By Andrew Williams

Oregon Demonstration Plant
Washington-based Rappaport Energy Consulting (REC) has recently secured $149,900 of DOE funding for a project to study the differential data from retrofitting a concentrated solar thermal array to the existing geothermal electrical generation system currently installed at the Oregon Institute of Technology (OIT) in Klamath Falls Oregon.
As Marc Rappaport, CEO at REC, explains, the team will use the installation as a research tool to learn about the synergies of a hybrid system before publishing a report providing an analysis of findings.
"We are planning on providing future engineering and design, along with appropriate partnerships, for the development of hybrid systems where feasible and reasonable," says Rappaport.
 

Utah
In another development, Oregon-based Utility Energy Forum (UEF) and PacifiCorp have recently released a joint concept paper outlining the feasibility of a hybrid geothermal/CSP solar plant at the PacifiCorp-run Blundell geothermal power plant at Beaver County, Utah.
According UEF Director Guy Nelson, there is potential for a hybrid application at Blundell 'because it has a significant geothermal resource and very high solar insolation rates, a condition that is dominant in the Western US.'
Since Blundell has a steam field management program and occasionally needs to drill additional production wells, Blundell plant manager Garth Larsen and Nelson decided to write a paper introducing the concept of tying in CSP with the steam management program in such a way that it could 'delay or eliminate the need to drill more wells.'
"The main outcome was to simply get the concept from words in the air to paper and start a conversation that may lead to a demonstration of the concept," says Nelson.
 

NREL
Elsewhere, the National Renewable Energy Laboratory (NREL) is collaborating with Idaho National Laboratory (INL) in a joint project aimed at examining the viability of using heat provided by solar thermal collectors to augment the energy input to a binary power plant. According to Desikan Bharathan, Principal Engineer at NREL, the analysis, due for completion in 2014, will evaluate the potential of using solar thermal augmentation to mitigate the risk and consequences of a resource 'being unable to provide the expected temperature and/or flow for which a plant is designed.'

"It is also foreseen that solar augmentation may help mitigate potential reservoir temperature decline over time," he says.
"Other risks perceived for financing the plant may also be reduced to result in long term reduction in the LCOE (levelized cost of energy) produced from the geothermal/solar hybrid," he adds.
Technological Challenges
Rappaport predicts a 'real future' for the development of hybrid systems 'when countries and utilities recognize the growth opportunities for reliable base load power that emits no pollution and can be sustainable for decades at a levelized cost.'

"We need to have the research pilot plant to gain first hand knowledge. We don't see any real significant technical hurdles, we just have to do our engineering carefully," says Rappaport.
For this pilot facility, REC will attach a plate heat exchanger to the geothermal brine 'just before it enters the ORC' and monitor the various input and output parameters to collect the required 'real world' data.

"Since the system will be tied to a college campus that uses the thermal heat for campus heating, we see a very important real operations component to provide enhanced operations data to draw analysis from," he adds.

Financial Hurdles
Nelson believes utilities will be 'very reluctant' to demonstrate the concept on their own and, in the US at least, argues that DOE funding 'seems the logical place to go.'

"Overcoming the financial challenge is a tough cookie. Some organization needs to strap on some courage and make the concept a priority over other concepts," he says.
Rappaport agrees that financial challenges remain, but is confident that use of the existing OIT facilities will lower the threshold for building the pilot plant. With over $4 million already spent on infrastructure costs, he says it will be a 'much smaller' cost to build the research facility, adding that the DOE grant 'helps with the research costs and provides the larger investment community with a vetting of the technology as worth pursuing.'

"We are still left with the cost of the equipment and construction and it would be great if several of the large investment arms of EPRI and EEI stepped up to assist us. This should be an area the utilities see value for the development of base load power that can also provide summer peak load that can follow the peak load demand," he says.