Marin goes 100% renewable…with natural gas


photo of PG&E's Pittsburg power plant (now owned by Mirant) in front of a horizon full of SMUD's windmills, courtesy Barbara George of Women's Energy Matters

I’ve been reading through the Marin Clean Energy plan, which is designed to offer customers in 12 potential cities in Marin County the possibility of powering their homes and businesses with 100 percent renewable energy. How can this be, and how can San Francisco do the same?

Their community choice aggregation plan offers folks two options: “light” green (25 percent renewable, ramping up to 50 percent by 2014) or “deep” green (100 percent renewable right out of the gate.) Initially, this will be achieved through power purchase agreements with third-party renewable energy suppliers, while at the same time contracting to build their own renewable power sources and encouraging citizens, through incentives, to put up their own solar panels and wind vanes. (Studies have shown that Marin County has the potential for as much as 846 megawatts of renewables, mostly from solar and wind, though biomass and methane capture are also achievable, especially with all those dairy farms.) The county’s draw is about 240 megawatts.

But my question was if they would still need to rely on natural gas or any other “conventional” power sources as they transition, or to meet peak needs and state-mandated reliability standards.

I queried Tim Rosenfeld, of the Marin Energy Management Team, who has been consulting the county on the plan. “We can’t abandon conventional natural gas generation,” he told me. “It will still be there for firming and shaping our grid, but we will be able to ‘green’ it through our renewable generation.”

When the wind blows and the sun is shining and the cows are shitting, the county will generate more energy than it needs, which can be sold into the state’s grid for “renewable energy credits.” Later on when the sun sets or the need peaks, the county cashes in those credits when purchasing conventional power from the market. “That’s how you can get to 100 percent, but you can’t do it all with renewable generation,” said Rosenfeld.

So, essentially they’re manufacturing their own carbon offsets to use when they have to rely on natural gas or some other “conventional” power. They’re planning on keeping that “conventional” draw to about 19 percent by 2017, with a long-term vision of building their own biomass cogeneration, implementing a “smarter” grid that distributes energy more wisely, and using enhanced transmission lines that bring in renewable power from distant areas.

What does this have to do with San Francisco? Well, our community choice aggregation plan calls for 51 percent renewables by 2017, mostly from more large city-owned solar installations, more energy efficiency and demand-response, and power purchase agreements with renewable providers, as well.

But that’s still only 51 percent, so we’re going to be buying our power from “conventional” sources, too.

Who owns those sources? All sorts of power companies throughout the state, who are now vending it to Pacific Gas and Electric. PG&E also owns their own plants, and is only building more.

According to their 2007 annual report, their projected capital expenditures are, as follows:

In 2005: $1.9 billion

In 2006: $2.4 billion

In 2007: $2.8 billion

In 2008: $3.6 billion

“and [from 2008 on] forecasts that capital expenditures will average approximately $3.4 billion over each of the next four years."

What are they spending the money on? To start: two giant natural gas burning power plants in Antioch and Colusa County, and a repower of their 50-year-old diesel plant in Humboldt Bay.

They're building to own -- and sell. If we, or any other city, gets into the power business through community choice aggregation or a full-blown publicly owned system, at the very least in the short term, we're going to be subject to power purchase agreements. The more PG&E has a lock on the available sources, the more indebted we are to them, the longer this relationship continues.

Which makes San Francisco's plan to build and own two peaking power plants seem that much more important, because the more power sources the city owns, upfront, the less we'll have to buy from PG&E later on down the line.