A new shock to an old system

The Alliance for Sustainable Colorado is revamping energy sources

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David Lauer

The Alliance for Sustainable Colorado is located in the world’s first LEED certified historic building, but the nonprofit isn’t stopping there — the century-old building will soon convert their electricity system from pure alternating current (AC) to also include direct current (DC).

“The Alliance is already a bastion of efficiency — we want to go even further,” says Christi Turner, the Alliance’s communications coordinator.

The Alliance for Sustainable Colorado is a non- profit organization working towards realistic measures of sustainability. In 2004, the Alliance purchased a historic commercial building on Wynkoop Street in downtown Denver, to serve as a physical space to convene and connect local community leaders working toward common sustainability goals. The 100-year-old building underwent massive and innovative energy efficiency renovations in an effort to demonstrate the use of historic structures in achieving sustainable cities.

Since The Alliance Center moved in, the building has collected a handful of prestigious awards for sustainable design, including two LEED certifications, and has established itself  as a national leader in sustainability innovation. Within its 40,000 square feet, the Alliance Center is only at 70 percent capacity, currently housing 43 different agencies and welcoming more than 180 people on average through their glass doors each day.

But the Alliance continues to push the sustainability envelope, including implementing a DC system that will boost the Center’s efficiency to new levels.

DC and AC systems differ in one major way: DC, used in batteries, runs a current that always flows in the same direction, while AC, the electricity you get from wall sockets, runs a current that alternates backwards and forwards.

In the late 1800s, AC voltage was easier to transport long distances. Power plants connecting the national grid established AC as the national standard while DC fell out of fashion.

Today, however, almost all electronics — anything that uses batteries, plugs into a USB cord for power, or uses a small black box (an AC adapter) to plug in the wall — runs on DC power. Many appliances are also equipped with an internal converter that changes the AC power it gets from the wall into DC power that is needed to operate the appliance.

Renewable energy sources like solar panels and wind turbines can only generate DC energy. To use that energy to charge your computer in a conventional building, first the energy must be converted to AC power, then run through wires around the building, and then it will be reconverted back to DC power. The heat emanating from the back of your computer as it charges is the energy lost in this conversion process, which can climb up to 20 percent.

The Alliance is looking to reduce this energy loss as much as possible. As they prepare to install solar panels along their rooftop, they are planning to purchase a set of large batteries that will collect and store the DC energy to be used daily, or on reserve. Rewiring the building to include DC power will eliminate the need to convert and reconvert energy.

“Everything we do is trying to maximize our efficiency,” says Sandy Vanderstoep, the Alliance’s special projects director.

The conversion will not remove the AC system, however, because powering an entire building with DC energy is not realistic. By simply supplementing their energy with DC power, Vanderstoep estimates a third of their load will still be cut.

“It’s our job to pull away and see what the greater good is,” Vanderstoep says, keeping in mind the Alliance’s goal is to provide an example other organizations can realistically follow. “Right now [the greater good] seems to be staying on the grid while also supplementing with DC power.”

The plan to convert the building is simple. The Alliance began construction in the summer of 2015, with the help of Positive Energies LLC, an energy project developing company. They will begin the move to localized energy production by rewiring the lighting and the TVs so they can hook directly to DC power.

According to Vanderstoep, there are 6,000 buildings in Denver alone that are ripe for this kind of conversion.

“We’re looking to set the benchmark for reasonable and realistic conversion to energy efficiency,” she says.

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