News from the GreenChemBlog
In 2013, the World Bank pledged to stop loaning money for new coal energy projects, unless no financially feasible alternatives exist. President Obama has said the same for the United States, “Today, I’m calling for an end of public financing for new coal plants overseas—unless they deploy carbon capture technologies, or there’s no other viable way for the poorest countries to generate electricity (President Obama, June 25, 2013),.”
In Kosovo a proposed coal-fired power plant has been under discussion for over a decade. The prime funders, ironically, are the World Bank and the U. S. government.
The landscape of energy no longer favors coal. Renewable energy and energy efficiency technologies costs continue to plummet. The World Bank and the U. S. government’s decision to fund this project or not will set a critical precedent for the future of coal financing, making Kosovo the global gatekeeper for new coal projects.
In fact, coal has become an increasingly risky investment in terms of energy, climate, and health. In a recent analysis performed in conjunction with colleagues from the Balkans we have found that the clean energy path is not only better for human and environmental health — it is simply less expensive.
The World Bank and the U.S government now have the opportunity and to set the international energy and climate investment agenda. Distributed renewable energy resources and energy efficiency are simply faster to deploy to meet local needs than the arduous process of building out new centralized coal facilities. Delay on adopting a clean energy policy for the region slows down not only the provision of critically needed energy resources that can spur economic growth, but also the larger process of EU integration, which is a regional priority.
The range of options available to the World Bank to replace an aging coal-fired power plant in Kosovo allows for technological innovation that avoids a one-size fits-all approach. Solar, wind, small-scale hydropower, biomass, and energy efficiency projects can all combine to form a reliable electricity mix and shift the conversation away from single-technology solutions. Not every site may be appropriate for solar, wind, small-scale hydropower or biomass, but winners can emerge based on local conditions. The highly adaptive nature of renewables and energy efficiency investments distributes capital investment risk instead of channeling all resources into coal projects.
New research on the hazards of particulate matter to human health and the environment from low-quality lignite coal intensifies the concern for the current generation of Kosovars. Pollution control technologies that claim “clean” coal are expensive patchwork investments that do not address problems of coal mining, climate change, or ash byproducts. A price on carbon hammers the nail in the coffin. World Bank President Jim Kim has already publicly advocated for the inclusion of a $30/ton carbon shadow price on all proposed World Bank projects. Therefore, it only makes sense that coal, the highest carbon-emitting electricity generation source per kilowatt-hour, becomes the most expensive option among the abundance of low-cost, low-carbon renewables including solar, wind, small-scale hydropower, biomass, and energy efficiency.
The World Bank and the US government face an historic choice and a chance to tip the energy and climate conversation. They can side with the emerging data and studies of clean energy economics to chart a reliable low-cost, and low-carbon pathway to renewable energy and green jobs. Failure to seize the moment would violate the prohibitions on coal projects that each institution has recently pledged. It is time to chart a sustainable path for people in need of energy now.
 World Bank. 2013. Toward a sustainable energy future for all: directions for the World Bank Group’s energy sector. Washington DC ; World Bank. http://documents.worldbank.org/curated/en/2013/07/18016002/toward-sustainable-energy-future-all-directions-world-bank-group’s-energy-sector
 US Treasury. 2013. Guidance for U.S. Positions on MDBs Engaging with Developing Countries on Coal-Fired Power Generation. http://www.treasury.gov/resource-center/international/development-banks/Documents/CoalGuidance_2013.pdf
- Sustainable Energy for Kosovo and Southeast Europe
- SWITCH: A high-resolution modeling tool for the electricity sector
Capturing Chromium(VI): Abby Knight is using a new class of molecules to remove metals from groundwater and blood
“Selective Chromium(VI) Ligands Identified Using Combinatorial Peptoid Libraries.” Knight, A. S., Zhou, E. Y., Pelton, J. G., Francis, M.B. J. Am. Chem. Soc. 2013. 135, 17488–93.Abby Knight, a graduate student in the Francis group at UC Berkeley
Abby Knight is a fifth-year PhD student in the Francis Group at UC Berkeley, and she and Julia Roberts share a mutual acquaintance: hexavalent chromium.
Roberts may or may not remember the chemical’s name, but it was her nemesis in the 2000 film Erin Brokovich, when she played a single mother agitating for PG&E to pay for contaminating her town’s water. Brokovich successfully forced the industry giant to stop polluting, and that was the end of the movie. But that wasn’t the end of the story, because although the chromium was stopped at the source, no method exists to remove what was already in the water. That’s where Knight comes in.
“There’s no good way to clean up chromium contamination in groundwater,” Knight says. “Right now, the EPA strategy is to just say ‘don’t drink this water’ and wait for it to diffuse. “
That’s not an ideal solution, especially when drinking water is in short supply. But it’s very hard to remove a problematic metal, like chromium, from natural waters because they have lots of other ions that get in the way. But Knight was up for the challenge: She set out to come up with a method to selectively remove chromium and other heavy metals from complex solutions—like groundwater, or human blood—while leaving the natural and necessary elements.
Drawing inspiration from within
Knight and her adviser, Matthew Francis, looked to nature for a chemical solution to this problem. They knew humans and animals have naturally occurring proteins that are able to remove small doses of heavy metals from the blood.
“Proteins are kind of your body’s natural therapeutic response to low doses of heavy metal poisoning,” Knight says. Proteins grab on to (chelate), the metal ions and get them out of your bloodstream, but they’re easily degraded by enzymes and so don’t work well for environmental applications. But Knight thought maybe she could use a compound with a similar structure to perform the same function.
She narrowed in on a specific class of molecules called peptoids, a recently invented class of synthetic peptidomimetic (peptide-like) molecules. They are similar to naturally occurring peptides—a backbone of carbon, nitrogen and oxygen with side branches of varying structure attached along the spine—but in peptoids the side branches are attached to nitrogen atoms in the backbone, while in peptide they attach to the carbon.
Knight chose peptoids as her binders of choice for their stability and customizability.
“The scientist who invented peptoids is right here at Lawrence Berkeley National Lab,” Knight says, “So I was able to get a lot of help.” This was important because peptoids are so new that no one else in her lab had ever worked with them before.
Dyeing beads and building a library
Thousands of different peptoids have been synthesized, and there are infinite ways in which they could be modified. To find the best chromium binder, Knight created a library of peptoids with varying side chains. After she built her library, the only way to find out which molecules best grabbed on to chromium was through trial and error.Knight with a vial of her peptoid-coated polyresin beads.
Knight coated small polystyrene resin beads with each peptoid she synthesized. She then added the coated beads to a chromium solution, and painted them with a dye that turns pink when it reacts with chromium. Then Knight and her undergrad research assistant, Effie Zhou, painstakingly removed the pinkest beads—those that had most successfully chelated chromium—and made more of the peptoid on that bead. Then they would test that peptoid again.
Through this iterative process Knight identified a few winners. Then it was time for a real world test. Knight and Zhou collected natural water from Ocean Beach in San Francisco and Strawberry Canyon on the UC Berkeley campus.
Moment of truthWater collected at Strawberry Creek on the UC Berkeley campus was used to test the efficacy of the peptoids
Fortunately, the ocean and creek water in the Bay Area don’t have high levels of chromium contamination, so Knight and Zhou had to pollute the samples of the? water before trying to clean it. They added chromium, in amounts 10 and 100 times higher than the EPA safety limit. After the water was sufficiently contaminated, the beads, armed with carefully selected peptoids, were sent in to do their job. They let the solutions incubate, and then measured the chromium concentrations to see if the peptoids had successfully removed the metal.
The results: 80-90% reduction in chromium concentrations. “We drastically out-performed the commercially available [non-selective] resin,” Knight says proudly.
There is still room for improvement—they started to lose efficiency and selectivity at lower chromium levels. But overall, she says this looks like a very promising method to clean up contaminated water.
A new toolbox
The peptoids were so good at removing chromium from groundwater, Knight decided to apply the same technique to new applications, and new metals. Her next project was getting cadmium out of human blood, and based on her preliminary results with human serum, this application seems succesful as well.
But Knight and peptoids are parting ways. She is graduating in May, and starts a post-doc at UC Santa Barbara in the fall. She’ll be working in the Hawker lab to create new, self-assembling materials. It’s a new problem, with new chemistries to explore, but Knight looks forward to the challenge.
“What I love about the day to day activities of ‘being a scientist’ is the opportunity to find new and creative solutions to problems,” Knight says.
“Iron-Catalyzed C-H Borylation of Arenes” Dombray, T.; Werncke, C. G.; Jiang, S.; Grellier, M.; Vendier, L.; Bontemps, S.; Sortais, J-B.; Sabo-Etienne, S.; Darcel, C. J. Am. Chem. Soc. 2015, ASAP. DOI: 10.1021/jacs.5b00895
C-H borylation, itself a green reaction for generating useful borylated compounds, is traditionally catalyzed by Ir and Rh. Much of the work has been conducted by John Hartwig’s group at Berkeley and Mitch Smith’s group at Michigan St. French scientists have now reported an iron-catalyzed version, which complements recent reports with Co complexes and dinuclear transition metal complexes. I especially like that the reported reaction is free of H2 acceptors and utilizes light to activate the catalyst.
The authors first tested the borylation of ethylbenzene with pinacolborane. The substrate is in excess and serves as the solvent. The optimized catalyst was Fe(Me)2(dmpe)2, where dmpe is bis(dimethylphosphino)ethane, providing the borylated product in 73 % yield after 72 hours at room temperature under 350 nm light as a 68:32 mixture of the meta and para isomers. Interestingly, the dimethyl iron complex provided higher yields of the C-H borylated product than the dihydride (73 % vs 52 %, respectively).
For the scope of the reaction they report the borylation of a variety of alkylated benzenes in moderate to good yields. In addition, their reaction seems to tolerate ether and amine functionalities and they are able to borylate furans.
Mechanistically, they cashed in when they reacted the starting dimethyl complex with pinacolborane directly. The reaction proceeds to form a 1:1 mixture of the cis and trans isomers of the hydrido-(boryl)iron complex Fe(H)(Bpin)(dmpe)2. Interestingly, upon evaporating to dryness the mixture converted to solely the trans isomer, which they were able to isolate as crystals suitable for X-ray diffraction.
Lastly, the researchers performed a series of NMR experiments to elucidate some preliminary mechanistic details. Under catalytic conditions in deuterated toluene or benzene they observed evolution of HD. They also found that the hydrido(boryl) complex was catalytically competent for the borylation. Moreover, in stoichiometric reactions of the hydrido(boryl) complex (under irradiation) they observed formation of the hydrido-phenyl complex. These observations led the authors to propose the mechanism below for the borylation of arenes.
The present work is a good example of extending homogeneous catalysis to the first-row transition metals. Going forward I hope to see better regioselectivity, otherwise the gains in using a cheaper metal will be lost in the purification of the products.
An international panel of scientists has found that endocrine disrupting chemicals likely cost the European Union over 100 billion dollars annually — and American officials say this expense could be even higher in the U.S.
The scientific panel, convened by the Endocrine Society, adopted strategies created by the Intergovernmental Panel on Climate Change to evaluate how much causation of a particular disorder could be attributed to a particular chemical. For example, they found 70-100% probability that polybrominated diphenyl ether (PBDE) and organophosphates contribute to IQ loss, based on previously published epidemiological studies. They then estimated the costs incurred to the European Union from health issues caused by exposure to endocrine disrupting chemicals. The health effects investigated included neurobehavioral disorders, male reproductive health issues, and diabetes, and the total cost was found to be at least 100 billion dollars.
Linda Birnbaum, the top U.S. environmental health official, told National Geographic news that the panel’s findings on endocrine disruptors are a “wake-up call,” and added that, “If you applied these [health care] numbers to the U.S., they would be applicable, and in some cases higher.” Levels of exposure to endocrine disruptors are generally much higher among Americans than they are for citizens of the European Union.
The biggest contributors to cost were the effects of the chemicals on children’s brain development, potentially resulting in attention-deficit disorders and lost I.Q. points.
The scientists released their work in a series of studies published in the Journal of Clinical Endocrinology and Metabolism (and summarized in this National Geographic news article). The studies were conducted at the behest of the European Commission for an impact assessment on the social cost of endocrine disrupting chemicals. The results will be used to inform future E.U. regulations as part of the REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) program and other legislation.
Mallory Pickett is a former chemist and a science journalism student at the UC Berkeley Graduate School of Journalism