Conducting a Distributed Chorus

Reciprocal Efficiency

Published In: Intelligent Utility Magazine January/February 2010

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UTILITIES ARE USING DISTRIBUTED GENERATION RESOURCES AS MORE THAN SIMPLY sources of supplemental power during peak demand or as an alternative when base-load generators cannot deliver reliable electricity. Judging by the global warming debate and a desire for draconian cutbacks in carbon emissions, the drive toward greater efficiency and environmentally friendly sources of generation is causing utilities to rethink their portfolios. For one Michigan utility, a proliferation of forward-thinking technologies, attitudes and grant-funded research support is encouraging a move toward cleaner, or simply smarter, sources of distributed generation.

Detroit Edison, a subsidiary of DTE Energy that delivers electricity to more than 2 million Michigan customers via 11,000 MW of capacity, relies on a fleet of reciprocating engines to support consumption during times of peak demand. ''The engines are positioned at strategic points on our distribution grid where we monitor the ratio between demand and generation. They will kick in when additional generation is needed and likewise take themselves off,'' said Haukur ''Hawk'' Asgeirsson, manager of power systems technologies.

OLD AND NEW

DTE Energy has used reciprocating engines since 2001, shortly after the U.S. Department of Energy (DOE) initiated its Advanced Reciprocating Energy Program ''to design, develop, test and demonstrate a new generation of reciprocating engine systems for [distributed energy resource] applications that are cleaner, more affordable, reliable and efficient than products commercially available today.''

Detroit Edison is also taking account of the generation resources managed by customers, which are interconnected with the distribution network. A DOE grant is helping to locate all such generators that produce 1 MW or more of power with a goal of aggregating and directing these resources to areas of load demand during peak hours or emergencies. Asgeirsson reckons DTE Energy can benefit by 600 MW from ''the little guys.'' This initiative has been demonstrated but the full-scale rollout has not yet advanced beyond the paper stage. Eventually, this data can be integrated into the utility's Internet-based operations center, which monitors and controls distributed generation resources and can be managed remotely.

RENEWABLES + PHEVs

To help the state achieve 10 percent renewable generation by 2015, DTE Energy is utilizing large wind farms and solar photovoltaic systems which can be connected to the distribution grid. DTE Energy is marketing significant cost savings to residential and commercial customers. Through its SolarCurrents program, the utility will purchase renewable energy credits (up to $25 million overall) from customers who install photovoltaic systems in exchange for partial reimbursement of installation costs and a credit to their power bill for 20 years.

DTE Energy is also well located for working with the state's automotive industry and is pursuing a Michigan Public Service Commission grant-funded initiative with General Motors and the University of Michigan to investigate the use of plug-in hybrid electric vehicles (PHEVs). Work teams are focusing on how PHEVs can serve as an economic development catalyst in the state, examining short-, mid- and long-term vehicle-utility interfaces including demonstrations, and probing the impact of PHEVs on environmental and electric utility systems.

The potential for vehicle-to-grid technology can also mean a greener, reliable source of distributed power. ''I think plug-in vehicles represent a great load for utilities if customers can be incentivized to charge them at night,'' said Asgeirsson, referring to when vehicle charging is not as likely to overwhelm generation capacity. ''This also represents an opportunity to tie renewable wind farm energy to charging plug-in vehicles, as wind resources are often better at night,'' he said.

Asgeirsson doesn't think consumption will grow so quickly that all generation (including distributed resources) must be coordinated immediately. A National Public Radio story suggested emissions from vehicles' internal combustion engines would decrease by 3 percent in 2009, which Asgeirsson suggested will mirror a similar drop in power consumption as consumers seek cost-saving measures during the economic downturn.

But even if that's true, DTE Energy is thinking long term and at least one other state utility (Consumers Energy) has proposed to develop a clean coal generation plant, improve energy efficiency and minimize energy loss through advanced metering infrastructure to offset the need for another generation plant. Coordinating the use of distributed generation resources relies on emerging technologies that offer utilities the chance to tap cleaner, reliable power and already-available resources. The specter of climate change urges haste.

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