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Photo of a Lego model of the Danish island of Bornholm

How a New Middleman Might Help Balance Electricity Grids

A few years ago almost two thousand bold households on the Danish island of Bornholm joined a surge pricing experiment run by their electricity utility. It was supposed to empower the utility and consumers with a simple, direct market (“The Smartest, Greenest Grid,” IEEE Spectrum, April 2013).

The EU-funded project, called EcoGrid, won widespread buy-in from residents, who could also earn small payoffs when they reduced demand.  Yet researchers reported last year that they could reduce demand by only 1.2 percent of peak load, despite early predictions of up to 20-percent reductions for so-called virtual power plants. The market model was missing something.

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Smoke pouring from smokestacks

ARPA-E Under Trump

Since the surprise victory of Donald J. Trump on 8 November, the future of United States’ leadership in the emerging clean energy industry has been a subject of speculation. As a climate change doubter and outspoken advocate of the coal and oil industries, the president-elect’s energy policies will undoubtedly represent a bold departure from those of the Obama administration—the most clean-energy-friendly presidency in history. But just what the new president-elect’s energy policies may be and how and when they come into force remains unclear today.

One of the Obama administration’s chief instruments for supporting advances in clean energy has been the Department of Energy’s tech incubator, the Advanced Projects Research Agency-Energy (ARPA-E). As a recent overview report notes, since 2009 ARPA-E has provided $1.3 billion in funding to more than 475 projects in next-generation batteries, grid operations, power electronics, and clean energy. These projects have to date resulted in 36 new companies, and $1.25 billion in publicly-reported, follow-on funding from the private sector. Yet the mandate and perhaps even continued existence of ARPA-E under President Trump is still an open question.

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A German flag with the coat of arms flies in front of a home with solar panels

Germany's Aggressive Switch to Renewables Will Save €149 Billion

The switch to renewables in Germany is saving money and creating jobs, according to a new economic analysis by the international consulting firm PricewaterhouseCoopers (PwC). The report finds that the German government’s 2015-2020 climate action plan and energy efficiency measures will save about 149 billion euros.

Research that appeared last month in Earth Systems Science Data suggested that global carbon dioxide emissions will be growing slowly, thanks in part to reduction moves by China and the United States. Several research projects have that a downturn in the use of fossil fuels in the United States that would come from switches to renewable energy could save U.S. consumers money, but coal’s not dead yet. President-Elect Donald Trump insisted during the campaign season that supporting the U.S. coal industry will help the economy and create jobs. Meanwhile, India plans to double coal production by 2020.

Germany’s goal is to lower its greenhouse gas emissions by 40 percent by 2020. Both the World Wildlife Fund (WWF)  and even Germany’s environment ministry have raised doubts about whether the government can actually reach the target in time, but its proposed measures include using more renewables, improving energy efficiency in buildings, and reducing agriculture or vehicle emissions.

Overall, PwC estimates that 79 specific measures from Germany’s plan will create investments of 125 billion euros in new technology infrastructure, leading to €274 billion in savings—a net savings of €149 billion, Deutsche Welle reports.

The PwC report finds that the energy sector would lose about €10 billion, but other business sectors would save about €84 billion and the state would save about €26 billion; an extra €73 billion would come to the government from related tax revenues. Consumers would end up saving about €25 billion.

PwC estimates that the program will also create 430,000 additional jobs.

All in all, that would be good news for Germany. The federal environment minister said in a press release that the climate action program is kind of like an economic stimulus package.

A security camera is seen outside the Communications Security Establishment (CSE) headquarters in Ottawa January 28, 2015.

Why Do Hackers Love to Attack Canada’s Energy Departments?

New data reveal that hackers compromised systems in Canadian government agencies dealing with natural resources, energy, and environment 2,078 times this year.

Last month, Canada’s Communications Security Establishment (CSE) reported that it had detected 4,571 instances when government systems were compromised by hackers since 1 January. By a large margin, the majority were in natural resources, energy, and environmental agencies. It found less in other areas of government—the next most-targeted sector was industry and business development (with 954) and then government administration (with 387). The statistics are the first of their kind, Globe and Mail reports.

Out of the 4,571 system compromises, the CSE only found three cases where data was “ex-filtrated”—once in the natural resources, energy, and environment sector. It reports that stolen information was unclassified.

“These statistics are a clear indication of the very real threat that exists,” says Canadian parliament member Matt Jeneroux, who requested the data from the CSE.

In the report, the CSE broke down the statistics into 11 sectors, instead of individual departments, because disclosing departments “could provide hostile actors with an understanding of the vulnerabilities of the Government of Canada” and how well the government can detect cyberattacks. Agencies within the affected sector had little to say about the report. Canada’s National Energy Board and Atomic Energy of Canada Limited did not respond to requests for comment. Environment and Climate Change Canada as well as Natural Resources Canada referred IEEE Spectrum to the CSE.

The agencies list some of their responsibilities on their public websites. Canada’s National Energy Board, for example, is involved in energy regulation and evaluation during pipeline or power line projects. Natural Resources Canada, meanwhile, offers policy or helps conduct research in fields from explosives to energy sources and distribution.

The news comes while around the world, electricity grid cybersecurity has become a growing concern. In December 2015, hackers cut off power to over 200,000 people in Ukraine—the first confirmed cyberattack to take out an electricity system. 

The Canadian numbers appear quite high when compared to those available in the United states. A Freedom of Information Act request by USA Today revealed that the U.S. Department of Energy detected 159 successful intrusions between 2010 and 2014. At the time, officials didn’t say whether any data was accessed that related to the operation and security of the U.S. power grid, USA Today reports.

A spokesman for the CSE writes in an email that the CSE will not provide details about “specific cyber threat actors or cyber security incidents,” in order to protect the efficiency of classified cyber-defense methods that secure the government’s networks. However, he writes that the CSE blocks over 100 million attempts to find vulnerabilities or compromise government networks every day. These hacks can come from “hacktivists” acting for political reasons, criminals, terrorists, and nation states.

Jeneroux will consider whether to request further information from the CSE. “It is important that the Government of Canada continue to identify these threats and determine ways to secure our information and protect our national security,” he writes.

A collection of Sanivation's poop-based fuel briquettes

Kenyan Startup Uses the Sun to Turn Human Waste into Cooking Fuel

In August 2015—after a couple of years of testing—a company in Kenya began commercially treating human poop with the sun’s heat to create an environmentally friendly fuel source. This week, Sanivation plans to turn on a new continuous-flow system that will help it scale up to support many more customers than it could previously.

“We can treat thousands and multi-thousands of peoples’ shit continuously,” says Sanivation CTO Emily Woods.

In developing countries, the International Energy Agency estimates that about 2.5 billion people cook with biomass: charcoal from forests, agricultural waste, animal dung, and other sources. In Kenya, charcoal provides about 82 percent of the energy in urban households and 34 percent of the energy in rural households, according to the Kenya Forest Service. Yet its use is leading to major deforestation2013 research found that the demand for charcoal was about 16.3 million m3, but there was only a supply of about 7.3 million m3. Not to mention that the air pollution from inefficiently burning solid fuels such as charcoal can kill about 4.3 million people a year.

One solution to these problems could be switching to cleaner cooking stoves, but some research points out that new technology adoption is difficult. Instead of swapping stoves, changing fuel is another possibility—research by the United Nations University Institute for Water, Environment, and Health concluded that the electricity generated from the world’s collective human feces could power up to 138 million households, for example.

And that’s where Sanivation steps in—providing an alternative cooking-fuel source to local small businesses and restaurants. Woods says Sanivation’s sun-treated poop fuel briquettes can burn two times longer than normal charcoal, yet release about one third of the carbon monoxide and particulate matter emissions. Each metric ton of the briquettes saves about 88 trees yet they are “comparable” in cost even with charcoal’s rapid price fluctuations.

Before this week, the team of about 50 was able to process about 2 metric tons of waste every month in batches. In the new continuous-flow system coming online this week in Naivasha, Sanivation estimates it will be able to process 6 to 8 metric tons of waste every month, decreasing the amount of physical space required for processing, and increasing the number of customers from hundreds to hopefully many more.

The process starts with fecal waste that the company collects from latrines and ends with a fuel briquette.

The first stage is treatment. Sanivation applies heat to sanitize the waste—waiting in a container—and remove any harmful pathogens.

Sanivation's waste treatment system: a solar concentrator with a receiver that heats up fecal matter
Photo: Sanivation
Sanivation’s waste treatment system uses a solar concentrator to heat up fecal matter. Primary components include the Scheffler dish reflector (mirrored surface), the beige hopper to load the poop, and the large-bore-pipe heat exchanger.

A glass and steel parabolic disk with an area of about 5 m2 acts like a solar concentrator. When the sun’s rays hit the disk, it reflects the light and focuses it onto the glass side of an approximately 13- by 13-centimeter receiver containing the waste. The waste starts warming up to about 60° C—the other sides of the receiver prevent the heat from escaping because they are insulators: cement or fiberglass.

The trick to the treatment is that once poop gets hot enough, pathogens disappear. One estimate says this happens after waste is heated to 60° C for one hour. Woods says many researchers are working on finding the lowest possible temperature and time to sanitize waste, but for now Sanivation errs on the side of caution and goes to 60° C for three hours.

Before this week, the team would check that the batches went above safety requirements and then mix the product with waste materials such as charcoal dust or sawdust. Feces have a high fiber content, so when cooled and dried after heat treatment, a hard and solid briquette forms. (Woods says the details of the processing are “kind of our secret” but “you get a nice, solid, very dense, very flammable material.”)

Sanivation's agglomerator
Photo: Sanivation
Sanivation’s agglomerator acts like a cement mixer to combine ingredients and apply tumbling pressure to the feces binder and the carbonized agriculture waste.

In the new continuous-flow system, the waste heats up for about five to 10 minutes, and is routed via pipes to insulating cement and fiberglass containers, where it sits for a total of three hours before moving into the briquette production stage. Sensors throughout the container monitor the temperature.

Woods says rolling out a new system like this is hard, because it’s difficult to get equipment such as a seal fixed or replaced due to the availability of parts and manufacturing quality limitations. “We can’t just swing down to the Home Depot and pick up a new seal,” she says.

Still, this week should be the week it goes live. “I think we’re about ready to put some poop in it,” she says.

Salim Mayeki Shaban, the founder and president of the African Christians Organization Network in Kenya, creates charcoal from an invasive species called water hyacinth instead of trees. He sells special stoves that can use and produce his charcoal sustainably—primarily as a fertilizer ingredient but also for fuel.

He writes in a Skype message that maybe about 70 percent of the people in Kenya still use normal charcoal in part because of cost deterrants but mostly because of a “lack of knowledge” that could be improved by going out in the field with demonstrations and training. He writes that most people switch to alternatives once they learn about them.

Björn Vinnerås, an environmental engineer at the Swedish University of Agricultural Sciences in Uppsala, develops on-site sanitation systems in Sweden, Africa, Asia, and Latin America. One of his projects collects poop and urine—but instead of converting it into fuel, he, like Shaban, also creates a fertilizer for plants. “If you can really turn the waste you have to manage into a resource,” he says, “I see a really big benefit of it.”

Unlike other alternative charcoal sources, Vinnerås says, Sanivation’s system addresses the problem of where to put waste that overfills latrines: if it winds up in a landfill, it act as a pollutant. He says the image of human manure might make it difficult to receive public acceptance, but at the same time, some people in rural areas already use cow dung as fuel. “So it can be found within the culture already,” he says.

Woods says people always bring up the poop imagery, but she says Sanivation hasn’t found it to be a problem. “Once people try it, they rarely still have a problem with it.” The company is upfront about it, but the briquettes don’t smell or look like poop. 

Besides social and political obstacles of not being from Kenya, she says the main challenge is quality of supply. The other materials Sanivation uses to create the briquettes are often filled with contaminants such as dirt that can lower the briquette quality.

She says Sanivation is doing particularly well with local businesses because it meets sustainability regulation—most of the charcoal sold in Kenya, she says, has been created illegally, so business owners don’t have to worry about the company suddenly disappearing like traditional fuel providers. In October, Sanivation sold about 8 metric tons of briquettes to about 20 small businesses and restaurants.

The company has targeted small businesses and restaurants first because they buy in bulk: a business would buy between about 200 kilograms to 2 metric tons of briquettes while a household could only buy kilograms. However, the company plans on expanding to the household market because households “will pay more.” Woods also hopes to reach out to more municipalities, both about the fuel briquettes and the custom toilets Sanivation sells to improve sanitation conditions.

“It’s all pretty simple technology, and that’s actually key to working and operating in Kenya,” she says.

Future improvements could include switching to conveyor belts to move the feces and other waste products around. Next year, the team hopes to get the system processing 30 metric tons per month.

“These other forms of fuel, they’re just so needed,” she says.

A coal-fired power station in Helsinki

How Finland Could Ban Coal by 2030

UPDATE 28 November: On 24 November, the Finnish government approved its national energy and climate strategy. The strategy calls for completely phasing out coal for energy production in the 2020s—a move requiring either taxation or explicit legal prohibition. The government is submitting the strategy as a report to the Finnish parliament, where discussion will begin on 30 November. 

On 24 November, as people in the United States are preparing to sit down for Thanksgiving dinner, Finland’s government will unveil its newest energy and climate policy. What will observers have to be thankful for? Many are hoping Finland’s energy plan will include a complete ban on coal by 2030. Scientists, politicians, and industry experts believe that such a ban is actually feasible.

“I think this could work,” says Peter Lund, a renewable energy researcher at Aalto University in Finland.

Olli Rehn, the minister of economics affairs, announced this month that the government was mulling it over. He told Reuters that “giving up coal is the only way to reach international climate goals.”

The Finnish government does not have the power to enact a ban itself—Finland’s parliament would have the final say—but several other places around the world have already made similar anti-coal commitments. Among them are the U.S. state of Oregon and the province of Ontario, Canada.

In Europe, the Danish government wants Denmark to be fossil-free by 2050, and the British government plans to phase out the last of its coal-fired plants by 2025. But neither country has enacted a law explicitly prohibiting coal. If Finland follows through with an anti-coal statute, it would be the first country to have a ban on the books, Helsinki Times reports.

In 2015, only eight percent of Finland’s energy generation—heat and electricity—came from coal, according to Statistics Finland. The country imports it from nations to its southeast—primarily Russia.

Riku Huttunen, Director General of the Energy Department of Finland’s Ministry of Economics and Employment, told IEEE Spectrum that a ban would be possible because of the direction the country is already heading.

Huttunen says that coal plants that generate only electricity and not heat are either under consideration for decommission or already scheduled for it. He expects only one of them to be left by 2030.

Plants that generate combined heat and power can typically use different fuels, he says.

On its current trajectory, coal could wind down to about 1 percent of Finland’s energy mix by 2030. (He writes in an email that some coal would still be stored for “exceptional” situations such as a lack of fuel supply during peak demand hours or a crisis, but not for regular use.) This drop to an even smaller trickle would happen in a couple of ways.

First, energy needs would be lowered with energy efficiency improvements for buildings, with a focus on “smart grids, demand response, and overall flexibility,” Huttunen says.

Meanwhile, coal would be replaced by two primary sources: additional nuclear power and wood-based bioenergy fed by leftovers from the forestry industry. Expanded wind power is also an option, he says.

The switch away from coal to alternative sources is already happening in Finland’s cities. In the capital, Helsinki, there are currently two coal-fired power plants. One will be shut down in 2024 and swapped for smaller plants running on biomass and geothermal energy, says the deputy mayor, Pekka Sauri.

“There’s no chance you can ban coal by tomorrow,” says Sauri. But, “with some luck,” it might be possible to do, even in as short of a timeframe as 2030, he says.

Lund, who chairs the energy panel of an independent European Union science advisory council made up of national science academies, analyzed some ways to address Finland’s energy efficiency as part of research published in Energy in 2007.

He believes that energy efficiency improvements could be applied across industry, businesses, and residences. Residents could lower their thermostats by one or two degrees, homes could use heat pumps instead of electric heating, and buildings could be built with better insulation, ventilation, and lighting. In the industrial sector, pump flow systems for liquids could be optimized—by replacing traditional on/off control or flow throttling with different regulation.

“That all piles up to major improvements,” says Lund.

Although he agrees that wood-based biofuel could be a short-term replacement for coal, he points out that the biofuel is not a sustainable fuel source. About 80 percent of the country’s bioenergy now comes from Finland’s forests, which cover about 75 percent of the country's land area.

When the forest industry produces timber for construction, paper, and pulp, the processes leave behind by-products such as black liquor, wood residues, and wood chips—suitable for energy use.

Huttunen says there is a surplus of trees, so there would be enough to meet increased demand. He writes that the energy produced is “economically and environmentally sustainable,” but Lund warns that the existing production strategy could “actually cause an increase in CO2 emissions.”

Trees naturally absorb carbon during photosynthesis, thus acting as carbon sinks. Huttunen writes that the trees eyed for use as biomass grow faster than they’re used; by 2030, he says, the sink could be pulling about 15 million tons of CO2 per year out of the atmosphere. Still, Lund worries that a plan relying on leftovers from logging for energy may make it difficult to meet the emission requirements of the Paris Climate Agreement. He says it takes 60 to 70 years for the cut trees to grow back.

An alternative could be importing bioenergy sources from other countries, or simply planting more faster-growing trees, such as Salix willow and poplar, Lund says.

Another potential issue Lund points out is a switch to nuclear. He thinks that the four existing nuclear reactors in Finland should be at the end of their lives by 2030, with maybe a couple years of wiggle room, depending on the results of safety inspections. But they would remain commissioned until 2035 at the latest.

According to Huttunen, two units might be shut down by 2030, but the others would probably continue to run afterward. A fifth unit would come online by the end of 2018, and the government might decide to build a sixth in 2018.

But even if proven possible, there’s still a leap from there to probable. Part of that gulf is financial concerns.

Sauri says replacing existing plants would require “considerable investment.” A spokesperson for Finnish Energy told Helsinki Times that there would need to be “substantial compensation” to energy producers. Huttunen writes that production would be cheaper with alternative sources, but also that CO2 taxation is a “clear incentive.”

“Now we know that the outlook for coal production is not really good,” says Esa Hyvärinen, a spokesperson for Fortum Corporation, an international energy firm with interests in Europe and Russia. While zero coal might work, he doesn’t think a ban would have a significant effect on Europe’s CO2 emissions.

The EU has a trading system where companies cover their yearly emissions with allowances. Hyvärinen explains that another member state could just increase emissions while paying less.

Hyvärinen believes there’s a better way to decrease CO2 emissions: Instead of limiting the technology toolbox, lower the existing emissions cap and let industry decide what technologies let it meet that goal.

Lithium-ion ain't the only power backup game in town

Building a Better Grid Backup

With all the news Tesla Motors makes, you might be excused for thinking that lithium-ion batteries are the answer to all the world’s energy storage needs—even storing wind and solar energy on the electricity grid.

But, as noted before, companies with new grid-scale battery chemistries are emerging to fill what had been a growing void. The U.S. Department of Energy’s Advanced Research Projects Agency-Energy (ARPA-E) has supported grid battery R&D to the tune of $85 million in research grants since 2009. And even as companies pitching the latest in large-scale energy storage appear in the marketplace today, ARPA-E continues to press ahead with research into even cheaper, safer, more powerful, and longer lasting grid storage.

Last month, for example, ARPA-E announced US $37 million in funding for research into a new class of solids in which some ions are mobile and thus can store and conduct energy.

The announcement follows up on the 2011 discovery of ion-conducting solids. In fact, the Japanese team that discovered the material noted in the paper documenting the discovery that it could act as a solid, non-volatile, and non-explosive battery electrolyte.

According to Paul Albertus, head of ARPA-E’s new Integration and Optimization of Novel Ion Conducting Solids, (IONICS) initiative, ion-conducting solids have at least two possible applications in the field of grid-scale batteries. The first, he says, is a more powerful and less volatile traditional rechargeable battery, like a next-generation Tesla Powerwall.

Albertus says research that IONICS underwrites will “help lead to batteries that, while having high energy density, nevertheless have improved intrinsic safety compared with today’s lithium ion batteries, because they will include a solid separator rather than one filled with a liquid electrolyte. The presence of the liquid electrolyte is a key reason for the fires that periodically occur in lithium ion batteries.”

The largest of IONICS’s solid-electrolyte grants, for $5.25 million, went to the Berkeley, Califorina-based company PolyPlus. A 2014 patent awarded to PolyPlus describes in detail the company’s approach to making lithium-based batteries with glass or ceramic as the electrolyte. The company’s website says its battery’s stability and light weight suggest initial applications providing portable power for remote sensors and for soldiers in the field.

A second application for the new materials, Albertus says, involves solving a longstanding problem in flow batteries, probably the gold-standard grid battery technology today. Flow batteries, like the current-generation of vanadium and iron-based batteries ARPA-E has helped develop, use a liquid electrolyte on the cathode side and a liquid electrolyte on the anode side. Both solutions can be scaled up by simply adding more tanks of electrolyte. This cheap and easy expandability is one of the main selling points for energy storage banks that need enough flexibility to power an entire neighborhood or office park during nights or cloudy or windless days.

One of the essential ingredients for any flow battery, says Albertus, is the membrane that separates the electrolyte on the cathode side from that on the anode side. It should selectively let ions pass, but shouldn’t facilitate any reactions that might degrade the battery materials, change electrolyte’s pH, or reduce the battery’s performance. For most materials, though, this is too tall an order.

“The chemistries of today's flow batteries are limited by the selectivity of the membrane,” Albertus says. “When the active materials pass through the membrane, they can react in a reversible or irreversible manner. Current membranes are not very selective, limiting the active materials to chemistries with the same element on both sides of the membrane such as the all-vanadium flow battery. Even a tiny amount of crossover—say, 0.01 percent per cycle—over the course of 5000 cycles leads to unacceptably high degradation. If the membrane had higher selectivity, a new paradigm allowing the use of a far wider range of active materials would be enabled, especially those that are less expensive, such as iron and chromium.”

With that in mind, ARPA-E, through IONICS, awarded $2.7 million to East Hartford, Conn.–based United Technologies Research Center for a flow battery with solid ion membranes that the company says could make flow batteries cheaper and more durable. ARPA-E also awarded $1.5 million to the Colorado School of Mines to develop a “hybrid polymer” membrane that the research team says could “offer a highly selective, robust solution for the production of flow batteries at a price point that allows their affordable integration into the power grid.”

In other words, says Albertus, ARPA-E’s latest research effort into grid-scale batteries could solve one of the crucial outstanding problems in flow batteries: making the perfect separator for a cheaper, more stable, and longer-lasting system.

“The goal for the IONICS program is a per-cycle selectivity of 99.995 percent, dramatically higher than existing membranes,” he says. “Which in turn have better selectivity than simple porous membranes. A specific goal of the IONICS program is to make sure that, even as researchers develop membranes that have higher selectivity, they pay careful attention to ensure their membranes are also stable, highly conductive, and low cost at the production volumes flow batteries may achieve in the next 10 to 15 years.”

Coal plants in Kosovo

The Numbers Don’t Add Up for Kosovo’s Coal Plant

Two aging coal plants puff away on the outskirts of Pristina, the capital of the regionally-disputed Eastern European territory of Kosovo. The question facing the world is what to do when they can no longer continue to generate electricity.

“The government is moving in completely the wrong direction,” says Visar Azemi, the coordinator of KOSID, a consortium for sustainable development in Pristina. Right now, the government plans to build a new coal power plant, but  Azemi and his colleagues argue in a 13 October analysis in Environmental Research Letters that a mix of renewables is both cheaper and better for health and the environment.

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.11 m^2 leaf-shaped, colorful photovoltaic modules with solar concentrators

Flashy Recyclable Photovoltaic System Breaks Record for Solar Energy

If you want your home to stand out, a flashy new photovoltaic module might be just what you’re looking for. The leaf-shaped prototype uses color and shape to redirect light to two silicon solar cells.

Researchers announced last month at the annual Photovoltaic Science and Engineering conference in Singapore that their 0.11-square-meter photovoltaic modules had achieved a record high for efficiency in converting the sun’s rays to electricity: 5.8 percent.

“[This technology could] become more attractive to architects and people involved in the building sector,” says Angèle Reinders, an industrial design engineer at University of Twente in the Netherlands.

With traditional silicon solar cells on roofs, costs can add up quickly. With that in mind, many researchers, with an eye toward commercial viability, have tried using materials that can concentrate light into one or two solar cells.

Typically, engineers place solar cells on the edges of panels and guide the light using novel materials such as quantum dots and organic dyes. For example, in research published in 2008, one group achieved 7.1 percent efficiency with four expensive gallium arsenide solar cells on the edges of a tiny luminescent solar concentrator with colored dyes. Earlier this year, a Journal of Renewable and Sustainable Energy article described research using silicon solar cells on the back of PMMA (acrylic glass) panels; those modules achieved only 3.8 percent efficiency.

Reinders favors the use of plastic because chemical processes exist to remove the PMMA and recover the electronics, so the photovoltaic modules are recyclable. In glass sheet photovoltaics, the solar cells and wires in between them end up as waste. But in order to improve the performance of medium-size solar concentrators using plastic, Reinders and her colleagues came up with new designs aided by computer simulations of different shape combinations, colors, numbers of silicon solar cells, and solar cell positioning.

Here’s how the designs work. When sunlight strikes a flat PMMA film mixed with a particular colored dye, the light reflects inside the film. Depending on the dye’s color, it adjusts the wavelength of the light so that it’s closer to the infrared range. This is advantageous because the two silicon solar cells at the bottom of the panel absorb more light in the infrared range. 

The researchers tried to strike a balance between the photovoltaic module’s size and accessibility of light.

The team built a prototype—which has continued to convert photons to electrons with 5.8 percent efficiency for the past 1.5 years—by cutting each of the two solar cells into three pieces and attaching them to the bottom of films featuring a red dye. In simulations, the geometry of a rhombic shape appeared to harvest more light rays than a rectangular shape.

Sue Carter, a physicist at the University of California Santa Cruz who was not involved in the study but has designed solar concentrators for greenhouses, points out several potential issues with the design.

First, she says the company she consults for, Soliculture, ships solar concentrator systems for greenhouses that can achieve up to 7 percent efficiency with reflective backgrounds. The work, says Carter, is unpublished because she is focusing on commercialization. Referring to the Dutch research, she said it’s misleading to list efficiency in the whole system, because efficiency can always be improved by adding additional silicon photovoltaic cells.

“People can make their own conclusions by going to the website,” Carter says.

She added that although photovoltaic cells function better on acrylic, it can become more expensive than glass and be more difficult to certify. Also, it is challenging to prove 20-plus-year lifetimes on the organic plastic luminescent materials; it took her team “a lot of work” to find a combination of techniques that made it possible, she writes in an email.

Carter says the size of a photovoltaic system wouldn’t have a noticeable effect on its overall efficiency, but Reinders says the main difference between her lab’s work and Carter’s work is that, because the new prototype uses smaller modules, it’s easier for photons to become concentrated because they aren’t as widely distributed across the surface. Also, there are differences in dye concentrations and in where the cells are positioned on the back of the PMMA film.

Reinders agrees that plastics are not as durable as glass—she says pieces of glass from Roman times are still found at archaeological sites—but she’s confident that they will stand the test of time. She says it’s not reasonable to expect that a plastic sheet would last 25 years. But it’s possible to make plastic headlights that can resist degradation for a period of 15 years, so a five to 10 year lifetime would certainly be reasonable as research progresses.

Reinders says she’s found that the plastics are about half the cost of glass—mainly because they are thinner. But the cost will ultimately depend on how the materials are processed, which requires further investigation. Usually plastics manufacturing is a lot faster than the glass production process.

As far as certification goes, Reinders points out that requirements in the United States could be different than those in the Netherlands. And as such, it might be difficult to meet all certification requirements with plastic. She doesn’t see any problems with electrical performance, but it is easier to scratch plastic than it is to scratch glass. This, however, could possibly be remedied by using some sort of coating.

Sayantani Ghosh, a physicist at the University of California, Merced, who was also not involved in the research, writes in an email that “once certain issues are addressed, this could potentially prove a novel way of capturing solar power in houses, with significantly lower costs” than covering a roof with silicon photovoltaic cells.

According to Ghosh, the questions that still have to be answered include whether the materials would be stable under weather conditions such as snow and rain, and how their thinness could affect their robustness. There’s also the issue of putting the cells underneath the solar concentrator tile instead of on its edge, which allows a “significant portion” of the reemitted light to escape because there isn’t a solar cell to capture it. Also at issue is whether other light harvesting materials could have a broader light absorption spectrum. Finally, she isn’t sure whether a proposed idea of mixing dyes would work in practice because the emission range of one would overlap with the absorption of another.

Reinders writes in an email that she has not tested the prototype in harsh weather conditions yet, but it “may be more suitable for climates with a diffuse irradiance than the glass sheet-based photovoltaic modules.” She writes that diffuse irradiance usually “goes hand in hand” with climates with lots of clouds and rain.

Reinders also admitted more work needs to be done on ensuring that it can handle the heat on rooftops. “We still can do a lot of research in this field,” she says. 

A small boat goes past the Lillgrund offshore wind farm

Offshore Wind Farms Don’t Harm Marine Life

When commuters take the train across the bridge from Malmö, Sweden, to Copenhagen, Denmark, they pass by Sweden’s largest offshore wind farm: Lillgrund. Similar power-generating farms are gaining traction in the United States—just take the Block Island Wind Farm recently built in Rhode Island.

More renewables is all good, right? Not quite. Normally, wind farms get a bad rap for deaths of birds and batsAnd they have been the suspected cause of increased sightings of other species such as shore crabs (which could lead to unknown consequences). But now, biologists report (on 25 October in PLoS One) that the Lillgrund farm doesn’t seem to harm local marine life.

“Engineers, they don’t think so much about the environment,” says Olivia Langhamer, a marine biologist at Chalmers University of Technology in Gothenburg, Sweden. She worked on the study of Lillgrund’s effect on the environment with the Norwegian University of Science and Technology in Trondheim. “It’s really important to discuss with them, what impact you can have so you can modify and you can improve.”

Langhamer points out that there is a delicate biodiversity balance in the marine ecosystem. The relevant food web goes like this: Fish such as cod eat crabs, seals eat the fish, and so forth. But has Lillgrund affected the food chain? After it became operational in 2008, the Swedish Agency for Marine and Water Management noticed that both fish and crabs gather around the turbines’ foundations. The agency’s 2013 report documenting this phenomenon explained why. Stones around the turbines’ foundations—meant to combat erosion from ocean currents—attract crabs. The foundations are like artificial reefs that marine animals can use as protection from predators. But this got Langhammer thinking: Would these artificial reefs upset the crabs’ ecosystem—leading to unexpected consequences? Invasive species, for example, can become dominant species and break the balance in food chains. A 2009 research paper published in PLoS One cited an extreme case where an invasive species probably led to mass extinctions millions of years ago, during during a period known as the Late Devonian extinction.

To find out whether Lillgrund was a hospitable home or a harmful habitat, Langhamer and her colleagues visited Lillgrund and two other sites (Sjollen, which is 13 kilometers north of the wind farm; and Bredgrund, 8 km south) during the summers of 2011 and 2012. Each of the bodies of water covered about 6,000 meters and had limestone, stone, and sand seabeds at depths between 4 and 9 meters. They also had similarly strong gradients of salinity.

The researchers collected Carcinus maenas shore crabs, which are easy to measure and rank among the world’s worst invasive species. The team caught 3,962 in 2011 and 1,995 in 2012. Crunching numbers, they found that while the crab populations had increased across all three sites, with a slight edge at Lillgrund, there was no statistically significant difference in the total crab numbers, body conditions, sizes, or male-to-female ratios.

Langhamer says one reason for stability in the crab numbers might be because cods are also attracted to the artificial reefs formed by the turbines’ foundations. She suspects that they might be keeping the crab population from exploding.

“Finding no effect could be due to so many reasons,” Magnus Wahlberg, a marine scientist at the University of Southern Denmark in Odense who was not involved in the research, writes in an email. “A large variation between years and sites for reasons we may not know may easily overrule” effects on the crabs.

Langhamer cautions that the work shows only that the wind farms don’t have a net negative effect, and doesn’t indicate whether there is something positive or negative going on behind the scenes.

Others are more optimistic. “We don’t have to worry about the crabs,” says analyst Linus Hammar, who studies the environmental effects of fishing and wind farms at the Swedish Agency for Water and Management. He was also not involved in the new research.

Because fish and seals have also been shown to be attracted to the foundations of wind farms, and the exclusion of animals that are not attracted is “insignificant,” Hammar says the marine ecosystem has stayed essentially in balance. “I think it will even out,” he says.

Langhamer says she hopes to continue studying the effect of renewables on the environment, with a focus on acceptability and the artificial reef effect. She wants to have more collaborations with engineers and the renewable energy industry.

“I think it’s really important to see and study what is happening when you place something in nature,” she says. “What are the risks, what are the mitigations, and what can you improve the design?”


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