The long awaited baseload wind power!
Spain is the second European country in total installed wind capacity after Germany. Spanish utilities deployed a total of 23 GW of wind power until the end of 2014 but no new installations have been made in the year 2015; as the 2015 production data was 48 TWh, an astounding (for wind power) 2087 hours capacity factor was performed (this figure for Germany is as low as 1650 h). Spain is a significant country in terms of both wind distribution and installed wind power. Moreover, the complete hourly wind production data in Spain for 2015 was collected and made available. Thus, we choose it as a convenient “case study” for a comparative analysis of wind power production between traditional wind turbines and the KiteGen technology for high altitude wind exploitation.
Figure 1 – “2015, Spain: Electric Power with wind Turbines”
The diagram in Figure 1 shows the actual energy produced in each 1-hour time interval, in the course of the year 2015, by all wind turbines installed in Spain. This is equivalent to the time behavior of the effective electric power, averaged over the same time span. The reading is at the network input, that is net of all production efficiencies. The recording shows a peak of 17436 MW on January 29th and a minimum of 234 MW on January 8th.
Now, we figure out to replace all installed wind turbines in Spain with KiteGen farms based on KiteGen Stem machines of 3MW nominal power each, thus considering the current wind turbine installations as our site certification anemometers to forecast the KiteGen production.
Of course, we assume equal conditions for both technologies (same wind and machine distribution, same nominal power installed, same machine-stop hours for maintenance, and so forth). Finally, we impose to limit the maximum power for KiteGen farms to the same power peak recorded in the year by the wind turbines. The latter is a very conservative assumption that we keep to be always on the safe side for our estimate (the theoretical limit would be the nominal installed power of 23 GW that is much higher than the imposed one).
How to estimate the production of the KiteGen farms? Starting from the real-time power exhibited by wind turbines, we go through the following steps:
- we assume 100m tall towers, that is turbine axis is at 100m height from ground;
- with the same wind speed, KiteGen wings can harness 3.3 times the power compared to synchronous wind turbines. The main reason for this large increasing factor is the possibility for the KiteGen energy collector, the wing, to move continuously away from the exploited area and fly always to regions of undisturbed winds. Of course, this is not true for wind turbines, whose blades intercept always the same wind streamlines, rotating around a fixed axis. For this reason, wind turbines are bound to follow Betz optimization that imposes a limit to the effective wind speed “seen” by the blades. Some authors questioned about the 3.3 improvement factor of KiteGen, due the rope drag penalisation (see for instance here), but a recent study clearly indicates that the over-simplified rope models appeared in several papers cannot give reasonable estimates of the drag losses. (A detailed article is in preparation about this issue). Comparing with most recently deployed variable speed wind turbines, this sharp advantage reduces from 3.6 to about 2;
- flying at 500m altitude, according to Hellmann’s exponential law, the wind blows 25% faster;
- and carries 2.0 times as much power (it grows with the wind speed cube);
- which makes KiteGen more productive by a factor of 3.6×2.0=7.2;
- in order to respect the constraint, chosen with the first assumption above, KiteGen machines are bound to work, at the most, at the maximum power exhibited by the Spanish wind turbines in 2015. This auto-imposed limit results in energy production of the KiteGen farms that is most of the time below its potential limit as calculated in the above steps. Therefore, all the maxima of the estimated KiteGen production are clipped and the corresponding curve in the next plot shows a flat profile with only downward peaks during the wind calm periods.
Figure 3 – Title “2015, Spain: wind Turbines vs KiteGen at 500m”
The picture in Figure 3 compares the power delivered starting from the same source (the wind) but by means of different technologies: traditional wind turbines (red curve) vs KiteGen (blue curve). The data for the wind turbines refer to year 2015 and come from measurements. The estimates for KiteGen are obtained from the same wind data and the assumptions reported in the text.
If we move up and fly at 1500m for instance, then the power available from the wind becomes 8 times greater than that at 100m. We proceed with the same assumptions and power limit as before, and we obtain an even flatter profile, which approaches the condition of production at constant power, as shown by the next plot.
Figure 4 – Title “2015, Spain: Wind Turbines vs KiteGen at 1500m”
Figure 4 is the same as Figure 3, but with the kites flying at an average height of 1500m, where the wind blows faster and carries 8 times as much power than at 100m height (turbine axis typical height).
Due to the great power potential of the KiteGen concept, combined with the choice of limiting the power during generation, KiteGen allows to approach a constant power production, even starting from an energy source, the wind, that is typically discontinuous at ground level. Of course, wind calm, in some locations, means production decrease, derived as the difference between the power target (that is the limit imposed to the maximum power) and the estimated KiteGen production.
Aiming at reaching a constant power supply, wind power should be integrated by other energy sources: in the worst case, there is an energy lack of less than 100GWh, at a maximum rate of 16GW.
Of course, production gets even more regular if we allow the kites to fly 1500m high, as it can be seen in the next plot.
Figure 5 – Title “KiteGen (1500m) Power backup requirement as of Spain 2015″
Figure 5 depicts a scenario with the kites flying at 1500m height from ground. Again, energy accumulation and power release is much less demanding if flying at 1500m. The same is true for the plots that follow, namely the zoom of the worst case, the highest peak of Figure 5.
Figure 6 – Title “KiteGen (1500m) worst case power backup requirement as of Spain 2015″
Figure 7 – Title “KiteGen (1500m) worst case power backup requirement as of Spain 2015 considering last generation wind turbines as reference”
Figure 7 assumes the lower advantage of KiteGen vs variable speed wind turbines than that assumed in Figure 6, in which synchronous wind turbines are the reference.
Grid issues and energy mix aspects of the scenario
In this case study, we have 23 GW of KiteGen generators installed nominal power. We have shown that the 18 GW peak power output (same of the wind turbines) of these generation plants would be quite steady, except for some short exceptional “wind calm” periods. These events can be forecasted with good accuracy but, in order to find possible grid issues due to the consequent power shortage, it is necessary to determine both the maximum power lack and its duration. In the analysed time frame, the worst wind shortage lasts for 16 hours and reduces the power output by 10 GW (see fig.5).
Figure 8 – Spanish grid management scenario with 23 GW KiteGen installed nominal power. The real power demand curve for a significant day of the 2014 calendar is shown. The picture depicts a sample energy mix scenario for a typical winter day. The hourly available power generation sources, including KiteGen, fulfill the demand.
The meaning of this figure can be better understood if we look at the main characteristics of the Spanish power grid, as reported in http://www.ree.es/sites/default/files/downloadable/preliminary_report_2014.pdf.
The Spanish baseload is covered by nuclear (7.8 GW) and coal (11 GW) power plants that produce 57 and 44 TWh per year, respectively. Thermal renewables (biomass/biogas 1 GW and solar thermal 2.3 GW) produce more than 10 TWh. Mid merit plants, like gas combined cycle and cogenerators, add 34 GW for a total production of 52 TWh: these plants normally act as reserve because the average plant utilization is just 18%. Total hydro power amounts to 20 GW (of which about 6 GW have a pumping facility) for a total production of 42.5 TWh (actually part of this, belonging to the fluent hydro plants, must be accounted in the baseload). Wind (22 GW) and Solar PV (4.4 GW) score 51 TWh and 7.8 TWh, respectively. Spain has also a huge rotating engine generation capacity, mainly located on the main islands (Baleares and Canarias). This 4 GW power capacity produces about 6.6 TWh. All these have a net production of about 254 TWh. 5.4 TWh are used for pumped storage and about 5 TWh are exported, thus the net grid demand is 243.5 TWh.
The power demand peak is near 40GW while the minimum demand is in a range from 20 GW to 25GW, say an average of 22GW. This means a baseload energy demand of about 190 TWh.
In the KiteGen 23 GW scenario, the new source would produce about 150 TWh, to be considered as baseload power. The Spanish nuclear power plants date from 1983 to 1988. The older 3 plants, of cumulative power 5 GW, are more than 30 years old. There are also more than 3 GW of old coal plants aged more than 30 years. Thus, the baseload energy coverage would be assured also if the oldest coal and nuclear plant were shut down. During the peak hours, gas turbines, cogenerators, diesel engines, solar and hydro power plants are able to fulfil the demand curve.
If an event of wind calm occurs, the grid could react in one or more of the following ways:
* Turning on all the gas turbine, diesel engine and hydro spare capacity and importing from France, Portugal and Morocco. During the worst event, the baseload misses 16 GW of KiteGen power at the 40 GW peak hour (the peak is 16 GW above the baseload), so the grid would require additional 32 GW from the reserve sources, the latter being the 34 GW currently under-exploited gas capacity and the 6 GW double basin hydro. This can be accepted easily, also considering that the current 22 GW windmill production has similar and more frequent power lacks and the Spanish grid normally faces the issue by increasing the double basin hydro power.
* Following the suggestion of many “smart grid experts” calling for a massive use of high performance battery packs to support wind and solar power. In the depicted scenario, a battery system able to store 160 GWh and react to the wind calm would cost about 190 G$ (1200$/kWh). A quite high cost even for a developed country.
* Removing the 1500 m altitude limit constraint. This allows the KiteGen generators to get higher in order to reach spots of stronger winds.
* Exploiting more high altitude wind resources to desalinate the seawater and/or produce hydrogen in order to use it as feedstock for the synthesis of fuel, fertilizer and so on. The additional baseload power demand due to these continuous processes can be interrupted when the wind calm events happen, helping to stabilise the grid. These events have been estimated to last a few hundreds of hours a year (see fig.5).
On January 25th the Cleantech Group published its annual list of the most interesting innovative companies in the cleantech sector in 2015, selected by a panel of experts coming from the most significant international companies. KiteGen is named in the category 100 Ones to watch, a subset that the selection committee follows with particular focus.
This year, 6,900 companies were nominated and progressively filtered to a short list of 323 companies for consideration by the expert panel. The 100 panelists evaluated the 323 shortlisted companies based on the following three criteria: innovation, market and ability to execute.
Among those almost 7 thousand cleantech actors, KiteGen turned out to be the only Italian company named in the prestigious list. And this time, it is not only a matter of prestige. The organizers are determined in explaining why the Cleantech 100 is something more concrete than a list of the champions. “Cleantech Group has designed the Global Cleantech 100 to achieve two unique objectives that distinguish it from other lists: the list offers a fair representation of global innovation and private company creation, and it is not our editorial voice, but the collective opinion of hundreds of individuals within the wider global cleantech innovation community.”
It is worth noting that KiteGen is the only Italian company named in the list. This was someway preannounced in the report published by the Italian Council of Innovation, clearly showing that KiteGen is the Italian company that owns the highest number of patents in the Renewable Energy Generation category (the report numbers 14 patents, but that data refers back to 2013. Meanwhile the number increased up to 18 patents, which considering their international extensions become around 3000), thus surpassing both ENI and Fiat.
This means for KiteGen a further demonstration of the goodness of the chosen path, aimed at developing an intellectual property that today allows to operate freely in the high altitude wind power field and widely criticized by those who sustain the uselessness of the patenting activity. This way of thinking is particularly widespread in the Italian academic and entrepreneurial environment. The same environment that shows an almost total absence from the innovation scenario as it is represented by the organizations aimed at investing money to make it possible.
The first model of the “Power Wing”, a wing specially designed for the production of energy, has been finally released by the KiteGen laboratories. We show you a preview.
The availability of a “Power Wing” is the main enabler for the mass production of low-cost energy from tropospheric wind.
The kite sports are made of very light materials but are not designed to produce great powers. The concept of “Power Wing” never existed on the market up to date and all the HAWE actors, after having successfully tested the production of energy (up to a few tens of kW) by using sport kites (first KiteGen in 2006), have had to deal with the lack on the market of a kite capable of resisting forces exceeding few tens of kW. This led to the difficult choice between developing a small, sometimes movable, power system, and designing a new, efficient, lightweight but strong wing, able to withstand megawatts forces.
This dilemma has of course also touched KiteGen, which eventually made the second choice. That choice appeared to us as obliged: in fact, to give up the Power Wing concept, would have meant confining the technology to a niche of small power systems. These systems are unable to compete with renewable sources – already available on the market and widely tested – since the scale factor, in tropospheric wind energy, strongly hits the performances of the systems, by determining their relative competitiveness, a main success factor, given also the novelty of the HAWE technologies.
The KiteGen Power Wing, therefore, represents a quantum leap in the field of tropospheric wind energy, and allows the shift from the experimentation of low power prototypes towards a new generation of megawatt class machines that, thanks also to the modular design and the “farm” deployability, allows the system to target the GW class, thus competing in the largest segment of the energy market.
The choice of the market segment in which the systems should position, is not only relevant for economic purposes but also from the point of view of its potential contribution to adverse the climate change and the depletion of energy, which is worsening the worldwide socio-economic crisis and stimulating access to dirtier resources, such as coal and shale.
The small systems would be confined to niche markets and their contributions to social and environmental issues would be in fact limited. The comparison of turnover and produced energy by micro/small wind turbines and big size wind generators is iconic.
The “Power Wing” is therefore an inescapable issue and KiteGen faced it by getting a first major success, which has required time and resources.
Initially, the effort has been directed to settle the intellectual property issues, with several patents describing the “Power Wing” key features and the auxiliary systems. Then we focused on the design, by deploying the most quoted tools for computational fluid dynamics on powerful parallel computing systems.
In the meanwhile the most suitable materials and composites have been selected and finally it has been invested on an industrial plant able to deal with the entire supply chain, from material procurement to the finished product.
A robotic line has allowed the production of 20 tons of molds used for manufacturing and curing the wing segments, which are made of composite materials. Even the production of accessories (ailerons and bulbs) is done by robots, while all assemblies and processes are labor intensive and involve highly qualified staff.
The result, as can be seen from the picture below has the dimensions of the wing of a large airliner but is lightweight and semi-rigid. The wing is formed by 9 ashlars hinged together by flexible joints, thanks to which it can easily change configuration in order to vary the wing lift factor.
Our readers that look always forward to news from KiteGen and are often disappointed by the lack of new footage of flights with sport kites (which are more and more produced by our competitors – see review) will finally understand that the time from the presentation of the latest movies is not spent in idleness but, on the contrary, led to opening a new perspective of being able to produce great powers from tropospheric wind.
The road to the refinement and optimization of the Power Wings is still long and can be compared to that covered by the blades of wind turbines (which are kind of wings, by the way), with substantial resources committed to research and development and many universities and companies involved, but the path to tropospheric wind machines of the MW class is definitely traced.
KiteGen will participate at the Green Week Conference 2013 with a stand (n. 7) entitled “When air turns into energy”, in the EU DG RTD area.
The event, this year dedicated to the air, will be held in Bruxelles, at the Egg Center, rue Bara 175.
Ironically, the KiteGen stand will be next to ALCOA’s one…
We would be pleased to meet there everyone interested in our project.
Link to the event.
Kite Gen Research has become the third group to express interest regarding the aluminum smelter located in Sardinia run until today by Alcoa.
In Italy we often hear on the news the name of this company, which sadly is associated with the risks of closure and the consequent social demonstrations of its workers.
The area where Alcoa operates is one of the poorest in Italy, where unemployment rate is one of the highest, while the root cause of the problems behind its past and its future are strictly connected with energy prices. The combination of these factors, together with the recent academic studies published by Nature Climate Change (Geophysical Limits to Global Wind Power) inspired KiteGen in proposing an alternative solution to this situation.
On September 10th KiteGen sent an offer to the Italian government and the relative parties involved (Sardinian Regional Government, Alcoa, Minister of Development, Etc): KiteGen proposed the implementation of its “Industrial Program 50 Machines” (currently also under negotiations with other parties) for the production of energy of the Alcoa’s smelter from what it will be the world’s first large scale tropospheric wind farm.
KiteGen received official interest from Alcoa and from the president of the Sardinian Region, Ugo Cappellacci.
On Monday the 17th a delegation from KiteGen headed by its president Massimo Ippolito was hosted by the president of the Region in Cagliari to discuss the contents of the proposal.
KiteGen would like to point out that the meeting has been positive, the Regional authorities present in the meeting together with the academic presence of Dott. Damiano from the Cagliari University, were competent, prepared and opened to the views shared by KiteGen.
The two steps outlined in the documents posted on the 10th of September were discussed and there seemed to be concrete interest from the Sardinian authorities.
KiteGen offers its expertise and its innovation for implementing a short-medium term solution to the Energy issue that Alcoa most of all, but all industries in general have to face sooner or later. KiteGen solution is different from the temporary energy price agreement that might keep the smelter open in the short term. KiteGen wants to provide clean, cheap and abundant renewable energy, the only remedy that could solve this and other difficult situation in Italy, Europe and Globally.
The cost of energy is one of the main reasons why the Sardinian plant has found it difficult to compete and could be sold or closed. A relatively big Kitegen Stem wind farm at regime (200 Stems= 600 MW) could provide continuous power to the smelter at 20 €/MWh, a price lower than the one required by Alcoa to be competitive, 25 €/MWh; lower than the one that Alcoa benefitted from bilateral agreements in the last 15 years of production, roughly 33 €/MWh; and ¼ of the average market value of electricity of 80€/MWh.
We hope that the authorities, both Regional and National will soon understand the potential of this source (KiteGen is merely a technology for extraction, the High Altitude Winds are the massive “Oil Fields” above our heads), also because KiteGen would be happier to develop first its technology on the Italian territory and in a social context of real need and only after this important Italian test bench start the commercial and industrial proliferation in other areas.
One of the strengths of the KiteGen proposal is that politicians are now searching for a quick solution, based on energy price subsides needed to keep the smelter on. Those subsidies, even if allowed by EU, could be granted only for a short time, or in any case they do not represent a long term solution, rather it is just a way to gain time and mitigate the problem until a solution “falls from the sky”. Whoever the new owners of the plant may be, they will find it hard to compete without new subsidies, and in a climate of recession the chance for new allowances would be harder. The KiteGen solution (which literally comes from the sky), could be rapidly deployed during the short term EU allowance that Italian Government is likely to obtain and it will gradually eliminates the need for new energy price agreements, helping securing the future of the Portovesme plant and hundreds of related jobs.
Kite Gen asks the government to apply for EU funds of 1.3 billion euros ($1.7 billion) available for innovative projects, to demonstrate the feasibility of the KiteGen Stem technology at the scale required for the Sardinian plant, and hopes the authorities will not lack such a strategic view of the problem, considering also that there are already so many investments in other directions less promising than the one proposed by KiteGen.
In our view the risks are outplayed by the great opportunities of a competitive and fully sustainable technology that only scratches the greatest source of kinetic energy that our planet has. Is it also your view?
Translated from Massimo Ippolito’s post:
On September 9th NATURE CLIMATE CHANGE Journal published a paper by Ken Caldeira, Kate Marvel, Ben Kravitz containing further confirmation of KiteGen positions and other brand new information of great importance. The following day, as a logical consequence and necessary act, we sent two letters to the Italian government with the proposed solution for ALCOA. Maybe it was an act too confident about the immediate impact of the NCC’s work and the good media coverage obtained by the article[Short video that introduces the study].
We counted on the contents of the scientific paper, full of meaningful information, in order to provide support to the economic arguments regarding the natural source and our technology. We thought that the Italian Minister of Economic Development Corrado Passera would jump up from his chair saying “Here’s the solution!”, instead, so far, all we heard through journalists is a skeptical comment.
Now let’s try to in this article to analyze the work of Caldeira, Marvel and Kravitz maybe step by step in several posts, of course well-reasoned comments from the readers are welcome.
Climate Change and Global Warming/Cooling?
The blog linked here (Italian), written by Physics and Mathematics professor Marco Pagani, identified and highlighted an aspect of the NCC work that turns out to be a novelty, perhaps a safety anchor of great relevance in relation to climate change/global warming. The graph analyzed by Pagani explains how it is possible to extract enough energy to power humanity with negligible changes in atmosphere temperature, while it is even possible to cool down the atmosphere if we could extract roughly 430TW (20 times humanity’s need) from the wind. The essential point is that Caldeira et all, clearly state that we can use as much wind power as we want, with negligible consequences to the climate, and that the only limits to wind energy technology might be relative to their costs and efficiency. While an extensive usage of this source might even be a solution to global warming.
How much can we get from wind?
Beside of climate change discussions, according to scientific publications and substantially confirmed by this latest paper, above Italy flows a total power whose magnitude is around the 100 TW. Let set 1TW as maximum extractable power from Italy, or an arbitrary 1% of what naturally flows, for the pleasure of round numbers and in order to offer a significant metaphor. Saudi Arabia produces 12.5 million barrels of oil per day, 521,000 barrels per hour, the thermal power equivalent of about 1 TW, equivalent to what hypothesized that we can extract from the Italian tropospheric wind while limiting climatic changes. This is great, isn’t it? Check the calculations if you do not believe it, they are fairly easy.
Technically we also have so much solar radiation, but to collect it we need devices deployed on the territory, while for wind power the photovoltaickinetic panel is the atmosphere itself! Already naturally deployed and maintained, KiteGen is only the PTO that collects the energy collected from the atmosphere.
I would like to highlight another graph showing in particular the advantage of tropospheric wind.
The blue line is attributable to KiteGen, the red line is attributable to wind turbines. The vertical axis indicates the size of the surface that intercepts the wind, compared with the rate of extraction of kinetic energy on the abscissa.
In order to draw a power of 480TW, each kilometer cube of the entire surface of the planet must have a “classic” wind turbine that catches a wind front of 10000square meters, one hectare, while in the tropospheric wind are sufficient equivalent of 23 square meters for km cube.
The tropospheric wind, however, is not limited to cubic kilometer near the ground, but the study uses ideally the whole atmosphere, and to clarify the calculation of the equivalence of the surface of 23 square meters must be multiplied by the number of stacked cubes, typically 10, corresponding to the entire troposphere.
So a wing brushes 230 square meters in altitude would be equivalent to a wind turbine that works against a wind surface of a hectare.
We said “wing brushing a surface”, but how big must the wing be?
A simplified method is to divide the area to be swept with the same aerodynamic efficiency of a wing with efficiency 10 so that we will have an area of 23 square meters equivalent to a 2.5 MW classic wind turbine typically “brushing” one hectare of wind.
The practical and technological interest is to obtain the desired power in an ideal compromise between workload and surface, which is why we chose the KiteGen Stem flying below 2000 meters with wings up to 150 meters of surface.
The fluidity of data and KiteGen performance, which depend heavily on configuration decisions: the wing, the altitude and the wind speed; are obviously one of the things that annoy people used to precise specifications, these people instead of enjoying the freedom of modulation and opportunities they tend to be cautious over the whole project, probably the view also of some government consultant.
In fact, in this latest media coverage, as I said, the only comment we heard from the Ministry that should support us (Innovation & Economic Development) was a very general kind of skeptical comment on KiteGen technology. Personally, it seems that politicians are no longer able to think independently without the lobbies that hound them constantly. Those sectors who has not created a lobby is excluded from all reasoning and opportunities, even if it is for the benefit of the country and the community.
But if it would be clear to everyone that we have the equivalent of a Saudi Arabia within the national territory, would we still be asking questions at the level of bankers, executives, politicians, ministers regarding the particular system of drilling to extract that energy and how to achieve it?
No! please, is complex, just trust all the patents “Granted”, the awards and the 12 proposals in response to calls for national and regional technological innovation, awarded funding but unfortunately still without coverage. Instead put us in a condition where we can keep working and we will solve all of your doubts.
Dear KiteGen followers,
Below you can find one of our interactive presentations about different aspects of KiteGen technology. This particular on describes the origins of the idea and how the KiteGen STEM works.
There are several of these work in our Webinars section (password protected), to access that section contact us.
to visualize it you might require Adobe Shockwave
Presentations developed by Ing. A.Papini
Image credit phis.org: The system developed at Langley flies a kite in a figure-8 pattern to power a generator on the ground
Originally written by Andrea Papini and Eugenio Saraceno
As our readers already know, one of the most titled teams that recently joined the at high altitude wind energy sector is that of NASA, which at the Langley Research Center in Virginia is developing its own project. According to David North, engineer of the team, in an article reported by phis.org:
“most tower turbines are about 80 to 100 meters (roughly 300 feet) high, which is pathetically down in the boundary layer of Earth. The boundary layer is where friction from Earth’s surface keeps the wind relatively slow and turbulent. The sweet spot for wind energy starts around 2000 feet up (600m). To use wind at that altitude to generate electricity, you’d have to build a turbine tower taller than the Empire State Building. Or you can fly a kite.”
Read more at: http://phys.org/news/2012-07-electricity-air.html#jCp. ”
Or the older article about the early stage of the NASA research http://phys.org/news/2010-12-green-energy-air.html#nRlv
The Langley Research Center is the only one, so far, who has also left also the sensors on ground. This choice derives from extreme simplification of the flight control, possible due to awareness of not having to create a commercial product yet. In essence the kite is “observed” by a special camera which communicates to a control system based on a shape recognition technology, similar to those adopted by some recent video games with which they can interact by means of the movements of the body (eg MS Kinetics).
We can say that lately, as well as KiteGen, other groups have reported being able to run the automatic control of the kite:
NASA Langley (in March).
TuDelft (In June)
( plus at least 5 other groups who are still working on that)
However, only KiteGen and SkySails are now able to perform take-off and landing automatically.
We are pleased to note that some of the concepts on which KiteGen is been insisting for years, are now being repeated by NASA:
- Flying the kite only reduces the weight (and therefore the cost) of the generator;
- Flying only the tip of the existing wind turbines, which are the parts of the blades that produce 90% of the total energy.
- The power depends on the cube of speed, and therefore it is better to have more efficient kites/wings (contrary to what is being developed by SkySails so far).
Related post ( March 2012)
An insightful analysis, as always, by Domenico Coiante argues about renewable energy issues and the need for daily and seasonal storage.
It seems a good opportunity to introduce and clarify the opportunities offered in this area by the largest source of concentrated energy on the planet, the tropospheric wind.
The graph shown here comes from the methodology section of the “atlas of the winds of high altitude” of Cristina Archer and Ken Caldeira. It is a sophisticated representation which expresses a competitive or collaborative comparison between the possible accumulation of traditional systems, and the ‘opportunities to exploit the naturally stored energy in the geostrophic wind. Furthermore, it introduces “a trick” to get an annual availability of 99.9%, or 8751 hours a year guaranteed, far higher than any traditional source and nuclear power plants.
My suggestion is to devote sufficient time to decipher the original document, because the implications are of extreme importance. On this graph I added the indications referred to an example of KiteGen 3MW to make it easier to understand the logic. Note that the KiteGen Stem machines that fit in the example should be equipped with wings of 150 square meters with an equivalent aerodynamic efficiency of over 20.
The winds that envelop the planet can be seen as a huge “flywheel” of energy storage. The atmosphere has a total mass of 5 million billion tons, 5 * 10 ^ 18 kg, that flow with an average speed as to bring the total of 100,000 terawatt-hours of energy accumulated. To provide a comparison, this figure corresponds to the energy needs of the current activities of humans for over a year, but with the advantage that this massive accumulation is permanently restored by the photothermal solar dynamics.
While the photovoltaic panels must be deployed on the territory in order to minutely collect the energy supplied by the sun, KiteGen instead, is the PTO of this wide ” photovoltaic photomechanical panel” already naturally established and maintained by the atmosphere itself. This panel has collected energy in the kinetic form, which is a noble form, and it is therefore available for an efficient electrical conversion.
In a specific place, the example is referred to the New York area, the KiteGen generator can reach and pick up energy from this flow, with the probability of finding it powerful enough to produce power at rated power for 68% of the time, an equivalent already amazing of about 6000 hours per year. However, there is a limitation that does not depend on the flow of the wind fading but simply by the fact that it changes cyclically and erratically latitude.
So what is the idea that the diagram shows to push the tropospheric wind up to a 95% availability or even to a 99.9%? Simple enough, you need two generators located throughout the area at a distance sufficient to have at least one hit by the wind flow. The two generators are to be considered as a single system that will double the need for 68% of the time, but that will give a guarantee of delivery of the nominal value of one (of course this will cost twice as much).
In the chart, a comparison is made with equivalent and hypothetical electric storage systems, to achieve the same result of the two generators spaced.
If we assume a cost of electrochemical accumulation of 1 € / Wh, a point I have shown in the figure (b) it suggests 34.5 MWh. From this we get 34.5 million euro only for the storage batteries necessary for carrying out the service and bring availability to a 95%, cost in the order of magnitude of more than 10 times compared to the brilliant idea of having a spatial distribution of tropospheric generators.
What do we get from these reflections?:
1) The intermittent supply that plagues conventional wind and solar can be successfully overcome with the tropospheric wind; attributing the exclusive of the baseload on thermal plants is no longer correct.
2) The economic balance of this double facility can easily sustain the redundant generators as it can count on 68% + 68% + 32% of hours of availability, which would correspond to 11560 hours / year equivalent.
3) In case of advanced deployment and sufficient spatial distribution of KiteGen Stem farms, or KiteGen Carousel, these reflections will lose their special value, since the effect of redundancy is achieved inherently.
4) The redundancy would lead to have an excess of potential output, but the KiteGen are easily and quickly adjustable by means of a central coordination, providing a precise adaptation to the demand curve.
5) The excess energy due the redundant operative systems could be contractually provided at discounted rate to interruptible customers
6) The graph refers to the New York area, but the orographic influence that slow the winds fades as we go at higher altitudes, making it a good example for most of the globe.