Category: Building and Cities

  • Can Sustainable Air Conditioners Stop Global Warming?

    Can Sustainable Air Conditioners Stop Global Warming?

    A recent report from the Australian think tank Breakthrough evaluates global warming as existential threat to human civilization. The report says it is essential to build a zero emissions system. Global mobilization is needed quickly to reduce the risk. While reading this I got very scared. But then I asked myself if there was good news as well?

    I think the good news is that we know how to reduce greenhouse gas emissions that lead to global warming. In his fantastic book Drawdown, Paul Hawken and a team of over 70 researchers from all over the world list 100 solutions to address global warming.

    On place number 1 is refrigeration management, so your air conditioner, fridge, and freezer. The chemicals used to cool the air are greenhouse gases that do harm during production, servicing, when they leak, and especially during disposal. Out of all 100 solutions, refrigeration management can avoid or remove the most amount of greenhouse gases. So let’s look into this. How can we design air conditioners without harmful chemicals?

    This week we are highlighting a team from Singapore. Ernest Chua teamed up with three other researchers from the National University of Singapore. Together they are developing an air conditioner that works without harmful chemicals, in fact, it uses water to cool down the air. Here is how it works:

    The first step is to dehumidify the air by directing it though a membrane. A nice side effect is that they are able to capture the water, which is almost as pure as bottled drinking water. After that, the dry hot air goes through a water-based evaporative cooler. The cold air is then released to the room.

    I’m happy to report that a totally green air conditioner that is chemical free and does not emit heat to the environment is a possibility.

    Ernest Chua at his talk at the World Economic Forum 2019

    The sustainable air conditioner consumes 40% less electricity and can cool a space as low as 18 °C (64 °F). Ernest and his coworkers are now working on iterating their working prototype. There is huge market for air conditioners worldwide. Unfortunately, with raising temperatures, more and more air conditioners are needed.

    What I like most about this project is that is helps in two ways. First, they don’t heat up the environment and second, they don’t use chemical refrigerants. I’m excited about their next steps and hope they are ready to cool down the world soon!

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  • Can Taking a Shower Curb Emissions?

    Can Taking a Shower Curb Emissions?

    As I’m learning more about carbon capture techniques, a Wired article about carbon capture for wastewater treatment caught my eye. While it’s best to safe water when you shower, what can we do with the wastewater we do have? An interesting idea is to use microbes to treat the water as well as capture carbon dioxide.

    Some microbes, like bacteria and microalgae, feed on CO2 itself. So one potential fix would be to replace the typical microbes used in wastewater treatment with these CO2-guzzlers.

    https://www.wired.com/story/the-water-in-your-toilet-could-fight-climate-change-one-day/

    The article is based on a Nature publication. So I checked it out, and now we are getting into more chemistry than I hoped for. Here we go. The authors are looking at different carbon capture approaches while also looking at environmental and economic benefits:

    Outcomes of carbon capture and utilization are clean water and fuels and chemicals, biomass, biochar, or carbonates.
    Capturing carbon with waste water

    Integrating carbon capture and utilization with wastewater treatment may transform energy-intensive, carbon-emitting wastewater treatment plants into integrated water resource recovery facilities that recover energy, nutrients, water and other valuable carbon products with economic, environmental and social benefits.

    https://www.researchgate.net/publication/329656760_Wastewater_treatment_for_carbon_capture_and_utilization

    Here are the five approaches they discuss:

    1. Use microbial electrolysis to enable wastewater treatment, generate hydrogen and mineralize carbon dioxide to carbonates (Microbial electrolytic carbon capture)
    2. Recover electrons from wastewater and reduce carbon dioxide to organic chemicals (Microbial electrosynthesis)
    3. Enrich naturally occurring microalgal communities to take up nitrogen and phosphorus while turning carbon dioxide in biomass (Microalgae cultivation)
    4. Integrate vegetation, soils, and microbial ecosystems to treat wastewater and capture carbon dioxide to plant biomass (Constructed wetlands)
    5. Produce carbon rich charcoal from sludge and other biomass feedstock to provide long term carbon reservoirs and increase fertility in soil (Biochar production)

    In the conclusion they point out all these approaches are early stages, a lot more research and development are needed. But they also highlight the potential:

    Carbon capture and utilization can bring tremendous value to the wastewater industry, CO2-generating industries, and to society as a whole.

    https://www.researchgate.net/publication/329656760_Wastewater_treatment_for_carbon_capture_and_utilization

    What I like most about the article is how it looks at a specific industry and rethinks how that industry can operate carbon neutral or even carbon negative. And while this is early R&D work, they are keeping it real by addressing how these approaches could have environmental as well as economic benefits.