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Clear Solar Panels Could Offer Energetic Window Retrofit

Engineers from Michigan State University (MSU) are designing transparent solar panels that could be retrofit to existing glass-covered buildings to generate electric power.

Traditional opaque solar panels such as silicon soak up much of the sun’s light, including visible light, and convert it to energy. A transparent panel allows visible light to shine through and making light that is invisible to the human eye—such as ultraviolet and infrared—do the work.

By making the solar panels transparent, MSU materials scientist and chemical engineer Richard Lunt and his team are creating the potential for them to cover existing windows.

However, making the panels clear is a challenge. So the team came up with ways to layer patterns onto the cell in a way that makes them uniformly transparent. The transparent solar cell under development incorporates thin coatings of organic and inorganic nanostructure materials that selectively harvest the parts of the solar radiation spectrum that are not visible to the eye.

“We actually used a variety of different stencils to pattern our devices,” Lunt says. Each active material has its own pattern. After every layer, the researchers put down a new stencil and in this way build complex structures, he adds.

Team member Margaret Young is testing whether the same process can be used on thin plastic.

“This is much lighter and much more flexible, so instead of rebuilding windows, we could just put this over an existing window,” she says.

Lunt says that he expects that in the next 20 years, this type of technology will be deployed extensively—turning cities and landscapes into solar harvesting systems, surfaces and solar farms without the aesthetic issues that today’s opaque solar panels create.

Could wind drones be the next evolution in wind power generation?

Drones will eventually be “as ubiquitous as pigeons,” London-based futurist Liam Young recently predicted. They are omnipresent already. Only five years ago drones belonged to the realm of the military, unaffordable for anyone else. Today, they are for hobbyists and even kids. Drones arrived in our lives and conquered the extreme ends of the market for technical goods. They proved to provide the best value for both, defense budgets and pocket money. Now the race is on to fill the gap in the middle: startups, corporates and analysts try to find the most promising commercial applications for drones. That is quite a challenge since drones can be used for a surprising variety of tasks. Much media attention was paid to Amazons’, Google’s and DHL’s announcement of using delivery drones. Others see the future for drones in surveillance, detecting fires, cracks in pipelines or illegal wood logging. They can also monitor farmland in detail for precision farming. Autonomous solar powered drones can also be used to hover at high altitude over an area for months to provide wireless communication similar to a satellite. Facebook and Google have invested in startup companies in this field. But there are other disruptive uses for drone technology which the current debate is largely unaware of.

One example is Elon Musk and his SpaceX company. He is working at landing and later reusing Falcon rockets after they have delivered their payload into space. It is impossible for a pilot to control a precision upright landing of a rocket that literally falls out of the sky. Only cutting-edge drone technology can do the job. If the rocket was to be recycled it would lower the flight costs from the cost of building a rocket to the cost of refueling it. That is $200,000 instead of $55 million.1 The business potential for the “rocket drone” would be enormous.

Or take Miles Loyd. In the energy crises of the late 1970s Miles Loyd worked as an engineer at Lawrence Livermore National Laboratory. He attempted to build the best wind generator imaginable.

He had the radical idea of building it without a tower, only using a flying wing connected to the ground by a tether, much like a kite. He calculated the expected energy output of his “flying wind generator”. Based on the formula he first established – today known as Loyd’s Formula – he found that a wing with the size, weight and aerodynamics of a standard plane wing of the 1970s could produce 6.7 MW of power. Even larger wings with an output of 45 MW seemed feasible. To put this into perspective: even today, 35 years later, the average wind turbine is still below 3 MW and the largest existing prototype has 8 MW. Loyd obtained a patent2 and published an article3 on this new technology.

And here the story ends. He could not convince investors to finance his flying wind generator, because he had no solution for one problem: how to control the flying wing without a pilot? Today, we have a technology that lets us control flying objects without a pilot. It is called: drones. If we can apply this new technology to Loyd’s old formula we can build a new type of drone: the wind drone.


How exactly does a wind drone work? There is a great resemblance to kite surfers. Kite surfers use a kite and a tether to pull a surfer through the water. The same mechanism can be used to generate electricity. The tethered kite or wing is connected to a drum and a generator on the ground and the tether is wound around the drum. The wing tears at the tether and turns the drum to generate electricity. Once the tether is fully unwound, the wing nosedives and the tether is quickly reeled in. Then the cycle starts again. This up-and-down motion inspired the name “yo-yo” type wind drone (%%0815-IF-Drone-1%%).

Google X, overseen by Sergey Brin, is working on a different wind drone in its Makani4 project. Google’s approach is to use little propellers (mini wind turbines) and generators directly mounted on the wing where they produce electricity. An electric cable is woven into the tether and transfers the electricity to the ground. In 2013 Makani presented a working prototype. They already built their first scaled up product with 600 kW output and announced that it will fly in 2015.

Google will be the first team to show a wind drone with power outputs comparable to today’s wind turbines. But they are not the only ones who have realized that drone technology is ripe to take on Loyd’s formula. Companies including 3M, ABB, Alstom, E.ON, Honeywell, Statkraft and Softbank have conducted research on wind drones and/or financed one of the dozens of airborne wind energy startups worldwide. Some of the prototypes use soft wings resembling a surf kite or a paraglider, others use hard wings like the wing of an airplane. The designs also differ in many other details. A dominant design has not yet emerged. But irrespective of their final design, wind drones share three characteristics that could turn them into the killer application for drone technology: they will disrupt their market, they will be one of the first autonomous drone applications to be market ready and they will have the largest market of all drone applications.


Producing wind energy is not a new idea and we already have a tried and trusted device for this task: the wind turbine. Wind drones will have to offer significant advantages over wind turbines to conquer this market. Airborne wind energy companies claim that wind drones can be built at half the price of wind turbines. In addition, they claim that downtimes for wind drones will be significantly lower and wind drones therefore produce twice as much energy with the same rated power. According to their calculations energy from wind drones could therefore be available at just one quarter of the price of energy produced by wind turbines. But are such claims realistic?


Can you manufacture wind drones more cheaply than wind turbines? The capital costs of a wind turbine which make up the bulk of the total costs of wind energy are the following (see %%0815-IF-Drone-2%%).5
The structural elements, the tower, the blades, the foundation and the rotor hub make up half of the total capital costs of wind turbines. Material requirements are extremely high: Up to 700 tons of steel for the tower,6 another 100 tons of steel for the rotor hub,7 up to 100 tons of glass-fiber reinforced plastic for the blades,8 and up to 4,000 tons of concrete for the foundation.

Wind drones lack theses massive structures. The tower is replaced by a thin tether. A wind drone with the power of the largest existing wind turbine (8 MW) requires a tether that is 2.5 inches/6 cm thick and would weigh less than one ton.9 Only minimal foundations are required and the wings can be much lighter requiring only 1 to 10 percent of the material of the blades of a wind turbine.10 The Google Makani 600 kW wing weighs below 2 tons including the tether and generators on board.11 A comparable 600 kW wind turbine weighs between 50 and 100 tons without foundation.

The required components for power generation are cheap in comparison: the costs for the electricity producing generator amount to less than 3 percent of total costs. Certainly, wind drones will need more and better sensors, processors and other control components, but these cost much less than the saved materials.


How can a wind drone save half the costs of a wind turbine? It is all about physics. A basic construction principle in engineering is to avoid a 90-degree force on an unsupported lever arm wherever possible. Large bridges are therefore supported by arches, columns, or suspension tethers. If parts cannot be supported they have to be made as short as possible.

Wind turbine engineers have done the opposite. Rightfully wanting to build ever larger and more efficient wind turbines they worked to increase the height of the towers and the length of the blades. Both are lever arms in a 90 degree angle to the wind force and they are not supported. Wind engineers would love to tether the tower and the blades. But it is not possible. The wind can blow from all directions, so the rotor has to be able to rotate around the tower and the blades have to spin freely. Nonetheless, wind engineers have excelled in building ever larger wind turbines. They hold the record for building the longest unsupported lever arms in the world. Undoubtedly a great achievement, but one that does not help saving material. The tether of a drone can be 1,000 times lighter than the tower of a turbine simply because it avoids lever arms.


A simple physical fact cuts costs in half. Can other physical facts double the output? Since wind drones are not restricted by lever arms they can fly higher. They easily reach altitudes twice as high as normal wind towers (300 m/1,000 ft. instead of 150 m/500 ft.). Physical facts: on average the wind speed increases with altitude; higher wind speed means more wind power; wind power increases with the cube of the wind speed. Double the wind speed therefore means wind power multiplied by eight (2³).

Altogether these physical facts lead to the conclusion that there is no such thing as a “bad location” for wind drones. Wind drones only know good and excellent wind sites. They will find enough wind at almost any site.

The impact of height differences can easily be illustrated by using wind data of Dresden, Germany (See %%0815-IF-Drone-3%%.12 At the altitude of wind turbines it is a very poor wind location. Not even with the support of the generous German feed-in tariffs does it allow economic energy generation. At wind drone altitude, the wind speed is 60 percent higher (grey columns). This does not sound spectacular, but due to the cubed relationship between wind speed and power the available wind power almost quadruples (blue columns).

At this altitude Dresden becomes an extremely windy place with a wind force only matched by few wind turbine locations such as coasts, mountains or offshore locations. The world’s largest offshore wind park London Array, has a comparable average wind speed of 9.2 m/s at 100-meter hub height.13 The reason is simple. Obstacles on land like forests, hills and buildings slow the wind down. Offshore winds partly owe their strength to the lack of obstacles. The same applies to high altitude winds: no obstacles to slow them down.

In addition, offshore or high altitude winds are steadier and therefore a more reliable source of electricity. Offshore wind turbines run at full capacity more often. Their idle periods per year are much shorter. Their so-called capacity factor is higher. They are therefore better suited to provide base load electricity. On average the output of offshore turbines is twice as high as that of onshore turbines with the same rated capacity.14 But since offshore turbines cost two to three times as much as onshore turbines, the advantage is quickly outweighed. Offshore wind energy is still more costly than onshore wind.15 According to research conducted by E.ON, Germany’s largest utility, offshore wind drones can boost offshore wind turbines’ high yields by another 50 percent. They can run at full capacity 70 percent per annum.16

In summary, wind drones have lower production costs, they can access much stronger high altitude winds and therefore run at full capacity for greater amounts of time. The estimate of many airborne wind energy startups seems realistic: electricity for a quarter of the price of today’s wind energy.

Google shares this belief in the cost-cutting power of wind drones. Google calculated that less than 16 percent of all the onshore U.S. sites are suitable for economic wind energy production with wind turbines. For wind drones this figure more than quadruples. 66 percent of the United States become viable.17

The higher capacity factor does not only lower the price, it also increases quality. The intermittency of most renewable energy sources causes a lot of concerns. Electricity grid operators face the challenge of matching the fluctuating production of renewables with demand. Current scenarios foresee the necessity to invest billions into stronger grids and energy storage. If wind drones can produce with a capacity factor of 70 percent as envisaged by E.ON, they could replace coal, nuclear and gas power plants without the necessity of massive new investments in grid and storage. Grid and distribution costs already make up for the greater part of our electricity bills. The high quality of wind drone power could become a decisive factor, even more important than its low cost.


The first wind drone prototypes are in operation. But when will they be market ready? Soon. Sooner than many other autonomous drones. The reasons: simplicity, safety, and the law.


Various drones have various tasks which vary in difficulty. Wind drones are the ones with the easy job. They fly the same simple pattern, say a circle, over the same space over and over and over again. Conventional wisdom has it that robots and drones will first get into the dull, dirty and dangerous jobs. Sorry, wind drones, we cannot get you dirty and dangerous, but when it comes to dullness it is hard to beat your job.

Flying the same patterns over the same area means that the sensors know exactly what to expect, that the software has to know only a few flight patterns, and that the only variation can come from different weather, namely changes in wind speed and direction. And if the wind drone has to land for inspection or due to extreme weather, the landing site is also always nearby.


No matter how simple a task, something can always go wrong and in case of flying objects the result can be a crash. To be a commercial success, every drone will have to prove that it is safe.
In the beginning wind drones will only be installed in controlled areas in the countryside, or over the sea, where unauthorized access is not allowed. If the public cannot access the flight area, the public cannot be harmed. This is the simplest recipe for safety. Amazon on the other hand might find it difficult to deliver its parcel to your doorstep while keeping a safe distance from people.

Wind drones also have a built-in safety feature that is unique to drones: They are kept constantly on the leash, pardon, tether. So even if all controls go out of control, wind drones can only crash within the area of the tether and will not do any harm outside.

Stationary operation and the strictly defined flight area of wind drones not only increase safety on the ground but also in the air. Wind drone parks can be included in air maps and turned into no-flight zones for low flying air traffic, just as wind parks are today. Air regulators have already honored the additional safety and special features of wind drones. A draft decree of the European airspace authority EASA has an exemption for wind drones (and other drones on the tether) allowing them to fly higher than other drones without the same restrictions.18 And under the new EASA “concept of drone operation”19 the degree of regulation will depend on a specific risk assessment for each use of drones. In case of operation in segregated areas, where drones do not pose a risk to the public, the operator might even approve its own risk assessment. Airspace regulators worldwide are currently working on regulation for drones. They will mostly use comparable flexible concepts, since applying existing strict regulation standards for manned aviation to drones would choke off the respective national drone industry without any safety benefits. So wind drones are not only safer in practice, but this additional safety in the air and on the ground will lead to much lighter regulations. This will make them faster, easier and cheaper to build than other more hazardous and therefore stricter regulated free flying drones or aircraft.

What is true for drones is also true for autonomous cars. Many believe that autonomous cars will become commercial reality in a few years. This is not true. Fully autonomous cars have long ago hit the market. They have been available for purchase since 2008. Where? At your local Caterpillar20 or Komatsu21 dealer, specialized in mining equipment. More and more mines are equipped with fully autonomous haul trucks, which transport rocks and minerals within the mine. Have the engineers at Caterpillar and Komatsu outclassed their counterparts at Google, GM, Tesla, BMW, Volvo, Toyota, Audi, Mercedes by launching their product a decade earlier? Not quite. Haul trucks perform limited and well defined repetitive tasks. They operate stationary in mines, which are controlled distant places with no access for the public. There is little or no regulation on their development and use. The conclusion for drones is obvious.


The strongest argument for wind drones is their potential market: it is huge.

To begin with, the global wind turbine market is a large market. Its volume amounted to $80 billion in 2013.22 Its growth rate averaged 25 percent per year over the last decade23 and the market will continue to grow strongly. But wind drones are not limited to the existing market for wind turbines. A look at the top 20 global companies with the largest revenue as compiled by the Fortune Global 500 list24 illustrates their full market potential:

Energy is big business. But wind energy is still minuscule and accounts for less than 1 percent of total global energy use.25 This will change. And it is mostly a question of competitiveness. Onshore wind turbines are on the brink of becoming competitive with coal and natural gas. This so called grid-parity has been reached in some regions. It means that wind energy is already the cheapest source of electricity even without subsidies. Add wind drones’ potential to slash these costs to one quarter, add steadier production and add their ability to be deployed almost anywhere.

This means that wind drones cannot only compete with wind turbines in their niche but will become the cheapest source of electricity. Cheaper than coal, gas, nuclear and hydro power.

And since electric cars are on the rise, the electricity produced by wind drones will be able to play in the energy major league and compete with oil as a transportation fuel. And oil will have a hard time competing, even at the current “cheap” oil prices. Taking into account the inefficiencies of the combustion engine, oil at $60 per barrel is still a more expensive source of power for a car than the electricity produced by today’s wind turbines. Based on the analysis above, oil would have to sell at a quarter of that price, below $15 per barrel to compete with wind drone energy on a pure cost of fuel basis.

The digital revolution has disrupted many markets, created vast riches and young billionaires. But we have to bear in mind that the digital revolution has only taken place in very limited markets so far. The so-called digital giants Google and Facebook — and many others — are all competing for a share of the online advertising market. This market has a total global volume of $150 billion.26 Compare this to the annual average $2 trillion investment into energy supply required in the next 20 years according to the International Energy Agency.27 Compare this to the $3.4 trillion revenue that the 11 largest energy companies on the Fortune Global 500 list share. Or compare it to the total global energy market that is assumed to have a size of $6 trillion to $10 trillion. This is a difference in market size that could come close to a factor of 100. We cannot imagine what it will look like when the drones the digital revolution created take on the largest market of the world, the energy market.


We have illustrated how the laws of physics in combination with sensors, chips and smart algorithms can replace the tons of steel and concrete wind turbines are made of. This can make wind drone power cheaper than electricity from fossil fuels. Their ability to harvest stronger winds higher up in the air gives wind drones the potential to provide power where it is needed irrespective of the existing wind resource. Cost-effective electricity made by wind drones could even provide the basis for the clean synthetic fuels of the future. And this fuel could be available at less than today’s oil price.

A lack of wind will no longer be a problem. We have seen how the wind resource dramatically increases by doubling the altitude. But this is only the first humble hop of wind drones into the air. Once these altitudes are mastered, it will be tempting to gradually go higher, until they reach the jet stream at 10 km/33,000 ft. Before, many technical and legal problems will have to be solved. But it will be attempted. The wind resources at this altitude are simply too enticing. The median energy density over New York at this height is more than 10 kW/m² 28 of which about 5 kW/m² can be used.29 The total energy consumption per person in the U.S. amounts to 10.5 kW. This includes all electricity use, heating, car and aviation fuels, and even industrial energy consumption.30 This means that harvesting wind in an area of 2m² (22 sq.-ft.) per person, the size of an open front door, could on average provide all our energy. If 10 wind turbines with today’s dimensions were installed in that altitude over New York, they could have the same rated power as an average nuclear power plant, over 1 GW.31 High-altitude wind energy is not only an extremely concentrated source of energy, it is also abundant. It can provide about 100 times of today’s global energy consumption.32 High altitude wind energy could allow us to live a greener lifestyle without the need to reduce our use of energy. For the energy sector this could mean nothing less than finally solving the conflict between economy and ecology.

Burning fossil fuels started the industrial revolution. It enabled the advances of mankind in the last 200 years. Without fossil fuels feeding 7 billion people on this planet would be impossible. But fossil fuels also destroy and pollute nature, poison our cities and homes and cause an ever more dangerous climate change. Furthermore, our reliance on fossil fuels leads to unjustified wealth and power imbalances, to wars over their control and to undemocratic regimes.

When mankind started to burn fossil fuels it made a huge leap forward. When it stops to burn fossil fuels, it will make another big step towards a better world. Drones will help to bring this day much closer than most of us believe today.

3 M. Loyd, Crosswind Kite Power, Journal of Energy, Vol. 4, no. 3, pp. 106-111, 1980
5 Additional Operations & Maintenance costs are 20% of total costs. Source capital costs breakdown: IRENA International Renewable Energy Agency, Working Paper Renewable Energy Technologies: Cost Analysis Series, Volume 1: Power Sector Issue 5/5 Wind Power, June 2012
6 All data is for the MHI Vestas V164-8WM, currently the largest wind turbine prototype of the world.
9 Calculated for 8 MW power and flight altitude of 250 meters. M. Diehl. Airborne Wind Energy, Airborne Wind Energy: Basic Concepts and Physical Foundations. Springer, 2013.
10 A detailed explanation of the higher efficiency of the wind drone wings is beyond the scope of this article. For an introduction to the physics of wind drones see M. Diehl. Airborne Wind Energy, Airborne Wind Energy: Basic Concepts and Physical Foundations. Springer, 2013.
12 ind Data source: Christian Geiss, Technical University Chemnitz, Studies on the vertical wind profile in Saxony (Untersuchungen zum vertikalen Windprofil in Sachsen), 2012
14 A doubling of power output is also roughly expected from average offshore compared to average onshore sites: IRENA International Renewable Energy Agency, Working Paper Renewable Energy Technologies: Cost Analysis Series, Volume 1: Power Sect or Issue 5/5 Wind Power, June 2012
15 IRENA International Renewable Energy Agency, Working Paper Renewable Energy Technologies: Cost Analysis Series, Volume 1: Power Sect or Issue 5/5 Wind Power, June 2012
18 Draft Guidance Material 1 (GM1) Standardized European Rules of the Air SERA.3138(a) paragraph (b) in: NPA 2014-09 .
22 Global Wind Energy Council, Global Wind Report 2013
23 International Energy Agency, World Energy Outlook 2013.
25 0,3% in 2011: Wind 434 TWh, Total Energy Demand: 13.070 Mtoe (= 152,000 TWh), International Energy Agency, World Energy Outlook 2013.
27 International Energy Agency, World Energy Investment Outlook, Executive Summary, 2014,
28 C. Archer, K. Caldeira; Global Assessment of High-Altitude Wind Power, Energies 2009, 2(2), 307-319; doi:10.3390/en20200307,
29 The theoretical maximum is the Betz limit 16/27 or 59%. Modern wind turbines are very close to this with efficiencies of about 50%, including losses in generators, drivetrains etc.
31 The Vestas MHI Vestas V164-8WM with a blade lengt of 82m features a swept area of 21,124 sqm. With 10kW/sqm and 50% efficiency, this results in 105 MW per Turbine or over 1 GW for 10 turbines.
32 K. Marvel et al. Geophysical limits to global wind power, Nature Climate Change, Vol. 2 no. 9 September 9, 2012; M. Jacobson and C. Archer. Saturation wind power potential and its implications for wind energy. Proceedings of the National Academy of Sciences, 2012 (doi:10.1073/pnas.1208993109)

About The Author

Udo Zillmann is the founder and managing partner of Daidalos Capital GmbH, a fund management company that specialized in investing in airborne wind energy companies since 2010 and is currently raising its second special airborne wind energy fund. Mr. Zillmann is author of “Financing Strategies of AWE Companies” in the book “Airborne Wind Energy” (Springer, 2013) and a regular speaker on airborne wind energy. Mr. Zillmann holds degrees in law and business.

EPRI says with R&D, coal power can be clean without carbon capture

Carbon capture with underground storage is considered by many to be the best option to reduce carbon dioxide emissions from coal-fired power plants. But development and application of CCS systems face technology, policy and cost challenges.

The Electric Power Research Institute looked at several technologies available or in development that have the potential to enable power plants fueled solely by coal to reduce CO2 emissions through more efficient combustion and use of heat. The results of EPRI’s study have been published in a new white paper, Can Future Coal Power Plants Meet CO2 Emission Standards Without Carbon Capture and Storage?

EPRI’s paper analyzes current and anticipated U.S. and global CO2 emission standards for coal plants, identifies key challenges associated with CCS deployment, and provides detailed descriptions of coal-only technologies that are not ready for commercial deployment but that present opportunities to reduce CO2 emissions.

Today’s most efficient coal-fired plants are the ultra-supercritical plants that produce steam at high temperature (above 593 degrees C or 1,100 degrees F) and emit about 800 kg (1,760 pounds) CO2/MWh. EPRI looked at several technology options for increasing the thermal efficiency of the processes for generating electricity with coal, including:

· Rankine cycles (used by most of today’s coal plants) with higher steam temperatures;
· Combined heat and power applications (also known as cogeneration); and
· Coal gasification integrated with one of four systems — combined cycles (gas turbine plants), supercritical CO2 Brayton cycles (which use the CO2 instead of water or steam as the working fluid), solid oxide fuel cells (SOFCs), and “triple cycles” (a combination of combined cycles and SOFCs).

However, none of the options considered in EPRI’s analysis are currently commercially available, economically viable, and suitable for broad deployment.

National R&D programs in the United States and elsewhere are making progress, but additional public-private R&D investment is needed to accelerate the deployment of many of these technologies.

“It’s critically important for the electric power industry to have as many generation technology and fuel options as possible,” said EPRI Vice President of Generation Tom Alley. “Reducing emissions will be one of the key drivers as the industry makes decisions about existing assets and about the designs and fuels used in the next generation of power plants. EPRI research like this can be invaluable in informing those decisions.”

Waving good buy? A hitherto-obscure piece of physics may be the secret to ocean power generation

THE idea of extracting energy from ocean waves and turning it into electricity is an alluring one. The first serious attempt to do so dates back to 1974, when Stephen Salter of Edinburgh University came up with the idea of “ducks”: house-sized buoys tethered to the sea floor that would convert the swell into rotational motion to drive generators. It failed, as have many subsequent efforts to perform the trick. But the idea of wave power will not go away, and the latest attempt—the brainchild of researchers at Oscilla Power, a firm based in Seattle—is trying to address head-on the reason why previous efforts have foundered.

This reason, according to Rahul Shendure, the firm’s boss, is that those efforts took technologies developed for landlubbers (often as components of wind turbines) and tried to modify them for marine use. The consequence was kit too complicated and sensitive for the rough-and-tumble of life on the ocean waves, and also too vulnerable to corrosion. Better, he reckons, to start from scratch.

Instead of generators with lots of moving parts, Oscilla is developing ones that barely move at all. These employ a little-explored phenomenon called magnetostriction, in which ferromagnetic materials (things like iron, that can be magnetised strongly) change their shape slightly in the presence of a magnetic field. Like many physical processes, this also works in reverse. Apply stresses or strains to such a material and its magnetic characteristics alter. Do this in the presence of permanent magnets and a coil of wire, such as are found in conventional generators, and it will generate electricity.

The core of Oscilla’s design is a bar made from an alloy of iron and aluminium, a mixture that is strongly ferromagnetic. Such bars need be compressed by only one part in 10,000 to have the desired effect. This means, to all intents and purposes, that the generator has no internal moving parts that can go wrong. But compressing a solid metal bar by even this tiny amount requires the application of a huge force. Fortunately, ocean waves are powerful enough to generate this force. Oscilla’s design, as the firm’s name suggests, does it by oscillation.


Its oscillating generators consist of two large objects connected by cables (see diagram). At one end of these cables, floating on the surface, is a buoy that contains the generating apparatus of alloy bars, magnets and coils, together with sets of hydraulic rams which can squeeze the bars as desired. At the cables’ other ends hangs a structure called a heave plate, which is kept stationary by a combination of inertia and the drag of the surrounding water. This arrangement means that, as the buoy rises and falls with the waves at the surface while the heave plate stays more or less put, the tension on the cables increases and decreases. That changing tension drives the rams. The whole system is kept in place by a second set of cables that moor it to the seabed.

A full-scale device, which Oscilla hopes to build by 2018, will be a foam-filled steel buoy 27 metres in diameter, six metres high and weighing 1,000 tonnes, tethered to a toroidal concrete heave plate 70 metres below the surface. It will carry 12 magnetostrictive generators within. Mr Shendure says that a single such buoy, placed a few kilometres offshore, should deliver an average of 600 kilowatts—about the same as an onshore wind turbine. A prototype four metres in diameter underwent a brief but successful open-ocean trial off the Atlantic coast of America last year.

Oscilla’s generators will, Dr Shendure acknowledges, be expensive to build and install. But their simple design, he says, should allow them to operate for decades with no more maintenance than an occasional scrub to remove accumulated barnacles. He calculates that the cost of producing electricity from them will be around ten cents a kilowatt hour. That compares with 16 cents a kilowatt hour for offshore wind farms and six cents for the onshore variety. A grid-connected fossil-fuel power station would be cheaper still—five cents or less. But ten cents represents a decent start for such a novel way of generating electricity.

Jan Allen Plans to Turn Everyone’s Food Waste into Renewable Energy with This Machine

Jan Allen has been involved in design, construction and operation of organics facilities for over 25 years. Now, he is the president of Impact Bioenergy, a company developing a machine that can convert organic waste materials into energy and fertilizer with zero waste. The machine has the capability to converting 25 tons of waste into energy each year.

Allen tells us about the machine, referred to as the “HORSE”, as well as the company’s goal of making communities more self-sufficient and granting individuals the opportunity to create renewable energy right on their property.

Electronics360: Can you tell me a little bit about your background? Do you come from a technical background since your work is generally focused around an electricity-producing machine?

Jan Allen: I have been involved in design, construction and operation of organics facilities since 1989. The aerobic (composting) facilities I designed have diverted over 10 million tons or organics from landfilling and the anaerobic systems produce 10 MW of renewable energy. I am the registered inventor of six U.S. Patents for composting, digestion and biofiltration. I’m a professional civil engineer and was educated at Purdue University in Indiana. I’m more of a microbiologist and nuts and bolts guy than an electrical guy.

Electronics360: Where did you come up with the concept for the HORSE?

Jan Allen: When I was in college, my advisor persuaded me to build three small digesters to convert waste into renewable natural gas. It was an inspiring project. Then much later in my career, I was working for a large firm in Boston that had a mission to build large urban power stations that are fueled by commercial food waste. When I was there, I was impressed at how many inquiries we received for smaller systems. My company did not want to bother with small projects. No one else in the industry did either.

So that was the main reason for starting Impact Bioenergy. There was a need and no one was filling it.

Now there are at least 35 companies selling or developing owner-operator anaerobic digestion technology in North America. Not one of them has scaled down to restaurant, office, campus, or hotel scale. Not one of them has brought the footprint and cost down to the onsite or community scale. It’s not that the technology can’t be scaled—it’s more about conventional wisdom with supersized facilities and long development timelines—on the order of two to 10 years. Conventional wisdom says that small projects take as much effort as big ones, but are not as profitable. These companies just don’t recognize the high cost and risk of permitting and waste transport.



Electronics360: Can you explain the science and technology behind the machine?

Jan Allen: It is a liquid system that uses microbes to mimic a living animal. We call it a HORSE, but it functions like a mechanical cow. The food waste is called feedstock and has to be ground and pureed into a smoothie-like consistency. It is metering into the system in small doses continuously and automatically. The system is maintained at 100 F°, is mixed, is airtight (anaerobic), and is monitored for pH, gas production, liquid level, pressure, etc. A gallon of feedstock takes 30 days to make it through the two stages and then overflows out as digested liquid plant food. There are only four moving parts: a mixer, heating pump, grinder pump and dosing valve. There is a gas manifold and a liquid manifold to manage the system.

Electronics360: How exactly does it generate electricity? How much power can it really produce?

Jan Allen: The machine makes natural gas. The gas is stored in a gas storage vessel until it can be used. To make electricity, the gas is used as a fuel in an engine generator. This is an ideal application for combined heat and power. The machine is rated for a full speed output of 15,000 BTU per hour. There are lots of choices for engine types, CHP systems, electrical efficiencies, etc. In general, making heat or hot water can be 90% to 94% efficient. Making electricity only can be 12% to 40% efficient. Making combined heat and power can be somewhere between these figures.

It will consume 25 tons per year of food scraps, beverages, fat and paper products. It can create 5,400 gallons per year of liquid fertilizer and up to 37 MW-hrs of raw energy. As renewable gas, that’s 125 Million BTU per year (4.3 MW-hrs of this energy is electrical output).

This is what that is equivalent to:


Electronics360: How do you envision the HORSE working in a community?

Jan Allen: The vision is to become more self-sufficient and to make renewable energy on your property and fertilize your own or a nearby garden or farm to grow food and flowers. The HORSE is both a sustainability and society game changer. It’s all about the quadruple bottom line: people, planet, profit and progress. There are 700,000 restaurants and 4,000 college campuses in North America. Each one should have their own HORSE. Just imagine the sustainable energy revolution for islands, resorts, zoos, museums, schools, parks, convention centers, farmer’s markets, music venues, apartments and corporate and municipal campuses as they turn food scraps into energy. This is just the beginning.

The HORSE will eradicate curbside garbage pickup and the carbon emissions associated with long distance trucking. It will create a whole new shared carbon-negative transportation model for local use: less trucking plus no landfilling plus renewable energy! Its combined benefit is disruptive and huge; It’s decentralized—it’s portable—it’s affordable. Imagine a technology that can divert waste and create energy off-grid. Imagine eliminating the organic waste from your trashcan. Imagine making it into two valuable new resources that you can personally or commercially use.

Electronics360: What are Impact Bioenergy’s goals at this point?

Jan Allen: To establish a few key partnerships and get these machines on the ground and operating. Everyone wants to see one working. We need reference facilities.

Electronics360: Where do you see yourself and the company in 10 years?

Jan Allen: We see a network of community supporting biocycling groups sharing information with each other. Impact Bioenergy is the core technology provider, designer, builder and supplier of the HORSE digester. CSB is the service end of a strategic partnering program that helps remove barriers to market this transformational technology in different locations. It is a partnering program between businesses such as breweries, restaurants, markets, urban farmers, and gardeners. What is Biocycling? Biocycling is the recycling of organic materials. In the context of our project, this term describes the process of taking organic wastes such as food scraps and converting it into liquid fertilizer and energy that can once more be used directly on the farm at which these food resources were originally produced. We like to say…Farm to fork to fertilizer and fuel, and back to the farm again.

Electronics360: Is there any other technology currently being developed behind the scenes?

Jan Allen: We are working on upgrading the biogas to CNG vehicle fuel. Back to the Future may be fictional, but the machine that converts food scraps into energy is here, because we just built it. This is a living machine that eats food scraps and makes energy and plant food using microbes with zero waste.

Electronics360: What do you find most challenging about being part of a company based on technology geared toward improving the environment?

Jan Allen: Right now the company needs operating systems on the ground so people can see the technology in action in an urban environment. To that end, a recent crowdfunding project has successfully reached its goal just this month to build a reference facility in Seattle. Remarkably, about 30% of the money pledged came from individuals in New York City.

Biggest lessons learned on the business end are:

that being disruptive means some existing stakeholders will not embrace your good idea
that triple bottom line decisions that account for environmental, social values in dollars is very rare indeed
that accountants rule the day on payback period, return on investment, cost savings, etc. Remarkably this technology does offer what the accountants want.
Biggest lessons learned on the social and cultural end are:

The idea of converting waste into energy and organic matter with zero waste really resonates. Impact Bioenergy has no payroll, but three full time workers, seven part time workers, and a constant stream of job seekers and volunteers

Overall there were 16,000 video starts on the crowdfunding page

People in 68 countries clicked into the crowdfunding page and video

The biggest lessons on the technology/environment end are:

This technology is no more complicated that having a real horse or a large aquarium. The machine wants to be fed lots of small meals, doesn’t like to be cold, and sometimes needs antacids

Visual art and odor control are essential. They are integrated into the design so it fits in the urban setting

The big win here is eliminating trucks hauling waste away and hauling food into the city. That is two groups of trucks! Trucking is a huge cost and environmental burden to the city in air quality, greenhouse gases, congestion, noise, fuel use and export of resources and jobs away from the community.

Using a HORSE eliminates the odor, flies, rats, seagulls and leakage associated with the traditional dumpster.

Question or comments on this article? Contact an editor:

Alstom to supply power transformers for Karadeniz Powership in Turkey


Karadeniz Energy Group has awarded a contract to Alstom to supply power transformers for the 486MW Karadeniz Powership Osman Khan (KPS12) power plant in Turkey.

Under the terms of the contract, Alstom will manage the design, engineering, production, supply, testing and commissioning of the 200MVA power transformers.

The transformers will be produced at Alstom Grid’s manufacturing site in Gebze, Turkey. The company is expected to deliver the transformers by early 2016.

Alstom Grid Power Transformers commercial director Tunc Tezel said: “Alstom is very pleased to work with Karpowership, the world leader in floating power plants, on this powership concept.

“This contract reflects the quality and the high-performance of Alstom’s transformers, as well as its technical expertise in this field.

“The ability to help countries meet short-term energy demand quickly and in a cost-efficient manner is an important step to providing more people access to sustainable and reliable electricity.”

Floating power plants or powerships are barge or ships mounted, converted from bulk carriers, heavy-lift vessels and they supply electricity to the countries falling under the purview of agreements signed under the Power of Friendship project.

Powerships are capable of connecting to the electricity grid immediately upon berthing, solving short-term energy problems.

According to Alstom, Karadeniz Powership Osman Khan is the world’s largest floating power plant.

Karadeniz aims to increase the installed power, from 1,500MW with nine energy ships, to more than 5,000MW by the end of 2017.

Charge-as-You-Drive Could Ease Electric Vehicle Range Anxiety

Efforts to curb carbon emissions via government automobile regulation means that ultra-low emission vehicles, including pure electric vehicles (EVs) and plug-in hybrids, will play an increasing role in the way we travel.

In California, for instance, by the 2025 model year, 15.4% of projected statewide sales of 1.75 million cars and light trucks sold by automakers will have to be zero emission vehicles (ZEVs). California will not be alone. Federal law permits other states to adopt California’s automotive emissions rules if they are stricter than federal regulations (and they are, since there is at present no federal ZEV mandate). As a result, nine other states and the District of Columbia say they will follow California and institute their own ZEV requirements.

However, among the current obstacles to widespread adoption of EVs are their long charging times and lack of available charging stations. Currently, the most common EV or hybrid EV power transfer system is the plug-in electric charger. These usually charge at between 3 kilowatts (kW) and 50kW (some, like the Tesla supercharger, can go up to 120kW) while the vehicle is stationary and switched off. This solution is adequate for charging at home or in parking garages since the vehicle must spend considerable time standing still.

However, what if the EV charging infrastructure could be extended via the application of inductive power transfer to the vehicle during driving? The concept is called Dynamic Wireless Power Transfer (DWPT) and studies have shown that introducing DWPT on roadways would increase the likelihood of consumers using an EV as their main car. The technology would address driver concerns about restricted driving range and the possibility of running out of power between charging stations.

Overview of the wireless inductive power transfer pads embedded underneath the roadway at Utah State University’s test track. Image source: Utah State University.

Overview of the wireless inductive power transfer pads embedded underneath the roadway at Utah State University’s test track. Image source: Utah State University.

From Tesla to Test Track

The principle of wireless power transfer is simple: it is an open-core transformer consisting of primary transmitter and secondary receiver coils and associated electronics. Magnetic induction (MI) schemes use an electromagnetic field of a given frequency generated by alternating current in the transmitter to induce a voltage in the receiver coil. (In a wireless inductive charging system, the primary coil resides in the charging device and the secondary coil is located in the device being charged.)

The notion that resonance could be used to improve wireless power transmission is well known. In 1894, Nikola Tesla was granted a patent for a resonant inductive coupling to supply electric current to the motors of streetcars from a stationary source. He proposed doing so without the use of contacts between the line conductor and the car motor.

The principle of wireless power transfer is simple; it is an open-core transformer consisting of primary transmitter and secondary receiver coils and associated electronics.

The principle of wireless power transfer is simple; it is an open-core transformer consisting of primary transmitter and secondary receiver coils and associated electronics.

Charge-as-you-drive technologies have already been pioneered in several places. In South Korea, the Korea Advanced Institute of Science and Technology (KAIST) has developed a wireless power transfer technology called OLEV, short for On-Line Electric Vehicles. It works using technology embedded beneath the road.

In the town of Gumi, a route has been built that allows buses to recharge while in motion. The technology supplies 60 kHz and 180 kW of power wirelessly to the transport vehicles. The route length is 35km, and the length of the DWPT section is 144m, comprised of four DWPT sections. Two buses are equipped to recharge while driving over this roadway; the OLEV buses have coils on their underside to pick up power through the electromagnetic field on the road. The DWPT system enables the buses to reduce the size of the reserve battery used to one-fifth that of the battery on board a typical electric car.

Bombardier, a leading manufacturer of planes and trains, has developed a charging system for trams called PRIMOVE. The technology allows vehicles to run continuously without overhead lines. A research project undertaken by Flanders DRIVE, a research organization supported by the Flemish government, allowed Bombardier to test its inductive charging technology on road-based vehicles using a test track built on a public road. During a feasibility study in Lomel, Belgium, between 2011 and 2013, a bus was retrofitted with the first-generation PRIMOVE system.

Two buses are equipped to recharge while driving over this roadway; the OLEV buses have coils on their underside to pick up power through the electromagnetic field on the road.

Two buses are equipped to recharge while driving over this roadway; the OLEV buses have coils on their underside to pick up power through the electromagnetic field on the road.

Fitting the bus with PRIMOVE charging equipment designed for a maximum energy transfer of 160kW proved the technical feasibility of high-power Two buses are equipped to recharge while driving over this roadway; the OLEV buses have coils on their underside to pick up power through the electromagnetic field on the road.

inductive energy transfer for electric buses both while parked (static charging) and while moving (dynamic charging). Bombardier is currently implementing a 200kW system for electric buses in Bruges, Belgium as well as in Braunschweig, Mannheim and Berlin in Germany. On the automotive side, the PRIMOVE team reports that it can offer its technology at three levels of charging power: 3.6kW, 7.2kW and 22kW.

Meanwhile in the United States, Utah State University has built an EV, roadway research facility and test track that uses wireless inductive power transfer pads embedded underneath the roadway. The installation allows EVs to charge while they are in motion. The facility, called EVR (for electric vehicle and roadway) has capacity for 750 kW of power with AC-to-track and DC-to-track provisions. Construction of the test track and lab building is complete with equipment, including a dynamometer for testing vehicle capabilities in place. Utah State’s EVR should be fully operational in the fall of 2015.

Ambitious UK Trials

One of the most ambitious trials may be in the UK where the government agency Highways England has announced plans to carry out test track trials of a wireless road-embedded EV charging technology. The trials will involve fitting vehicles with wireless technology and testing the equipment installed underneath the road. The trials are expected to last for approximately 18 months and, subject to the results, could be followed by tests on existing motorways. Additional details of the trials will be made available when a successful contractor has been appointed.

The upcoming trial follows a feasibility study conducted by Highways England that examined how wireless charging infrastructure might be installed in the country’s major roads. Two different example layouts for DWPT systems were investigated in the study:

Individual power transfer segments up to 8m in length would be combined into power transfer sections of up to 50m long (consisting of four segments with gaps between each segment). Up to two segments can be energized in any given 50m section. Power transfer was set up to 40kW for light vehicles and up to 100kW for buses, trucks or other heavy-duty vehicles. Each 50m segment could supply two vehicles with power.
Individual power transfer segments would be created up to 40m long. A gap of around 5m would be placed between adjacent segments. Each 40m segment could supply power to one vehicle. Power transfer was limited to 40kW for light vehicles and to 140kW for buses or trucks.

The Highways England analysis showed that under different traffic conditions—and using an assumed scenario for vehicle and technology penetration—average demand could be as high as 500kVA (0.5MVA) per mile. When use of the system fell short of the maximum value, the expected demand was found to be similar across both layouts. The number and length of segments under these conditions would not have an impact on total power demand, the study showed, as the number of power transfer segments that can be occupied is limited by the number of vehicles on the road. Power demand from the second layout example was found to be slightly higher than from the first example due to the higher power transfer capability for heavy-duty vehicles.

While the study concluded that systems with shorter coil lengths (up to 10m) are likely to be safer and better able to cope with higher utilization, different coil lengths will be investigated during the trials to understand the variability and implications on safety.

Highway England also considered three types of road construction for DWPT, including trench-based constructions (where a trench is excavated in the roadway for installation of the DWPT primary coils), full-lane reconstruction (where the full depth of roadway is removed, the primary coils installed and the lane is resurfaced), and full-lane pre-fabricated construction (where the full roadway is removed and replaced by pre-fabricated full-lane width sections containing the complete in-road system).

Both of the first two methods were found to be viable. The study concluded that the full lane pre-fabricated method is likely to be prohibitively expensive, although further investigation is required as this is a relatively new construction technique. The upcoming trials are expected to offer more data for all three proposed construction methods.

Could Fuel Cells Solve the Emissions Problem for Coal Plants?

With a little extra engineering work, some researchers believe fuel cells could become one of the most affordable ways for coal plants to keep their doors open as pollution regulations tighten.

The Department of Energy selected FuelCell Energy Inc. (FCE) last week as one of eight funding recipients to pilot low-cost carbon dioxide capture and compression technologies. The $23.7 million project (with $15 million coming from the DOE and $8.7 million from FCE) will see a 2-megawatt fuel cell deployed at a coal-fired power plant designed to capture about 60 tons of CO2 per day, while simultaneously producing about 40,000 kilowatt-hours of electricity per day.

This first-of-its-kind application is a modification to FCE’s existing Direct FuelCell technology, which the company says has already generated more than 4 billion kilowatt-hours of electricity. Researchers have been exploring the use of fuel cells for carbon capture since the early 1990s, but only recently has the technology declined enough in cost to be seriously considered as a solution.

Carbon capture only works with a molten carbonate fuel cell, a chemistry that relies on CO2 to operate. Flue gas from a coal plant contains 5 percent to 15 percent CO2, with the remainder made up largely of nitrogen, as well as other gases. In FCE’s application, the flue gas is routed into the fuel cell at one electrode, where the cell selectively takes up the CO2 and releases it in a concentrated stream at the other electrode. During this process, approximately 70 percent of the smog-producing nitrogen oxide is destroyed.

Once the CO2 is captured, it’s cooled and compressed utilizing standard refrigeration equipment. The purified carbon can then be sequestered or used for enhanced oil recovery.


Today’s commercially available carbon-capture technology has proven to be extremely expensive and energy-intensive, nearly doubling the cost of electricity from a coal-fired power plant. FCE’s technology also increases the cost of electricity from coal-fired power plants, but the DOE believes that increase could be one-third or less.

“At an estimated cost of $40 per metric ton of carbon dioxide, these second generation technologies are showing they could potentially achieve a 30 percent increase in the cost of electricity, which is a significant drop compared to today’s commercially available technologies,” said José Figueroa, senior carbon capture project manager at the DOE, in an interview.

“The challenge of emissions reduction has always been to find a proven technology that’s affordable, and that’s reasonable to deploy, as opposed to spending billions,” said Arthur Bottone, CEO of FCE. “We’ve met that challenge with our solution.”

As states act to meet their compliance obligations under the EPA’s Clean Power Plan, several stakeholders will seek new technologies to clean up their coal plants. FCE has only tested its carbon-capture technology in the lab to date, but the application is already the attracting interest from the power industry and legislators in states with a high reliance on coal, said Bottone.

Questions about efficiency, scale, climate impact and cost

FCE is currently evaluating multiple sites for the DOE-supported pilot with interested utility and independent power producers, and it expects to announce the site selection this fall.

One of the selection criteria is that there needs to be a nearby supply of natural gas to power the fuel cell. Molten carbonate fuel cells take in CO2, but still need a fuel source to operate.

The chiller used to condense CO2 also needs a power source. To meet that demand, the system is outfitted with a 2.8-megawatt fuel cell, which the chiller brings down to around 2 megawatts of actual power output.

Even with these extra steps, Bottone said the fuel cell application is much more efficient than other carbon-capture technologies. Rather than drain productivity at the power plant, FCE’s technology generates additional power — and revenue — in exchange for the energy it consumes.

“This is a power generation device that concentrates CO2 at the same time. It’s a completely different thought process, versus a device that’s doing nothing but capturing CO2,” he said. “We’re multitasking on the same asset as compared to a different way of doing it, which would only be a cost and not necessarily a benefit.”

This dual use makes the project easily financeable by private capital, because the electricity generated by the fuel cell creates a reliable revenue stream, Bottone added. Selling the purified CO2 for use in other applications like enhanced oil recovery would create additional revenue, although FCE didn’t factor those sales into its financial modeling.

Another benefit is that the technology is modular, so it can be scaled up incrementally as funding becomes available.

FCE sees the DOE-supported pilot as the first phase of a much larger project. In the second phase, once the application engineering is established, FCE will seek private capital to install 11 additional fuel-cell power plants. This 25-megawatt system is expected to capture a total of 700 tons of carbon dioxide per day, while generating about 648,000 kilowatt-hours of electricity per day.

At a 500-megawatt coal plant, 25 megawatts of fuel cells would reduce emissions by between 5 percent and 6 percent, said Bottone. Under the Clean Power Plan, emissions have to fall by roughly 3 percent over a 10-year period. So by installing FCE’s technology in phases, a coal-plant operator could meet the 32 percent overall emissions reduction target in a few years, while adding about 100 megawatts of power generation to its site.

“On paper, it’s a massive market opportunity,” said Bottone. “The question is how fast we can go.”

“We think that given the significant assurance of the technology we’ve developed for other businesses, we can go pretty quick, not to mention the fact that some of these utility customers and others are already our customers,” he added. “So the business model, and the confidence in us, frankly, is already there.”

But several questions remain. For one thing, while the system captures CO2 from the natural gas fed into the fuel cell, as well as from the coal plant itself, there are still concerns about the net climate benefit because of the emissions associated with natural gas production.

There are similar concerns with enhanced oil recovery. Pumping CO2 underground could help unlock new oil resources, and the CO2 could then be sequestered underground once the reservoir is depleted. But the net benefit is unclear, since the carbon sequestration would be offset by the continued use of oil. Plus, there’s the added complexity of getting the CO2 to the oil well to begin with.

Another issue is that flue gas from a coal plant contains pollutants, such as sulfur and chlorine, that could degrade the fuel-cell stack over time. How much FCE’s application ultimately costs will depend on how much the coal plant exhaust has to be cleaned up before it enters the cell.

“A coal-fired power plant has a lot of environmental control systems to meet environmental regulations, so those emissions are very low. But fuel cells are still sensitive to many contaminants, and so the flue gas would have to go through a polishing step to get it to even lower contaminant levels before getting to the fuel cell,” said Figueroa.

Lab tests to date show that the fuel cell sees little degradation using a simulated polished gas, but more testing is needed to see how the fuel cell performs in real world conditions.

“Understand this technology is still at a small scale,” said Figueroa. “Conceptual cost estimates, versus what it will look like at a 500-megawatt scale, with all of the flue gas that needs to be processed at that level, can differ.”

“There’s a lot that can still happen as you scale up and that’s why they’re performing more research, and that takes time,” he said.

Wind Turbine Pile Test Shows Potential to Cut Costs

A recently completed pile testing campaign by DONG Energy and ESG shows cost reduction potential for the offshore wind industry.

Pile testing by DONG Energy and ESG shows cost reduction for the offshore wind industry. Source: DONG

Pile testing by DONG Energy and ESG shows cost reduction for the offshore wind industry. Source: DONG

The piles under test are made of a cylindrical steel tube and their depth is adjustable to suit environmental and seabed conditions. The piles are one of the most commonly used foundations in the offshore wind market based on ease of installation in a variety of water depths.

The two testing sites, located in Cowden, England, and in Dunkirk, France, carried out tests on 28 piles. The purpose was to assess and validate new design methods development by a joint industry project PISA (pile soil analysis) for offshore wind farms. The PISA academic working group included Oxford University, Imperial College London and University College Dublin. The group supervised testing as the 28 piles were pulled sideways into the soil until failure occurred.

The two test sites involved feature diverse soils—clay till in Cowden and dense sand in Dunkirk, representative of surface soil conditions in the North Sea. Previous oil and gas engineering pile testing at both sites provided field and laboratory soil data. Results confirm that traditional design methods are conservative and that by reducing the quantity of steel in the foundation it may potentially reduce electricity production costs.

The testing was undertaken as part of the PISA research project and carried out by industry working group headed by DONG Energy including EDF, RWE, Statoil, Statkraft, SSE, Scottish Power, Vattenfall, Alstom and Van Oord. PISA operates under the framework of the Carbon Trust Offshore Wind Accelerator (OWA).

The PISA academic working group will analyze the data and deliver a final report to project partners in early 2016.

The Solar Sunflower: Harnessing the power of 5,000 suns

The Sunflower has a massive total efficiency of around 80%, thanks to very clever tech.

Behold, the Solar Sunflower! Here they are trying a bunch of different reflector materials, which is why the segments all look slightly different. Some of the reflectors are covered up to protect them from the elements, or to stop them from frying a nearby engineer.

Behold, the Solar Sunflower! Here they are trying a bunch of different reflector materials, which is why the segments all look slightly different. Some of the reflectors are covered up to protect them from the elements, or to stop them from frying a nearby engineer.

High on a hill was a lonely sunflower. Not a normal sunflower, mind you; that would hardly be very notable. This sunflower is a solar sunflower that combines both photovoltaic solar power and concentrated solar thermal power in one neat, aesthetic package that has a massive total efficiency of around 80 percent.

The Solar Sunflower, a Swiss invention developed by Airlight Energy, Dsolar (a subsidiary of Airlight), and IBM Research in Zurich, uses something called HCPVT to generate electricity and hot water from solar power. HCPVT is a clumsy acronym that stands for “highly efficient concentrated photovoltaic/thermal.” In short, it has reflectors that concentrate the sun—”to about 5,000 suns,” Gianluca Ambrosetti, Airlight’s head of research told me—and then some highly efficient photovoltaic cells that are capable of converting that concentrated solar energy into electricity, without melting in the process. Airlight/Dsolar are behind the Sunflower’s reflectors and superstructure, and the photovoltaics are provided by IBM.

The two constituent technologies of the Solar Sunflower—concentrated solar thermal power and photovoltaic solar power—are both very well known and understood at this point, and not at all exciting. What’s special about the Sunflower, however, is that it combines both of the technologies together in a novel fashion to attain much higher total efficiency. Bear with me, as this will take a little bit of explaining.

The reflectors are simply slightly curved, mirrored panels. Airlight has tried a variety of different reflector materials, from glass to mylar, but it looks like they have finally settled on aluminium foil, which isn’t prohibitively expensive and has very high reflectance. Aluminium foil does need additional material to protect it from the elements, though, as it’s very flimsy. The Sunflower has six “petals,” each consisting of six reflectors. At the focal point of the 36 reflectors there are six collectors, one for each block of six reflectors.

The collectors are where most of the magic occurs. To begin with, each collector has an array of gallium-arsenide (GaAs) photovoltaic cells. GaAs is much more efficient at converting sunlight into electricity (38 percent in this case, versus about 20 percent for silicon), but it’s much, much more expensive. With the Sunflower, though, space is at a premium: the sunlight is only focused on a very small region, so you need to use the absolute best cells available. The GaAs array in each collector only measures a few square centimetres, and yet it can produce about 2 kilowatts of electricity (so, one Sunflower generates about 12kW of electricity in total).

Photovoltaic cells, like most semiconductors, become less efficient as they get hotter. The GaAs cells used by the Sunflower have a max operating temperature of around 105°C. The problem is, when you focus the power of 5,000 suns on a single point, things get a lot hotter than 105°C. During one test, Airlight told me that they used the reflectors to melt a hole in a lump of iron (which has a melting point of 1538°C); during another test, the reflectors were misaligned and “we had molten aluminium dripping everywhere.”

How then do you stop your collectors turning into very expensive puddles of molten metal?

What a complete Solar Sunflower installation would look like, providing heat and electricity to a nearby house/office/factory.

What a complete Solar Sunflower installation would look like, providing heat and electricity to a nearby house/office/factory.


Cooling with hot water? Cool.

The answer is a very clever cooling system, borrowed from one of IBM’s specialities: supercomputers. In high-performance computing (HPC) installations, heat is one of the limiting factors on how much processing power you can squeeze into a given volume. Computer chips are tiny; you could physically cram hundreds of them into a 1U server chassis, if you so wished. Cooling them, though, is another matter entirely. You can use fancy heat pipes, or perhaps immerse the whole thing in liquid, but it only gets you so far.

Over the last few years, IBM has been working on advanced methods of liquid cooling, primarily to boost compute density, but also to reduce the amount of waste heat (getting rid of it increases efficiency and reduces costs). In a conventional liquid cooling setup, there’s a water block (a lump of metal with some channels for liquid to flow through), a pump, and a radiator. The liquid is usually water, but it could be something else, like Fluorinert or mineral oil. Heat is transferred from the computer chip to the liquid, and then carried to the radiator and released into the atmosphere. This is inefficient for two reasons: there’s a limit to how much heat can be “picked up” as the fluid passes through the block; and the heat being radiated into the atmosphere is wasted.

IBM solves both of these problems with its hot-water cooling technology. First, instead of the hot water passing through a radiator and venting the thermal energy out into the atmosphere, the hot water is simply used as hot water: to heat homes, or to drive industrial processes, such as desalination, pasteurisation, drying, cooking, etc. IBM already has an example of this in Aquasar, a supercomputer at ETH in Zurich, where the hot water is used to heat university buildings.

Second, to increase heat transfer from the chip to the water, IBM has replaced the dumb ol’ water block with a piece of silicon with microfluidic channels. This piece of silicon, which is then stuck to the back of the computer chip like a tiny water block, has thousands of tiny channels that bring the water to within just a few microns of those pesky heat-generating transistors. This massively increases the amount of heat that can be dissipated, plus all of those discrete channels do a lot better job of dealing with chip hot spots (small regions that are more active than others) than the handful of giant channels in a conventional water block.

Okay, Seb, get back to the sunflowers…

The Solar Sunflower uses this exact same cooling technology—but instead of computer chips, those microfluidic slices of silicon are stuck to the backside of those gallium-arsenide photovoltaic cells. The cooling system ensures that the GaAs efficiently converts photons into electrons, while at the same time whisking away the thermal energy of 5,000 suns. It’s pretty cool, to be honest. Or hot. Or something.

The end result is a device that produces about 12kW of electricity, along with 21kW of thermal energy (with water temperatures up to 90°C). Neither Airlight or IBM would reveal the exact pricing of a single Sunflower, but the fully installed cost will likely be in the tens-of-thousands-of-pounds range—and that’s just the first caveat of many.

For a start, concentrated solar power only works with direct sunlight: the reflectors need to be pointed directly at the sun, and anything less than totally clear skies will significantly reduce power generation. The Sunflower has some control software that automatically tracks the sun, but IBM gave me a distinct “no comment” when I petulantly probed them about their ability to rid the world of clouds.

Second, there’s the lack of energy density: the Sunflower is very efficient, but it still only produces 12kW of electricity. That’s enough to power maybe three or four homes—during the few hours of the day that the sun is visible, anyway. You would need a large field of these things to power a town—and again, you’d need some kind of energy storage solution to get through the evenings, winters, and periods of inclementousness.

Perhaps the largest problem, though, is cost. When Airlight and IBM started work on the Solar Sunflower, the cost of bog-standard silicon solar cells was about £1 ($1.60) per watt. Over the last few years, as China has ramped up production, the cost has dropped precipitously to about 25p (40 cents) per watt—plus the efficiency of silicon PVs has improved, too. With its GaAs cells, fancy plumbing, control systems and motors, the giant lump of concrete, and the time it takes to construct the whole thing, the Solar Sunflower simply can’t compete with hectares of boring-ass silicon photovoltaics.

What a completed Solar Sunflower installation might look like in the future. Maybe. (This is a computer render.)

What a completed Solar Sunflower installation might look like in the future. Maybe. (This is a computer render.)