This group brings together the best thinkers on energy and climate. Join us for smart, insightful posts and conversations about where the energy industry is and where it is going.


100 Percent Renewable Energy is 100 Percent Possible

Rosana Francescato's picture
Communications Director Clean Coalition

Rosana is Director of Communications at the Clean Coalition, a nonprofit organization whose mission is to accelerate the transition to renewable energy and a modern grid through technical...

  • Member since 2018
  • 133 items added with 69,743 views
  • Apr 23, 2013

Your access to Member Features is limited.

getting to 100 percent renewable energy

The future is here — it’s just unevenly distributed. This old quote found a new application at the Pathways to 100% Renewable Energy conference in San Francisco last week. An international crowd of energy experts, financiers, clean energy advocates, elected officials, government employees, academics, and more gathered there to discuss how to bring the renewable energy future to all.

Even those in favor of renewable energy have been known to debate how much of our power it can provide. But at the conference, the question was not whether we can get to 100%. Instead, speakers asked, How do we get there? And how soon?


Answers vary, and multiple approaches are needed — many of which were shared at this event. Out of all the details and perspectives, a few themes came to the fore.


Our thinking is out of date


What’s the biggest barrier to 100% renewables? According to keynote speaker Frances Moore Lappé, it’s all in our heads. That’s because it’s hard for us to see beyond our mental map and cultural filters. Instead of talking about scarcity and limits to growth, which are part of this mental map, she believes that to find solutions we need to reframe the issue.

An animated Frances Moore Lappé


Other speakers echoed this sentiment and urged us not to let what we see today cloud our vision of tomorrow. After all, the one given in the world of renewables is that a lot will change. We too need to change when it comes to how we approach the problems.


We need to look at things differently. For example, why not switch to driving electric vehicles? Is it just because we’ve internalized and accepted the reality of gas-powered cars?


The same principle can be applied to the power industry itself; the industry’s current reality isn’t the only one possible. It’s bound to change as renewables make more sense economically, climate change becomes harder to deny, and consumers gain more control of power generation. Some say the industry won’t be recognizable by 2050.


In moving beyond our set views, we may realize that more is possible than we think. People said it wasn’t technically possible to integrate as much renewable power into the grid as Germany has done — and yet it was done, with no adverse effects.


Predictions underestimate the growth of renewables


That’s just one of many predictions gone awry when it comes to renewables. Keynote speaker Eric Martinot, after providing many examples of fast growth in renewables, noted that we’re already exceeding conservative scenarios. Projections from the World Bank and others have generally been a decade off or a factor of 10 lower than actual outcomes. That’s right: we’re heading down the path to 100% renewables more quickly than predicted.


Examples are plentiful of regions on this path. In Freiburg, Germany, the average household energy consumption has been reduced by about 80%. For 2050, Germany as a whole is aiming for 80% renewable electricity, Denmark for 100% renewables. San Francisco has an earlier target of 100% renewable electricity by 2020; Lancaster, California, has set a goal of 100% renewable energy for the same year.


Some areas have already reached 100%. Case in point: Rhein-Hunsrueck, Germany. Starting with energy efficiency and moving on to generating its own power, the region of 101,000 inhabitants now produces not 100% but 104% of its energy from renewable sources. The future is here.


Technology is not a barrier


So what’s holding us back? Speaker after speaker emphasized that despite many misconceptions, it’s not technology.


The many roadmaps we already have — such as IEA’s World Energy Outlook, recent NREL studies, the IIASA Global Energy Assessment, and the REN 21 Renewables Global Future Report — all show that the barriers to 100% renewables are not technological.


That’s not to say that technology isn’t important. Solar and wind forecasting will play a role in moving us to 100% renewables, as will demand-response technologies, storage, and microgrids.


We already have viable means of storing energy, and they’re only getting better. But most storage is not yet on the grid, because  the grid was built when it was thought energy couldn’t be stored — another example of how we need to change our thinking.


And our thinking needs to include transportation and buildings. Going all electric would reduce global energy demand by 32%, and EVs can help support the grid by storing power and sending it back to the grid when it’s needed there. Buildings, representing 25% of global energy use, can be made more energy-efficient.


A study of conditions in 2005 and 2006 showed that in that period, California could have met its electricity needs for 99.8% of all hours from solar and wind — without using demand-response, much storage, or oversizing. In Mexico, a combination of wind and solar can greatly reduce intermittency problems, with hydro or geothermal easily making up the remainder of electricity needs. Those who doubt these assessments need look no farther than the increasing number of areas that have already reached 100% or are close to doing so.


As more regions move to renewables, more people will see the value of making the switch. That increased public awareness and acceptance will help overcome the real challenges, which are social and political.


Renewables make financial sense


Costs can also be a challenge, but that too is changing quickly as renewables become more competitive.


The biggest cost of renewables is in the up-front investment; once they’re in place, they don’t need to be supported by infrastructure like pipelines. Many can be sited locally, reducing the need for costly transmission lines.


Nuclear power is not a good option when it comes to costs. Nuclear requires large subsidies and plants need upgrades and repairs, which always seem to cost much more than projected.


Meanwhile, fossil fuel costs are rising, even if you don’t count the many externalities like health care costs. We’re all paying for fossil fuels, in the form of $600 billion in subsidies in the last 60 years. What did we get for that? Increased power costs. When we subsidize renewables, on the other hand, our costs decline. So what’s the better investment?


Investors are catching on. For example, they’re beginning to understand solar as an asset class and are realizing it’s a great bet: It’s a proven technology, it harnesses an unlimited source of power, and the default rate on solar projects hovers around zero. Solar provides a hedge against volatile future power costs.


Investments in renewables are expected to double by 2020 or 2030. Given the way renewables tend to outperform predictions, perhaps we’ll see that even sooner.


And new business models are emerging to finance renewables as well as to lower their costs. That includes programs supported by the SunShot Initiative that help lower the soft costs of solar, which now account for about half the cost of solar systems in the US.


Local action is key


Given that we have the technology and the favorable economics, how do we get to 100% renewables?


We need strong, stable policies like Germany’s feed-in tariff, which has led to 40% of renewables there being owned by individuals. And that brings us to an important point. Power needs to be decentralized and controlled more by individuals and communities.


Hundreds of communities are getting into the action with policies and targets to support renewables. Some are taking up community choice energy, which allows local governments to pool residential, business, and municipal electricity loads and to purchase or generate on their behalf. It provides rate stability and savings and allows more consumer choice and local control.


Other communities are taking their own paths to renewables. Lancaster, California, for example, decided to become the solar capital of the world and is making progress toward that goal. This didn’t happen from the top down — it happened because the community decided it was important. With the will to make the change in place, it wasn’t hard or costly to implement policies to support the community’s goal, such as streamlining the permitting process.


Greensburg, Kansas provides another great example of a community-driven move to renewables. In 2007, 95% of the town was destroyed by a tornado. The community decided to rebuild in a more sustainable way, and now Greensburg is living up to its name as a showcase for how a community can go green.   

Part of the crowd of 180 conference attendees


Renewables are for everyone


As you can imagine, Greensburg is not a hotbed of radical environmentalism. But it’s a fine example that when it comes to renewables, there’s something in it for everyone. We need to remember this as we tackle the many misconceptions we face.


The people of Greensburg built on their farming ancestors’ heritage of conserving resources, reframed to fit their modern situation. Indeed, conservatism at its heart is compatible with protecting our planet. If that’s not compelling enough, most conservatives care about public safety and national security. And for most people, conservative or liberal, the strongest argument for moving to renewables is the economics.


Whatever the angle, it’s crucial to get the message out that renewables make sense. According to Kirsten Hasberg, that will be facilitated by the democratizer of communication, the digital revolution. She’s founded a new media outlet where she invites us all to participate in harnessing the power of that revolution, Energy Democracy TV. Another way to get involved and learn more is to join Go 100% Renewable Energy, a campaign just launched by a coalition of leading NGOs — including the Renewables 100 Policy Institute, which organized the conference.


As Stefan Schurig of the World Future Council reminded conference-goers, the path to 100% won’t be easy. Resistance tends to get stronger the more successful our efforts. But he left us with a well-known quote that’s worth repeating here:


First they ignore you,

then they laugh at you,

then they fight you,

then you win.



This post was originally published at PV Solar Report.

Rosana Francescato's picture
Thank Rosana for the Post!
Energy Central contributors share their experience and insights for the benefit of other Members (like you). Please show them your appreciation by leaving a comment, 'liking' this post, or following this Member.
More posts from this member
Spell checking: Press the CTRL or COMMAND key then click on the underlined misspelled word.
I K's picture
I K on Apr 23, 2013

Would America have landed man on the moon if it was done via “moon advocates” or these types of “we can do it, we just need to think about thinking differently” meetings? Energy is a technical field it won’t happen with hope and faith.

There are technologies that will reduce demand massively, eg the computer driven vehicle but you will still need to generate many terra watts of “clean” power. It is possible with a global grid not with fantasy micro grids or mini storage systems.

Also pointing out that this or that small region has achieved 100% renewable is just as pointless as pointing out that Mr Smith down the road has a 100% solar home, ignoring the fact that he has the national grid to balance his PV output and that if everyone did it, he could not balance his output for love nor money.

So majority wind/solar powered earth is possible with a global grid. Big reductions are possible with some technologies which are not far away. But unfortunately a future of mini solar with mini storage in mini grids is a fantasy, and no, thinking about thinking of different ways to think about this problem wont change anything…

Max's picture
Max on Apr 23, 2013

Those towns in Germany may produce as much renewable electricity as they consume electricity, but not at the same time, which is the core problem.

For 100% Renewables, significant grid energy storage will be required. That is neither easy nor cheap.

Paul O's picture
Paul O on Apr 23, 2013

Unfortunately, I doubt that the author appreciates the point you’ve made. Even more unfortunate is that hoards of GW Enthusiasts continue to be misled by the Title of this post up, and think that those who disagree are somehow evil mutants that hate The Planet.

Schalk Cloete's picture
Schalk Cloete on Apr 24, 2013

I would again like to caution against the habit of renewable energy advocates to promise technological fixes to the limits to growth problem. The longer we persist with our blind faith in technology to magically expand the limits of our finite planet, the more vulnerable we become as a global society. If you spend just a few months studying the full implications of economic factors such as unpayable burdens of debt and unfunded liabilities and societal factors such as shifting demographics, rising inequality, structural unemployment, continued population growth and the degenerative disease epidemic, you will quickly realize how vulnerable we already are to the implications of limits to growth.

My guess is that, as was the case with nuclear, the law of receding horizons will hit renewable energy (other than hydro) very hard as it progresses to about 5-10% of global energy supplies (it is at about 1.5% at present). The only problem is that, by the time the world realizes this, another two decades of inaction would have passed and societal resilience would have eroded further. Thus, to contrast the final quote in this article, I would like to put forth the old saying: the road to hell is paved with good intentions. 

Yes, we definitely need to reduce per-capita energy consumption and we definitely need to reduce the carbon intensity of the energy sector, but there are many mechanisms other than renewables that can achieve this aim much more effectively. If we remove all energy subsidies and replace most of the income tax with both a carbon and an overall energy tax, the free market will quickly find the most effective way. Renewables would probably not do very well on such a level playing field. 

Rick Engebretson's picture
Rick Engebretson on Apr 24, 2013

I like open minded people. So thanks for the open minded report, Rosana.

While the RE people are looking to restart, many others are out in the kitchen recharging their biological batteries eating calories produced by the sun somewhere, sometime.

I don’t know why advancing the science of producing stored chemical energy from solar energy seems so hard to grasp for RE “experts” and critics alike. Seems like a pretty natural extension of living. So I just think the pros and cons just like to argue about why nobody is going anywhere fast. Maybe you are different.

Nathan Wilson's picture
Nathan Wilson on Apr 24, 2013

Renewables make great poster-children for clean energy, and we very much need to switch to clean (or at least very low CO2 emitting) energy.  But this 100% renewables push is a different matter all together.  The best analysis by respected technical groups like the IEA indicate that energy portfolios that are 100% renewable cost much more than those that also include nuclear and fossil fuel with carbon capture and storage.

Why does the cost matter?  It hurts the poor, and it decreases the likelihood that society will adopt clean energy.  Effectively, for societies that are willing to spend only a little more for clean energy, the renewable-only approach is dirtier.

Advocates of 100% renewable power are in some ways the most closed minded people in the environment movement.  Their minds are closed, not only to alternative ideas, but to economic reality.

Schalk Cloete's picture
Schalk Cloete on Apr 25, 2013

Hi Jim, I took a look at the links you provided and have a few comments:

The first of these is that the total technical potential estimates provided appear to assume that almost the entire ocean area between the polar circles will be used for 100 MW OTEC plants spaced about 30 km apart. Getting the majority of the world’s energy in the form of electricity from the middle of the Pacific appears to be a bit of a long shot. 

Secondly, an engineer looking at any energy technology will always look first at the energy return on investment (EROI). The embodied energy in the massive structures that will make up an OTEC plant together with the vast amounts of energy that will have to be invested to install such a plant in the middle of the ocean and connect it to the grid are likely to result in a very low EROI. In addition, the corrosive ocean environment will reduce plant lifetime, thereby further reducing the EROI. 

Thirdly, OTEC will not have a meaningful impact on global warming even if we assume that 25 TW was technically feasible. The current global energy imbalance is about 0.6 W/m2 which translates to total global energy accumulation at a rate of roughly 300 TW – more than one order of magnitude greater. This number will of course increase as more greenhouse gasses are emitted. Most importantly though, taking energy from the ocean and consuming it on land will essentially only transfer that heat from the oceans to the atmosphere where it will contribute most effectively to climate change.

For these reasons it is hard to see how OTEC plants will be realized in more than a few highly suited locations (very large thermal gradients close to shore).  

Nathan Wilson's picture
Nathan Wilson on Apr 25, 2013

“…With the heat pipe and counter-current you extract 2TWh from the surface, produce 1TWe …”

Whoa, that sounds like a violation of the Carnot equation.  How can that efficiency be possible without a 800C temperature difference?

Schalk Cloete's picture
Schalk Cloete on Apr 26, 2013

Thanks for the info, Jim. We have to put all options on the table, but we also have to be realistic in what each option can deliver. I therefore wish you well with this initiative, but would urge you to fully detach from any subjectivity and critically assess the real world potential of this technology. 

The two primary measures that determine the promise of any energy technology is its total technical potential and its EROI. The stated total technical potential of OTEC depends on putting hundreds of thousands of plants in  the middle of the ocean – hundreds or even thousands of kilometers offshore. I don’t think that is realistic. 

The EROI concerns I outlined above still stand and will be augmented by the large amount of energy conversion you speak of (electrical-to-chemical conversion usually cuts EROI in half). Real world plants also tend to be significantly less efficient than optimistic first estimates. A complex civilization such as ours probably needs an overall energy sector EROEI of 5:1 at the very minimum. Anything lower than that is simply out of the question as a major energy source. Some peer reviewed EROI studies on OTEC will therefore be required before we can make any meaningful conclusions on its potential. 

Lastly, I would just like to apologize for my poor choice of words in my third point in the post above. Of course 25 TW of low-carbon energy would slow down global warming by slowing the greenhouse effect. What I meant was that this effect will not have a significant effect on the overall oceanic energy imbalance – i.e the rate at which the greenhouse effect puts heat in will be more than one order of magnitude greater than the maximum rate at which OTEC can take the energy out. 

I K's picture
I K on Apr 26, 2013

You seem to be missing a few big things

First the heat energy you take out of the ocean and turn to electricity isn’t cooling the planet. That electricity is largely turned back into heat via whatever it is powering. Also I would be skeptical about the notion of deposoting 300TW into the depths of the ocean and it staying right there for ever. Water is a fluid not a solid so it will probably disapate.

Also all the co2 sruff you posted seems nonsense. All atmospheric gases are in some equilibrium with the oceans and the soil. 


So for instance last year abiut 8ppm co2 was added to the air via ff burning while the recorded inceease was only 2ppm. The reason for this is that the equilibrium is shifted to the side that makes co2 ddissolve out of the air and into the soil and oceans. 

Therefore if last year we did not burn any FF the co2 in the atmosphere would have fell roughly 6ppm in just one year. 

The warming cheerleaders seem to have got this nonsense into the public realm that co2 stays for thoisands maybe millions of years in the atmosphere its to put it politely plain wrong


The interesting part is that the equilibrium is so far to the side of removing atmospheric co2 that we may soon get to a situation where burning fossil fuels adds absolitely no net co2 to the air.  My guess is rhat may occur in the 2020s to 2030s. Right now the earth ‘scrubs’ nearly 70 to 80 percent to the co2 we put into the air from fossol fuel burn. 

I K's picture
I K on Apr 26, 2013

Question.  25twh every how many time period?

Q. To generate 1TWh from a low temp heat engine operating at 3percent efficiency requires you to move how many TWh of heat? 

Q. If your aim is to cool the surface of the ocean what happens to the temperature difference of your cold and hot sink and how does that impact your heat engine? 

Q. If carbon dioxide stays in the air for thousands of years how did the earth scrub around 6ppm in just 12 months?


The above is basic physics and chemistry and if you take the time to figure out those answers you will know why your idea about cooling tge ocean surface is not going to work and also why the many Internet experts who talk to thousands of years for co2 to react to concentration changes is crap. It is instantaneous


I K's picture
I K on Apr 26, 2013

That’s a mighty long post to say the efficency fairies will do it

The equation his on about is

Efficency = 1 – (temp cold / temp hot)

And all heat engines built to date are equal to or lower than this let alone one designed on an Internet chat forum…


Whats more important is that you seem to want to cool tge ocean surface so what was a 15 kelvin differential heat engine becomes a 5 kelvin differential heat engine. Spot the problem yet? You are looking at just 1 percent efficency if you can at all build a heat engine to operate at such a low difference.  The pumps needs would probably exceed any power generation

I K's picture
I K on Apr 26, 2013

I really do take issue with your ‘current projections are global warming is locked in for a 1000 years’

Pure cheerleading nonsense. 

Take any chemical or physical reaction and change the concentration of one of the substances and there is no magic 1000 year or 1 million year time lag….it is instantaneous.


In the real world caseit appears we are adding 8ppm whilr only seeing an increase of 2ppm. Thst means earth is scrubbing 6ppm at current co2 concentration levels.  So stop burning fossil fuels today and co2 in the air will fall by 6ppm in the first year alone.  Assuming fossil fuels are indeed the driver for net co2 changes


I K's picture
I K on Apr 27, 2013

You seem to be confusing your units. TW is a measure of power.  TWh is a measure of energy. 

So are you suggesting you will be to produce 25TW of electricity constantly via otec. 

Are you aware that means about 30x as much heat need to be moved.  So approx 750TW of heat from the top of the ocean to some kilometres below it.

750TW…… that is a tremendous amount of heat. I can’t rule it out but it is one of those numbers which rings alarm bells. You would need to reheat the surface with that much power to allow it to work constantly.


Anyway good luck to you.

Get Published - Build a Following

The Energy Central Power Industry Network is based on one core idea - power industry professionals helping each other and advancing the industry by sharing and learning from each other.

If you have an experience or insight to share or have learned something from a conference or seminar, your peers and colleagues on Energy Central want to hear about it. It's also easy to share a link to an article you've liked or an industry resource that you think would be helpful.

                 Learn more about posting on Energy Central »