Tuesday, August 18, 2009

Distributed Generation? Try Distributed Storage.

One of the hot topics in renewable energy is "distributed generation." If every home and business would install some solar panels or small wind turbines to generate their own electricity, then any excess electricity could be sold back to the grid. Build enough small solar photovoltaic systems and windmills, the theory goes, and we won't have to build as many coal-fired power plants.

Those who support this concept make analogies to the internet, where the computing power and brainpower of numerous individuals and their personal computers can be harnessed via distributed computing and wikis and social networks into something really big and powerful.

Will the same concept work with “distributed generation” of electricity?

Not exactly.

Asa an energy efficiency measure, putting solar panels and wind turbines on individual facilities is a very good idea. It will reduce the need for that facility to draw power from the grid. But for large scale production of electricity and selling back to the grid, distributed generation does not provide the quality control and economies of scale necessary for the efficient generation and distribution of electricity. Let’s look at those two issues:

Power Quality. The internet works by allowing everyone to post whatever information they want, without any initial filter on quality. That won't work on the electric grid.

An efficient power distribution system requires that power quality (voltage, harmonics, etc.) be maintained at all times. That is difficult enough to accomplish with highly variable generation sources such as wind and solar. Every time the wind dies down or clouds start to cover the solar panels in one geographic area, the grid would have to find power elsewhere to maintain adequate voltage levels. That is a very difficult and complicated task when you are dealing with large wind and solar farms. It is even more difficult when the wind and solar power is being supplied by thousands, or tens of thousands, or hundreds of thousands of different sources, each with its own variations in power quality.

Economies of Scale. Building small windmills and solar photovoltaic arrays is not very cost efficient. The number of workers required per megawatt -- and the gasoline they will use going from one site to another -- makes this a very inefficient process. And what about maintenance? Can we really afford a renewable energy system that requires maintenance crews to take care of generation capacity that is located at hundreds or thousands of different locations?

Does that mean our electric power systems will continue to be centralized? Yes, but only on the generation side. On the storage side, distributed networks may offer an excellent solution to the problem of matching generation with demand.

The biggest inefficiency in our current electric power system is caused by the need to build excess generation capacity to meet peak demand. Many electric utilities have generators that are used less than 40% of the time. They exist solely to provide extra power when it is needed -- like from 7 am to 7 pm when every office building has its lights, computers, fax machines and HVAC systems turned on. And on that very hot August day when everyone turns on their incredibly inefficient window air-conditioning units at the same time.

Power companies must build enough generating capacity to handle the highest possible peak demand for electricity. When we operate substantially below peak capacity (like, almost every night of the year), that peak capacity goes wasted.

The real problem is not generation, but storage. If we could use that generating capacity at night and store the electricity for the next day, then we would have a truly efficient system.

Fran Lamparello, my good friend and business partner, sees the future of energy storage by looking at the past. Fran has spent his entire working life in different aspects of the energy industry, from designing building controls systems to running a home heating oil distribution business. He envisions a time in the near future when the electric utilities will address energy storage the same way the home heating oil industry did. At the customer's home or business.

By putting storage tanks at each customer's home or business, the oil companies turned their customers into a "distributed storage" network. It was a very efficient system. The distributor could buy home heating fuel during the off season when prices were low, and then store it until the winter. The distributor did not have to pay for storage of large fuel inventories because it could store that inventory at the customer's home or business. Properly sized, an oil tank at the home or business also reduced the number of trips that had to be made to deliver fuel to the customer.

Fran and I predict that you will see the same type of distributed storage system with electricity. As the efficiency and cost of fuel cells and other storage mechanisms for electricity improve, you will see utilities offering to put that storage mechanism on site at the customer's location. It may be in the form of electric cars as Tom Friedman predicts in his book "Hot, Flat, and Crowded," or it may be in the form of fuel cells.

The real value of the internet model for electricity is not “distributed generation.” It is “distributed storage.” Do not put a solar panel on every roof. Put a hydrogen fuel cell in every backyard or basement! Or an electric car in every garage!

John Howley
Manila, Philippines

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