Artificial photosynthesis

/ Winter 2015 / By

[vc_row][vc_column width=”1/1″][vc_column_text disable_pattern=”true” align=”left” margin_bottom=”30″]How can we generate large amounts of power with little to no greenhouse gas emissions? One possible answer: build a leaf. Scientists around the world, including in the U.S., Japan and the European Union, are racing to be the first to develop a stable and economical method of producing energy from artificial photosynthesis — essentially splitting water molecules to produce fuel. Similar to the natural process in plants, artificial photosynthesis uses sunlight, water and carbon dioxide, but instead of producing sugar and oxygen, the end goal is hydrogen. While the technology and necessary infrastructure is decades away from filling your tank with hydrogen fuel, artificial photosynthesis has the potential to unleash a new industrial revolution, powered by a low-emission, plentiful energy source that could be stored and transported, much like natural gas is today. These infographics compare natural and artificial photosynthesis.[/vc_column_text][mk_blockquote style=”line-style” font_family=”none” text_size=”16″ align=”left”]Plants use sunlight and water to perform incredible energy conversions, changing 1,000 BILLION metric tonnes of CO2 into organic matter EVERY YEAR.[/mk_blockquote][/vc_column][/vc_row][vc_row][vc_column width=”1/1″][mk_custom_box border_width=”1″ bg_position=”left top” bg_repeat=”repeat” bg_stretch=”false” padding_vertical=”5″ padding_horizental=”20″ margin_bottom=”0″ min_height=”100″ border_color=”#1e1e1e” bg_color=”#2f5f2f”][vc_row_inner][vc_column_inner width=”1/1″][mk_image src=”https://energy-exchange.net/wp-content/uploads/2015/01/Photosynthesis_Infographic_Background-copy2d.png” image_width=”800″ image_height=”1566″ crop=”false” lightbox=”false” frame_style=”simple” target=”_self” caption_location=”inside-image” align=”center” margin_bottom=”0″][/vc_column_inner][/vc_row_inner][/mk_custom_box][/vc_column][/vc_row][vc_row][vc_column width=”1/1″][mk_custom_box border_width=”1″ bg_position=”left top” bg_repeat=”repeat” bg_stretch=”false” padding_vertical=”10″ padding_horizental=”20″ margin_bottom=”10″ min_height=”100″ border_color=”#1e1e1e”][vc_row_inner][vc_column_inner width=”1/2″][vc_column_text disable_pattern=”true” align=”left” margin_bottom=”0″]If artificial photosynthesis moves from the lab to large-scale commercial production, hydrogen could be used to generate electricity, replace fossil fuels in transportation — which currently accounts for 60 per cent of global oil consumption — and as a feedstock in other industries, such as the production of fertilizer, pharmaceuticals and plastic.[/vc_column_text][/vc_column_inner][vc_column_inner width=”1/2″][vc_column_text disable_pattern=”true” align=”left” margin_bottom=”0″]Like natural gas, hydrogen could be transported by pipeline in gaseous form, or in a cooled, liquid form, which could make transport by road, rail or sea more economical. In liquid form, more potential energy is concentrated into a given volume.[/vc_column_text][/vc_column_inner][/vc_row_inner][/mk_custom_box][mk_padding_divider size=”20″][/vc_column][/vc_row][vc_row][vc_column width=”1/1″][mk_custom_box border_width=”0″ bg_color=”#e4edc2″ bg_position=”left top” bg_repeat=”repeat” bg_stretch=”false” padding_vertical=”20″ padding_horizental=”20″ margin_bottom=”0″ min_height=”100″][vc_row_inner][vc_column_inner width=”2/3″][vc_column_text disable_pattern=”true” align=”left” margin_bottom=”0″]

NATURAL PHOTOSYNTHESIS

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  1. Sunlight and carbon dioxide (CO2) are absorbed from the plant’s leaves, and water (H2O) is absorbed through its roots.
  2. Light energy stimulates chloroplasts, light-sensitive organelles in plant cells, and sets off a number of chemical reactions involving chlorophyll and other proteins and enzymes to split H2O molecules into hydrogen, electrons and oxygen.
  3. The oxygen is expelled; the hydrogen and electrons react with the CO2 molecules to produce glucose.
  4. The glucose becomes fuel for the plant.

[/mk_custom_list][/vc_column_inner][vc_column_inner width=”1/3″][mk_image src=”https://energy-exchange.net/wp-content/uploads/2015/01/nat-photo-image-b.png” image_width=”800″ image_height=”350″ crop=”false” lightbox=”false” frame_style=”simple” target=”_self” caption_location=”inside-image” align=”center” margin_bottom=”0″][/vc_column_inner][/vc_row_inner][/mk_custom_box][mk_padding_divider size=”40″][/vc_column][/vc_row][vc_row][vc_column width=”1/1″][mk_custom_box border_width=”0″ bg_color=”#89c241″ bg_position=”left top” bg_repeat=”repeat” bg_stretch=”false” padding_vertical=”30″ padding_horizental=”20″ margin_bottom=”10″ min_height=”100″][vc_row_inner][vc_column_inner width=”1/2″][mk_image src=”https://energy-exchange.net/wp-content/uploads/2015/01/splitting-water-b.png” image_width=”800″ image_height=”350″ crop=”false” lightbox=”false” frame_style=”simple” target=”_self” caption_location=”inside-image” align=”center” margin_bottom=”10″][/vc_column_inner][vc_column_inner width=”1/2″][vc_column_text disable_pattern=”true” align=”left” margin_bottom=”0″]

SPLITTING WATER

Splitting a water molecule requires about 2.5 volts of electrical energy. As with natural photosynthesis, light energy combined with a catalyst is necessary to get this process moving in the artificial environment. Substances such as manganese, dye-sensitized titanium dioxide and cobalt oxide are a few of the light-sensitive substances scientists have used as catalysts.[/vc_column_text][/vc_column_inner][/vc_row_inner][/mk_custom_box][/vc_column][/vc_row][vc_row][vc_column width=”1/1″][mk_padding_divider size=”40″][mk_custom_box border_width=”0″ bg_color=”#d3e4b7″ bg_position=”left top” bg_repeat=”repeat” bg_stretch=”false” padding_vertical=”20″ padding_horizental=”20″ margin_bottom=”0″ min_height=”100″][vc_row_inner][vc_column_inner width=”2/3″][vc_column_text disable_pattern=”true” align=”left” margin_bottom=”0″]

ARTIFICIAL PHOTOSYNTHESIS

[/vc_column_text][vc_column_text disable_pattern=”true” align=”left” margin_bottom=”0″]Nanowires, conductive and microscopic artificial structures composed of silicon-like materials, and a few thin membranes form the structural “leaf” to create artificial photosynthesis. This is one example of an artificial leaf. Scientists are working with a variety of materials and structures to develop artificial photosynthesis.[/vc_column_text][mk_custom_list icon_color=”http://energyexchange.wpengine.com/wp-content/uploads/2014/04/energy-exchange-favicon.png” margin_bottom=”30″ align=”none”]

  1. Sunlight, water (H20) and carbon dioxide (CO2) are absorbed by nanowires in the surface membrane of the leaf structure.
  2. The light energy excites electrons in a catalyst (see “Splitting water” above), causing a chemical reaction that splits the H20 into oxygen and protons.
  3. The oxygen is released into the atmosphere. The protons and CO2 move through the nanowires and a second membrane housing another catalyst. A chemical reaction occurs between the catalyst, protons and CO2, yielding hydrogen fuel.

[/mk_custom_list][/vc_column_inner][vc_column_inner width=”1/3″][mk_image src=”https://energy-exchange.net/wp-content/uploads/2015/01/art-photo-b.png” image_width=”800″ image_height=”350″ crop=”false” lightbox=”false” frame_style=”simple” target=”_self” caption_location=”inside-image” align=”center” margin_bottom=”0″][/vc_column_inner][/vc_row_inner][/mk_custom_box][mk_custom_box border_width=”1″ bg_color=”#d9d9d9″ bg_position=”left top” bg_repeat=”repeat” bg_stretch=”false” padding_vertical=”30″ padding_horizental=”20″ margin_bottom=”10″ min_height=”100″][vc_row_inner][vc_column_inner width=”1/6″][mk_image src=”https://energy-exchange.net/wp-content/uploads/2015/01/largest-challenge.png” image_width=”800″ image_height=”350″ crop=”false” lightbox=”false” frame_style=”simple” target=”_self” caption_location=”inside-image” align=”left” margin_bottom=”10″][/vc_column_inner][vc_column_inner width=”5/6″][vc_column_text disable_pattern=”true” align=”left” margin_bottom=”0″]The largest challenges facing artificial photosynthesis as a commercial energy source are reproducing the proper chemical processes, finding inexpensive and stable catalysts and protecting the entire system from sunlight degradation. Should technological breakthroughs in efficient hydrogen production occur, new storage and distribution infrastructure will need to scale up accordingly. So will the deployment of new, H2 powered technologies, such as fuel cells (Toyota has just introduced new fuel cell models for sale in Canada and the U.S.).[/vc_column_text][/vc_column_inner][/vc_row_inner][/mk_custom_box][vc_column_text disable_pattern=”true” align=”left” margin_bottom=”0″ el_class=”Story-Author”]— by Michela Rosano[/vc_column_text][vc_column_text disable_pattern=”true” align=”left” margin_bottom=”0″ el_class=”Photo-Caption”]INFOGRAPHIC: CICADA CREATIVE INC.[/vc_column_text][mk_padding_divider size=”40″][mk_button dimension=”three” size=”large” outline_skin=”dark” outline_active_color=”#fff” outline_hover_color=”#333333″ bg_color=”#13bdd2″ text_color=”light” icon=”moon-reading” url=”/resources/energy-exchange-magazine/issue-3/” target=”_self” align=”left” fullwidth=”true” margin_top=”0″ margin_bottom=”15″ animation=”fade-in”]Read more stories from the Winter 2015 issue of Energy Exchange magazine[/mk_button][/vc_column][/vc_row]