AS OF THIS DATE, no less than 120 companies are directly or indirectly involved in the research, development and deployment of combined heat-and-power systems based on hydrogen fuel cell technology. In this, the last of a 12-part series on the history and future of hydronics, we look at the potential of HFC technologies and their role in CHP plants for residential and light commercial buildings.
President Bush has committed $1.7 billion for the research, development and utilization of hydrogen-based technology to be spent over the next five years. While much of the president’s focus is on the transportation sector, the heating sector will benefit from this research.
The technology of hydrogen fuel cells has been around for quite some time and has been proven technically feasible many times over. The primary reason that it is not commercially viable today is being overcome with great leaps in available technology to produce the hydrogen necessary to operate these devices.
One key component to its commercialization is the requirement of using the existing “pipelines” that currently deliver energy to the end user. This will avoid having to construct a new distribution method to meet the needs of this new technology.
Gas and liquid reformers are devices that will separate hydrogen from carbon in natural gas, propane and fuel oil. In addition to the byproduct of thermal output from the proton exchange membrane, a device is on board that incinerates the residual carbon left over from the reformer process and produces some thermal energy in the process.
A typical 2 kW HFC generator, which is considered as the lower end of residential needs, will produce a side stream thermal output of 4.5 kW per hour (15,358 Btuh). The temperature of this heat output will be in the neighborhood of 158°F to 176°F.
If the HFC is applied in a way that all excess electricity is sold back to the grid, the thermal side stream will represent a major challenge to the home builders and the hydronic heating contractors of the future. The cooler the proton exchange membrane is kept, the more efficient its electrical generation capacity will be. If the thermal capacity cannot be thoroughly utilized, the HFC becomes less economically viable.
This will require the installation of large, super-insulated, mass-intensive, underground or under-home storage tanks. The heating systems of the future will require an extremely energy-efficient home (less than 10 Btuh/sq. ft.), which in turn will dictate an extremely low temperature of operation. If the water temperature is too low to meet the needs of the home, the system may require the use of a water-to-water heat pump to increase the temperature to the level required to heat the dwelling.
Using my own dwelling as an example, if I could have built a storage tank 4-ft. deep below my 30-by-60-ft. home, I’d have 449,820 gal. of super-insulated storage. If I would have installed a 2 kW hydrogen fuel cell, its thermal output of 15,000 Btuh would raise the water temperature from 40°F entering temperature to 75°F, an ideal entering water temperature for a water-source heat pump. If the tank were only 2-ft. deep, it would have raised the water temperature to 110°F, a nearly ideal temperature for a large surface radiant heating system.
These numbers are overly simplistic, but I think you can see where we’re headed. The retrofit market for these units is going to be dictated by the end user’s ability to thoroughly utilize the thermal output capacity of the HFC or the economics will kill the deal.
This will require even more thinking outside the box. Possibly, one HFC could serve the electrical needs for a family of one, but also the thermal needs of four houses by way of a miniature district heating system.
One thing is for certain. This technology is here to stay, and the hydronics contractor who learns how to design, install, service and maintain efficient hydronic heating systems that will dovetail well into this new methodology will have millions of people knocking on his door to apply this marvelous technology.
I would like to take a moment of your time now to say thanks. Too often, we get caught up in the whirr of life and forget to stop, take a breath and say thank you. Thanks to you, my readers, and thanks to Penton Media, my publishing company; thanks to all my partners, and a million thanks to the folks in foreign lands putting their lives on the line to ensure our homeland peace, security and freedom.
Happy Holiday Hydronicing, and we’ll see you in the New Year.
Mark Eatherton is a Denver-based hydronics contractor. He can be reached via e-mail at [email protected] or by phone at 303/778-7772.