Durham: Why I voted to OK TEP's natural gas power plant upgrade

At the Tucson City Council meeting this Tuesday, we considered a Planned Area Development relating to a 345-acre site at Alvernon Way and Irvington Road that Tucson Electric Power calls the Irvington Campus. The PAD was needed to allow TEP to modernize the generating plant, initially by building a Reciprocating Internal Combustion Engine generating plant. The RICE plant will replace two of the four steam generators and reduce the use of the other two.

I voted to approve the PAD in a unanimous 5-0 vote. The RICE plant burns natural gas, and I want to be clear, I don't believe we should be burning any fossil fuels, but I voted as I did for a number of reasons.

As you know, sustainable power generation, clean air and reducing our carbon footprint are high on my priority list. Since I took office, I've pushed the city to make our buildings more energy efficient and install more solar. So I questioned TEP pretty hard, both before and at the Council meeting, about the RICE plant. Here's what I learned.

The RICE technology is newer, cleaner (60 percent reduction in nitrous oxide (NOx) emissions) and more fuel efficient (by about 30 percent) than the 2 steam generators (also fueled by natural gas) that it's replacing (2 newer steam generators will remain). It also saves a lot of water—the current steam plants use 2,200 acre feet per year. The RICE units and remaining steam generators will use 700 acre feet (a 70 percent savings). (An acre foot is just under 326,000 gallons.) But equally important, it's quick to power up and power down (called "fast ramping"). One of the disadvantages of renewable energy, both solar and wind, is that it is intermittent. It's important for an electric utility to have backup sources that can come online quickly (for both solar and wind) and operate at night (for solar) to keep the system in balance and meet demand.

The goal is that batteries will provide this backup, but batteries are more expensive. For example, TEP estimates that the RICE plant will cost about $200 million to build compared to about $400 million for a solar farm and batteries of equal capacity. But the batteries will have a life of 10 to 15 years compared to the RICE plant's 30-year life. (I don't like the idea of burning natural gas for another 30 years, but that's a decision we'll face a few years from now.) After 10 to 15 years, the batteries will need to be replaced. Nobody knows what batteries will cost then, but just to pick a number, let's guess $200 million (and I'm also ignoring the cost of natural gas for the RICE plant in this very "back-of-the-envelope" calculation). And solar panels wear out too. Bottom line: using these numbers, the solar plus batteries approach might cost about $400 million more than the RICE plant.

When low- and moderate income families can barely afford their electric bill in the summer (and many can't), I'm just not willing to impose this cost on TEP ratepayers.

Because it is fast ramping, the RICE plant actually will support additional renewable energy. TEP estimates that the RICE plant alone will support an additional 290 to 385 megawatts of renewable energy, supplying enough fast ramping capacity to support additional renewable energy until the early to mid- 2020s. Hopefully by then, batteries will be better and more affordable. So the RICE facility will be a bridge to our zero carbon future.

Bottom line: Solar plus batteries sounds nice, but the batteries are just too expensive right now.