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August, 2015:

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.)

Here comes the sun: India’s trains go solar

My time at The Engineer last week was dominated by repurposed trains and nuclear waste, and in the blog last Friday I signed off by suggesting nuclear-powered trains might become a reality at some point, potentially solving two problems at once. The wider point I was trying to make was about the need to maximise our infrastructure and resources, whether by refitting old London Underground stock, or extracting more energy from nuclear waste instead of burying it a kilometre under the ground.

In hindsight, a nuclear reactor on board a vehicle moving at several hundred kilometres per hour may not be the safest or most practical idea I’ve ever had. Indian Railways (IR), however, has come up with a much more sensible way to harness nuclear fusion while maximising its infrastructure – solar energy.

Car ownership in India is low, with about 20 vehicles per 1,000 people. The railways are the lifeblood of the country, helping to keep the population moving and the economy ticking over. IR is also the fourth biggest employer in the world, providing work for over a million people. Having travelled on it fairly extensively myself many years ago, I can attest that the rail network is a huge source of national pride, and extremely well run.

Unfortunately, the diesel-powered trains are not exactly world-leading when it comes to energy efficiency, and IR consumed over 17.5 billion kWh of electricity during 2013-14. This works out at roughly 4000 MW, or about 1.8 per cent of the country’s total power generation. As part of a nationwide push towards integrating more solar into India’s energy mix, IR has been tasked with generating 1,000 MW of solar capacity within the next five years, alongside 200 MW of wind capacity. Considering that installed solar capacity across the whole country is only just over 4,000 MW, it’s an ambitious target.

Trains would still of course require diesel-run engines for locomotion, but the current plan is for solar to take on the lighting and cooling load. One report has claimed that a train using solar power could cut diesel consumption by up to 90,000 litres per year, reducing CO2 emissions by over 200 tonnes. It may not save the planet in one fell swoop, but it’s a promising move in the right direction for a country that has become one of the world’s biggest polluters during its economic boom.

A pilot project is underway, with one coach of the passenger train Rewari-Sitapur having solar panels fitted to its rooftop. The panels have been generating 17 kWh of electricity every day, which has been used for the lighting load. It’s about one billionth of the overall annual consumption of IR, but it’s only one carriage over one day. Extrapolate over every train carriage in India, over an entire year, and the picture begins to change. Add in plans for regenerative braking, LED lighting and the wider adoption of biodiesel, and the numbers could start to have some real impact.

But trains aren’t the only assets that Indian Railways can gear up for solar. It’s estimated that the country has over 8,000 stations, and while it may not be practical or economical to outfit them all, there’s certainly a whole lot of juice out there to be harvested. In the renewables mix, wind still outweighs solar by about six to one, but with some parts of India averaging more than 3,000 hours of sunshine per year, it’s a resource the country is increasingly looking to. What better place to start than on the country’s iconic rail network.

CSIRO’s Tobacco oil project: The Digest’s 2015 8-Slide Guide

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Building more landfills never an option

‘Building more landfills never an option’ shows the total lack of understanding of many HK people about incineration.

30% by weight of what is incinerated remains as ash, that has to be landfilled, ad infinitum. Moreover about 10% of that ash is highly toxic fly ash that has to be encased in cement. HK food waste 3600 m3 per day is ultra wet 90% water content with a calorific value less than 2Mj/kg whereas you need 7 Mj/kg for combustion.

Our daft Govt intends to burn the food waste, meaning accelerant needs to be added making incinerators a waste of energy , not waste 2 energy facility.

Using German test data, burning 1 kg of MSW releases 1kg – 1.2kg of CO2 into the atmosphere, as well as other toxic RSP’s. Interesting that the Environment chief expects to reduce CO2 emissions here on the one hand whilst intending to increase them on the other.

Incineration requires the MSW contacts the flame for at least 2 seconds at 850 deg C – if the waste is wet the burn temperature has to be increased or dioxins can & do form.

We have no source separation of waste legislation, we have no Zero Waste policy, Mass burn mixes batteries & plastics, it is impossible to recycle items tainted by food waste. Our sewer system has such capacity that Stonecutters could handle & treat our daily food slops if industrially garburated in a matter of minutes, a fact supported by CIWEM UK but conveniently ignored by local blinkered ENB officials.

Published on South China Morning Post > Letters to the Editor, August 27, 2015

Building more landfills never an option

Letters to the Editor, PUBLISHED : Wednesday, 26 August, 2015, 5:10pm

The decision to build an incinerator in Hong Kong has presented a challenge to the government.

It has had to put a lot of effort into trying to persuade citizens, especially nearby residents, that they will not be adversely affected by it.

There is no doubt that over the last decade the government has tried hard to solve Hong Kong’s waste problem.

When a waste reduction strategy is decided on, it is important to look at the short-term and long-term consequences of any policies.

With an incinerator the chief concerns are environmental, such as air pollution and concentrated chemical waste byproducts. There are worries not just about people’s health, but the possibly devastating effect on biodiversity.

However, incineration is better than building more landfills, which are not sustainable. The government has found itself in a Catch-22 situation when it comes to the incinerator. It is always difficult to strike the right balance. What is important is that all Hongkongers should cooperate with the government to try and reduce the volumes of waste generated. We have to think about our children, so we cannot be indifferent.

Yoyo Tang Wing-tung, Kwun Tong

Wireless power transfer tech: Trials set for England’s offroads

Wireless charging technology that is built into the road, powering electric cars as they move, is to undergo trials on England’s offroads. Announced on Tuesday, the technology will address the need to power up electric and hybrid vehicles on England’s roads. The trials will get under way later this year.

Key questions that the trial will address: will the technology work safely and effectively? How will the tech allow drivers of ultra-low emission vehicles to travel longer distances without needing to stop and charge the car’s battery?

The announcement referred to “dynamic wireless power transfer” technologies where cars are recharged while on the move.

Transport Minister Andrew Jones said that the government is already committing £500 million over the next five years to keep Britain at the forefront of this technology. The trials will involve fitting vehicles with wireless technology and testing the equipment, installed underneath the road, to replicate motorway conditions.

These are offroad trials and are expected to last for approximately 18 months. Subject to the results, they could be followed by on-road trials.

Highways England, the government-owned company in place for managing the core road network in England, had already commissioned a feasibility study for preparing a strategic road network for electric vehicles. TRL, a research, consultancy, testing and certification group for transport, was commissioned to look into Wireless Power Transfer (WPT) technology for use on motorways and roads to prepare for greater EV take-up.

TRL made the point at that time that “the purpose of the project is not to find an alternative to current plug-in charging infrastructure but rather to develop a comprehensive charging eco-system capable of delivering power to EVs via different methods.”

TRL added, “This is to facilitate greater and more flexible use of EVs in the UK, overcome range anxiety and allow switching to zero emission vehicles for vehicle types which have traditionally been accepted as not suitable for electrification, e.g. HGVs and coaches.”

To be sure, range anxiety has been one of the talked about factors challenging future uptake of EVs. Brian Milligan said in BBC News earlier this year, though, that figures from the UK car industry suggested “we might finally be waking up to the electric revolution.” He noted a jump in purchases of plug-in hybrids and that there were many more plug-in models to chose from; he also noted a network of charging points had expanded, in places in the UK where drivers can plug in.

Meanwhile, in the United States, “Some of the factors contributing to the relatively fast adoption of electric vehicles (EV) in some American metropolitan markets have been identified and characterized by a new study from the International Council on Clean Transportation (ICCT),” reported Clean Technica. The dominant factors included, among others, a broader range of offerings, as well as a more developed charging infrastructure.


Why are we still addicted to burning waste?

A major barrier to reducing the wasteful mindset of business and society is overcapacity and stranded investments in waste-to-energy incineration

MEPs are calling on the European commission to ban the incineration of recyclable and biodegradable waste by 2020 as part of the latest plan for the EU circular economy package.

But as landfill is phased out across Europe, incineration is increasingly being turned to as a way to deal with municipal solid waste (MSW), while also producing energy and heat.

There is a certain circular logic in powering and heating homes with the rubbish they generate, but it comes at a price. For every ton of waste incinerated, about 20% ends up as hazardous ash containing heavy metals and toxic substances that must be dealt with.

“Waste-to-energy is a diversion of materials that come from petroleum sources. Some of the plastics might have a high calorific value, but they’re not renewable,” says Joss Blériot, executive lead, communications and policy at the Ellen MacArthur Foundation. He stresses that waste should be designed out as much as possible.

Recycling waste

Designing out waste involves finding alternatives to composite packaging and materials such as crisp packets that consist of atomic layers of metal which cannot be separated and recycled. But even materials that are recyclable, like plastic bottles, steel and paper, can lose 75% of value after first use. Eventually, this leads to a stream destined for incineration.

There are, however, a growing number of ways to treat MSW incinerator ash to minimise waste.

Eleanor Banwell, a biochemist and 2015 Schmidt-MacArthur circular economy fellow, believes incineration could play a part in the circular economy by collecting resources that would otherwise not be recovered. Her Royal College of Art design graduate project, MetaBlaze, considers how the value locked in ash could be exploited, assuming we can chemically process it.

“It opens the way for a new approach to sustainable design,” she says. “Rather than completely designing out waste, you can begin to reconsider hi-tech materials like composites. Until you close that loop on the utterly useless residual stuff, all you have is a slowing down of a linear economy. What matters is that the resources go back into circulation.”

Some businesses are already collecting precious metals from incineration. In the UK, waste company Veolia manages 500,000 tons of bottom ash every year and recovers metals such as gold and silver, which are sold on to ore manufacturers. Richard Kirkman, technical director at Veolia, says: “It’s not a perfect circular economy, but we’re working on getting more and more value out of the end-of-pipe.”

Rotterdam-based company, Inashco, uses a patented technology developed by the Technical University of Delft to recover and upgrade non-ferrous metals from municipal waste-to-energy ash for sale to global metal markets. Founded in 2008, Inashco is owned by the Fondel Group, a metals mining, production and supply company. Inashco is helping recover part of the aluminium, copper, silver and other metals worth €45m (£32m) lost annually during incineration in the Netherlands.

Incinerator ash can also be used to create new products, for example, producing aluminium castings for the automotive industry, secondary aggregates in road construction, cementor glass, or as synthetic zeolites for use in catalysts.

Treated in this way, however, the resources within MSW ash are locked into our urban infrastructure. A truly circular economy would see the MSW incinerator ash broken down into constituent parts that could be fully recycled and used again and again in manufacturing.

A dirty solution

This is no small technical challenge, nor would it be without polluting by-products. The composition of incineration ash contains an array of dioxins, chlorides, heavy metals and other hazardous substances and to cycle these completely would require intensive chemical processing at each stage.

“Essentially, incineration output is very messy. It’s far better to extract resources at the front end,” says Warwickshire county councillor and incineration campaigner Keith Kondakor, whose work is currently based around waste prevention strategies.

While mining incineration ash would still be better than conventional mining, which often entails land conflict and the destruction of habitats, incineration doesn’t do much to shift mindsets away from the industrial revolution’s dirty legacy. One fundamental issue preventing a shift in waste management mindset is overcapacity and stranded investments in incineration.

A recent study by the Wuppertal Institute suggests that in six of the 32 European countries analysed, incineration capacities exceed more than 50% of the annual waste generation. “As soon as you have built [an incineration] plant, the sunk costs involved cause dynamics that clearly undermine waste prevention and sorting as prerequisite for high quality recycling,” says Wuppertal Institute researcher Henning Wilts.

How Building a Better Wind Turbine Began with Styrofoam Balls

Scientists at GE Global Research spent the last four years building a more efficient wind turbine. The result rises 450-feet above the Mojave desert in California – almost half the height of the Eiffel Tower — and looks like it has a silver UFO stuck to its face.

It may appear strange, but you are looking at the future of wind power. The team explains how it came about.

In 2011, Mark Little, GE’s chief technology officer and the head of the GRC, challenged principal engineer Seyed Saddoughi and his team to build a rotor that could harvest more wind.

Michael Idelchik, who runs advanced technology programs at the GRC, gave them another clue: “Since we know that the inner parts of wind turbines don’t do much for energy capture, why don’t we change the design?”


The team came up with the idea of putting a hemisphere on the center part of the wind turbine to redirect the incoming wind towards the outer parts of the blades. “The biggest unknown for us was what size the dome should be,” Saddoughi says.

The group decided to do some experiments. They bought on the Internet a 10-inch wind turbine and a bunch of Styrofoam balls of different sizes, then took the lot to a wind tunnel at GE’s aerodynamic lab (see above). “By cutting the Styrofoam balls in half, we created our domes of different sizes and then stuck these domes on the center of the small wind turbine and ran our experiments at different tunnel air speeds,” Saddoughi says.


The team hooked up the turbine to their instruments and measured the amount of voltage it produced. “Invariably we got a jump in voltage output with the dome placed at the center of the wind turbine; albeit the increases differed for different size domes,” Saddoughi says.

The scientists reached out to a colleague who did simple computer simulations for them and confirmed that even a full-size turbine was more efficient with a nose upfront.

“Of course overjoyed by the very limited experimental and computational results, we wanted to come up with a name for this design, such that it really represented the idea – and was also something that everybody would remember easily,” Saddoughi says. “The team gathered in my office again, and after an hour of playing with words the name Energy Capture Optimization by Revolutionary Onboard Turbine Reshape (ecoROTR) was created.”




Saddoughi is attaching differently shaped noses and turbine blades in Stuttgart. All image credits: GE Global Research and Chris New (ecoROTR)

Saddoughi is attaching differently shaped noses and turbine blades in Stuttgart. All image credits: GE Global Research and Chris New (ecoROTR)

The team then built a 2-meter rotor model of the turbine and took it for testing to a large wind tunnel in Stuttgart, Germany. The tunnel was 6.3 meters in diameters and it allowed them to dramatically reduce the wall effects on the performance.

The researchers spent couple of months working in Stuttgart. “We conducted a significant number of experiments at the Gust wind tunnel for different tunnel air velocities and wind turbine tip-speed ratios with several variations of domes,” Saddoughi says. “The wind tunnel was also operated at its maximum speed for the blades in feathered configurations at several yaw angles of the turbine to simulate gust conditions.” They ran the turbine as fast as 1,000 rpm and carried out surface dye flow visualization experiments (see below).

When dye hits the fan. Saddoughi after the dye flow visualization.

When dye hits the fan. Saddoughi after the dye flow visualization.

When they came back in the second half on 2012, they started designing the actual prototype of the dome that was 20 meters in diameter and weighed 20 tons. The size presented a new batch of challenges. “Unlike gas or steam turbines that are designed to operate under a relatively limited number of set conditions, wind turbines must operate reliably and safely under literally hundreds of conditions, many of them highly transient,” says Norman Turnquist, senior principal engineer for aero thermal and mechanical systems.


They ran more calculations to make sure that GE’s 1.7-megawatt test turbine in Tehachapi, Calif., would be able to support the dome. They looked at performance during different wind speed and directions, storms and gusts. They also designed special mounting adapters and brackets to attach the dome. “The design looked really strange, but it made a lot of sense,” says Mike Bowman, the leader of sustainable energy projects at GE Global Research.

The team then assembled the dome on site. “Early on, it was decided that the prototype dome would be a geodesic construction,” Turnquist says. “The reason is simply that it was the construction method that required the least amount of unknown risk.”

For safety reasons, the workers assembled the dome about 300m from the turbine and used a giant crane to move it to the turbine base for installation. But there was a hitch. “After the adapters were mounted to the hub it was discovered that bolt circle diameter was approximately 8mm too small to fit the dome,” Turnquist says. The team had to make custom shims to make it work.



The dome went up in May on Memorial Day and the turbine is currently powering through four months of testing. “This is the pinnacle of wind power,” says Mike Bowman. “As far as I know, there’s nothing like this in the world. This could be a game changer.“