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Huge Offshore Wind Farms Could Tame Hurricanes

What happened when the hurricane ran across thousands of offshore wind turbines? It sounds like a climate scientist's idea of a joke, but a new study has found that offshore wind farms could protect coastal cities by slowing hurricane winds and reducing storm surge.


The spinning turbine blades of offshore wind farms can sap a hurricane's strength by slowing the rotating winds in the outer edge of the rotating storm—an action that leads to smaller waves and eventually slows the wind speeds of the entire hurricane. Simulations have shown that such effects could have significantly dampened the impact of real-life hurricanes Sandy, Isaac and Katrina, according to a new paper detailed in the 26 February 2014 issue of the journal Nature Climate Change.

"We found that when wind turbines are present, they slow down the outer rotation winds of a hurricane," said Mark Jacobson, a professor of civil and environmental engineering at Stanford University, in a news release. "This feeds back to decrease wave height, which reduces movement of air toward the center of the hurricane, increasing the central pressure, which in turn slows the winds of the entire hurricane and dissipates it faster."

Jacobson worked with his colleagues at Stanford and the University of Delaware to simulate hurricane collisions with tens of thousands of offshore wind turbines, based on a computer model that can account for air pollution, energy, weather and climate. They then ran simulations based on the real-life cases of Hurricane Sandy's impact on New York in 2012, Hurricane Isaac's strike on New Orleans in 2012, and Hurricane Katrina's devastating blow on New Orleans in 2005.

In Katrina's case, an array of 78 000 wind turbines off the coast of New Orleans slowed simulated wind speeds by 130 kilometers per hour and decreased storm surge by up to 71 percent. In Isaac's case, the same array of turbines could have decreased peak wind speeds by up to 92 kph and reduced storm surge by up to 60 percent.

Other simulation runs found that even bigger arrays of 272 000 turbines or even 543 000 turbines—located offshore of Cuba and stretching from Florida to Texas—could have dropped Katrina's wind speeds by 158 kph and reduced storm surge by up to 79 percent.

An array of 112 000 turbines stretching from New York City to Washington D.C. could have slowed Sandy's peak winds by 130 kph and decreased storm surge by up to 21 percent. A larger array of 414 000 turbines along most of the U.S. East Coast could have dropped Sandy's wind speeds by almost 141 kph and decreased storm surge by up to 34 percent.

The huge wind farms would do more than just slow down the hurricanes. The largest wind turbine arrays could have extracted up to 2.65 terawatts of peak power from Hurricane Sandy and up to 1.18 terawatts of peak power from Hurricane Katrina—peak power representing the most power extracted at any time during the simulations.

Such simulations suggest that huge wind farms have an edge over traditional coastal city defenses because they slow both wind speeds and decrease storm surge. By comparison, seawalls can only stop storm surge. The cost of building seawalls can also run between $10 billion and $40 billion per installation, whereas expensive wind farms could pay for themselves through energy generation over time.

Hurricane damage to the huge arrays of wind turbines is a risk, Jacobson said. But he pointed out that current wind turbines can stand up to wind speeds of 180 kph within the range of category 2 or 3 hurricanes. And the presence of the huge wind farms could help prevent hurricanes from ever building up to superstorm wind speeds. (The study assumed the wind turbines had a cut-out speed of 180 kph in most of the simulation runs to prevent damage to the turbines.)

Huge arrays of offshore wind turbines remain a far cry from today's reality when the U.S. has yet to build any offshore wind farms. But the new study raises the possibility of hurricane protection as added incentive for building offshore wind farms. Policy planners could consider storm protection as the cherry on top of wind power's known benefits involving renewable power generation, national energy security and the reduction of the human impact on climate change.

Photo: iStockphoto

Terrafore Looks to Cut Molten Salt Energy Storage Costs in Half

As we have seen in recent months, energy storage is becoming a pretty big deal. California has the country's first energy storage mandate in place, and plants like Solana in Arizona have started trying to incorporate storage in from the beginning. Solana uses molten salt energy storage, a common idea wherein salts are heated, retain that energy for relatively long periods of time, and then discharge it by heating steam to turn a turbine. Solana, a concentrating solar thermal plant, can keep running for six hours after the sun drops below the horizon.

Storage like that, though, is still expensive. A company called Terrafore Technologies wants to cut the price almost in half. Terrafore was an exhibitor at the Advanced Research Projects Agency–Energy Summit this week in Washington, D.C., and the company's CEO Anoop Mathur told me he was hoping to raise $5 to $10 million (maybe from the gaggle of venture capital folks that wandered the Summit's halls) in order to scale up his process.

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Crowd-Sourced Thermostats, Modular Fusion Reactors, and Other Ideas From ARPA-E Future Energy Pitching Session

Early this week at the ARPA-E Energy Innovation Summit in Washington, D.C., a group of entrepreneurs, researchers, and investors gathered for a session that was equal parts innovative, smart, optimistic, and downright crazy. At the ARPA-E Future Energy Pitching Session, eight early-stage start-ups have three minutes—strictly enforced—to sell a panel of venture capitalists on their companies. The venture folks ask a few questions and then offer advice, and generally knock the excited presenters down a peg or two.

At last year's summit, the pitches included rotation-free wind power, uranium molten-salt nuclear reactors, and a device designed to pull energy out of the air thanks to ambient temperature changes. Some of these ideas are very high-risk, and potentially very high-reward; perfect for venture capital, and sometimes, for ARPA-E itself to throw in some money.

"The fire exits are on your lefthand side, should you need them," began the moderator. Indeed they are; off we go with some of the best ideas:

Onboard Dynamics: Refuel any vehicle for $1 per gallon from any natural gas line

Natural gas is now being produced in huge volumes in various parts of the United States, and proponents say it could be an extremely cheap alternative to oil-based gasoline. But one major hurdle is infrastructure: There are less than a thousand compressed natural gas (CNG) refueling stations around the United States right now. Onboard Dynamics wants to eliminate the need for a lot of that infrastructure by putting the gas compressor on to vehicles themselves.

By letting the car or truck do the compressing, we wouldn't need any filling stations at all. "Sixty million homes and businesses could become natural gas refueling stations," said presenter and CEO Rita Hansen. The idea is to hook into any low-pressure gas source and use one or two of an engine's cylinders as a natural gas compressor, when the car is not moving. The remaining engine cylinders run to power that compression and to provide cooling. When refueling is finished and the car needs to actually move again, all engine cylinders run as normal.

The company has its first customer, Deschutes County in Oregon, but the investors on the panel warned how hard it would be to, essentially, convince car part manufacturers to change everything that they do overnight. The road is long and the climb is steep when it comes to changing our primary vehicle fuel source.

CrowdComfort: People-sourced building control

Do you work in an office? Someone is always cold, right? Or hot. Or somehow uncomfortable. And either everyone keeps changing the thermostat to suit their own needs or complaints get sent to maintenance, who maybe after a few months might make a change. In the meantime, someone is paying for energy to cool or heat a building to points that no one seems happy about. Time to use those angry crowds to fix that.

"We sought to empower people with their smartphones to create the world's first crowd-sourced thermostat," said Eric Graham, the company's CEO. It's actually a straightforward idea: I'm cold, so I tap a button on my phone saying so. Over my whole floor, maybe a few people say they're extremely cold, a few say they're somewhat cold, and so on, and a software-based recommendation engine generates a number for how the building should actually be heated. This can be done in very basic fashion, where a manager turns a knob based on the generated number, or the software can integrate with larger buildings to more automatically affect the building's climate. It wouldn't cost all that much to install or to run, according to Graham, and there is potential for energy savings if unnecessary heating and cooling can be avoided.

The problem, say the money guys, lies primarily in that very simplicity. Can't anyone do this? The company has a few patents, but it isn't much of a stretch to imagine multiple ways into this idea, especially now that Internet-connected thermostats, like the Nest, are available. The really promising part of it, though, is when you extend the idea past just temperature. If thousands of people in really big buildings start telling an app all about their current experience: temperature, leaks, dirty bathrooms, or even letting an app just track where they walk and which staircases or elevators they take, the data might start to point the way toward much smarter—and energy efficient—buildings.

Helion Energy: Modular fusion reactors within reach?

It always comes back to fusion. The unicorn of all energy sources, it has been 20 years away since work on the idea began. After decades of lackluster progress, billions still get poured into the idea, and it still remains just off the horizon. Unless you ask Helion Energy, that is.

This company says they can have a 50-MW fusion nuclear reactor actually online and producing power by 2019. That is five years from now, if you are counting at home. They use a technique called pulsed magneto-inertial fusion, which CEO David Kirtley said lies somewhere between the commonly attempted methods of magnetic fusion and laser fusion (their prototype is pictured above). The details on how exactly it works seem a bit thin, but there's a "simple" five-step process described here. Let's just agree that the odds of this being as perfect and planet-saving as the company suggests are . . . slim.

The upsides to it actually working are obvious: you can use seawater to generate fuel, no weapons-grade material is produced as with fission reactors, and there is no possibility of meltdown. But, as Kirtley acknowledged, "it still has the word 'nuclear' in front of it." That means a steep regulatory climb, not to mention a rightfully skeptical public.

"Being in fusion, you've got this credibility issue," said Andrew Garman, of New Venture Partners, during the session. "Is this really going to be ready in 2019 for a plant? Or is it more like 2099?"

The Grid From the Ground Up: What to Do If We Could Do It Again

Among the primary reasons that innovation in electricity grid technologies tends to move slowly is that the grid makes for a poor test site: You can't bring it down to try something out. So, instead, here's a thought experiment: If you could bring the whole thing down and start over from scratch, what would you do? What technologies in use today would be scrapped or downscaled, and which ones would we implement from the outset? A panel of experts—hosted by EnergyWise contributor Katherine Tweed—at the Advanced Research Projects Agency—Energy (ARPA-E) Energy Innovation Summit laid out some ideas on Monday.

"Power engineering is not rocket science. It's much more important than that," said Terry Boston, the CEO of grid operator PJM Interconnection, citing the one-day 2003 Northeast blackout and its $6 billion price tag. He started out by saying that Thomas Edison was righthigh voltage, direct current is probably the way to go if we're starting our grid anew, instead of the alternating current that dominates the American grid. Beyond that, standardization is a crucial component that is sorely lacking from today's grid.

"We tend to use 23 different communication standards in our industry," said Clark Gellings, a fellow at the Electric Power Research Institute. Ideally, every node on every corner of the grid should be able to communicate with every centralized generation facility and all the substations and other nodes between them. "We talk about a common information model," Gellings said. "That's a wonderful idea, but we're not deploying it."

Another idealized grid characteristic is in fact happening incrementally as we speak: a balance of distributed generation, like rooftop solar panels, with the big bulk generators such as natural gas plants and utility-scale solar and wind. Today we talk about creating microgrids that, while connecting to the main grid, can function somewhat independently; if this sort of combined form of generation and distribution were implemented from the beginning, there is a good chance that the resilience of the grid—meaning, its ability to bounce back from disasters like, say, Hurricane Sandy—would improve dramatically. Adding electricity storage capability, from the large-scale options like compressed air or big battery arrays on down to even the household or smart-appliance level, would eliminate some of the problems the grid has with dispatching power where and when its needed.

Along with some of those tech fixes, Lawrence Jones, the vice president of utility innovations and infrastructure resilience at Alstom Grid, said we should first determine precisely what we want this magically regenerated grid to do. Since reliability in the face of natural disaster is always among the foremost concerns when it comes to the grid, putting all transmission underground might be a reasonable idea. (This thought experiment now rests firmly outside the bounds of economic and logistical confines, of course.) "The physical things in the world that affect the grid... extreme weather, hotter and colder temperatures—these are things that we haven't designed for," Jones said. "I think it needs to be an anticipatory design strategy."

So if Santa brought us a new grid, it would use HVDC, incorporate renewables and storage at all scales, focus on resilience issues that would allow it to recover from insult, and feature standardized protocols allowing smooth communication from top to bottom. Some of these goals are on their way into our actual grid, but the uptake is slow, and others appear to be a bit of a pipe dream. But John Hewa, the CEO of Pedernales Electric Cooperative in Texas, pointed out that this sort of dreaming isn't coming from a place of utter poverty: "It's a system that is achieving nearly four nines of reliability in some parts of the country." That is, it is functioning just fine nearly 99.99 percent of the time. Maybe we don't need to build from the ground up after all.

China Pushes Past U.S. in Smart Grid Spending

As smart meter installations wane in the United States, China has become the new leader in smart grid spending.

China spent US $4.3 billion on smart grid investments in 2013 as the U.S. market contracted 33 percent to $3.6 billion, according to new figures from Bloomberg New Energy Finance (BNEF). It is the first time that China has topped North American spending in smart grid investment.

Spending on grid modernization was up globally last year to nearly $15 billion, but that is only slightly higher than 2012. China may take the top spot, but there are other areas of activity, especially in Europe.

Advanced metering infrastructure, often referred to as smart meters, are still driving investment in next-generation grid technologies, but other categories of spending will dominate in the future.

China is installing more than 60 million smart meters, which makes up the bulk of its spending, but there are some other countries to watch. The UK will install about 47 million smart gas and electric meters between now and 2020.

It has taken a while to work out some of the details in the UK, such as who will own the meter in the deregulated UK energy market, and who will build the communications network. With many of the issues now being settled, large retailers such as British Gas have started to roll out meters.

In China, the landscape is far simpler. The State Grid Corporation of China controls most of the electrical grid in the country, so when it decides to move forward with metering it can do so more quickly than in a fragmented, deregulated market.

There are other markets to watch in Asia and Europe when it comes to metering. France is expected to install 35 million meters by 2017. And Japan, which already has one of the most reliable grids in the world, will install millions of smart meters as it looks to squeeze even more efficiency from its grid in the face of generation challenges after the Fukushima disaster in 2011.

But it’s not all rosy news for two-way digital smart meters. In North America, the market has slowed to a halt now that funding from the American Recovery and Reinvestment Act for smart grid projects has all been spent. Other large markets, such as Brazil and Germany, have dialed back smart meter targets in recent years.

Smart meters, however, are just one node in the smart grid. Many in the electricity industry would argue that building a real smart grid involves distributed intelligence and sensing across the entire grid, from generation down to the smart meters at the very end of the distribution network.

One of the most active areas in smart grid is distribution automation, which brings sensors and automation to the distribution network. Global spending on distribution automation rose by $1 billion to $5.4 billion in 2013, according to BNEF.

Distribution automation technologies can allow for more distributed generation such as rooftop solar photovoltaics, can reduce outage and restoration times, and can fine tune voltage to save energy.

“The fundamental drivers of the smart grid—greater grid reliability, further integration of renewable energy, and improved demand-side management—are stronger than ever,” Colin McKerracher, senior energy-smart technologies analyst at Bloomberg New Energy Finance, said in a statement.

With tens of millions of smart meters and sensors going into the grid, the next step is managing the sharp increase in data. GTM Research expects the United States to spend more than $8 billion on smart grid analytics between 2012 and 2020.

“Asian and European markets will drive growth through 2020,” said McKerracher, “while in North America the focus will continue to shift from hardware to software as utilities look to squeeze additional value out of the vast amounts of grid data now available.”

Photo: Xinhua/eyevine/Redux 

India Plans to Install 26 Million Solar-powered Water Pumps

India’s government wants to replace 26 million groundwater pumps for irrigation with more efficient pumps that run on solar power, in an effort to relieve farmers of high costs of diesel fuel. Diesel generators are commonly used when grid power is unavailable, a not uncommon occurrence. And the power used for pumping irrigation water is also one of the largest strains on the Indian power grid.

The initiative is expected to require $US 1.6 billion in investment in the next five years just to switch out the first 200 000 pumps, according to Bloomberg.

Pumping water is critical for Indian agriculture, which otherwise relies on seasonal rain. It's also very contentious—Indian farmers are currently drawing more water than is sustainable, removing about 212 million megaliters from the ground each year to irrigate about 35 million hectares.

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Liquefied Air to Store Energy on U.K. Grid

When it comes to storing energy on the grid, giant batteries are the only game in town. Now, a number of companies are building mechanical systems that use air as the storage medium.

U.K.-based Highview Power Storage last week said that it has been awarded an £8 million grant from the U.K. Department of Energy and Climate Change to build a commercial-scale facility that uses liquified air to store energy. Highview is already running a smaller pilot plant, but the full-scale version will be able to store enough energy to deliver five megawatts of power for three hours. That puts it on a scale that would entice utilities to use the technology, says company CEO Gareth Brett.

"We're treating this (demonstration plant) as a shop window on the technology," he says. "Utility companies are pretty conservative and they want to see this bit of kit working at a scale that they can buy one."

Liquid air energy storage is similar to compressed air energy storage in that air is compressed and released to store and then generate power. With Highview’s technology, though, ambient air is compressed, then cooled and liquified. That liquefied air, which is almost -200 °C, is stored in large tanks.

When power is needed, the liquid air is released and pumped to high pressure. That causes the liquid to evaporate, turning it into a high-pressure gas which is then run through a turbine to generate power. The planned demonstration plant will be located at a waste processing center. Heat from the waste plant’s gas turbines, which run on captured landfill methane, will be piped in to improve the efficiency of the evaporation process.

One of the advantages of liquid air storage is that it uses off-the-shelf equipment. The tanks for storing liquid air, for instance, are the same as those used in the industrial gas industry. Highview’s expertise is in engineering the different components into a working system with the highest possible efficiency. “Getting the supply chain right is really what our technology is all about. What we’re trying to do is get a system to work with widely available kit,” Brett says.

This commercial-scale plant also gives an indication of how much liquid-air energy storage costs. For 15 megawatt-hours of storage, it will cost about £533 (about $900) per kilowatt-hour. But Brett projects the economies of scale from a larger plant would allow Brightview to get the cost under $500 per kilowatt-hour. At that price, energy storage on the grid can be cost competitive with power plants for a number of applications, such as storing wind and solar energy for delivery during peak hours, say experts.

Highview’s plant will be used to relieve congestion on the grid. For example, stored energy can supply power to the local distribution grid when substations are maxed out during peak hours.

The U.K. has emerged as a leader in advancing liquid air storage technologies. Last year, the Center for Low Carbon Futures released a report that identified liquefied air and liquid nitrogen as a valuable “vector” of research for storing energy for both the grid and transportation. And last year, the University of Birmingham won a £6 million grant from the U.K. government to establish a Center for Cryogenic Energy Storage.

Although liquid-air energy storage is a relative novelty in the utility industry, storing energy in the form of compressed air has a long track record. Two compressed air plants—one in Huntorf, Germany, and one in Alabama in the United States—have been operating for decades. Though the technology is considered reliable and relatively low-cost, these two plants use underground caverns to store pressurized air.

A few companies are now developing systems to store compressed air in above-ground tanks or pipelines, which makes siting easier. Because liquefied air is stored in tanks, Highview facilities can also be located in a wide range of industrial sites, Brett says. And because liquid air is four times as dense as compressed air, its tanks take up less space than those holding compressed air; liquid-air storage is also cheaper because the medium can be contained in less-expensive, low-pressure tanks, Brett says.

Still, Highview Power faces a number of competitors, including many battery makers that hope to slash the cost of storage. One of the biggest advantages Highview has is its potential to scale up quickly. Because it’s using off-the-shelf equipment, it doesn’t need to build a new plant or develop new manufacturing methods as new battery companies may need to. In theory, that means, if it has the orders, it can build and engineer storage plants without having to invest in its own production facilities.

Its large-scale demonstration site is projected to go online next year and, if utilities like what they see, the technology’s next step is a commercial plant.

Image: Highview Power Storage

Nearly Half of U.S. Power Plants Don’t Reuse Water

In the past half century, power plants in the United States have made considerable strides in water use, but there is still a long way to go, according to new figures from the U.S. Energy Information Administration (EIA).

More than 70 percent of electricity in the United States comes from plants that require some water for cooling. Most plants that generate steam to make electricity use water to re-condense the steam for reuse. While many plants return that water to the environment, others use less water but lose that water to evaporation in the cooling process. In total, it’s a huge demand on fresh water supplies: More than 40 percent of fresh water used in the United States is withdrawn to cool power plants.

Originally plants were once-through systems, where the water was only used once and then put back into the ecosystem. 

But other cooling techniques have been adopted in newer plants, though perhaps not fast enough given ongoing drought conditions. Because of environmental standards, most new plants use recirculating water systems and, to a lesser extent, dry cooling. The trend towards recirculating plants began in the 1960s, but the long lead-time on the switch over still means that many power plants still in use are once-through water systems. In the United States, 43 percent of plants do not reuse water, according to the EIA.


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Richard Branson Wants Caribbean Islands to Swap Diesel for Renewables

Dirty diesel is the most common form of electricity generation throughout Caribbean island nations, but that will change if billionaire Richard Branson has anything to do with it.

Branson is using his private island in the British Virgin Islands, Necker Island, as a test bed for a microgrid that will run on renewable generation. The project on Necker, which is supported by NRG Energy, is not just an exercise in bringing renewables to the region at any cost. It aims to make renewables affordable to island economies.

“What we’ve learned in the renewable world is everyone wants to save the world,” David Crane, NRG’s chief executive, told The New York Times. “But very few people want to pay more for energy.” The average price of electricity in the Caribbean is about four times higher than it is in the mainland United States.

The push for clean energy is the core mission of the Ten Island Renewable Challenge led by the Carbon War Room, a nonprofit founded by Branson. The problem for most islands is that the upfront cost of renewable technology and storage is relatively expensive given that most island nations have small populations. Because the projects are relatively small, compared to projects in the US or Europe, it can be difficult to get financing. 

At the same time, however, islands across the globe depend on diesel, which makes electricity incredibly expensive compared to regions that rely on other fossil fuels such as coal or natural gas. Hawaii, for example, has the highest electricity rates in the United States, about double the price of the next closest state.

Branson's challenge in the Caribbean already has the support of Aruba, British Virgin Islands, St. Lucia, and Turks and Caicos. Aruba, for example, already has a wind farm and is planning more.

Other islands are looking at solar, wind, LED lighting for municipal applications, waste-to-energy, and geothermal. For years, Barbados has been toying with the idea of using a special breed of sugar cane for co-generation, but has yet to invest in a large-scale project. Late last year, Puerto Rico mandated energy storage to go with wind and solar projects on the island, which could be a model for other islands if it is successful.

On the 74-acre Necker Island, the microgrid will combine wind, solar, and batteries that can support about 80 percent of the island’s energy requirements. On small islands, like Necker, microgrids may seem like a natural solution, but cost remains an issue if they are powered by renewables.

Although the cost of renewables have come down, and might be competitive with expensive diesel power, intermittent renewable energy requires expensive storage and sophisticated controls to balance grid conditions on that small of a scale.

Branson has the will and the deep pockets to invest in such a project, but the results will have to be replicable at a price that non-billionaire utility customers can afford on other islands.

Some of the solutions may be in attractive financing, rather than in proving the technology. In some places, subsidies for diesel make it more affordable and if those are ended, renewables look more attractive. Short-term tax benefits for renewables can also help to get projects off the ground. The Carbon War Room said it would help islands with assistance in attracting project engineers and financiers.

“There’s tens of thousands of islands burning diesel fuel that’s really destroying their economies because it’s so expensive,” Crane told the The New York Times.

Branson is hoping for quick results, and not just on Necker Island. "We're hoping to get a number of islands to sign up to get as carbon-neutral as they can over the next few years," Branson told “Immediately afterwards,” he wrote in a blog post, “we want to head to the Pacific Islands and implement everything we will have learned.”


Photo: Todd Vansickle/AP Photo 

Bio-Energy Box Coverts Beer Waste to Electricity

People have long known there is energy in wastewater; extracting it economically is the problem. Startup Cambrian Innovation claims its technology can do it and a brewery and a winery are now using it to clean their wastewater while producing energy.

The company's EcoVolt machine is a shipping container-size reactor that uses microbes to convert dissolved carbon in industrial wastewater into biogas, which can be burned on site for electricity or heat. Its first demonstration unit is running at the Clos du Bois winery in Sonoma county, and last month nearby Bear Republic Brewery in Cloverdale, Calif. flipped the switch on the second system.

Typically, food and beverage businesses remove the organic material in wastewater—measured as biological oxygen demand (BOD)—by aerating water with pumps. But that can be an energy-intensive process. The Bear Republic Brewery expects it will be able to eliminate 80 percent to 90 percent of the BOD of its wastewater with the EcoVolt and reuse 10 percent of its water. By burning the biogas, the brewery thinks it can cover 50 percent of its electricity needs.

The return on investment for the brewery is about four years in reduced energy costs, says Cambrian Innovation CEO Matthew Silver who I spoke to at the company’s headquarters in South Boston. Silver had planned to work in aerospace but became fascinated by advances in biotech and genetic engineering while a research scientist at MIT. Under a NASA grant, he led research into how bioelectric systems could be used to manage water in space. In doing that, he saw the potential for using electrochemically active microbes to clean water in industry. There's plenty of need: About three percent of the U.S. electricity is consumed treating wastewater, and producing one bottle of beer typically results in up to ten times as much in wastewater.

Making biogas from waste has been done for years and is not necessarily high tech. Industrial anaerobic digesters, which often look like farm silos, use naturally occurring bacteria to consume organic material to make biogas, which is siphoned off.

Cambrian Innovation's EcoVolt achieves a similar result but with a different anaerobic process. Its reactor has microbes that consume organic matter as food and deposit electrons directly on a metal electrode. Found in soil, these microbes, sometimes called exoelectrogens or anode-respiring bacteria, are the active component in some types of microbial fuel cells.

The EcoVolt system uses these microbes to produce a flow of electrons from a bacterial-film-covered anode to a cathode. They do this by breaking down organic molecules into hydrogen and carbon dioxide. At the cathode, another set of microbes, with the aid of the electric current, convert the CO2 and hydrogen from the first reaction to methane. A byproduct of that reaction is clean water.

The company is also working on a microbial fuel cell under a Department of Defense contract, which is part of US $8 million Cambrian Innovation has secured in DoD and National Science Foundation grants. The plan is to make a self-powered wastewater treatment facility for operating bases or for off-grid applications in the developing world.

CEO Silver has confidence that it can make an economic microbial fuel cell, but decided to target its first commercial product on the wastewater industry. By taking advantages of advances in other fields of engineering, the company was able to design a product that has compelling economics, he says. "We realized we needed to combine the advantages of biological systems with electrochemistry and information technology and really create a package," says Silver. It's now targeting companies in the food and beverage industry and seeking applications in other industries.

One of the advantages of the EcoVolt over traditional anaerobic processes is that it can be remotely monitored in real time. By viewing the rate and the health of reactions on the electrodes, Cambrian Innovation engineers can adjust flow rates and other bioreactor parameters. That’s much quicker control than a typical anaerobic reactor, which requires taking a sample and doing tests, says company chief technology officer Justin Buck. Company engineers have also developed techniques to adjust the reactor’s biology, which allows the EcoVolt to be robust and work with different types of waste streams, he adds. “We make sure that the proper community of microbes gets established on these electrodes,” he says. “If we don’t do that, incoming water will bring in new microbes, which is essentially a source of contamination.”

There are several reseachers and companies trying to take advantage of microbes to make electricity from wastewater. A group at Penn State, for example, combined a microbial fuel cell with reverse electrodialysis, a way to capture energy from a difference in water salinity, in an effort to increase electricity output.

Israeli company Emefcy (a play on the acronym for microbial fuel cell) has engineered a microbial fuel cell optimized for municipal wastewater. Another wastewater-to-energy startup is Arizona State University spin-off, Arbsource, an Arizona State University spin-off, uses anode-respiring bacteria to produce electricity, as Cambrian Innovation does, as well as hydrogen, ammonia, and other chemicals. And a number of municipalities produce biogas with digesters and use it to generate electricity and heat through fuel cells.

By contrast, the EcoVolt system is designed specifically for wastewater reuse. Cambrian Innovation hopes to appeal to businesses with high energy costs from wastewater treatment and, in general, bring more innovation to the slow-moving and conservative world of water treatment. "Up until now, compliance (with water treatment regulations) was viewed as a cost of doing business and a big part of the industry is designed around avoiding liability,” he says. “Now wastewater can be a source of revenue.” 

Image credit: Cambrian Innovation


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