A Look at Wind and Solar

Part 1: How Far We've Come


Wind and solar have come a long way in recent years, contributing over 10 percent of all new electricity demand between 2003 and 2013. But large penetrations of wind and solar, commonly celebrated in countries like Germany and Denmark, look less impressive when considering the whole grid. A more comprehensive view is required to understand how wind and solar will fit in to a high-energy, low-carbon planet.

May 26, 2015 | Alex Trembath

This post is coauthored by Alex Trembath and Jesse Jenkins.

After decades of incipient growth, it seems that wind and solar power are finally ready for prime time. These two renewable energy resources are growing rapidly and are beginning to move the needle in global energy supplies.

Renewable energy’s growth has been fueled for years by deployment subsidies and other support policies — feed-in tariffs, tax credits, portfolio standards, and the like — exactly the kind of proactive public policies that the Breakthrough Institute (where one of us worked and the other still does) has supported since its inception.

While we have both called for reforms to improve the efficacy and sustainability of dominant approaches to deployment policies, we also recognize the tremendously important role deployment policies — however imperfect — have played in driving nascent industries. Just as government investment in research development and demonstration and subsidies for early deployment were central to unlocking the shale gas revolution or giving rise to the modern nuclear power sector, public investment in renewable energy adoption has taken the wind and solar industries a long way.

How far have we come exactly? In 2013, wind turbines generated almost three times as much electricity globally as they did in 2008. Solar generation grew by more than a factor of 10. Together, wind and solar increased from 1.1 percent to 3.3 percent of global electricity over that same period, not an inconsiderable feat as overall global electricity demand simultaneously expanded 14 percent. Of the 6,340.1 terawatt-hours (TWh) of power generation growth between 2003 and 2013, 10.9 percent came from wind (564.8 TWh) and solar (122.8 TWh).

Unfortunately, wind and solar will have to sustain rapid growth rates in order to truly compete with coal and other fossil fuels, not just for relative market share, but to drive fossil fuels from the global energy marketplace in absolute terms. [See “Has Renewable Energy Finally Ended the Great Clean Energy Stagnation?”]

At the same time, global figures can mask the larger contributions that wind and solar are already making today in certain grids around the world. As wind and solar move in from the power grid’s margins, the global conversation has shifted in important ways. No longer is the discussion about if renewables will play an important role in the global energy system, but how much of a role and how will they impact energy systems when their penetration levels reach scale?

In short, it is time to start thinking of wind and solar power less as niche technologies and start thinking more about their place in fueling the low-carbon, high-energy world we need in the 21st century.

In that spirit, this post will provide a quick lay of the land on wind and solar’s best performances to date. In a follow-up post, we will consider what implications we can draw from both practical experience and emerging research in power systems modeling. 

Wind and solar leaders

When it comes to renewable energy leadership, Germany almost certainly spills the most ink, but it is actually not the world leader in terms of penetration of variable renewable energy sources (or VRE, our shorthand here for wind and solar).

Italy actually out-generates Germany in terms of solar’s contribution to the grid, and Denmark has long held the mantle of global wind leader.

Likewise, several states in the United States have earned accolades for generating significant shares of their electricity with wind –– including Texas, Iowa, Colorado, and California.

Unfortunately, the shares of VRE in these jurisdiction’s energy mixes often overstates the real penetration of these renewable energy sources.

The reality is that while wind may provide 32 percent of Denmark’s electricity and solar generates 8 percent of Italy’s, for example, these countries and states are really part of much larger power grids. Renewable energy advocates sometimes obfuscate this fact, implying that VRE has reached much higher shares of the power system than they truly have. [Data above from the 2014 BP Statistical Review.]

Integrated grids

For example, the American Wind Energy Association (AWEA) has celebrated that Iowa generated 28.5 percent of its electricity with wind power in 2014. But Iowa is part of a regional energy market and power system run by the Midcontinent Independent System Operator –– which spans parts or all of 13 states, from North Dakota, Minnesota, and Iowa in the Great Plains to Michigan, Wisconsin, Illinois, and Indiana, down to Arkansas and Louisiana. As a whole, wind power supplied 5.7 percent of MISO’s demand in 2014.


At the same time, MISO is strongly interconnected with power systems controlled by other market and grid operators, including the PJM market, the largest organized electricity market in the United States (in terms of total demand), which spans from Illinois to the mid-Atlantic coast. The MISO and PJM grids are so well integrated they are moving towards establishing a common power market. At this scale, wind provides just 3.7 percent of combined MISO-PJM demand.


Finally, Iowa is part of the 610 gigawatt Eastern Interconnection, a synchronized grid spanning virtually the entire eastern continental United States (excepting parts of Texas) as well as the Canadian provinces of Saskatchewan, Manitoba, and Ontario. Wind energy accounted for 3 percent of electricity generated in the American portion of the Eastern Interconnect in 2013 (for which data is available from the EIA).


Similarly, wind supplied more than 10 percent of electricity consumed in Idaho, Colorado, and Oregon, according to AWEA. But each of these states is a member of the 160-gigawatt Western Interconnection, a synchronized grid spanning the entire western half of the continental United States plus Alberta and British Columbia, which gets only 6.6 percent of its electricity from wind.

Finally, most of Texas is supplied by its own synchronized grid known as ERCOT — Texas has always had a go-it-alone mentality! Here, wind penetration finally tops double digits at the grid-wide level, reaching 10.6 percent of electricity demand in the ERCOT system in 2014.

We mention all of this not to diminish the importance of wind energy, but rather to bring the scale of analysis to the power system level. When evaluating the impact that VRE has on the grid, it’s essential to look at the whole grid. We’ll illustrate this with a quick detour to Europe.

Taking the whole system view: a tour of Europe

We start our spin through Europe in Denmark, which for decades has been held up as a model for deployment in wind power. Wind generates about one-third of Denmark’s in-country electricity consumption, but again, looking at the whole grid is important. Denmark is a member of the Nordic Synchronized Area, which also includes Norway, Sweden, and Germany.

Here’s what total generation in the Nordic Synchronized Area looks like, where about 8 percent of electricity generation comes from wind power, while 43 percent comes from fossil energy, 22 percent comes from large hydro, and 17 percent comes from nuclear.

Indeed, when we look Denmark as part of the integrated Nordic system, we immediately see one of the main factors that enabled Denmark to achieve such a large share of its electricity from wind. Denmark benefits tremendously from its interconnections with all three of its Nordic neighbors, using this integrated grid to balance out fluctuating output of wind by importing and exporting over a third of its electricity annually.

On windy days when Danish wind turbines exceed the local demand, Denmark can effectively “store” its excess production in Norway’s flexible hydropower reservoirs, and then import that power again later once the wind dies down. As much as 40 percent of Denmark’s wind generation is exported, according to an analysis by Johannes Mauritzen.

As Roger Andrews at the blog Energy Matters has concluded, “It would appear that Denmark’s ready access to balancing power from the Nordic Grid allows it generate a lot more wind power than it would otherwise be able to, whether it consumes it or not.”

Another window into the Denmark wind situation is the through the Nord Pool Spot, which makes available data on power production from Nordic/Baltic countries (Denmark, Norway, Sweden, Lithuania, Estonia, and Finland). Among this club, wind penetration is approximately 4 percent. This graph shows the generation balance in these countries over the past 4 years:


This analysis itself is incomplete, since Denmark and the Nordic system is also well integrated with the rest of Europe, which is creating a single, unified pan-European electricity market that will enable trade and flow of electricity across the continent. Yet even at the scale of the Nordic system, we see the importance of looking at power systems holistically.

So while countries like Germany and Denmark get most of the ink, it turns out Iberia and Ireland are the true leaders in variable renewable energy penetration Europe at the grid-wide-level.

Spain and Portugal are relatively isolated from the rest of the European grid, and both are VRE leaders. Wind generated 20 percent of Spanish electricity and 24 percent of Portugal’s power in 2013. Solar contributed another 4.9 percent of Spain’s electricity and half a percent of Portugal’s, making the Iberian Peninsula the world leader for grid-wide variable renewable energy penetration.

The Irish grid, which supplies both Northern Ireland and the Republic of Ireland, is a close second, with 16.3 percent of its electricity from wind in 2013. It is a truly island system with a 500 MW undersea DC cable to the UK its only connection to other grids. (Wind and solar in turn supplied about 8.4 percent of UK electricity in 2013.)

In our next post, we’ll look ahead to the future of wind and solar energy, and what that future tells us about how to build zero-carbon power systems on a high-energy planet.

Part 2: Is There an Upper Limit to Intermittent Renewables?


Jesse Jenkins is a PhD student and researcher at MIT and a freelance writer and consultant. He pens the Full Spectrum column at TheEnergyCollective.com. He previously directed the Energy and Climate Program at the Breakthrough Institute from 2008 to 2012.

Alex Trembath is a senior energy analyst at the Breakthrough Institute, where he authors the Energetics column.


About Alex Trembath

Alex Trembath is Director of Communications at the Breakthrough Institute. His writing has been covered by the New York TimesForeign Policy, CNN, Resources for the Future, the American Energy Innovation Council, and the National Bureau of Economic Research, among other media and academic outlets. He also directs Breakthrough Generation, Breakthrough's program for hosting research from emerging scholars. Follow him on Twitter @atrembath