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Global Futures Report 2013 - Buildings

26 many utilities have focused on flexible use of natural gas. And indeed, gas companies themselves are projecting greater demand for natural gas in the future, driven by the need to balance variable renewables.26 Some utilities go further, to more controversial options: “Important research areas include … increasing the flexibility of lignite power plants,” said Vattenfall. “When solar and wind [output declines], the base load is best balanced through flexible conventional power plants capable of ramping up and shutting down again quickly,” said E.ON.27 Notwithstanding historic and current resistance by utilities to the integration challenge, it was clear to virtually all industry experts that utilities will eventually employ these options in increasingly creative, extensive, and broad-based ways to manage the vari- ability of renewables and ensure stability. However, the manner, time frames, and extent of employing each of these options is still quite uncertain, said experts. Many expected to see these measures employed by utilities and grid operators to increasing degrees in the future, although perhaps over a relatively long span of 15–25 years. One utility manager from a Danish grid operator foresaw many flexibility measures implemented in the 2020–2030 time frame, including demand-response aggregation of many individual customers, competitive balancing-services markets, and addition of less-variable resources like CSP with embedded storage and offshore wind. Experts also expected to see new market rules and structures that recognize and place value on flexibility.28 Interconnection standards and net metering/billing for local distrib- uted renewables (i.e., on customer rooftops) is another key element of utility-grid integration.a Net metering allows customers to benefit from retail electricity prices for any locally generated power that they supply back to the utility (rather than for self-consumption). In the absence of net metering, utility-set prices for reverse (customer-to-utility) power sales may be lower than retail elec- tricity rates. An increasing number of utilities around the world are required by regulation to allow customer net metering for various sizes of installation.29 Integrating renewable energy at the power plant level with fossil fuels was another form of utility-grid integration pointed to by some experts.30 (See Box 4.) Finally, the broad range of technologies and practices implied by the term “smart grids” underlies the utility-grid integration challenge. (See also Chapter 4 for more on smart grids at the local/city level.) The concept of “smart grids” implies all of the necessary information and communication technology (ICT) infrastructure to implement the strategies noted in this section for balancing variable renewables on utility grids. The concept also implies the necessary ICT for much more efficient use of energy in buildings, transport, and industry that goes along with the integration of renewables into these sectors (see following sections). And “smart grids” implies ICT for control- ling local micro-grids and combining centralized generation, local generation, demand management, and energy storage at all levels.31 (See also “Great Debate 5” on page 27.) Box 4 | Hybrid Fossil Fuel/ Renewable Power Plants Another way for renewables to integrate with utility power grids is through the hybrid combination of fossil fuel and renewable technologies at the power plant level. Some experts expressed optimism that such hybrid technologies would become a significant part of future energy systems, although few scenario models incorporate such hybrids. Said one power technology expert, “renewables advocates don’t like to include fossil fuel technologies when talking about the future, but hybrid technologies need to be on the radar also.” Such hybrid technologies have been the subject of research and development for decades, much of it by the fossil fuel industry. And commercial applications have been growing, particularly for biomass co-firing with coal or gas in conven- tional power plants. There were some 100 co-fired plants operating in Europe, another 40 in the United States, and several in Australia and Japan. Other hybrid technologies cited by experts include: (1) solar thermal power (CSP) plants integrated with combined-cycle natural gas turbines; (2) biomass and coal co-gasification systems to produce synthetic natural gas, with a typical mix of 20% biomass and 80% coal; (3) wind farms that are inte- grated with compressed-air energy storage and simple-cycle natural gas turbines to provide constant-output power from a remote location and thus maximize transmission capacity; and (4) CSP plants that preheat feed water for a coal power plant to increase its efficiency. Source: See Endnote 30 for this chapter. RENEWABLES GLOBAL FUTURES REPORT 02 INTEGRATED FUTURES: CHALLENGES AND POSSIBILITIES Buildings Integration of renewable energy into buildings involves several technologies and forms of infrastructure, including solar heating and cooling, low-energy or “passive” buildings, district heating and cooling, small-scale combined heat and power (CHP) plants, biomass-fueled heaters and stoves, “building-integrated” solar PV, and thermal energy storage.32 Experts and scenarios underline that a transition to much higher efficiencies for buildings and heating and cooling equipment is fundamental to the integration of renewables. For example, GEA (2012) models a roughly 50% reduction in heating and cool- ing energy demand by 2050 through best practices in design, construction, and technology. This section presents many of the key technologies and infrastructure that experts and sce- narios show will be part of future integration with buildings.33 (See also buildings and district heating in Chapter 4, and biomass technologies in Chapter 6.) a) Net metering allows a two-way flow of electricity between the electricity distribution grid and customers with their own generation system. The customer pays only for the net electricity delivered from the utility (total consumption minus self-production). A variation that employs two meters with differing tariffs for purchasing electricity or exporting excess electricity off site is called “net billing.”

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