//
you're reading...

Alternative Energy

Artificial photosynthesis uses CO2 drawdown for fuel

Reference: Patterson, B.D., Mo, F., Borgschulte, A., Hillestad, M., Joos, F., Kristiansen, T., Sunde, S. and van Bokhoven, J.A., 2019. Renewable CO2 recycling and synthetic fuel production in a marine environment. Proceedings of the National Academy of Sciences, 116(25), pp.12212-12219.

DOI: 1902335116

How would removing CO2 help?

With global fossil fuel emissions, atmospheric CO2 production is drastically increasing with a current value of ~ 400 ppm. Heightened atmospheric CO2 results in higher global temperatures through the greenhouse effect, essentially trapping more and more heat as CO2 emissions rise. Atmospheric CO2 readily diffuses (or dissolves) into surface oceans, therefore the atmospheric CO2 concentration is very similar to the oceanic CO2. As oceanic CO2 increases, another important carbon species (bicarbonate) separates into a carbonate ion and free hydrogen ion. An increase in free hydrogen ions results in a decrease in pH, also known as Ocean Acidification. Several methods can be used to help reduce this effect by removing some of this atmospheric CO2 from the environment (CO2 drawdown). One method, Carbon Capture and Storage (CCS), captures, compresses and stores CO2 in geological features deep underground (IUPAC). While other methods are used to drawdown CO2 to use for fuel, one such method was evaluated by Patterson et al. (2019) to demonstrate the methods efficacy. If global drawdown and subsequent transformation into usable fuel works well enough, it could have a major effect on global atmospheric CO2 concentration and subsequently global climate change.

An artist’s rendering from Patterson et al. (2019) of the ‘floating islands’ of solar panels (photo-voltaic cells) held together by concentric circles of tubing and ropes with a netted floor. The structure is floating and flexible allowing for durability in rough conditions. Methanol production would occur on a separate island or ship. Image Credit: Patterson, B.D., Mo, F., Borgschulte, A., Hillestad, M., Joos, F., Kristiansen, T., Sunde, S. and van Bokhoven, J.A., 2019. Renewable CO2 recycling and synthetic fuel production in a marine environment. Proceedings of the National Academy of Sciences, 116(25), pp.12212-12219.

How do you take CO2 and turn it into fuel?

Taking CO2 from the environment and efficiently turning it into a usable fuel source requires three main steps, 1) Water desalination, (see surprise impacts of desalination post) 2) CO2 extraction, and 3) Fuel (methanol) production, using solar energy and technologies that currently exist. The authors propose using floating islands of solar panels (photovoltaic cells) to absorb energy to drive these processes (see floating island image).

Water desalination is a critical step when dealing with seawater. Without this step the anode used to generate currents to extract CO2 is in competition with a common salt in seawater (chloride) that produces a corrosive chlorine gas. As a result of competition with this chlorine evolution reaction, efficiency of the anode and therefore the overall extraction process decreases. Desalination of seawater only requires 0.063% more energy than freshwater electrolysis. Another consideration during the desalination process is the build-up of insoluble magnesium chloride (Mg(OH)2) and calcium carbonate (CaCO3) that reduce the efficiency of the cathode. Some solutions include deionization or an acidic solution from the anode.

After desalination extraction of CO2 from the seawater can occur. Because seawater CO2 is, for the most part, in equilibrium with atmospheric CO2, extracting CO2 from the seawater will also drawdown CO2 from nearby air. After desalination, extraction of CO2 from the seawater can occur. CO2 can be removed by heating or increasing the acidity of the water. There are several ways to do this relatively easily by manipulating membranes that only allow hydrogen ions (H+) to pass through. CO2 gas then diffuses and is collected using a vacuum pump. Because seawater CO2 is, for the most part, in equilibrium with atmospheric CO2, extracting CO2 from the seawater will also drawdown CO2 from nearby air.

Once the CO2 is extracted it is converted to methanol, a process that occurs more readily with increased temperature, pressure, and a catalyst. There are multiple technologies that can currently do this, therefore, there are multiple production options.

There are many considerations that must be taken into account when building these floating solar panel islands. Wave action must be low enough that the solar panels aren’t frequently damaged in storms. Other restrictions include a maximum depth of 600 m and a low risk of hurricanes. After applying these limitations, only 1.5% of the world’s oceans are viable for these floating islands (see map of areas where these floats could be deployed). However, if every part of the 1.5% of oceans was used for these floating solar panel islands, with a separation of ~ 300 m, the process would remove 12 gigatons of carbon/year, surpassing the yearly emission of CO2. Even though the task seems daunting, creating even a few thousand of these floating islands would make an impact on global carbon emissions and help reduce global warming.

What remains to be answered

The authors do mention a few problems that still need to be resolved before these islands can be produced, including mass production technical issues, construction techniques for long-term durability in the marine environment, and whether or not methanol fuel is the best choice long term. With continued research some of these questions can be answered, and because most of the technology in this paper is already in use, manufacturing these islands could happen relatively quickly. Hopefully this, and many other climate change mitigation technologies can be implemented soon to help reduce our impact on the environment.

Discussion

No comments yet.

Post a Comment

Instagram

  • by oceanbites 2 weeks ago
    Happy Earth Day! Take some time today to do something for the planet and appreciate the ocean, which covers 71% of the Earth’s surface.  #EarthDay   #OceanAppreciation   #Oceanbites   #CoastalVibes   #CoastalRI 
  • by oceanbites 2 months ago
    Not all outdoor science is fieldwork. Some of the best days in the lab can be setting up experiments, especially when you get to do it outdoors. It’s an exciting mix of problem solving, precision, preparation, and teamwork. Here is
  • by oceanbites 2 months ago
    Being on a research cruise is a unique experience with the open water, 12-hour working shifts, and close quarters, but there are some familiar practices too. Here Diana is filtering seawater to gather chlorophyll for analysis, the same process on
  • by oceanbites 3 months ago
    This week for  #WriterWednesday  on  #oceanbites  we are featuring Hannah Collins  @hannahh_irene  Hannah works with marine suspension feeding bivalves and microplastics, investigating whether ingesting microplastics causes changes to the gut microbial community or gut tissues. She hopes to keep working
  • by oceanbites 4 months ago
    Leveling up - did you know that crabs have a larval phase? These are both porcelain crabs, but the one on the right is the earlier stage. It’s massive spine makes it both difficult to eat and quite conspicuous in
  • by oceanbites 4 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring Cierra Braga. Cierra works ultraviolet c (UVC) to discover how this light can be used to combat biofouling, or the growth of living things, on the hulls of ships. Here, you
  • by oceanbites 4 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Elena Gadoutsis  @haysailor  These photos feature her “favorite marine research so far: From surveying tropical coral reefs, photographing dolphins and whales, and growing my own algae to expose it to different
  • by oceanbites 5 months ago
    This week for  #WriterWednesday  on Oceanbites we are featuring Eliza Oldach. According to Ellie, “I study coastal communities, and try to understand the policies and decisions and interactions and adaptations that communities use to navigate an ever-changing world. Most of
  • by oceanbites 5 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Jiwoon Park with a little photographic help from Ryan Tabata at the University of Hawaii. When asked about her research, Jiwoon wrote “Just like we need vitamins and minerals to stay
  • by oceanbites 5 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring  @riley_henning  According to Riley, ”I am interested in studying small things that make a big impact in the ocean. Right now for my master's research at the University of San Diego,
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Gabby Stedman. Gabby is interested in interested in understanding how many species of small-bodied animals there are in the deep-sea and where they live so we can better protect them from
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Shawn Wang! Shawn is “an oceanographer that studies ocean conditions of the past. I use everything from microfossils to complex computer models to understand how climate has changed in the past
  • by oceanbites 6 months ago
    Today we are highlighting some of our awesome new authors for  #WriterWednesday  Today we have Daniel Speer! He says, “I am driven to investigate the interface of biology, chemistry, and physics, asking questions about how organisms or biological systems respond
  • by oceanbites 7 months ago
    Here at Oceanbites we love long-term datasets. So much happens in the ocean that sometimes it can be hard to tell if a trend is a part of a natural cycle or actually an anomaly, but as we gather more
  • by oceanbites 7 months ago
    Have you ever seen a lobster molt? Because lobsters have exoskeletons, every time they grow they have to climb out of their old shell, leaving them soft and vulnerable for a few days until their new shell hardens. Young, small
  • by oceanbites 8 months ago
    A lot of zooplankton are translucent, making it much easier to hide from predators. This juvenile mantis shrimp was almost impossible to spot floating in the water, but under a dissecting scope it’s features really come into view. See the
  • by oceanbites 8 months ago
    This is a clump of Dead Man’s Fingers, scientific name Codium fragile. It’s native to the Pacific Ocean and is invasive where I found it on the east coast of the US. It’s a bit velvety, and the coolest thing
  • by oceanbites 9 months ago
    You’ve probably heard of jellyfish, but have you heard of salps? These gelatinous sea creatures band together to form long chains, but they can also fall apart and will wash up onshore like tiny gemstones that squish. Have you seen
  • by oceanbites 9 months ago
    Check out what’s happening on a cool summer research cruise! On the  #neslter  summer transect cruise, we deployed a tow sled called the In Situ Icthyoplankton Imaging System. This can take pictures of gelatinous zooplankton (like jellyfish) that would be
  • by oceanbites 10 months ago
    Did you know horseshoe crabs have more than just two eyes? In these juveniles you can see another set in the middle of the shell. Check out our website to learn about some awesome horseshoe crab research.  #oceanbites   #plankton   #horseshoecrabs 
WP2Social Auto Publish Powered By : XYZScripts.com