The energy systems of the future will probably require storage capabilities for medium and long term energy storage. One of the options is the conversion of (excess) electricity into a chemical energy carrier called an electrofuel. We interviewed Ning Yan, assistant Professor at Van ‘t Hoff Institute for Molecular Sciences (HIMS).
When we want to convert excess electricity to hydrogen for storage, what are the main technologies that can be used for this conversion?
The most straightforward approach is the electrolysis of water. By passing an electric current through the water, we can split it into oxygen and hydrogen.
What would be the advantages of hydrogen for energy storage?
Hydrogen has one of the highest energy density values per unit mass, higher than conventional fossil fuels. Besides, converting hydrogen back into electricity does not generate greenhouse gases or pollutants.
And what are the disadvantages?
Because the hydrogen molecular is so small, light and highly flammable, the efficient and safe storage of hydrogen is challenging. Besides, converting excess electricity to hydrogen via electrolysis is not very efficient either.
At some point the hydrogen will have to be converted back to electricity. Which technologies are available for this process?
Fuel cells are perhaps the best technology. They are electrochemical devices that enable direct conversion of hydrogen into electricity with high efficiency.
What would be the efficiency of the whole cycle from electricity to hydrogen to electricity?
This depends on the type of the applied electrolyzer and fuel cells. Typically, the practical efficiencies for both electricity-hydrogen and hydrogen-electricity conversions are around 50%, making the whole-cycle efficiency equal to 25%.
Do you expect that there is much room for improving this efficiency?
Considering that the theoretical efficiency for both processes is much higher, I would say that there is yet much room for improvement.
Has the principle of storing hydrogen for energy been applied on an industrial scale?
I would say Yes and No. A number of automobile manufacturers have launched their fuel cells powered cars. These vehicles are fuelled by hydrogen which is stored in the pressurized tank. Nonetheless, storing excess power from the grid in the form of hydrogen on an industrial scale has not been implemented yet.
How does hydrogen energy storage compare to battery storage in terms of energy density, efficiency and cost?
Compressed hydrogen has much higher weight energy density than typical Li-ion batteries (can be up to 100 times). The cost for storing of hydrogen is also significantly cheaper than most batteries counterparts. Therefore, it is usually believed that the battery is unsuitable for large scale energy storage though it is highly efficient.
If we want to create more complex electro fuels like transport fuels, which ones show the most promise?
In addition to hydrogen, hydrocarbons, such as methane, methanol and formic acid also show promise as transport fuels.
What are the technologies that can be used to create these fuels?
Conventionally, all these fuels are synthesized from syngas, a mixture of carbon monoxide and hydrogen. Electrochemical and photo electrochemical reductions of CO2 are also viable approaches for such synthesis.
Which carbon sources could be used for these processes? Is it for instance possible to use CO2 from point sources as a feedstock?
Natural gas, biogas and syngas are all possible feedstocks. Recently, CO2 has attracted much attention as a sustainable carbon source. In the laboratory, researchers have successfully converted CO2 into fuels with help tailored catalysts. However, the high energy cost associated with the CO2 capture and conversion prevents its practical use as the feedstock at the moment.
Can you mention one or more research projects at HIMS in the area of electro fuels?
In the Sustainable Chemistry Research Priority Area program at HIMS (www.suschem.uva.nl), we have a number of projects focusing on the sustainable synthesis of such fuels. For example, my team are now researching carbon and perovskite oxide materials, which are much more cost-effective and abundant than noble metal catalysts, for efficient water splitting. The research team led by Prof. Joost Reek are studying molecular catalyst for the generation of “solar fuels” using the sun light.
Are electro-fuels an economically viable option at this moment for energy storage and transportation fuels or do we need major technological breakthroughs to accomplish this?
Though such electro-fuels are not a good option for energy storage at the moment, I see a bright future for its real-life application if we can increase the efficiency of the conversion using the affordable catalysts.
Research on biodiversity has mostly been performed in small scale controlled experiments. A new study by the Smithsonian Institute and the University of Michigan has researched the effects of biodiversity in the wild. We interviewed Emmett Duffy, the lead author of the study.
Can you tell us how the study on the effects of biodiversity on real world ecosystems was performed?
We searched for all the scientific studies we could find that measured productivity of a natural ecosystem along with the number of species present and environmental factors like temperature and rainfall. Then we used statistical methods to separate and compare the contributions of diversity and environmental factors to productivity.
Did you look at productivity only or also at other ecosystem properties?
We focused on biomass production because this is the ecosystem variable that has been most widely measured and because biomass production is central to so many other ecosystem features such as habitat structure, nutrient cycling, and so on.
What were the main conclusions from the study?
The main conclusion is that the diversity of life forms in an ecosystem is just as important as climate and nutrient inputs in determining its productivity. In fact, biodiversity is even more important in wild nature than expected from experiments, which was a big surprise.
Real world ecosystems are very complex so how did you control for other environmental factors in your research?
In the last decade or so, powerful statistical approaches have developed for cutting through the Gordian knot of complexity in wild ecosystems. As the old saying goes, correlation is not causation, meaning that it’s hard to nail down causes definitively without experiments. Still, because the patterns we found are so consistent with previous experiments and with theoretical predictions, we feel pretty confident they are real.
How does the influence of biodiversity on ecosystem productivity compare to other influences like climate and nutrient availability?
The biggest surprise of this study was that biodiversity appeared to affect productivity just as strongly as climate and nutrients, which are widely considered, master drivers of ecosystem processes. We were all blown away by this – it was really unexpected,
What do you consider to be the explanations for this strong relation between biodiversity and productivity of ecosystems?
There are several possibilities, probably all of which are acting in one situation or another. First species can help one another mutualistically, as plants do with pollinators or corals do with their symbiotic algae. These partnerships have a big influence on how ecosystems work. For example, coral reefs would not exist without that relationship. Second, diversity can provide insurance when conditions change, as they are always doing. Having many species in a system can ensure that at least some of them thrive when conditions change, just as a diversified stock portfolio protects investors from market fluctuations.
Is the effect of biodiversity immediate or do you see a growing impact when the timeline is longer?
We were not able to drill down to that level in our analysis because most of the field studies we found did not include a series of measurements through time. But controlled experiments in both land and marine plant communities indeed show that biodiversity has a stronger influence on productivity through time as the community matures.
What do the finding mean for policy makers?
These results confirm what has been suspected from experiments but never proven in nature: that loss of species can strongly reduce nature’s productivity. This could compromise fisheries, timber production, and other resources we depend on just as human population and needs are growing rapidly. In other words, biodiversity is more than just a pretty face. Having healthy, diversified biological communities is central to the productivity and stable functioning of ecosystems that humanity depends on.
Photo’s courtesy of Emmett Duffy.
Spider silk is a bioactive material with a wide range of medical uses. Researchers at KTH in Stockholm have synthesized artificial spider silk and combined it with nanocellulose to produce hybrid silk fibers. We interviewed researcher My Hedhammar from KTH.
What process did you use to create the artificial spider silk?
Our artificial spider silk is produced using recombinant DNA technology and a lab bacteria.
What are the advantages of this process compared to the alternatives?
This process is simple, cheap and allows control and scalability.
Does the artificial spider silk have the same properties as natural spider silk?
Our artificial silk contains one miniaturized spider silk protein, which makes it more defined and reproducible than natural spider silk. The initial mechanical properties are essentially the same, with high elasticity and strength. However, the artificial silk is not as extendible as natural silk. Since the artificial silk is made from a defined protein solution, it is possible to process it into a wide variety formats e.g. fibers, films, nets and foam. The recombinant technology also allows functionalization of the artificial silk with bioactive domains such as enzymes, growth factors, affinity modules etc.
Can you tell us something about the properties of the cellulose nano fibrils?
Cellulose nano fibrils can be obtained from trees and are thus renewable and available in large volumes. Moreover, they are biodegradable, virtually non-toxic and offer outstanding mechanical properties.
Which technology was used to combine the spider silk and the cellulose nano fibrils?
We utilized a new method for constructing fibers from nano fibrils, based on flow focusing. Since there are favourable interactions between silk and cellulose, it is possible to include a fraction of silk fusion proteins in the process to obtain composite materials.
What are the main properties of the composite?
The silk-nanocellulose composition gives ultrastrong fibers which have specific bioactivities (from the silk fusions) and are also biodegradable.
Can the properties of the composite be tuned by using a different ratio of silk and cellulose?
By the addition of different silk fusions it is possible to obtain a variety of functional materials with specific bioactivities.
What do you consider to be the possible applications of the composite within healthcare?
For example these composites could be used to develop wound dressings with healing and/or antimicrobial properties, or engineering of load bearing tissue.
Do you also see applications outside healthcare?
Depending on the functionality chosen in the silk fusion, it could be used for e.g. biocatalysts, biosensors or affinity matrices.
Are you licensing the technology for commercial use?
The technology is patented by Spiber Technology AB.
There is a lot of attention on the effects of fossil fuels on climate change. But the effects of deforestation and the use of forest lands for agriculture are often overlooked. A recent study by Cornell University addresses the effects of deforestation on climate change. We interviewed the Natalie Mahowald, the lead author for the study.
To put things into perspective, can you give an estimate of the effect of deforestation on the climate?
Right now it is contributing about 40% of the warming we are experiencing. By 2100 it could force a warming of 1 degree.
Which areas have the most deforestation at the moment?
Tropical areas are at most risk for deforestation right now.
What are the main mechanisms between deforestation and climate change?
Deforestation directly releasing carbon dioxide during the deforestation. In addition much of the deforested lands are converted to agriculture or pasture usage, both of which cause emissions of green house gases like methane and nitrous oxide. These contribute to the warming from deforestation.
There is a lot of attention on CO2 as a greenhouse gas, but does deforestation also causes higher emissions of other greenhouse gasses?
Deforestation leads to agriculture and pasture usage in many cases, and both cause emissions of green house gases…
In the study you stress the importance of looking at these effects on a longer time-scale, or multi-centennial legacy of current land-use decisions. Can you explain why this is important?
Solving climate change is a really really difficult problem which will require at a minimum a conversion of our energy sector to sustainable energy extremely fast: potentially faster than can be technically done, but perhaps also faster than is politically feasible. Deforestation, as we show here, and the conversion to agriculture and pasture usage also contributes to climate change. In addition, to avoid the worst of climate change, we also need to remove carbon dioxide from the atmosphere, which we don’t have good technologies for, unless they use a lot of land, which has many environmental impacts, as well as causing climate change themselves. Thus it is likely that we will be dealing with the impact of climate change for a long time: thus understanding the long term implications of land use, which not only causes emissions of CO2 during conversion, as well as the emission during agriculture and pasture usage, but also causes the removal of a long term natural sink of carbon in the forests.
What are the possible measures available to revert the process of deforestation?
Deforestation is a difficult process to control, but understanding that stopping deforestation not only protects biodiversity but climate could bring more resources to bear on the problem. Deforestation can be driven by large businesses but often is driven by individual poor citizens looking for a way to feed themselves. So providing incentives for locals to protect the forests, as well give them a livelihood has been successful approach for protecting forests.
Is it also possible to change our agriculture in a way so that the soil functions more as a carbon sink and emits fewer greenhouse gasses?
Yes, there are ways to make agriculture more sustainable, and these efforts need to be enhanced and incorporated. Most of these approaches also enhance soil fertility so this is a win-win situation.
A new study from the University of Sheffield shows that Perovskite solar cells have the potential to dramatically reduce the energy payback periods for solar cells and can be a game changer in future energy systems. We interviewed Professor Lenny Koh about the results.
Can you explain what Perovskite is and how it can be used in solar cells?
Perovskites refers to a class of materials that share a similar structure, which exhibit a wide array of exciting properties including superconductivity, magneto resistance and many more. Perovskite are easily synthesized materials with distinctive structures which makes them perfect for enabling low-cost and efficient photovoltaic’s, rendering them materials for future solar cells. They are also predicted to play a role in next-gen electric vehicle batteries, sensors, lasers and much more. Perovskite is the mineral CaTiO3, named after L.A. Perovski, a Russian mineralogist and entails all compounds which crystallizes in the same ABX3 structure, where A and B are cations and X is the anion species.
How do Perovskite cells compare with silicon cells in terms of yield and life expectancy?
Currently, with recent improvements in materials design and device architecture performance conversion efficiency (PCE) of > 20% are routinely reported for laboratory-based Perovskite solar cell. Lifespan (i.e. life expectancy) of other existing PV technologies are already well-established, but no exact value in terms of lifespan has been reported for PSC technologies given that they are still at an early research and development phase. On a lab scale, PCE of > 20% was sustained for up 2.5 days for a compact-layer-free planar cell. Similarly, it has been demonstrated that in an instance where a hole conductor- free mesoscopic, PSC exhibit stability across one month at ambient temperature under light source.
What is the energy payback period for Perovskite cells?
Depending on the Perovskite architecture, they offer an ultra-low energy payback period of less than one year.
Availability of resource materials can be a bottleneck for some solar technologies. How is this for Perovskite cells?
Part of the success of Perovskites is due to their ability to form crystals of very high quality rapidly using solution processing methods and moderate temperatures. The material requirements for PSC may depend on critical and precious materials, so consideration of resource materials availability is essential to achieve optimum trade-off which may be needed to meet overall supply chain sustainability.
Can you explain what a hybrid life cycle assessment is?
Hybrid life cycle assessment (HLCA) is a well-established systematic approach used for the identification, quantification and assessment of the associated environmental impacts throughout the entire value chain of an activity, product or process. It has the competitive edge of addressing the limitation of the general approach to LCA, which is termed process-based LCA, which suffers from system boundary truncation, through the augmentation of upstream and downstream inputs within the LCA system in instances where specific process LCA data are lacking. It enhances supply chain visibility, yielding results that are more complete.
What was the outcome of the assessment for Perovskite solar cells?
The main outcomes, presented along with sensitivity analysis, show that PSCs offer more environmentally friendly and sustainable option, with the least energy payback period, as compared to other PV technologies. The analysis presented provide valuable insight and guidance in identifying pathways and windows of opportunity for future PV designs towards cleaner and sustainable energy production.
What do you consider to be the biggest shortcomings of Perovskite cells?
Although PSC benefits from most essential parameters of PV technologies including material and performance parameters, production processes and manufacturing complexity, economics, and key technological challenges for further developments, there exist challenges pertaining to their high proneness to moisture, cell stability and scalability. There are also concerns about how end-of-life scenario such as recycling and decommissioning will influence the environmental impact of PSC due to the toxicity of lead, however improved encapsulation materials can help in addressing this potential shortcoming.
Can you give an estimate of the cost per kWh with a Perovskite cells in the UK?
Given that PSC is still operating on the lab scale, there is currently no information on the cost per kWh of electricity produced by PSC. However, if the PCE values reported so far can be maintained and the issue of scalability is addressed, the cost per kWh will be considerably lower compared to other PV technologies. The cost of fabricating one cell is below 20 cents, based on simple laboratory experiment leading to fabrication of methyl ammonium lead triiodide (MAPbI3) PSC using a simple step-by-step deposition procedure, followed by measurements with routine equipment and it takes 2−5 h.
With the advantages that you mentioned, what is the industry waiting for?
Clearly, the use of expensive materials such as gold and operations such as vapour deposition and spin coating which are energy-intensive will require material substitution and optimisation respectively, to achieve better environmental profile for PSCs. Furthermore, to migrate from lab scale production to large scale industrial production, a number of issues including the use of flexible substrates, ease of deposition, patterning, chemical stability and encapsulation must be addressed. Once all these issues are addressed, then PSC have the potential to revolutionise the PV industry.
Graphics: courtesy of Professor Lenny Koh
E.Coli in drinking water can be a serious health hazard. Researchers at the University of Waterloo have developed a frugal test to test drinking water for E.Coli at a low cost. We interviewed Sushanta Mitra who lead the research and co-founded Glacierclean Technologies, the company that will commercialize the test.
What are the health hazards of E.Coli in drinking water to the individual?
It can cause diarrhea. But more importantly, it is an indicator organism for water quality. If E. coli is present, most likely other pathogens like norovirus etc. are present, which can be very deadly.
Is there a clear view about the causes for E. Coli outbreaks?
Yes, it happens due to faecal contamination by run-off during rainy seasons or cross-contamination between drinking and sewage lines. Also, poor hygiene could be another reason.
How many people are affected by E.Coli worldwide and in which areas particularly?
It can affect billions of people.. 70 % of diseases worldwide are due to water-borne illness. Most vulnerable are the limited resource communities worldwide including those in developing countries.
You developed a paper strip to test for E.Coli. How does the technology to detect E.Coli work?
It is made of paper strip. Paper is a porous material. We apply sugar at the bottom of the paper to attract E. coli (almost fishing bacteria from water). Once E. coli is in contact with paper, due to capillary action both E. coli and water front moves up inside the paper and reach the reaction zone, where we have proprietary chemical reagents that react and produce the colour change.
How accurate is the test?
Currently, we are able to meet the recreational water standards. Work is in progress to meet the US EPA standard for potable water.
You founded Glacierclean Technologies to commercialize the test. When do you expect that the new test becomes available?
It should be available within 9 months. A number of organizations have shown interest in doing field trial with us and we are partnering with them to make our products more robust and field-deployable.
Can you give an indication of the price of the test?
It would be less than 20 cents per test.
What are the other advantages of the new test compared to existing tests?
It is fast, cheap, easy to carry and empowers individuals to have a choice of clean and safe drinking water.
Apart from not drinking the water, what can be done once the E.Coli is detected in the drinking water?
A quick solution is to boil water and also put chlorine tablet. Our rapid detection methods allows individuals to take these measures quickly, thereby avoid falling ill.
Photo’s: courtesy of Sushanta Mitra