Saturday, May 26, 2012

Recognition for Ground Source Heat Pumps -- the little g in Geothermal

Over the years, proponents of some forms of geothermal energy have suffered from a bit of an identity crisis. There is, of course, Big G which generally refers to hydrogeothermal resources of the type that create geothermal electrical generation common to northern California, Nevada, Indonesia, etc. and shown below in the new Hudson Ranch I system that recently went online in the Salton Sea of California.
Big G also commonly refers to geothermal resources used for direct use as in hot springs resorts and the district heating system in Pagosa Springs, Colorado.
Then there is "little g" which refers variously to geothermal heat pumps (GHP), geoexchange, or, more appropriately, ground source heat pumps (GSHP) -- a fundamentally different energy resource and technology than Big G. It doesn't help that both Big G and little g, and which both suffer from a bit of a Rodney Dangerfield complex, are often discussed at the same conferences which only further confuses the two. Rather than a resource for electrical generation or direct use heating, ground source is better looked at as an energy efficiency device that can provide both heating and cooling for space conditioning (I won't go into the details here. Interested readers might want to start out with the Wikipedia entry). 

The basic problem with ground source is the high first cost of installing the loop field. While improving technology has increased the efficiency and cost effectiveness of the heat pump component of the system, there has been little improvement in the cost of installing the loop (see the excellent article by Tom Konrad in Forbes here). Thus, for residential systems in particular, GSHP remains at a competitive disadvantage -- especially in light of low natural gas prices. 

I have long argued that ground source deserves more recognition in utility demand side management/energy efficiency programs, most of which focus on weatherization programs (good) and nothing more sophisticated than rebates for kitchen appliances and compact fluorescent light bulbs (questionable). Some states have enhanced their renewable energy standards with new thermal energy standards. These have tended to focus more on solar hot water heating and, occasionally, biomass... still not much recognition for the only technology that provides both heating and cooling. 

During this legislative session in Colorado, a group convened to attempt to foster greater recognition for ground source in a thermal energy standard that was being discussed. Unfortunately, the single paragraph that discussed geothermal or ground source in what became Senate Bill 12-180 was lost in what morphed essentially into a biomass/forest conservation bill. That the bill was introduced late in the session and was tagged with a large fiscal note did not bode well for its prospects and it was soon killed in committee. That was probably just as well since the bill was a mess and the best it would have done would have been to create a thermal energy working group. In the present economic environment, and with little support for new incentive programs, I suspect that ground source is going to have to continue to rely on technological advance and new financial innovations (similar to the PPAs that have fostered greater PV adoption) to reduce the first cost to consumers so that it can compete with more established space conditioning technologies.

Saturday, May 19, 2012

World's Largest Concentrating PV System Goes Hot in Colorado!

Fans of utility-scale solar PV are likely aware of the world’s largest highly concentrating PV (HCPV) system that has been under construction in the heart of Colorado’s San Luis Valley. On May 10, Cogentrix Energy, LLC (a unit of Goldman Sachs) announced that it has achieved commercial operation at its 30MW HCPV project which will provide solar energy to Public Service Company of Colorado (PSCo) for compliance with the utility’s wholesale DG obligation under Colorado’s Renewable Energy Standard. The Amonix MegaModule® assemblies that form the heart of this system rely on Fresnel lenses to concentrate solar irradiation 500 suns onto triple junction solar cells originally developed by SpectroLab (a Boeing company) as part of the US space program. Looking like something out of the movie Transformers, the project consists of over 500 60kW (nominal) dual axis trackers on approximately 225 acres approximately 14 miles NW of the southern Colorado town of Alamosa (click here for a Google map). 

Truly an impressive facility, this project was bid into the 2009 All Source Solicitation conducted as part of PSCo’s 2007 Electric Resource Plan (Colorado PUC docket 07A-447E). Electricity from the plant, estimated at approximately 75,000 MWh for the first full year of operation, is provided to PSCo under a 20-year PPA. Financing for the approximately $145 million project was facilitated by a $90.6 million loan guarantee from the US Department of Energy proving that not all DOE-backed funding necessarily had to result in Solyndra-like failures (in fact, there is a fundamental difference between providing a loan guarantee for an energy development project such as this and a manufacturing facility such as Solyndra). The one downside, albeit a significant one, is that the Colorado PUC exempted this project along with another 30MW project in the San Luis Valley developed by Iberdrola Renewables from the 2% rate cap in Colorado's renewable standard. As I’ve pointed out previously, compliance with Colorado’s RES has been achieved, and even exceeded, but at a cost far greater than the 2% rate cap stipulated in the statute. 

Back in October 2011, I had the opportunity to tour the facility with Cogentrix VP Jef Freeman while it was still under construction. Below are a handful of the pictures I took at that time.

Approaching the plant from the southeast, it is difficult to get a true appreciation for the scale of the facility.

Looking closer, it isn't clear if this is a solar facility or a spaceport!

Loading the Amonix MegaModule panel assemblies onto the pedestals.

Look close and you might see the workers attaching the panel assembly to the pedestal from below.

To get a feel for the scale, check out the pickup truck in comparison to the trackers.  The Solectria inverter on each tracker can be seen in the foreground.
When not tracking the sun, or stored due to high winds, the panels will remain horizontal as shown here.

All photos Copyright Richard Mignogna, 2011.