Achieving 100% renewable energy was not so long ago seen as a dream. Now recognized to be viable, many cities around the world have set such targets.

Still it is not a trivial task to get to 100% renewable energy, while at the same time ensure reliable and affordable electric power. A key enabling factor is being connected to a large and robust electric grid.  It gives access to remote renewable resources and it is the most cost efficient way to balance the variability of wind and solar. Let’s take a closer look at a couple of cases.

Burlington, Vermont, population 42,400 (2010 census) was in 2014 the first city in the U.S.A. to achieve 100 %.  As discussed in Burlington, Vermont, Beats Germany’s New Renewable Record key components were hydro power and biomass, which helped keep the cost for electricity low. For the reliability of the system being part of New England ISO (Independent System Operator) was more or less a prerequisite.

Greensburg, Kansas, population 780 (2010 census), and Aspen, Colorado, population 6660 (2010 census), became the second and third cities to reach 100%. Aspen has many similarities with Burlington in having a large amount of hydro power, about 46 % of its energy supply. 53 % comes from wind and the last 1 % comes from landfill gas.

Greensburg was on May 4 2007 hit by a massive tornado destroying or severely damaging 95 % of the city. As part of the restoration efforts the city leaders, business owners and residents with experts from Department of Energy (DOE) and the National Renewable Energy Laboratory (NREL) set a vision of building a Greensburg Green Town ™. One of the goals was to make the new buildings more energy efficient, 30 % less energy use than similar buildings built to code.  By rebuilding to LEED (Leadership in Energy and Environmental Design) certification the city not only reached but exceeded the goal, on average now using 40 % less energy. In terms of the renewable energy the source is locally generated wind power.  The City of Greensburg, John Deere Renewable Energy (now Exelon) and the Kansas Power Pool built a new 12.5 MW wind farm, financed by the Rural Development Agency at the U.S. Department of Agriculture.

Georgetown a city of 55,000 north of Austin, Texas, by 2017 will probably become the fourth city in the U.S. to achieve 100% renewables.  In March this year the city announced a 25 year power purchase agreement (PPA) with SunEdison for annually 150 MW. SunEdison will build a dedicated solar farm in West Texas. Last year Georgetown signed a 25 year PPA with EDF for wind power from a wind farm 50 miles west of Amarillo. Interestingly the city’s spokesperson, Keith Hutchinson, said that the primary reason going all renewable was price. In fact the deals locked in cheaper electricity than what the city’s expired contract with Lower Colorado River Authority guaranteed.  As quoted in The Texas Tribune he said “We don’t know what’s going to happen in the future for regulations (or market shifts) for fossil-based fuels. This really removes that element from our price costs going forward.”  Quite impressive considering that the cost in Georgetown is already slightly below what the average customer in Texas pays!

John Farrell in an article “Low Cost Switch To 100% Renewables” (originally published on the Institute for Local Self-Reliance website) points at two key factors enabling Georgetown to make this shift to 100% renewables.  The first factor is that Georgetown by having a municipal utility can chart its own electricity future. The second factor is that Georgetown municipal utility had no legacy or stranded cost issues. Their last own power plant was closed in 1945 and its major supply contract expired in 2012.

A third and equally important factor is that Georgetown is connected to the Texas grid and part of ERCOT (Electric Reliability Council of Texas). It enables to Georgetown to managing the variability of the wind and the solar by buying and selling power on the spot market.

In fact in all the cases above being connected to a large and robust grid is the common denominator in achieving 100% renewable energy, while at the same time maintain reliability and keeping costs affordable. Without access to a large grid it is a much bigger challenge to achieve 100%. (However, it is not impossible, which we will discuss in another article/blog.)

Access to a robust electric grid is even more important for large cities now targeting 100% renewable energy. San Francisco, population 825,800 (2012), is ambitiously targeting to get there by 2020. Starting point in 2011 was a mix of 30%large hydro, 16% “non-large” hydro, 18 % nuclear and 36% fossil fuel. 2012 The Mayor’s Task Force on Renewable Energy, which was set up in 2012, formulated six strategic elements for more renewable energy including increased energy efficiency and more local renewables. By mid-2013 18.5 MW of In-City renewables (15 MW of PV and 3.5 MW of biogas cogeneration) had been added. It is impressive but far from what will be needed to replace the nuclear and fossil fuels. Whatever the additional renewable solutions will be the bulk of them will have to be brought to the city by transmission lines, the grid.

Munich, Germany, population of around 1.5 million in the city and 5.8 million in the Munich Metropolitan Region, has set its target to become the first million people city in the world to achieve 100% renewables. The city has committed to the goals of reaching 100% renewable electricity for households by 2015 and for all users by 2025. Through its municipal utility, Stadtwerke Munich GmbH (SWM), the Renewables Energies Expansion Campaign was launched 2008. With a budget of around 9 billion euros (about $10 billions) and with German determination they have charged forward and already achieved the 2015 target!

SWM has according to their press information “focused exclusively on cost-efficient projects that are self-sustaining”. The priority has been projects in Munich and surrounding areas. For example SWM is operating one solar thermal plant, 22 photovoltaic (PV) plants and has a part ownership in another PV plant, 13 hydro plants, a biogas plant, a biogas processing plant, two geothermal plants and a wind park, all in the Munich region.

In addition wind power is playing an increasingly important role. However, with the wind comes the dilemma that it is remote and has to be brought to Munich by the grid. The most suitable sites for wind are distant from Munich and Bavaria. SWM operates today over 100 onshore wind turbines in mostly in central and northern Germany. SWM also owns three wind farms in France and since September this year a wind farm in Sweden. Further SWM owns 11% of the IPP (Independent Power Producer) wpd Europe GmbH. This IPP is active in 11 European countries and has already operating wind farms in Poland, Croatia, Belgium, France and Finland.

In terms of offshore wind SWM got a 576 MW wind farm in Liverpool Bay (Irish Sea) in operational in June this year. SWM together with Vattenfall are developing three very large wind farms in the North Sea with a total capacity of with 976 MW. Further SWM is partner in a 50 MW solar thermal plant in southern Spain.

Without access to the German grid as well as to all the neighboring grids Munich’s 100% renewable goal would not be possible to achieve. The grid is not only needed to move the renewable energy to Munich. The grid also provides access to capacity reserves such as brown coal plants in Germany, nuclear plants in France and Czech Republic, hydro plants in Norway and Sweden, etc.

As Munich and all Germany continue to move forward on the Energiewende, the need not only for an expanded and strengthened European electric grid but also for more developed and integrated European electricity markets (energy, capacity and ancillary services) has been highlighted with the intensity of a super trooper spotlight.