“I think one of the most striking memories I had was of helping uncover an entire tanker truck full of chlorinated solvents that was buried in one piece.” ~ Ron Gehl, president EOS Research, Ltd.

I’ve got a great show for you today. My guest is Ron Gehl, founder and President of EOS  Research. Ron has spent thirty years tackling difficult engineering problems in environmental protection and renewable energy. He’s also Chair of the Solar Thermal Division of the American Solar Energy Society. We’re going to talk about solar thermal or solar hot water heating, the sometimes underappreciated workhorse of the renewable energy world. Ron started his career in hazardous waste remediation before discovering his passion for solar thermal applications.

Ron Gehl, President of EOS Research

RG: My name’s Ron Gehl. I’m president of a company called EOS Research and am chair of the solar thermal technical division of ASES.

DB: Alright. And where do you live and work Ron?

RG: I live in New Hampshire. Our office is in Rochester and I live in the middle of nowhere.

DB: So you don’t go into the office everyday then.

RG: I try not to but unfortunately I’ve got to spend a little more time there than I would like. I’d rather be out in the field all the time.

DB: So, solar thermal. I think a lot of people just don’t know much about solar thermal really. They think of photovoltaic panels when they think of solar.

RG: Constant struggle for those of us that are solar thermal practitioners. I’ll just point out that I’m not one of the guys who goes up on the roof and installs solar thermal systems but we kind of approach it from a control systems standpoint and from that angle have been able to see a lot of different systems being installed and what works well and how to optimize performance and all that. But from the standpoint of ASES’s solar thermal division, our work has to be focused on pointing out how much more efficient a solar thermal application is than a comparably sized photovoltaic application. So we’re always three to four times as much energy that can be generated from a solar thermal installation of the same size as a photovoltaic installation.

DB: Can you explain why that is?

RG: Well it’s basically the process of converting the sun’s photonic energy into useable energy for humans is more efficient when you can transfer infrared radiation to, typically water is the medium that we use in solar thermal, versus converting it to electrons in photovoltaic panels.

DB: So you have a whole different set of challenges with using that energy and storing it and transporting it. So give us a flow chart for what a solar thermal system is.

RG: Okay. Well you mentioned storage and that’s one of the components of a solar thermal system that is really advantageous. It’s much easier to store solar thermal energy than it is to store electricity of course. But, generally speaking what you have are a series of panels that are of different designs, they can be evacuated tubes they can be flat plates, but generally speaking they’re dark colored and they absorb infrared radiation and the idea is to transfer as much of that as possible to a fluid medium, typically water or a glycol solution, and then bring it down to the ground or to a storage tank where you can actually hold it aside for when you need it or put it to immediate use. So the applications can be as simple as domestic hot water heating. They are increasingly being used for industrial processes or things as mundane as a car wash, that’s a fantastic example of a solar thermal application that’s really beneficial, to even solar cooling applications. So through the use of absorption and adsorption chillers you can actually convert solar thermal heat to cooling that can be very beneficial particularly for larger buildings. We’re going to have a fair bit of content talking about that here at the conference.