Category: Paper of the Month

At Frontis Energy we believe that even in times of hyperactive publishing, there are still gems in the haystack. Here is what we believe matters.

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You Can Have the Pie and Eat It

In Paris, humanity has set itself the goal of limiting global warming to 1.5 °C. Most people believe that this will be accompanied by significant sacrifice of quality of life. That is one reason why climate protection is simply rejected by many people, even to the point of outright denial. At Frontis Energy, we think we can protect the climate and live better. The latest study published in Nature Energy by a research group around Arnulf Grubler of the International Institute for Applied Systems Analysis in Laxenburg, Austria, has now shown that we have good reasons.

The team used computer models to explore the potential of technological trends to reduce energy consumption. Among other things, the researchers said that the use of shared car services will increase and that fossil fuels will give way to solar energy and other forms of renewable energy. Their results show that global energy consumption would decrease by about 40% regardless of population, income, and economic growth. Air pollution and demand for biofuels would also decrease, which would improve health and food supplies.

In contrast to many previous assessments, the group’s findings suggest that humans can limit the temperature rise to 1.5 °C above preindustrial levels without resorting to drastic strategies to extract CO2 from the atmosphere later in the century.

Now, one can argue whether shared car services do not cut quality of life. Nevertheless, we think that individual mobility can be maintained while protecting our climate. CO2 recovery for the production of fuels (CO2 recycling that is) is such a possibility. The Power-to-Gas technology is the most advanced version of CO2 recycling and should certainly be considered in future studies. An example of such an assessment of the power-to-gas technology was published by a Swiss research group headed by Frédéric Meylan, who found that the carbon footprint can be neutralized with conventional technology after just a few cycles.

(Picture: Pieter Bruegel the Elder, The Land of Cockaigne, Wikipedia)

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Mapping Waste-to-Energy

Most readers of our blog know that waste can be easily converted into energy, such as in biogas plants. Biogas, biohydrogen, and biodiesel are biofuels because they are biologically produced by microorganisms or plants. Biofuel facilities are found worldwide. However, nobody knows exactly where these biofuel plants are located and where they can be operated most economically. This knowledge gap hampers market access for biofuel producers.

At least for the United States − the largest market for biofuels − there is now a map. A research team from the Pacific Northwest National Laboratory (PNNL) and the National Renewable Energy Laboratory (NREL) published a detailed analysis of the potential for waste-to-energy in the US in the journal Renewable and Sustainable Energy Reviews.

The group focused on liquid biofuels that can be recovered from sewage sludge using the Fischer-Tropsch process. The industrial process was originally developed in Nazi Germany for coal liquefaction, but can also be used to liquefy other organic materials, such as biomass. The resulting oil is similar to petroleum, but contains small amounts of oxygen and water. A side effect is that nutrients, such as phosphate can be recovered.

The research group coupled the best available information on these organic wastes from their database with computer models to estimate the quantities and the best geographical distribution of the potential production of liquid biofuel. The results suggest that the United States could produce more than 20 billion liters of liquid biofuel per year.

The group also found that the potential for liquid biofuel from sewage sludge from public wastewater treatment plants is 4 billion liters per year. This resource was found to be widespread throughout the country − with a high density of sites on the east cost, as well as in the largest cities. Animal manure has a potential for 10 billion liters of liquid biofuel per year. Especially in the Midwest are the largest untapped resources.

The potential for liquid biofuel from food waste also follows the population density. For metropolitan areas such as Los Angeles, Seattle, Las Vegas, New York, etc., the researchers estimate that such waste could produce more than 3 billion liters per year. However, food leftovers also had the lowest conversion efficiency. This is also the biggest criticism of the Fischer-Tropsch process. Plants producing significant quantities of liquid fuel are significantly larger than conventional refineries, consume a lot of energy and produce more CO2 than they save.

Better processes for biomass liquefaction and more efficient use of biomass still remain a challenge for industry and science.

(Photo: Wikipedia)

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The Photosynthetic CO2 Race − Plants vs. Algae

Algae store CO2 but also release it. Some of us may know that. However, so far it was unknown that algae may release additional CO2 due to global warming. That’s what researcher Chao Song and his colleagues of the University of Georgia in Athens, GA, found out.

As they published in the journal Nature Geoscience, the metabolism of algae and other microbes is accelerated by higher water temperatures in large streams. This could lead to some rivers releasing more CO2 than they do now. This could, in turn, further accelerate global warming. Although photosynthesis in algae would accelerate, plants along the river banks would be even faster. Decomposition of the plant material would immediately release the so fixed CO2. With extra nutrients from plants, competing microorganisms would overgrow the river algae or the algae would degrade the plant material themselves.

To calculate the CO2 net effect, scientists monitored temperature, dissolved oxygen, and other parameters in 70 rivers worldwide. Then they used their data for computer models. These models suggest that over time, accelerated photosynthesis in some rivers may not keep pace with plant growth. This net increase of 24% of the CO2 released from rivers could mean an additional global temperature increase of 1 °C.

However, the computer model still lacks some data. For example, the sedimentation rates are not taken into account. In addition, not all banks grow plants. Many rivers pass only sparsely vegetated land. As always, more research is needed to get better answers.

(Photo: Wikipedia)

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Cobalt Nanocrystals Make Lithium-Ion Batteries Age More Slowly

In todays Li-ion batteries, cobalt oxide cathodes improve performance and durability. While, such cobalt cathodes show the same performance as nickel oxide cathodes, they come at a higher price. Nickel cathodes, in turn, crack and dissolve quickly, which reduces their lifespan. Nevertheless, nickel cathodes are very popular because they are so cheap.

Now, the research team led by Jaephil Cho of the Ulsan National Institute of Science and Technology in South Korea has developed a cathode made of more than 80% nickel. The researchers reported in the journal Energy & Environmental Science that a cathode coated with nanocrystals of cobalt aged more slowly than conventional nickel cathodes. After recharging 400 times at room temperature, the battery was able to retain 86% of its original capacity.

The novel nickel cathodes could help meet the growing demand for rechargeable batteries in electric vehicles if cobalt prices rise in the future.

(Photo: Wikipedia)

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Decarbonizing Planet Earth – Nuclear vs. Renewable

Adding to the controversial scientific debate whether renewable or nuclear energy decarbonize the atmosphere quicker, Lovins et al of the Rocky Mountain Institute in Basalt, Colorado, argue that renewable energy is doing a better job. In their recent study, published in Energy Research & Social Science, they analyzed 17 years of recent energy resource development worldwide to support their conclusion. Their paper stands in contrast to numerous previous studies, including a 2016 report published by Cao et al in Science, claiming that nuclear power is better suited for fast decarbonization. However, the nuclear waste problem still remains unresolved.

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Starting up Power-to-Gas Reactors

In their paper “Effect of Start-Up Strategies and Electrode Materials on Carbon Dioxide Reduction on Biocathodes“, which was recently published in Applied and Environmental Microbiology, Saheb-Alam et al. teach us how to start-up bio-electrical systems for CO2 conversion to methane gas. They compared pre-acclimated with pristine electrodes and found that there is no difference in start-up time. Their findings stand in contrast to previous observations where pre-acclimation has indeed helped to improve reactor performance. For example, LaBarge et al. found that electrodes acclimated with methane-forming microbes, called Methanobacterium, do reduce start-up time.