Not just for barbecues, some companies are switching over completely.
The reviews of the new report from the UK's Committee on Climate Change have been mixed; I complained about its reliance on hydrogen, carbon capture and storage, and electric cars, but I seem to be more negative than most.
One point that troubled me was a reliance on heat pumps, which I considered problematic because they are full of Fluorinated gases (F-gases) that are powerful greenhouse gases, as much as 1700 times worse than Carbon Dioxide.
Architect Mark Siddall confirmed my concerns, pointing to a study on the impacts of leakage from refrigerants in heat pumps, published in 2014. But evidently help is on the way from a very old-fashioned source – propane, or as they now call it, R-290.
Anyone who has ever looked at the propane tank of their barbecue has seen or felt how cold it gets as propane changes from liquid to gas; it is an excellent refrigerant. However, the reason Freon and other fluorocarbon refrigerants replaced ammonia and propane is that they didn't poison you or explode.
But the propane heat pumps, like these new ones from Wolf, have a lot less propane in them than your barbecue tank, a small enough amount that they are considered safe. I worried also about the noise of all these units pumping away, but they are working on that too: "Numerous technical details such as a slowly-rotating fan in owl-wing design and tracking geometry, as well as the installation of the components in a sound-insulating EPP core ensure that noise from the heat pump disturbs neither operators nor neighbours."
According to cool|therm, you need less propane than other refrigerants:
Since its thermodynamic properties are well suited to the temperatures typically encountered in building services engineering, the refrigeration cycle coefficient of performance (COP) is comparatively good. As a result, the refrigeration charge for propane can be 40-60% less than other common refrigerants. Propane is non-toxic, and has an ozone depletion potential (ODP) of 0 and a global warming potential (GWP) of 3.
They are also outside of the home; propane is heavier than air so you don't want it inside where it will sink to the floor. Other companies are switching to R290 as well; Elmar Zippel of German heat pump maker Vaillant is switching over too. “We don’t want to follow an intermediate solution,” Zippel said. “Our aim is to step [by step] introduce R290 in all our products.” They are making units that can heat and cool a 2,000 square foot house.
Agreed, Lloyd, heatpumps are the way to go; noise can be reduced to the very low levels we already have with passive house certified ventilation systems. And we've already measured annual performance factors near 5 (heating); cooling even better— Wolfgang Feist (@WolfgangFeist) May 5, 2019
As Dr. Feist, the co-founder of the Passivhaus Institute notes, this is the future. "Much better than direct electric (1) Of course: Electricity generation has to go (almost) completely renewable – but that's the easiest path to go renewable. (2) Of course: Buildings have to be 'nearly zero' (passive house or better). Then heat-pump is the path with least effort to go sustainable."
I think apartments may be different case though - easy to be < 500 W max heat load for whole dwelling. Communal heating has significant efficiency loss, especially with such minimal heating demand - and causes overheating.— Alan Clarke (@AR_Clarke) May 5, 2019
Of course, as engineer Alan Clarke notes, you can even probably do without heat pumps if you go multifamily and build on the Vienna model. But that's another post.
In the meantime, it's good to know that there will soon be quiet and efficient heat pumps filled with relatively benign refrigerants that don't add to global warming. Just don't try to do it yourself.