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Global Futures Report 2013 - Great Debate 3

25 in combination with a more flexible electricity system. In the 80% cases, variable renewables (solar PV, wind, and ocean) supply 40% of all U.S. electricity.21 The NREL study incorporates several forms of flexibility, including demand response, flexibility of conventional fossil fuel power plants, and energy storage (100–150 GW of storage in the 80% cases). Attaining higher flexibility would require new grid management practices, electricity market rules, business models, system plan- ning, and more highly interconnected transmission infrastructure, according to the study. The Lovins/RMI (2011) “Renew” scenario shows 100 GW of storage. And Greenpeace (2012) projects a high (31%) share of variable renewables by 2030, based on smart grids, demand-response, and storage.22 The variability of renewables connected to a power grid has histori- cally been a major reason why utilities have considered renewable energy “inferior” to conventional power generation and resisted its introduction. That is, the integration challenge is not just techni- cal, but one of utility perception, willingness to change and inno- vate, and the institutional and regulatory frameworks that govern utility decisions. The IEA, in its 2011 book Harnessing Variable Renewables, puts it this way: “The extent of the challenge [of man- aging variability of renewables] is one of the most disputed aspects of sustainable-energy supply; detractors claim that variable renew- able energy technologies, at high levels of deployment, introduce a level of uncertainty into the system that makes it just too difficult to meet the moment-by-moment challenge of balancing supply and demand for electricity across a power system.”23 Utilities today still consider variability to be a major issue, but some have taken softer tones in recent years when discussing large renewables shares: “[Without] electricity storage breakthroughs … intermittent energy sources will be complementary and not com- petitors of traditional base load plants,” said EDF. “To increase the proportion of wind and solar energy in our power generation mix as planned—and to ensure economic viability and supply security at the same time—we require energy storage and conventional power plants as a complement,” said E.ON. “Until better technolo- gies become available for the storage of electricity, wind farms usu- ally require back-up from conventional forms of base-load power generation,” said CLP Hong Kong Power. “[Variable renewables] mean that additional base load generation (traditional fuel sources) still must be built and interconnected to protect the system against unexpected generation swings” from renewables, said AEP.24 Oil companies as well use the variability issue to position renewables as merely an adjunct to fossil fuels. Said ExxonMobil, “intermittent sources such as wind and solar … must be integrated with other on-demand or “dispatchable” sources such as natural gas, coal, and nuclear.”25 These traditional utility statements reflect historic views on the continued need for “base load” fossil and nuclear, and the perceived dependence of renewables on future energy storage technologies. Given many prevailing utility views that storage technologies are at least 20 years away, these utilities likewise see high levels of variable renewables 20 years in the future. In the shorter term, Great Debate 3 | Is Energy Storage Necessary for High Levels of Renewables? As noted in this chapter, the conventional view persists that high shares of renewable energy will require expensive storage technolo- gies that must await further development. Many experts disputed this view, saying that the wide range of other options to manage variability mean that high shares are possible without storage. “We think little or no storage will be needed, at least in the United States,” said one U.S. energy expert, who believed that in most cases, storage can be confined to distributed applications, notably in electric vehicles (see following section on transport). Many experts believed that storage will indeed be needed before 2030, but for now, “the immediate need is not that great; we can manage fine with pumped hydro and gas, even up to high levels,” said one. Another utility expert noted: “storage has to come down to one-tenth the cost of generation for us to use it in a big way. We really don’t need it as much as we think. It’s cheaper just to add more generation to compensate for variability than it is to have lots of storage.” And another said, “We don’t need any storage breakthroughs over the next 15–20 years, so we have something of a ‘15-year reprieve’ from needing storage because we can accomplish grid stability with other options, foremost among them demand-response.” Notes and discussion: See Annex 4. Great Debate 4 | Is the Concept of “Base Load” Meaningful for Future Energy Systems? Historically, as noted in this section, utilities have claimed that renewables are not “base load” and are thus inferior to conventional fossil fuels and nuclear. This claim was disputed by many experts, who pointed out that several different definitions of “base load” exist, some mutually inconsistent. Experts noted that meanings can be technical, economic, or institutional in nature, and that according to some meanings, renewables themselves would be defined as “base load.” Thus, experts raised the question of whether the concept itself was meaningful in discussing future energy systems, or whether other concepts, many of them pointed to in this section, would better serve future thinking. Notes and discussion: See Annex 4. 02

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