of people. Furthermore, the even larger sociopolitical context often has a

direct impact on the system. In complex systems, single-component failures can occur in unanticipated ways, leading

to or working in conjunction with other failures to produce major accidents.

A narrow view of engineering ethics focuses on single-failure problems; a broader view is needed to deal with the

possibilities of multiple-failure problems. A whole range of problems and failures surrounded the shuttle accident,although not all were immediate issues with a direct connection to the disaster. Taking them one by one:

Cold temperatures

The temperature at the launch site was expected to fall to 10F at dawn on the day of the launch, creating several

problems: the O-rings in the field joints of the booster rockets might be too stiff to seal properly; the water in the

trough used to absorb the shock wave would be frozen; and the pressure transducers in the nose cone were not

rated to give reliable results at that temperature.

The responses to these problems varied: the possible effect on the O-rings was ignored (as will be discussed later);

the troughs were doped with antifreeze and the water was left to run in the hoses to avoid freeze-up; and the

temperature criterion for the transducers was rewritten twice, first to 28F on the Monday and then to 10F on the

actual day of the launch. Allowing the water to run in the fire hoses created a new set of problems: the drainpipes

froze, allowing water to flow all over the launch structure and create sheets of ice and large icicles. This waspotentially dangerous since the ice could have been sucked into the engine during take-off or could have fallen off

and damaged the sensitive tiles on the shuttle.

Field joints

Since the failure of the O-rings in the field joints was found by the Warren Commission be the primary cause of

failure, it has received a lot of media coverage. I will review only a few of the central issues. Erosion of both the

primary and secondary O-rings had become so common by the eighteenth flight that it was considered acceptable

and did not require review after each flight. The manufacturer had the problem closed because they were working

on it. New designs were being considered, but very little had been done to correct the fault. One of the changes that

did occur was an increase in the pressure applied during ground testing. This is now believed to have made this

problem worse.

Hatch closing indicatorA faulty microswitch (indicating that the shuttle door was not closed) eventually led to an earlier launch being

scrubbed. What went wrong was a micro-example of failure in handle of the hatch had to be removed. However, the

threads of the bolts were stripped and could not be removed without drilling. A battery-powered drill carried by the

technicians for this environment was found to have a dead battery. Of the nine batteries eventually sent up as

replacements, only one actually worked. The metal was eventually found to be too hard to be drilled out, so the bolt

was cut off. All this took hours. By the time the problem was fixed, the wind had picked up and the launch had to be

postponed.

Wind shear

While the temperature problem has received a lot of attention, the importance of a large wind shear that day was

not recognised until much later. Some calculations have shown that the wind shear was large enough to exceed the

structural capacity of the rocket. This occurred at 58 seconds into the flight, just before the fatal explosion. While itis clear that the O-rings did fail at the moment of ignition, the failure did not lead to the fatal accident at that point.

It is likely that propellant oxides resealed the joints. The Challenger may have made it had the shear forces not been

so powerful a minute later.

Production pressures within NASA

NASA was on record as saying that their highest priority was to make the shuttle system fully operational and cost-

effective in providing routine access to space. The goal was twenty-four flights a year by 1990 and at least fifteen in

1986. However, this was unrealistic; they had only four shuttles, with enough spare parts for two. Only half of the

$200 million cost per flight was being recovered from fees. Each minute of a shuttle mission requires three person-

years of preparation, with 14 000 people being involved. The pressure to keep on schedule was very high and felt by

everyone; many worked long work weeks with no breaks.

Production pressures within Morton ThiokolUp to this point Morton Thiokol was the sole source of the booster rocket. There was pressure to have open

competition for the contract. They could ill afford to admit problems in design, and could not afford a redesign.


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Storm in the Atlantic

A major storm in the Atlantic had forced the recovery ships for the booster rockets to leave their post. This meant a

loss of $50 million in hardware. Why was the launch not postponed? This becomes clear when we consider some of

the political factors.

Political pressure/involvement

This was present in a number of ways. There is some evidence of conflict of interest and political connection in the

awarding of the contract to the company that designed and built the shuttle. Other designs did not require a low-lift

space glider that had to land on its first try. The decision not to launch on Sunday 26 January had been made

because Vice President Bush would have been able to make the launch but there was fear of bad weather thatwould result in a cancellation, with associated bad publicity. It turned out to be a perfect day for a launch. January 28

was the last possible day to launch if the next shuttle flight was to go before 6 March. This next flight was to carry a

special project to view Halleys Comet. The politicians wanted to scoop the Russian Vega 2, which would send back

its pictures on 9 March.

One other political connection involved the Presidents State of the Union address. The speech was to mention NASA

in connection with the Teacher in Space program. NASA wanted to have the shuttle in orbit to capitalise on the

administrations emphasis on education.

The nature of expert decision making

People who get involved in projects of this nature often demonstrate a very high level of technical skill and tend to

have a can do attitude. In some ways they get wrapped up inthe task for the sake of the task. A sound level of

scepticism does not always accompany these virtues; there is a tendency to take risks and perceive risks differentlyfrom the general public. This is often linked to over-confidence and blind spots due to previous successes.

We see this in how the O-ring erosion problem eventually became acceptable. Sometimes there is long agonising

over whether it is safe to fly with a certain known risk. The decision to go is made and nothing goes wrong. Then

there is a feeling that it was not so risky after all. Next time it will not be so much of a concern.

Sometimes experts have difficulty in handling uncertainty. Evidence is not always conclusive and there is always a

need forjudgement. If a launch was postponed every time any engineer had some doubts, it would probably never

happen. After a while, engineers get used to making decisions with uncertainty. The concern about the O-rings was

another case of uncertainty. Had the managers not been engineers, and consequently accustomed to ignoring some

degree of uncertainty, they might not have been so quick to over-rule their engineer subordinates this time.

In order for the final launch to occur there was a lengthy pre-launch certification process, involving several levels of

command. Often the upper levels were more sceptical than the lower levels. Theoretically this is a good procedure.In reality, however, this procedure was flawed. Lower levels could waive constraints, the details of which were not

communicated to the upper levels. For this particular launch, for example, the hesitation of Morton Thiokol and their

concern about the effect of the cold temperature had not been communicated between Levels III and II in the launch

chain of command.

The above analysis has shown that the accident was due to a number of factors: if only the weather had not been so

cold; if only the design of the field joint had been changed in time; if only the production pressure was not there; if

only there was not pressure for the 6 March flight; if only the managers had not been engineers; if only they had had

more experience with failure; if only the concern had been passed up the chain; and if only there had not been

strong shear winds that day. Charles Perrow, in his book Normal Accidents, argues that multiple-failure systems

accidents are normal for complex, tightly coupled technologies; the failure is to a large degree inherent in the

technology. Perrow distinguishes between component failure accidents, where failure is linked in an anticipatedsequence, and system accidents, where there is an unanticipated interaction of multiple failures that nevertheless

start with component failures.

Space missions are more complex than chemical plants but are less tightly coupled because of the number of built-in

redundancies. (These are back-up devices that provide an alternative action if something fails.) There are, however,

over 700 critical items for which there are no redundancies: failure in any one of these would lead to the loss of a

mission.

Was there a failure due to one or more persons failing to act ethically? All of this analysis is not to excuse unethical

behaviour, but to illustrate the need for a concern wider than that of individual ethics. A broader view would

consider not only the human operators, but also the nature of the technology and the nature of the process of

design and operation of the technology.

Concerning the nature of the process, engineering design and operation are very much human activities. Manager-engineers need to be aware of, and know how to handle, the pressures that affect their work. These pressures can

be political, economic, social or even personal. Multiple lines of communication would help here.


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More deeply, however, as engineers we need to recognise the blind spots inherent in being an expert. Our

perception of risk and uncertainty is affected by our past successes and by the distance we can take from the

consequences of our projects.

Concerning the nature of technology, we need to consider the characteristics that get built in. The tendency for

highly complex and tightly coupled systems to behave in totally unexpected ways has been demonstrated many

times. This is the nature of the system we deal with, so we need to design policies and procedures accordingly. In the

operation of these systems, if anomalies occur we should be careful not to ignore them or rationalise them away;

they may be unexpected interactions, common to complex systems.

In this regard it is important to encourage people to talk about problems they experience; there is a tendency tosuppress unpleasant information. In the risk analysis of complex systems we need to widen our worst case scenarios

to include three or four simultaneous component failures.

Source: Case study contributed by Robert Hudspith, Professor of Engineering, McMaster

University, Hamilton, Ontario. Originally published in IEEE Hamilton (On) Newsletter,

April 1988; many of the problems described are based on McConnell (1987).

References

McConnell, M. 1987, Challenger: A Major Malfunction, Doubleday, New York.

Perrow, C. 1984, Normal Accidents: Living with High Risk Technologies, Basic Books, New York

Question 11

If you were a registered engineer working for Morton Thiokol and you told your superiors that you can solve the

booster rocket dilemma while in fact you have little experiences with booster rockets, which section of the ECSA

code of conduct did you breach?

1. Competency

2. Integrity

3. Environment

4.

Public interest

A. 1

B. 1 &2

C. 1, 2, & 3

D. 1, 2, 3 & 4

Question 12

According to the ECSA code of conduct, a registered person may not without satisfactory reason destroy or

knowingly allow anybody else to destroy information within ____ years of completion of the work concerned.

A. 2

B. 5

C. 10

D. 20


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Question 13

Experts at Morton Thiokol argued about whether or not to inform NASA about their concerns .Which one of the

following sets best describes possible unfairness in this debate:

1. Unequal funding.

2. Domination of the research by a few experts.

3.

Career penalty due to unwelcome advice.4. Secretive administration procedures.

A) 1 & 2

B) 1, 2 & 3

C) 1, 2 & 4

D) 2 & 3

Question 14

An example of induction reasoning is:

A. We havent had an o-ring failure thus the o-ring will not fail on this mission.

B. Space craft are dangerous, Challenger was a spacecraft, and thus Challenger was dangerous.

C. Engineers make decisions under uncertainty and that can lead to the wrong decision being made.

D. All of the above.

Question 15

If we consider Systems Engineering as described in our textbook, the Challenger case study clearly illustrates:

A. How poor management decisions can lead to disaster.

B. How political ambition can interfere with engineering.

C. The importance of emergent properties with respect to the complexity of systems.

D. Environmentalfactors can jeopardize a project.

Question 16

In studying a system, we draw system boundaries. In the Challenger example the system boundaries are:

A.

The space shuttle and rocket boosters.

B.

The space shuttle, rocket booster and the launch environment.

C.

The space shuttle, rocket booster, the environment and the personnel.

D.

We can draw our system boundaries however we want to.


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Question 17

Even though the space shuttle program has stopped, it has given valuable insight into spaceflight.

If the rocket fuel developed in the space program was, after cancelation of the space program, sold to airliners as a

jet fuel this would be an example of?

A.

Market pull.B. Heuristics.

C. Technology push.

D. Inductive reasoning.

Question 18

Inspecting the o-rings at a higher pressure was an attempt at:

A. Product innovation.

B.

System innovation.

C. Process innovation.

D. Program innovation.

Please read through the following case study and answer the questions

Engineering managers have a professional responsibility to shape productive workplaces that are (at the

very least) not damaging for those employed there. This is their common duty as civilised human beings.

It is part of their social and ethical responsibilities, as spelled out in their professional codes of ethics. It

is a prerequisite for the quality production that is now essential to the success, and even the survival, ofmanufacturing and other enterprises. It is also a legal requirement, and failure to address harassment

issues promptly and effectively can leave a supervisor open to immediate dismissal and even to civil

lawsuits. This case study presents one American woman engineers description of her own experience,

and her reflections on how the situation in which she found herself should have been handled.

Monday 10:00 pm

How many times have I driven this highway? Fifty? Sixty? As I drive, I begin to reflect on the events of the last few

months. Nine months ago, my supervisor proposed a new assignment. I wasnt too surprised. I had never stayed very

long in one position. Management was moving me quickly through various assignments and I should feel flattered.

This would be the fourth assignment in four years, three of them in different departments. When my supervisor

described it, however, I was a little overwhelmed. It involved a substantial increase in responsibilities and exposure.

I would be design-responsible for a major component in the redesigned version of the highest-selling automobile my

corporation manufactured. From a monetary viewpoint, this represented $45 million per year at manufacturers

cost. The vehicle was being launched in a few months. On the bright side, the component was very similar to a part I

had worked on before. But when I took that assignment, the vehicle had already been in production for two years.

The major problems were solved and I was fine-tuning the design. Now I would be responsible for taking the

component into production. I needed to learn the design quickly. I travelled right away to the main vehicle assembly

plant to watch the last few cars of the pilot build. In total, three plants would be manufacturing this automobile.

Two were in the Midwest and one was in Mexico. The main or lead plant was only four hours away by car. Since

flying basically took the same amount of time as driving, almost all engineers drove to the plant. Management also

preferred us to drive as it was significantly less expensive. The lead assembly plant was relatively new but was known

throughout the corporation as the most difficult plant. Although labour union and management relations were


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improving in other areas of the corporation, this facility still had its share of problems. This was to be my first

experience working with them and I was apprehensive.

According to other engineers, not only was there an abnormally large rift between union and management, but the

assembly plants relationship with central engineering was also strained. I was very familiar with the other Midwest

assembly plant, since I had worked there for a year and my last component was built there. I was glad I already knew

those contacts and I enjoyed working with them. By and large, union, management, plant engineering and central

engineering enjoyed a good working relationship, and hierarchy was not an issue. The third assembly plant, in

Mexico, built a number of different vehicles. Because of its location, the plant was largely self-sufficient.

They were well known throughout the corporation as very co-operative and they usually tried to solve their

problems before contacting central engineering. My first visit to the facility was scheduled a few months away. As far

as allocation of production volumes, the majority of the redesigned vehicles would be built at the lead assembly

plant. That was the only product they would manufacture and they had the final say in any production or design

decisions for all three assembly plants. In Mexico, the redesigned vehicle amounted to approximately half of their

total production but most of their production was for the local Mexican market.

I was told that central engineering in Mexico controlled the local market cars and I was responsible for the relatively

few vehicles to be imported into the United States. Finally, in the second Midwest plant, the redesigned vehicle was

a small fraction of their total production, filling in capacity gaps. In order to ease the burden on central engineering,

the start-ups at the three facilities were staggered. First was the lead plant in the fall, next Mexico a few monthslater and finally the second Midwest plant in the spring. The start-up at the lead plant was long and painful. A certain

degree of pain is expected during all vehicle start-ups. I expected to work long hours and I wasnt disappointed.

Starting in September, I would usually work Monday at the office, drive to the plant Monday night and work 1214

hours per day, Tuesday through Friday. Working Saturday was common.

Every month, I would also travel to Mexico for a week. In Mexico, the start-up was progressing much smoothly.

Because the start-up in Mexico was later than at the lead plant, Mexican engineers travelled to the Midwest to

watch and learn. This helped accelerate their learning curve. The start-up at the second Midwest plant was not

planned for another six months. It soon became apparent that my component was causing installation difficulties. In

an effort to empower the assembly workers, an Andon system, or stop -cord, was installed on the assembly line

prior to the model change. If assembly workers experienced difficulty in their job or noticed a quality problem, theycould pull the cord and stop the line.

The area where my component was installed had the cord pulled frequently. When I started to look at a redesign, I

found I was at a disadvantage because I did not originally design the component. I had to find out why certain

decisions had been made and investigate all the build variations of the vehicle. Fortunately, my supervisor asked

another engineer in our group to help me; he was also responsible for a component in the same vehicle. We started

sharing rides to the vehicle assembly plant. This made travel easier, but the extra responsibility of the redesign

added Sundays to our work routine. So many problems and not enough time. Since the redesign would take many

months, a short-term solution had to be implemented first.

There was considerable pressure on each engineer to fix their problems quickly since the assembly line was downmore often than running. In addition, the slow start-up was starting to make national news. Consequently, I broke

almost every purchasing rule in the book, chartered airplanes to fly material to the plant and reworked material

inside the plant. This relieved some of the build difficulties, but inherent design problems existed and a totally new

design needed to be found. The months flew by. There was also one other problem that was nagging me: the

constant harassment at the vehicle assembly plant.

Being a young, female engineer, I had anticipated this. In my previous assignments, I had worked at another

Midwest assembly plant for about one year. When I started there, catcalls were common, but as the months wore

on and the assembly workers started to know me, the harassment eventually ceased. I found that my love of

meeting people and talking to them helped significantly to combat the harassment. In the plant, I quickly learned

that the people building the cars carried the essential knowledge. Whenever I heard about a problem from the field,I immediately went to the assembly line to talk to the workers. I respected them and they eventually began to trust


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and respect me. But it wasnt working at this assembly plant. In fact, the harassment was getting worse. It was as if

the entire plant was playing a cat-and-mouse game with me.

When I walked with my male colleague, no one bothered me, but when I was alone the harassment was inevitable.

The insults ranged from catcalls to one man that stalked and stared at me and a supervisor that liked to touch me. I

sat down and talked to my supervisor about the harassment a month ago. He suggested that I yell back at them.

Well, I was not going to even try this. Last week, I told my supervisor that yelling at people did not fit my personality.

I couldnt do it. He then suggested that I ignore it. I become conscious of driving again. My hands are gripping the

steering wheel tightly. At least they arent shaking. In order to support my extended working hours, my caffeineintake has increased significantly. That is why my hands shake. I hate to talk about the harassment.

I am receiving management praise for the redesign and I look like a hero. I am trying every trick I can think of to

deter the harassment on my own: I wear absolutely no makeup, very baggy pants, shirts buttoned to the very top

and my hair pulled back. I know I look terrible. In fact, my supplier asks me if I am sick. My supervisor also confirms

that my dress should not invoke harassment. What else can I do?

Tuesday 3:00 pm

I have only been in the plant for eight hours but I cant take it. Today three workers circled me and started barking

like dogs. I left the plant floor and went to the plant offices. I couldnt stop the tears. I feel really embarrassed and I

sense that the other engineers are embarrassed for me also. So Im leaving. Im going to just drive four hours back tothe office.

A few weeks later

Im driving again on this road to the assembly plant. Im starting to hate this road. I talked to my supervisor again

yesterday. I told him that Im really tired. I cant get out of bed in the morning and my hands are shaking a lot. I

frequently come in late to work. He said he doesnt mind. He said, You get as much accomplished in half a day as my

other engineers do in an entire day. I guess that should make mefeel good. Im a hard worker. At the office, there

have been a lot of complaints and rumours. Other engineers are starting to voice their frustrations concerning the

strained working environment at the lead plant.

This makes me feel a little better, since I no longer feel like I am the only person experiencing abnormally high levelsof stress. Also, it seems that all the engineering changes are not helping the line speed ramp-up at the lead assembly

plant. People are starting to wonder if all the cord pulling is really necessary. I know that a lot of people were laid off

at the lead plant prior to start-up because the redesigned model required fewer man-hours to build. Was the

excessive cord pulling a labour initiative to pressure management to rehire some of the laid-off workers? On the

other hand, the plant in Mexico was running smoothly.

Several weeks on

I blew up at my director, my supervisors boss, today. He asked why Ive been so quiet. I said I didnt care if the lead

assembly plant was blown into a million pieces. He had a look of shock on his face. I asked him if my supervisor had

told him about the harassment. He said no. How could he not tell him? Ive been talking about this for months.

Afterwards, I went to talk to an acquaintance of mine. She was a manager in engineering but now she is a managerin an assembly plant. I thought she might be able to tell me what I can do differently to curb the harassment. Instead

she was very upset. She said I should have said something earlier. I said I did.

What could I have done differently?

if action wasnt taken immediately, talked to an engineering manager one level up

about my supervisor;

talked to someone in the Personnel department;

not let it go on for so long;

reprioritisedput my health ahead of work;

trusted and listened to myself. What was going on was wrong and it was not my fault.


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Question 23

Why, according to our textbook, can we classify the female engineer as a professional?

1) Shes got extensive intellectual training.

2) The occupation she chose has a degree of autonomy and self-regulation.

3) There are high wages in her profession.

A. 1 & 2

B. 1 & 3

C. 2 & 3

D. 1, 2 & 3

Opportunities and challenges for a sustainable energy

future

Steven Chu&Arun Majumdar

Nature, 488,294303, (16 August 2012),

http://0-www.nature.com.innopac.up.ac.za/nature/journal/v488/n7411/full/nature11475.html

Abstract

Access to clean, affordable and reliable energy has been a cornerstone of the world's increasing prosperityand economic growth since the beginning of the industrial revolution. Our use of energy in the twentyfirstcentury must also be sustainable. Solar and waterbased energy generation, and engineering of microbes to

produce biofuels are a few examples of the alternatives. This Perspective puts these opportunities into alarger context by relating them to a number of aspects in the transportation and electricity generation sectors.It also provides a snapshot of the current energy landscape and discusses several research and developmentopportunities and pathways that could lead to a prosperous, sustainable and secure energy future for theworld.

Main

The industrial revolution began in the mid-eighteenth century, and provided humans with capabilities wellbeyond animal and human power. Steam-powered trains and ships, and then internal combustion enginestransformed how people moved and produced goods around the world. Electrification and relatedtechnologies continued the revolution in the nineteenth and twentieth centuries. Today, a growing number of

people keep their homes warm in the winter, cool in the summer and lit at night. They go to the local marketin cars with the power of over a hundred horses and fly across continents in wide-body aeroplanes with the

power of a hundred thousand horses. This power is derived largely from our ability to exploit fossil sourcesof energy. However, in the transition from human and horse power to horsepower, the carbon emissions thatresult from the equivalent of over a billion horses working continuously have created significant climate-change risks.

At the beginning of the industrial revolution, the population of the world was 700 million. Today, thepopulation is 7 billion and is estimated to grow to 9 billion by 2050, and about 10 billion by 2100 (ref.1).Most of this population growth will be in Asia and Africa, where rapidly rising economic growth will placeadditional demands on energy supply. The International Energy Agency (IEA) based in Paris has projectedthat the world's energy demand will increase from about 12 billion tonne oil equivalents (t.o.e.) in 2009 toeither 18 billion t.o.e. or 17 billion t.o.e. by 2035 under their 'current policies' or 'new policies' scenarios,
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respectively2. Carbon-dioxide emissions are expected to increase from 29 gigatonnes per year to 43 Gtyr1or 36 Gt yr1under the current and new policies, respectively. The actual path we follow will depend onhow efficiently and effectively we use existing and new sources of energy.

The world needs another industrial revolution in which our sources of energy are affordable, accessible andsustainable. Energy efficiency and conservation, as well as decarbonizing our energy sources, are essentialto this revolution. Reducing carbon emissions on the timescale needed to mitigate the worst risks of climatechange will not be driven by our inability to find cost-effective sources of fossil fuels. Despite the significantgrowth in the use of renewable energy, the fractional sum of non-carbon- emitting sources of energy thatremained constant during the past two decades is sobering (Fig. 1).

Figure 1: Statistical review of world energy.

a, Fossil energy comprises roughly 86% of the world's main energy consumption. Although the consumption of oil has increased

by 31% between 1980 and 2008, the known reserves have increased comparably owing to improvements in exploration and

extraction technologies. Much of the world's shale-gas reserves are not 'proven' and are not included. The fractional sum of

non-carbon emitting sources of energy remained constant during the same time period. b, Growth of renewable energy was

offset by the decline in nuclear power generation. Renewable energy sources in power generation grew by 17.7%. Wind

generation (25.8%) accounted for more than half of renewable power generation for the first time. Renewables accounted for

3.8% of global power generation, with the highest share in Europe and Eurasia (7.1%). Adapted with permission from ref. 72.
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Energy systems can be divided into transportation and stationary. The supply, demand and distributioninfrastructures within each system are highly coupled, but are currently largely independent of each other. Inthis Insight, the Reviews focus on specific subareas of biofuels, solar electricity generation, and electricitygeneration from salinity gradients and waste water. The systems discussed are largely at the research anddevelopment stage, and are not yet ready to displace more mature sources of energy. Nevertheless, weshould be constantly looking for innovations that make a marked improvement on today's approaches or

provide an entirely new approach. To place the topics discussed in the Reviews in context, this Perspectivediscusses transportation and stationary power systems, and indicates how the topics discussed in theReviews fit into the energy landscape.

Many important and challenging research areas have the potential to significantly affect our future energyneeds. For example, energy efficiency and the integration of energy sources with electricity transmission,distribution and storage are vitally important, but these are only briefly mentioned in this Perspective.Excellent reviews of these topics include the National Academies' report America's Energy Future3and theUS Department of Energy's (DOE's)Report on the First Quadrennial Technology Review4.

Transportation

Petroleum-derived liquid fuels are the overwhelming source of energy in the current transportation

infrastructure. The geographical distribution of petroleum resources is changing as reserves are found andaccessed with improved technologies for discovery and production. However, this distribution of oil supplygenerally does not coincide with where the demand is located. For example, many countries import oil at anunprecedented scale, which can lead to significant balance-of-trade and national-security challenges. In2011, about 2.690 billion tonnes of oil were consumed; of this, 1.895 billion tonnes of crude oil and 0.791

billion tonnes of refined products crossed national borders5and significant discoveries of oil, natural-gasliquids and natural gas could potentially alter the global-energy landscape6.

We will review some of the opportunities and challenges related to transportation technologies. Forexample, most of the future infrastructure of the world will be built in locations where we have the greatestopportunity to transition to sustainable mobility. Desirable and affordable public transportation that is fullyintegrated into urban planning7,and the use of information technologies to assist and displace transportationcan significantly reduce fuel consumption, but are not discussed in this Perspective.

The Quadrennial Technology Review (QTR) of the US DOE provides a broad overview of state-of-the-arttechnologies and opportunities for future research8. Improvements in energy efficiency of vehicles cangreatly reduce oil dependency. These improvements include increased use of light-weight materials, such asadvanced ultra-high tensile strength steels, aluminium and magnesium alloys, polymers, and carbon-fibrereinforced composite materials9.The integration of lighter weight materials is especially important if morecomplex parts can be manufactured as a single unit. The potential for reducing the weight of vehicles hasalready been shown, and in the next 1020 years, an additional 2040% reduction in overall weight, without

sacrificing safety, seems to be possible10

.For every 10% weight reduction of the vehicle, an improvement infuel consumption of 68% is expected11.

Reducing energy losses as a result of friction is also possible12(Fig. 2). Advances in cost-effectivetechnologies such as tribology, tyres, braking and waste-heat energy recovery, and aerodynamics could

potentially lead to efficiency improvements of 20% in the short term and more than 60% over a longer term(1525 years).

Internal combustion engines

The internal combustion engine using liquid-transportation fuel (or liquid ICE) will probably continue tohave a major role over the next few decades. However, improvements to the efficiency of the liquid ICE are

possible because the efficiency of most spark-ignition engines is typically 2535%, whereas that forcompression-ignition diesel engines is about 4050%. With direct injection, lean burn and turbochargertechnologies, the spark-ignition ICEs operating on premium octane ratings can approach diesel efficiencies.
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The combination of in situ measurements of prototype ICE designs with detailed simulations, which aremade possible with high-performance computers, are increasing the energy efficiency and have loweredemissions13, 14. Finally, low-cost waste-heat recovery can increase efficiency, especially in heavy-dutyvehicles. Approaches include use of the Rankine cycle to convert waste heat to work, and the developmentof low-cost and high-efficiency solid-state thermoelectric systems15.

Figure 2: Vehicle energy losses.

Of the energy that fuel provides to vehicles a substantial proportion is lost. A breakdown of the average losses of internal-

combustion-engine cars (fleet make up 70% petrol and 30% diesel) is shown. Heat lost constitutes 3037% of the energy as a

result of exhaust gases with lower energy content and convection. The other losses come from heat dissipation (2533%),

mechanical losses (3340%), air drag (312%), rolling friction (1245%) and brake losses (about 5%). These losses mean only

about 21.5% of the energy is used to move the car. Adapted with permission from ref.12.

Battery-based electrification

Plug-in hybrid and all-electric light- and medium-duty vehicles have the opportunity to displace a significant

amount of liquid fuel use in transportation. The main challenges are performance and cost of the batterysystems. The performance of battery systems is quantified by usable energy density, power density(including fast charging), cycle lifetime and robustness. In the past 56 years, a remarkable amount of

progress in research has been made in battery cathodes, anodes and electrolytes. Large volumetric changesin the electrodes have led to designs in which micro- or nanostructures are embedded in a conducting andflexible matrix to allow for the relief of mechanical stresses. State-of-the-art batteries based on graphiteanodes and lithium-manganese-oxide composite cathodes for lithium batteries are being commercialized 16.Within the next few years, battery system packs of 200 Watt-hour kg1at a charging rate of full charge in 3hours, which is double the current cell-energy density, are expected to become available. The current

production cost of a vehicle battery is estimated to be US$650 kWh1of usable energy storage, but this isexpected to drop to below $150 kWh1by 2030 (ref.17).

The US DOE is supporting a research and development effort that would allow a four or five passengerplug-in hybrid electric vehicle (PHEV) or an electric vehicle with about a 160-km range to be competitive as
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a mass-market ICE car within a decade. The US DOE EV-Everywhere challenge for PHEV, will require thecost of the battery system to be reduced by an estimated $190300 kWh1, depending on whether the car is aPHEV or an electric vehicle. The development of anode-protecting materials and non-flammableelectrolytes that are stable at high voltage and tolerate 55 C are desired characteristics of third-generationlithium-ion batteries. Developing batteries beyond lithium-ion batteries, such as lithium-sulphur and metal-air batteries, could achieve up to ten times the energy density of the current lithium-ion batteries, butmaterials research is needed to develop anode and cathode protection, as well as non-flammable electrolyteswith electrochemical stability over a large potential range.

Battery packs typically use about 50% of the total battery capacity, and the charging rates are limited toincrease the lifetime18.If sensor technologies are developed that can continuously monitor the properties ofindividual cells, such as internal impedance, temperature and state of charge, the lifetime and useful capacitycould be improved. Standardized battery cells that are designed to be integrated with the original equipmentmanufacturer's thermal management systems could also reduce cost19.

Fuel-cell-based electrification

The high efficiency of fuel-cell-powered electric vehicles makes this form of electrification a potentiallyviable option for the future. Investment in this technology is driven by the potential of extended range and

faster fuelling times of moderately low-priced cars. Fuel-cell cost has been lowered and their lifetimeincreased20, but further gains are needed. Platinum-group catalyst loading has been reduced fivefold since2005; however, further reductions are needed4, 21, or these catalysts need to be replaced with less costlyalternatives. Costs can also be lowered and performance improved through robust higher-conductivity andhigher-temperature membranes, improvements in balance-of-plant components, such as humidifiers andcompressors, as well as thermofluid design and control.

There are inherent volumetric energy density issues for hydrogen-gas storage. To achieve a range of 480 km,fuel-cell electric vehicles need to store about 47 kg of hydrogen4, 22. A carbon-fibre-composite tank

pressurized to 700 bar is the best current option for personal vehicles, but this costs 23about $3,000. Researchis under way to develop materials and manufacturing processes to reduce the cost of composite tanks. In

parallel, researchers are searching for lower-pressure storage assisted by high-surface area materials thatcould physisorb or weakly chemisorb hydrogen and still maintain fast-fuelling times24, 25.

The supply infrastructure and a low-carbon source of hydrogen are also a challenge. The technologyadvances in shale-gas production, and the possibility of large reserves in Europe and Asia, in addition to theconsiderable reserves in North America, could have a significant affect on the transportation sector. Inaddition to the direct use of natural gas as a fuel (see later), low-cost natural gas could spur the deploymentof local reforming or hydrogen filling stations for near-term hydrogen production. Alternatively, commercialreforming plants, such as hybrid power plants that produce hydrogen as well as CO 2, for enhanced oilrecovery located near oil-field and refinery sites can serve as an economical source of hydrogen 4, 26. Inregions that are close to a large commercial production plant, delivery to local filling stations can be madethrough high-pressure gaseous tube trailers, but in the long run, a cost-competitive method to producehydrogen with considerably lower net carbon emissions is needed.

Natural gas for transportation

The projected low cost of natural gas in the United States in the next few decades compared with that ofpetrol is expected to lead to wider adoption of natural-gas vehicles. Displacing diesel fuel with liquefiednatural gas (LNG) for class 8 tractor-trailer trucks commonly used on long routes in the United States isalready economically viable because a typical long-haul truck uses about 90,000 litres of fuel per year(about $80,000 per year in fuel costs, today). The incremental purchase price of LNG trucks can be upto $100,000 per truck for cryogenic tanks and related upgrades, as a result of low-volume market conditions.

Even so, the payback period is currently 34 years on a net-present-value basis using a 7% discount rate, andwould drop considerably with even modest increases in production volumes27. Developing a fuellinginfrastructure for LNG long-haul trucks would require fuelling stations about every 240320 km for a truck
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range of 800960 km. Commercial viability is reinforced by plans in the private sector to make the requiredinvestments in infrastructure. LNG-powered freight trains are also being considered.

Compressed natural gas (CNG) has been used for buses, delivery trucks and light-duty vehicles. To makevehicles using CNG economically viable without subsidies, low-cost CNG storage technologies are needed.In the United States, light-duty vehicles account for 75% of on-road fuel consumption. There are roughly160,000 gasoline (petrol) service stations in the United States28;creating a similar nationwide infrastructurefor CNG vehicles would be prohibitively expensive (more than $100 billion). However, about 60 millionhomes in the United States have natural-gas delivery. Economic viability for CNG cars and refuellingsystems can be achieved if the payback period for the additional system-level cost is typically 5 years orless; at present it is about 1015 years for a vehicle with average mileage. For vehicles with high annualmileage and for vehicles with low kilometres per litre, natural-gas vehicles can have less than a 5-year

payback, even today. Research into fibre-matrix composites for high-pressure light-weight tank materials isneeded, as well as into natural-gas sorbents for low-pressure storage. Although seldom discussed, multifuelICEs can be designed to operate on CNG for 30-60 km (the CNGICE hybrid equivalent of a PHEV) andthen switch to petrol. Similar to a PHEV, a CNGpetrolICE vehicle could compensate for the partialcoverage of CNG fuelling stations.

Natural gas can also be converted into liquid fuels using either the FischerTropsch or the methanol process.The capital cost per barrel of liquid fuel reduces with increasing capacity of a FischerTropsch plantaccording to scaling laws. However, with increasing capacity, capital costs are suggested to deviate and arehigher than scaling law predictions, which increases the financial risk for gas-to-liquid plants. Research isneeded to find alternative approaches for exciting the carbonhydrogen bond and synthesizing carboncarbon bonds. Biological approaches that use organisms, such as methanotrophs, that can metabolize naturalgas and produce long-chain hydrocarbons seem worth exploring. Even if this approach is successful atlaboratory scales, it will need to be scalable to large-volume production. Large quantities of methanol arealready produced from natural gas for industrial purposes at costs that are roughly equivalent to petrol.Methanol could be used in a petrolalcohol blend, much like ethanol in the United States. However, pure orhigh-percentage methanol-based transportation could face distribution-infrastructure challenges.

Alternative liquid-transportation fuels

Liquid fuels derived from oil became the main form of energy for transportation largely because of theirhigh energy densities. Associated with their high energy content, the energy transfer rate during vehiclerefuelling is about 6 MW; in contrast, electrical charging will be tens of kilowatts. Apart from inherentlimitations in battery chemistries, there are practical limits to the size of the electrical connector that couldaccommodate megawatt-scale power transfer. However, a search for alternatives to oil for transportationenergy is required to deal with the growing concerns over the rising and volatile price of oil, thevulnerability to supply disruptions, and balance-of-trade issues. Biofuels, particularly those produceddomestically at competitive prices, would strengthen a nation's energy and economic security.

There are a number of approaches to alternative transportation fuels being actively explored (Fig. 3). Theestimated future (1015 year) costs for classes of alternative fuels can vary29(Fig. 4). The US EnvironmentalProtection Agency (EPA) estimates that Brazilian sugarcane ethanol already price competitive with oil-

based fuels in Brazilreduces total life-cycle greenhouse gas emissions, including direct and indirect land-use change emissions, by 61% (ref.30). There are numerous, and sometimes contentious, studies of carbonlife-cycle emissions30, 31, 32. Minimization of indirect land-use concerns and the sequestration of processCO2 could result in net-negative carbon emissions, so that fuel production and use becomes a net carbonsink. On the other hand, if biofuels based on energy-intensive crops were coupled with poor-landmanagement this could result in environmental costs that are far higher than those associated with oil-basedfuels29.
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Figure 3: Methods of producing alternative fuels from various feedstocks to products.

Various feedstocks are being explored, and the pathways for producing energy or fuel investigated. Adapted with permission from

ref.8.

The production of ethanol by domesticated yeast for fermentation is perhaps 4,000 years old. In this Insight,Paralta-Yahya et al.33review the application of metabolic engineering and synthetic biology to altermicrobes for the production of advanced biofuels, and of precursors to drop-in substitutes for petrol, dieseland jet fuels. Static adjustment of transcription, translation and post-translational modifications does notallow engineered organisms to respond to changing bioreactor conditions and cellular changes. Remarkably,dynamic sensing and regulation of fatty-acid ethyl ester (FAEE) intermediates in Escherichia colihas beenshown to increase FAEE yield by threefold, to reduce the cellular concentration of toxic intermediates and tosignificantly improve the genetic stability of producing strains.

Successful commercial-scale deployment of this class of technologies will depend on microbial productivityand robustness. The cost of microbial feedstock is also a major factor: production of advanced fuels fromsimple sugars and starches is further along in the development of these fuels, but it is held back by high

feedstock prices. Lignocelluloses, including agricultural and wood-waste streams, are roughly an order ofmagnitude less costly, and are generally viewed as the end-goal feedstock. Much attention is now focussedon reducing the cost of converting lignocelluloses into forms that are more readily used by microbialorganisms.

The net energy yield per hectare per year is a major factor in determining feedstock cost. The overall yieldfor biofuels varies widely: Brazilian sugarcane can produce as much as 800 gallons per acre-year, which isabout twice as high as productivities based on North American maize. High-yield grasses or fast-growingtrees that could be feedstocks for advanced biofuels have the potential to surpass sugarcane productivities by1.3 times or more34.Most lignocellulosic feedstocks have low-volume energy density: relative to fossil fuelsthey are 'light and fluffy'. To improve the economies of scale of biorefineries, especially thermochemical

refineries, increasing the feedstock collection radius is desirable. Biofuels could become more competitive ifa means of efficiently concentrating the biomass during the harvesting process (such as combining thereaping and pelleting the woody materials) could be developed. The same densification of the feedstock
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could also lead to the biofuel equivalent of grain elevators. Reducing 'first touch' costs are an integral part ofefficient agricultural practice, and progress in this area would significantly lower the overall feedstock costdelivered to biorefineries.

Figure 4: Alternative fuel costs.

Estimated costs, achievable within 1015 years, of alternative liquid fuels produced from coal, biomass, or coal and biomass with

a CO2price of $50 per tonne and capital costs are 20% lower than the America's Energy Future panel's estimates. BTL, biomass-

to-liquid fuel; CBFT, coal-and-biomass-to-liquid fuel, FischerTropsch; CBMTG, coal-and-biomass-to-liquid fuel, methanol-to-

gasoline; CCS, carbon capture and storage; CFT, coal-to-liquid fuel, FischerTropsch; CMTG, coal-to-liquid fuel, methanol-to-

gasoline. Adapted with permission from ref.3.

In this Insight, Georgianna and Mayfield35discuss the use of algae to produce next generation biofuels.Algae can provide high fuel yields, especially if areal sunlight collection can be used to drive volumetricgrowth of algae. However, algal growth in closed systems requires very high capital investments relative toenergy crops such as grasses or trees. In open-pond systems, water use is a major issue but may be partiallyameliorated through the use of species that can grow in brackish or salt water.

Other approaches to bio-based fuel production include the manipulation of photosynthetic bacteria toproduce biofuels, diverting high-energy Calvin-cycle intermediates upstream of glucose for example

energy-dense terpene (a biofuel precursor) production in trees or microbes or developing alternatives toC3and C4carbon fixation.
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Biological enzymes can synthesize carboncarbon bonds with an unparalleled high specificity, butphotosynthesis may not be the only approach to converting sunlight into hydrocarbon fuels36.Several non-photosynthetic alternatives are under investigation that could potentially overcome many of the limitationsof photosynthesis. To appreciate the potential of such approaches, the energy conversion process can bedivided into three steps. First is to identify what reducing equivalents, other than solar photons capturedthrough photosystems I and II, can be accepted by various microorganisms. Several organisms are known to

be capable of growth on hydrogen sulphide, hydrogen, electrons, ammonia and reduced ions such as iron(II). Second is to investigate opportunities to fix CO2using pathways other than those used in C3or C4plants.Potential systems may include the reverse tricarboxylic-acid cycle (often called the reverse Krebs cycle), theWoodsLjungdahl cycle used by acetogens, the hydroxypropionatehydroxybutyrate cycle or newlydesigned biochemical pathways. The final step is to determine whether we can metabolically engineer directcarbon products into a molecule such as acetyl-CoA, which is a precursor for many energy-dense fuels.These three steps can be engineered into autotrophic organisms, an approach that is now being supported bya US DOE Advanced Research Projects Agency-Energy programme called Electrofuels37.

Finally, researchers are investigating highly efficient non-biological energy-conversion approaches thatgenerate fuel from sunlight by the oxidation of water into hydrogen and oxygen and reduction of CO 2tofuel. The Joint Center for Artificial Photosynthesis, a US DOE funded Energy Innovation Research Center,

was established to identify Earth-abundant, robust light absorbers with optimal bandgaps to harvest sunlightmost effectively and efficiently, to accelerate the rate of catalyst discovery for solar energy-to-fuelconversion reactions and to provide system integration and scale-up so that laboratory experiments canquickly transition into prototypes for commercial development.

Clean and affordable electricity generation

The IEA has projected, to 2035, how electricity is expected to be generated 38(Fig. 5). In the agency's newpolicies scenario, the growth of carbon emissions is curtailed, but does not decline. The scenario assumesthat government policies such as carbon pricing are adopted in several Organisation for Economic Co-operation and Development countries and in China, but the projections of cost reduction in renewableenergy are overly conservative. As an example, the agency estimates the full levellized cost of electricity

(LCOE) of onshore wind to be about $90 MWh1 in 2010 real dollars by 2020 (ref.39). Similarly, the USEnergy Information Administration estimates40the LCOE of wind for 2016 will be about $80120MWh1(Fig. 6).

In contrast to these estimates, an analysis of the LCOE of various forms of renewable energy, based on theavailable data from projects in which investment or purchase contracts have been completed 41, shows thatwind at level (class) 4 sites in the United States is currently about $73 MWh 1(Fig. 7). These costs do notinclude transmission line costs, which average42at about $300 kW1. Some experts estimate that by 2020, theLCOE of wind energy at level 4 sites will fall below$60 MWh1. In the United States, utility-scale solar

photovoltaic projects are being installed in 20112012 at an unsubsidized cost of about $150 MWh1(the US

investment tax credit has been taken out

43, 44

), which is consistent with the Bloomberg New Energy Financeestimates41.Utility-scale solar photovoltaics are projected to be between $60120 MWh1in good insolationareas. The lowest LCOE for combined-cycle natural gas is about $5060 MWh1 in the United States,assuming gas costs of $34 per million British thermal units. Although LCOE is an important factor, time ofdelivery, LCOE at various size scales and the potential for energy storage are also important.

Affordable and environmentally sustainable electricity generation is already at cost parity in areas in whichenergy costs exceed $200 MWh1. On the basis of the current and projected learning curves for wind andsolar energy, renewable energy will become increasingly affordable on a global scale. In addition, energystorage with durable and inexpensive batteries will allow electricity accessibility in micro- or meso-scalegrids to leapfrog the need to bring centrally generated electricity to distant rural areas.
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Figure 5: Projections from the International Energy Agency for the generation of electricty until 2035.

In the top panel, the relative energy mix in 2009 and that projected in the International Energy Agency's 'new policies' scenario. In

the bottom panel, in the new policies scenario, carbon emissions continue to grow, but slower than the 2009 fuel-mix curve. The

2009 fuel-mix curve is based on emissions that would have been generated for the projected level of electricity generation were

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