Chemistry

Chemical Reactions: Flying on sunshine

Can we make jet fuel from industrialised photosynthesis?

In this lesson you will explore this question and others such as:

• What molecules are involved in the process of photosynthesis?

• How can the similarities between photosynthesis and syngas production be used to make clean, green jet fuel?

• What is syngas and how is it made?

• What do the public think about alternative energies?

So, let’s take off on a jet propelled investigation into the latest and greatest alternative energy investigation!

This is a print version of an interactive online lesson. To sign up for the real thing or for curriculum details about the lesson go to www.cosmosforschools.com

Introduction: Reactions (P1)

The Sun could be the source of a huge amount of the energy we use here on Earth. But usually when we talk about “solarpower” we mean the electricity that is generated using solar panels that convert the Sun’s energy to electricity.

Now scientists have come up with a brand new way of using sunlight to make fuel to drive aeroplanes and cars, and the inspirationcomes from nature.

Plants convert sunshine to usable energy in a process called photosynthesis. In a process that is similar, scientists have combinedcarbon dioxide and water, driving the reaction with concentrated energy from the Sun, to make carbon monoxide and hydrogen, acombination known as syngas, that can be used to make jet fuel.

At the moment the process is too expensive to be used by airlines, but the important thing is that it has been proven possible. Andscientists are confident that if they made big quantities, it might become a more viable option.

Read or listen to the full Cosmos magazine article here.

Left: The “solar chemical reactor” uses sunlight to split water and carbon dioxide, producing carbon monoxide andhydrogen. Right: Scientists observe the solar reactor in operation. Credit: ETH Zurich.

Question 1

Speculate: Click here and examine the cartoon by Joe Haller. What do you think the cartoonist is trying to convey? Justify why youthink the conveyed message is representative or unrepresentative of public opinion on alternative energy solutions. What is yourown opinion?

Gather: Reactions (P1)

Photosynthesis rap. Pay close attention to the first verse (until 0:42) and enjoy the rest. Credits: Rhythm, Rhyme, Results& YouTube.

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The Cosmos article describes a process of manufacturing jet fuel called "industrialised photosynthesis". The process of normalphotosynthesis can be described using the following chemical equation:

6CO + 6H O C H O + 6O

This reaction can only happen in the presence of light. The compounds on the left hand side of the arrow in the chemical equationare known as reactants. The compounds that result from that reaction are listed on the right hand side of the arrow and are knownas products.

2 2 → 6 12 6 2

Question 1

Relate: Use the text tool below to type the full name of each of the reactants (CO and H O) and the products (C H O and O ) inthe chemical equation that describes photosynthesis.

Hint: The first verse of the rap will help you (0:00 - 0:42).

2 2 6 12 6 2

Question 2

The rap describes the process of photosynthesis in terms of:

sunlight

energy transfer

chemical reactions

all of the above

Question 3

Glucose is represented chemically by the formula C H O

True

False

6 12 6

You may occasionally see photosynthesis described by the following, slightly different, equation:

CO + H O C H O + O2 2 → 6 12 6 2

Question 4

Count: Look at the chemical equation written above in green. Complete the table below by counting how many atoms of carbon (C),oxygen (O) and hydrogen (H) are on each side of the reaction.

Hint: As an example, one molecule of CO possesses one carbon atom (C) and two oxygen atoms (O).2

Atom Number of atoms in reactants Number of atoms in products

carbon (C)

oxygen (O)

hydrogen (H)

Question 5

Compare: Examine the two equations we have seen used to describe photosynthesis so far:

6CO + 6H O C H O + 6O

and

CO + H O C H O + O

What is the difference between the two chemical equations? Which version of the same process do you think better explains theprocess of photosynthesis and why?

2 2 → 6 12 6 2

2 2 → 6 12 6 2

There are a number of different ways to visually represent molecules. The images above represent molecules with "ballsand sticks". The balls represent atoms, while the sticks represent the bonds between them. Try to figure out which ball

colour corresponds with which atom.

CLL_molecule_1.png CLL_molecule_2.png

CLL_molecule_3.png CLL_molecule_4.png

Question 6

Represent: Download the above images of carbon dioxide, water, glucose and oxygen molecules and upload them into thesketchpad below. Use any number of these images along with the sketchpad tools to illustrate the process of photosynthesis, asdescribed by the fully balanced equation:

6CO + 6H O C H O + 6O

Hint: Click the boxed mountains icon to upload an image into the sketchpad.

2 2 → 6 12 6 2

Process: Reactions (P1)

Left: Syngas is a key ingredient for making jet fuel. Right: Energy from the Sun plays a critical role in the syngasmanufacturing described in the Cosmos article. Credit: iStock

Question 1

Explain: The Cosmos article describes the process of manufacturing syngas in the solar chemical reactor by combining water(H O) and carbon dioxide (CO ) to produce carbon monoxide (CO) and hydrogen (H ) and oxygen (O ). Using your experience withworking with the chemical equation for photosynthesis on the previous section, write a chemical equation for this reaction.Remember to start by identifying the reactants and the products and then put them on the correct side of the arrow.

Hint: Use the "Text" tool and the "Add math" button to write your equation.

2 2 2 2

Question 2

Order: The Cosmos article explains the process of creating syngas using sunlight and a metal oxide called ceria. Label the whiteboxes in the sketchpad below with the numbers 2-6 to correctly order the stages of this process. The first stage has been labelledfor you.

1

Energy can be measured in a unit named joules (J). The Cosmos article states that converting solar energy into chemical energy (inthe form of syngas) is only 1% efficient, which is not economically viable. However a long term efficiency goal of 15% would be.Efficiency is calculated using the following formula:

For example, if an appliance uses 200 J of electrical energy to produce 40 J of heat energy, then we have:

Energy out = 40 J.

Energy in = 200 J.

So the appliance is 40 ÷ 200 x 100 = 20% efficient.

× 100 = efficiency (%)energy outenergy in

Question 3

Calculate: Use the efficiency formula above to calculate the efficiency of various current alternative energy processes.

Alternative energy Energy out (J) Energy in (J) Efficiency (%)

Standard solar cell 98 000 537 000

Wind turbine 206 000 000 410 000 000

Biofuel production 150 15 000

For example, 20,000 J of energy could also be written as 20 kilojoules, or 20 kJ. Similarly, 450,000,000 J of energy can be written as450 MJ.

Question 4

Convert: Use the prefixes above to rewrite the units in the table:

Alternative energyform

Energy out (J) Energy in (J)(using prefix given

in the next column)Usethis

prefix

Energy in (J) Energy out(using prefix given in

the next column)

Usethis

prefix

Standard solar cell 98 000 kJ 537 000 kJ

Wind turbine 206 000 000 MJ 410 000 000 MJ

Biofuel production 150 J 15 000 kJ

Question 5

Draw: The Cosmos article lists a number of alternative energy sources such as syngas, the topic of the article, as wellas biofuel and solar energy. Use good internet searching techniques to find examples of other alternative energy options and usepencil and paper to create a mind map about alternative energies. Make sure you identify any links between any of the alternativeenergies if they exist. For example in the article this lesson is based on, solar energy is used to manufacture syngas. Solar energycan also be used to grow plants for biofuels, or used directly to produce electricity in photovoltaic cells (solar cells).

Once you have completed your mind map, photograph it and upload it below.

Drag and drop file here

Scientists use a prefix convention to deal with expressing large numbers like those in the table above. These prefixes are:

kilo (k) = thousand

mega (M) = million

Apply: Reactions (P2)

Research and compose

Credit: iStock and Wikipedia / Pelamis Wave power.

Question 1

Create: Remember back to the original photosynthesis rap? It was written to help explain a fairly complex scientific idea in aninteresting and engaging way. Now it's your turn to write either a rap or a poem about alternative energy. You can use the mindmap produced in the last part of the Process section of this lesson to help target your theme. You could either further research oneof the alternative energies identified in the mind map or write a rap or poem about alternative energy in general. Your targetaudience is your own age group and the intention is to try to encourage your peers to make the switch to sustainable, alternativeenergy forms.

You may write your rap below using the "Text" tool, or alternatively you may record an audio or video recording of your rap and upload it

using the "Files and media" tool instead.

Career: Reactions (P2)

Hundreds of mirrors face upward, tracking the Sun as it moves across the sky, and directing sunlight to a solar tower thatstands nearby. These mirrors are called heliostats, and they help scientists like Dr. Jim Hinkley use sunlight in order to doexperiments with concentrating solar power

As a kid, Jim was always interested in science, but he didn’t knowif he wanted to become a scientist when he finished school. Hestudied chemical engineering at Canterbury University, NewZealand, and eventually he found work at two coal preparationplants in Newcastle, Australia.

After having worked in the coal industry for six years, Jim foundhimself feeling discontent with jobs that stripped Earth of itsnatural resources. Luckily, in his sixth year at the preparationplants, Jim heard that CSIRO Energy Technology was buildingsome world-class solar research platforms nearby. He knew thathe wanted to be a part of the action and work in renewableenergies, so he joined the team right away. At CSIRO, Jim workedon a project that investigated the use of solar energy to heat airto high temperatures, which then makes electricity in a turbinesimilar to a jet engine. He says that “it’s kind of neat to knowthat in some small way I am making a difference!”

One of the most exciting things about Jim’s work is the travel hegets to do. He worked at the German Aerospace ResearchCentre for three months, and is currently working inJapan teaching graduate students about solar heat. In his freetime Jim likes to go skiing in Japan with his family and, when hereturns to work back home in Newcastle, Australia, he loves torow and compete at masters regattas.

Question 1

Imagine: You are sitting in a class where Jim has been teaching you about solar power. What question would you want to ask himabout his career?

Cosmos Lessons team

Education director: Daniel PiklerEducation editor: Bill CondieArt director: Robyn AdderlyProfile author: Megan ToomeyLesson authors: Kathryn Grainger and Hayley Bridgwood