Converting brownfield to solar brightfield

Siemens and PCI Solar have completed work on a 1.8-MW brownfield solar project for the City of Wasco, California, that allows the city to use under-utilized land?"and generate power to offset the energy consumed in city-owned buildings.

By Paul MacDonald

In energy terms, the region around Wasco, California, may be well known more for oil and natural gas than renewables, but the city is now home to a major solar power facility built on a brownfield site.

An energy savings performance contract (ESPC) with Siemens has allowed the city of Wasco, located in sunny central California outside of Bakersfield, to use energy savings to fund a solar project located on a former burn dump.

The renewable energy produced will help offset approximately 60 percent of the city's current energy usage and costs associated with its municipal buildings, as well as the treatment and distribution of water and wastewater.

"This project means a great deal to our city—it's our first ever renewable energy project," says Gilberto Reyna, Mayor of Wasco. "By the end of the performance contract, we're projecting to have saved enough energy to power nearly 3,100 homes for a year."

In municipalities, water and wastewater utilities are typically the largest energy consumers, often accounting for 30 to 40 percent of total energy consumed.

Operating expenses to treat water, pump it to homes and businesses, and then treat the resulting wastewater can be costly. Wasco is no exception, as it uses approximately 4.7 million kWh annually and spends $713,000 a year for water/wastewater treatment and distribution.

To help reduce its water pumping and treatment expenses, the city entered into a 15-year performance contract with Siemens to build a 1.8-megawatt solar power system on a six-acre site adjacent to the city's wastewater treatment facility. Wasco is projected to realize $410,687 in energy savings and reduce its energy usage by 2.8 million kWh the first year post-construction, with expected total energy savings of more than $8.6 million over the life of the contract.

Siemens selected PCI Solar to be the contractor for the Wasco brownfield-to-solar project. PCI Solar serves customers across the U.S. on a broad range of project sizes and types, including ground mount, roof mount, solar carport, and solar shade canopies.

"Performance contracting is part of Siemens' Total Energy Management approach," explained Andrew Krynen, Zone vice president, Siemens Building Technologies Division. "It can provide options for reducing energy usage and operating costs, increasing energy efficiency and sustainability, and making better use of existing infrastructure.

"The solar project with Wasco combined all three elements, while also helping the city remain fiscally prudent," said Krynen.

On top of this, the Wasco solar project makes use of a very under-utilized resource: a now-closed landfill. The project was capped in the 1970s and, in 1992, had been certified by the local county.

The solar project also takes advantage of a Pacific Gas & Electric (PGE) program called Renewable Energy Self-generation Bill Credit Transfer (RES-BCT), which allows cities to build up to 5 MW of renewable generation on one site, and provides a credit for excess solar energy that is produced.

Wasco is located about 140 miles northwest of Los Angeles in the agriculture-rich San Joaquin Valley. Its former burn dump was capped and remediated in the 1970s, and has very limited use. However, it provided an ideal location for a sizable solar panel installation.

"We're tapping into a program that will offset our energy costs for water pumping and treatment, and we're able to make creative use of a site that would otherwise be left vacant. We're looking forward to the years ahead," says Reyna.

So as not to disturb the soil on the Wasco landfill site, solar panels are mounted on GameChange ballasted racking systems and surrounded by a ballasted protective fence.

Siemens selected PCI Solar to be the contractor for the Wasco brownfield-to-solar project. PCI Solar is a division of Performance Contracting Group, a specialty building contractor with over $1 billion in annual revenues. The PCI Solar team serves commercial, government, and channel partner customers across the U.S. on a broad range of project sizes and types, including ground mount, roof mount, solar carport, and solar shade canopies.

Siemens cited PCI Solar's extensive experience, both in California and with local governments, in choosing the company.

PCI Solar's Ryan Holcombe oversaw the project. When he first did a site walk at the Wasco landfill, the city and Siemens were considering several options for the size of the solar project, from 1.3 MW to 2 MW. "We did designs for three different sizes, and they eventually decided on 1.8 MW," he says.

Holcombe noted that the Wasco landfill was notably different from a traditional landfill, in that it was used as a burn site and handled green waste, such as garden waste rather than household waste. "When we got there, we had a fresh site to work with. Now it's basically a dirt site, perfectly flat. It was a very constructable site. Our only direction was that we could not penetrate the cap.

"We had a lot of liberty with what we were able to do on the landfill site," Holcombe added. "It has a two-foot deep clay cap, but there are no restrictions in driving on it. With a regular brownfield landfill site, with household waste, you have far more considerations about what you can do."

Regular landfills/brownfields have caps with a fabric membrane, with methane gas vents, and there would be considerable limitations on vehicle traffic on the site. "We did not have that—it was like a regular ground mount solar project." With that one big difference, he added: they could not go into the clay cap.

	With the solar project now in place, the city of Wasco is projected to realize $410,687 in energy savings and reduce its energy usage by 2.8 million kWh the first year post-construction, with expected total energy savings of more than $8.6 million over the life of the contract.

Some civil work was done by the city of Wasco prior to solar construction. The city wanted the site to have a slope, for water drainage, so one end of the site was built up five feet. Soil was brought to the site and graded to achieve that slope.

Holcombe noted that with Siemens projects, the company provides the components. At the Wasco site, this consisted of 5,346 Silfab 345-watt solar panels and 27 ABB Trio 50-KW inverters. So as not to disturb the soil, the panels are mounted on GameChange ballasted racking systems and surrounded by a ballasted protective fence.

The ballasted fence was a unique feature of the project. The north side of the site is not actually on the landfill, so the fencing for that side was built or replaced in a conventional way. "We could drill footings for the fencing on that part of the site—it was not part of the cap," explained Holcombe. "But for the east fence, most of the west fence, and all of the south fence, it was on part of the cap, so we could not penetrate the soil."

After trying with no luck to source a fencing solution, they came up with their own approach. They brought in 24" by 24" pre-cast concrete blocks and had a custom steel plate welded to the bottom of each fence post. The plate was then attached, with four bolts, to the concrete block. It was all engineered to withstand local wind conditions.

"So every 10 feet around the perimeter of that part of the site is a concrete block," says Holcombe. "And it works great."

With the fencing complete and the site secure, they were able to move materials on to the site itself. They had good road access since there is a nearby wastewater treatment plant. "The infrastructure we had for the project was fine," says Holcombe.

Another challenge faced during installation was maintaining accessibility with above-ground conduit. Commercial ramps were available, but they were too small, and intended to be used for cables, such as what you would see at a music concert. PCI Solar discussed fabricating ramps, but they ended up finding a solution with the purchase of heavy duty conduit ramps that are typically used on mining sites.

This was PCI Solar's first brownfield-to-solar project, and having completed it successfully, they have since bid on other brownfield sites. They now have a good introductory knowledge base of what is involved with such projects—and want to learn more. "It was a good project to cut our teeth on because it was kind of half-way between a regular site and a fully fledged landfill," says Holcombe.

"The next brownfield project we do will probably be more difficult and restrictive in how we do it—but it will also be a bit easier because we did the Wasco project."

He adds they were pleased to be involved with a brownfield-to-solar project.

"It's a real positive story, because you are taking land that is not being used and adding value to it for the city of Wasco."