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rudolphsteiner (< 20)

which renewable energy technologies will power the future? part 1



June 17, 2008 – Comments (14)


Although wind power only accounts for about 1% of global electricity production, it is one of the fastest growing energy sectors. Installed capacity of wind generation grew by about 25% globally in 2006, to 74 GW. Between 1997 and 2006 wind energy increase by a factor of 10. Wind energy has a huge potential for electricity generation. For instance, the power of the wind, if harnessed, could supply all of the United States electricity needs. However, because wind is not an entirely dependable resource, using existing infrastructure wind power is expected to supply no more than 20% of electricity needs in any given region. If, in the future, wind power were stored in the form of hydrogen, pumped water, compressed air, or other means, it could have a much greater share of energy production.

More information: World Wind Energy Association


Arguably, all energy used on earth, except nuclear, tidal, and geothermal, comes from the power of the sun. The fossil fuels that drive our economy are the result of millions of years of solar energy stored in transformed plant materials. Even fossil fuels are renewable, but the energy we are consuming in a matter of centuries will take millions of years to renew. However, there are options to begin harvesting the power of the sun more directly to meet our energy needs. It is hard to quantify, but solar energy provides roughly 10% of the energy used worldwide, most of which is in the form of solar heating.

Solar Electricity

Currently, solar electricity generation accounts for less than 0.01% of total Global primary energy production, but like wind it is growing very rapidly. Generation of electricity from the sun can be accomplished either by concentrating solar heat and using steam to generate electricity, or using solar photo-voltaic panels, the majority of the growth is in the latter technology. Worldwide photovoltaic capacity increased by 1,460 MW in 2005 (from 1,086 MW installed in 2004) - in 1985, annual solar installation demand was only 21 Megawatts.

Solar photo-voltaic panels are undergoing a technology revolution, with many emerging companies and technologies competing for market share. Historically, most solar cells have been designed around crystalline silicon (c-Si) semiconductors to collect light and convert it to electricity. However, crystalline silicon needs a considerable thickness (several hundred microns) of material in order to work, and is relatively expensive to produce. To overcome this problem solar technologies are moving in two new directions. The first is the addition of solar "concentrators" that focus light onto the silicon material, increasing the efficiency of the conversion to electricity. The second direction of research is "thin-film" solar cells, which use far less materials, and are most commonly based on either amorphous silicon (a-Si, silicon in a different form), or the polycrystalline materials: cadmium telluride (CdTe) and copper indium (gallium) diselenide (CIS or CIGS). Thin-film solar cells are now being commercially produced, and the production capacity coming largely from startup companies is expected to grow significantly over the next few years.

More information: Solar Buzz

Solar Thermal

Solar thermal energy is another hot item in the energy toolkit. The power of the sun has been used to heat buildings since the first crude shelters were erected, however with modern efficient windows solar space-heating has started to become a very practical option. This type of heating, termed "passive solar," largely depends on placement of windows to maximize heat gain in winter and minimize it in summer. Passive solar design can greatly reduce the need for heating, but generally cannot replace it. Solar hot water heating is an extremely practical way to use the sun's energy. Solar hot water heaters have a very significant presence in China, which accounts for 70-80% of the solar hot water heating market, and also in Germany, Greece, and Austria. On average, the solar thermal market grew 14% per year between 1990 and 2001. Installing a solar hot water heater is something any homeowner can do with a relatively low investment and reasonable pay-back time.

Hydro-Electric Power

Hydropower provides about one fifth of the world’s electricity supply (about 700 GW), but the potential for new expansion is limited. Also, while hydropower is a completely renewable energy source, large hydro projects have been shown to have significant greenhouse gas emissions for many decades after construction due to methane emissions from flooded areas. Small hydro projects, especially "run of the river" hydro-electric generation (without reservoirs), offer the greatest potential for new climate-friendly capacity. New hydro potential, including hydro "mega-projects" is estimated at 1 400 GW of capacity, roughly twice the present installed capacity. The development of all of this potential would undoubtedly have large social and environmental consequences, including greenhouse gas emissions from reservoirs.

Ocean Power Tidal Power

Tide mills are actually a very old form of power, that was used along the coasts of western Europe in the Middle Ages, and was only abandoned with the initiation of the fossil fuel era. In modern times, a tidal dam was built across the Rance estuary in Brittany, France, in the 1960’s. This project has an installed capacity of 240 MW, and has operated successfully for over thirty years. The cost of tidal generation is higher than traditional hydro-electric and can have impacts on marine estuarine environments. Deep marine currents, which are largely driven by tidal movements, offer a very stable energy source with low environmental impacts, but the technology has been very little studied. This type of generation is most comparable to wind, but has the advantages of predictability and high power-output per size of turbine. The future of tidal power is uncertain, but likely to grow.

Wave Power

Wave energy has only been harnessed in a scattering of pilot projects around the world, without any major commercial application to date. However, that will likely change over the next few years, with projects potentially coming on-line in Portugal, The United States, South Africa, and elsewhere. Wave power is most commonly harnessed several km out from shore, where the waves are most consistent. Often some form of buoy is used, which generates electricity as it bobs up and down, however a long snake-like structure has also been created by one company that generates power as the wave moves along it.

More information: World Energy Council


Biofuels are an extremely fast-growing, but also very controversial form of alternative energy. Two key questions remain unclear regarding the use of biofuels: do biofuels provide more energy than it takes to grow, harvest and transform them? And, is there enough land available for biofuels to grow any meaningful quantity? The answers to these two questions are linked.

Current biofuel crops and processes are extremely inefficient. For instance, the U.S. department of energy concludes that "the 'net energy balance' of making fuel ethanol from corn grain is 1.34; that is, for every unit of energy that goes into growing corn and turning it into ethanol, we get back about one-third more energy as automotive fuel." However, other studies, including a 2005 study from a Cornell University researcher, conclude that it actually takes more fossil fuel energy to create ethanol than you actually get back in the resulting fuel. In short, according to these studies, using a litre of ethanol actually contributes more to global warming than just using a litre of gasoline. Biodiesel has similar controversy, although the energy returns are somewhat better. Also, According to the USDA, amount of the total corn crop consumed to make ethanol will rise from 12 percent in 2004/05 to 23 percent in 2014/15. This will likely drive up the price of corn used for food, and even while using almost a quarter of the U.S. corn crop, ethanol will make up a fairly small proportion of the fuel used in the United States. The food to fuel problem is the strongest argument against the current generation of biofuels. Globally we have been using more food than we are growing most of the last decade, and literally eating away at grain inventories, which are now at historically low levels. The implications for human misery are significant. A report from PotashCorp on this trend in agriculture reads as follows:

"Grain consumption has outpaced production in seven of the last eight years, the only exception being a single year of excellent growing conditions in almost every major global agricultural region. With the growing demand for food and now a surge in the production of biofuels, the annual increase in grain consumption has grown from its historical rate of 1.2 percent to 2.0 percent. That has led to a widening gap between consumption and production – one that would become even more pronounced if production failures or other supply disruptions occur."

Biofuels only have a meaningful future if the means of production are shifted away from agricultural crops. For ethanol this means using cellulose materials such as straw or wood and breaking them down into sugars using enzymes. The efficiency of "cellulosic" ethanol will likely be significantly better than corn or wheat-based ethanol. For biodiesel, or vegetable oil production, the future may lie in growing the oil in algae ponds, where the theoretical rate of oil production can be up to 100 times as great per hectare, and will likely have much lower fossil fuel inputs.


Hydrogen is not an energy source, it is an energy carrier, and potentially a means of storing energy. Currently, most of the world's hydrogen is produced from natural gas by a process called steam reforming. Using this process, Carbon Dioxide is still released leading to climate change, and non-renewable resources are still consumed. There is another way to make hydrogen, however, which is the use of electricity to break water down into hydrogen and oxygen. If this is done using renewable energy sources, the 'hydrogen economy' is born. Hydrogen can be used to very efficiently generate electricity in fuel cells. Fuel cells are based on the chemical reaction in which hydrogen and oxygen combine to make water, but instead of letting the reaction happen explosively, it happens in a controlled process that generates large amounts of electricity and relatively little heat. Because it can be stored and transported without losses, hydrogen may be an important intermediary in going from our fossil-fuel economy to one based on renewable energy, and because it is a high-energy fuel it may be particularly important in tranport, although batteries may instead fill this role.

More information: The Hydrogen Economy


Geothermal energy is the energy of the core of the earth. This energy is replenished by the slow decomposition of nuclear isotopes in underground rocks. The core of the earth is at about 4,000 degrees Celcius, and hot springs near the Earth's surface can reach 350 degrees Celcius. This energy can be used to heat homes or generate electricity in areas of geological activity where it is most readily available. Today, 22 nations are generating geothermal electricity, in amounts sufficient to supply 15 million houses. Geothermal energy is also used as a direct heating source in areas where it is available. Most modern geothermal electricity plants use a binary technology, where a heat exchanger transfers the heat from subsurface water to a liquid with a lower boiling point than water, which is then used to generate electricity. This has the advantages of no emissions to the atmosphere and low consumption of water, and allows power generation from lower temperature reservoirs. A huge advantage of geothermal electricity is that it can provide baseload power, which sets it apart from almost all other renewable technologies (the most notable exception being hydroelectricity)

A second, unrelated type of geothermal heating system uses the relatively small amounts of heat in the ground in non-geologically active areas to generate heat in a system quite similar to a refrigerator. These heat pump systems, while relatively efficient, are costly to install and still require significant amounts of electricity to run.

This is from my website - comments and criticisms welcome! 

14 Comments – Post Your Own

#1) On June 17, 2008 at 12:52 PM, Jro81 (< 20) wrote:

Uranium is the answer ....


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#2) On June 17, 2008 at 2:10 PM, eldemonio (97.77) wrote:

What about using humans contained in jelly filled pods as batteries?  We could keep them in some kind of artificial consciousness so they wouldn't even know they are being used as battery slaves!  I suggest we start with criminals and the homeless - both groups should be good for at least a couple hundred mega watts.

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#3) On June 17, 2008 at 7:52 PM, binv271828 (< 20) wrote:


I checked out your website: excellent! I definitely agree with your way of thinking. If you have looked at any of my blog posts, you can see we are looking toward the same future.

There are so many awesome renewable energy concepts: Photovoltaics, Solar Thermal, Wind Energy, Wave Energy, Ocean Tidal, Ocean Wave Acoustic, Hydroelectric, Geothermal, Mechanical storage (flywheels in vacuum), Biomass, Biodiesel, Algae (awesome!), Methane collection and concentration, Space based power, Hybrid Vehicles, Plug-In Hybrids, Air Cars, and so many more that I am not remembering right off.

I love all of these ideas, some are crazy and some are really crazy :), but some are right at our finger tips. I think that the are three near term technologies that will be coming online in a big way in 2 years that will be game changing: Solar Thermal, Plug-In Hybrids, and affordable thin-film Solar

I have written a blog about Solar Thermal: Investing in Solar Thermal Energy Production. I lay out some of the reasons why I think it will be the next big thing in grid-type energy production.  Here is part of that post:

The system is clean. The system is simple. The technology is very low tech or very well understood. Mirrors are very low tech and can be made economically. Self-contained control systems that allow the heliostats to track the sun can be made very economically (a few decades worth of development, devices used in many industries). Steam turbines are very well understood (these have been around for several decades). All of the pieces are there and have been for decades.

There is nothing new or revolutionary about any of these technologies. They are not dependent on a rare element like Tellurium, or the future of polysilicon production. Additionally it could be argued that zoning and land deals for placing solar thermal stations is easier that it is for wind farm. The windy areas tend to have population centers, and the people are almost always against the sight of wind farms (I personally think they are beautiful and looking at them gives me hope for the future and reassures me that their operation means less of a dependence on foreign oil, or coal or natural gas. But some people don't see it that way). There are either drawn out zoning studies or bird migration studies for wind farms. But thermal solar fields are just out in the middle of the desert. Usually in sparsely populated areas.

So while not every location in the US is ideal for solar thermal, there are many locations and I think the land / location issue with the population will prove to be much less of an issue.

The next-two are a combined approach: Thin-film solar and Plug-in Hybrids for transportation-energy. The real potenential game-changer here is Nanosolar. If they can build cheap and highly efficient panels with their technology, essentially bring their operating costs to how low they can go theoretically with their materials, There will be grid parity in no time. And can you imagine charging up a battery with a highly efficient rooftop panel and plugging in your hybrid when you get home? Both the Chevy Volt and the Prius+ are right around the corner.

So those are my 3 near term winners. Longer term, biodisel from algae is the future gasoline replacement. I have literally found 15-20 startups, but none of them are close to viability yet. But the idea of clean renewable energy from microorganisms is exactly the kind of science fiction that I have been dreaming of and has the potential to change the world.

Excellent post and excellent website! Please keep bringing up topics like this, I love reading and writing about it. I think this is the future (alternative energy) because the world is having to deal with peak oil.

Also congrats on #4!!!! Way to go man!

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#4) On June 18, 2008 at 5:02 AM, rudolphsteiner (< 20) wrote:

Thanks for bringing solar thermal electricity generation back to my attention binv, I want to look into it more. I remember seeing a crazy picture of a tower somewhere in Europe (Spain I think?) with hundreds of giant mirrors focused on it... it was unreal.  I don't know much about the economics of it, but without looking into it myself I could believe your pitch that it is close to being cost competitive with some of the more established technologies. Too bad there are no publicly traded companies. Like you, I am waiting for a Nanosolar IPO. It will be huge. Biodiesel from algae could be big, if someone can figure out how to bring it to a production level. So far I'm not holding my breath, but we've talked about that before.

I would at least add geothermal to your top three, because it's baseload power. That is really key. And we know it works well. From what I've read the binary systems have the potential to open up a lot of new areas because they can work with lower temps, so it's Ormat all the way. I wish I'd picked up a bunch more of their stock when it dropped to 39$ a month or two ago. It seems to bottom out along with most other stocks whenever there's a big stock market correction (which I've noticed isn't always true of energy stocks), so I am going to try to wait it out. P/E isn't great, and these high P/E 's in many renewables can't hold up to investor panic (which is fair enough, the whole stock market is probably still overvalued).

Likewise, thanks for your posts, I always check them out, and usually agree with your thinking. 

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#5) On June 18, 2008 at 5:23 AM, jester112358 (28.12) wrote:

Let me point out that nanosize crystalline domains are much less efficient at current collection than microcrystalline which in turn are worse than single crystalline Si.  As I scientist who does original research in nanoscience, I'm amazed at the hype and nonsense on many of the companies out there.  Don't be fooled.  If we could inexpensively grow large single crystalline Si modules, these would provide by far the largest efficiencies.  The scientific reason is simple:  electrons scatter and dissipate their energy when there are more imperfections and boundaries.  Nanomaterials are thus the worst for this application.

 However, direct photochemical splitting of water using sunlight, to create hydrogen would be ideal-this is my area of research and expertise.  This can best be done with nanosize dispersed semiconductor particles.  So, this is a legitimate application of nanotechnology.

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#6) On June 18, 2008 at 10:32 AM, rudolphsteiner (< 20) wrote:

Thanks for that comment Jester, so far I have tended to avoid thin film because of the hype (although I am sometimes sad I didn't buy FSLR at 28$ when I first noticed it!). Your comment confirms my wariness. However, if Nanosolar isn't totally full of it, then their production costs are very low. If they can produce PV panels at $1 per watt (though I have yet to see evidence of this) then who cares what the efficiency is? I'd be interested in your perspective on that, since it seems to be accepted wisdom.

Do you think solar concentrators might turn out to be a big deal then? What really excites me is that there is a solar power race going on at all - though I'm still hesitant to back any of the horses, yet.

Your own research sounds fascinating. If you make that work at high efficiencies, heh voila, the hydrogen economy is born - just when many folks are giving up on the idea.

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#7) On June 18, 2008 at 5:43 PM, HatchingPlans (30.44) wrote:

You're doing exactly what I've always wanted to do (but never had the inside knowledge to pull off)...

As our current means of energy production begin to dwindle and/or increase in price... There will be a HUGE gap just begging to be filled. Even if these alternative energies aren't amazingly cost efficient yet... If there are some that can, for instance, heat homes for the winter, and do it more cost effectively than expensive heating oil will be able to... Then you've got a product.

Take this and expand it to every aspect of our lives that we use energy for... Energy is just such a huge slice of the whole economy pie. Whichever one succeeds will strike its investors rich! 

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#8) On June 18, 2008 at 9:26 PM, adventurerneil (20.10) wrote:

Nice post and website! Please keep it coming, the world needs this stuff and it needs it now. Couldn't help but think of this as I was reading...

I'm curious as to the best ways and best companies to invest in renewable, so I'll add you as a favorite and be sure to check back.

Ever go to It's my go-to site when I need some positive news. :)

Also, congrats on reaching # 3!

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#9) On June 19, 2008 at 4:37 AM, jester112358 (28.12) wrote:

Most experts agree solar thermal will be the first large scale solar contributor and you are correct that concentrator system can be useful.  However, higher temperatures due that much concentation of energy can degrade performance over time.  I'm guessing that will turn out to be the case if CdTe films are made too thin too.  They will separate from the substrate.  The area used actually is important since the copper used for the collection grids and the even the glass surface area figure into the costs.  I've heart about 2 panels of CdTe are required to produce the same photocurrent as microcrystalline Si.  Si will win out in the long run due the much greater availbility of Si vs Te.  (not to mention the toxicity issues associated with CdTe).

Its too bad there aren't any publically traded solar thermal outfits since I would be tempted to put real capital into those. 


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#10) On June 19, 2008 at 8:12 AM, binv271828 (< 20) wrote:


Yeah, I too wish some of these solar thermal companies would go public. eSolar is my favorite, because of the modularity concept. It is really a top-notch design. But I like the BrightSource system too. I will probably be investing in the first one to go public :)


Dude, up to #3!!! Only two more to go :)

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#11) On June 19, 2008 at 11:17 AM, rudolphsteiner (< 20) wrote:

haha, thanks for that adventurerneil. And thanks Jester, Binv and everyone for the great discussion which has doubled the value of this post. When I have time I'm going to put together part2 which will look more at net energy and also at some of the investment opportunities and risks. I'm looking forward to the discussion on that one too.

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#12) On June 19, 2008 at 3:49 PM, Tankota (30.86) wrote:

Trick question.

The correct answer is oil.

What renewable energy will best supplement oil in the future?

Better question.

The correct answer is solar.

Too early now, but in the future...

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#13) On June 25, 2008 at 7:50 PM, XMFSinchiruna (26.50) wrote:

rudolph... I really enjoyed your website!!  What a fantastic resource you've provided there!  I hope you don't mind... I just have to post that graphic on renewable energy spending vs. Iraq war spending.  I think it speaks volumes.

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#14) On June 30, 2008 at 9:38 PM, XMFSinchiruna (26.50) wrote:

Rudolph... This post was so great I had to link to it from the following article on solar power:


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