The differences between wood-burning, natural gas, propane and ethanol as fuels for modern fire pits. Part 2 discusses ethanol.
Ethanol is a fairly recent entrant into the outdoor fire pit product category. It is becoming an increasingly popular choice for indoor fireplaces and something of a buzz word in the eco-fireplace dialogue.
Ethanol used in fireplaces and fire pits, also referred to as bio-fuel, simply put, is alcohol. It falls under the ‘denatured’ category, in that it is rendered undrinkable, but at its base it is the same as the alcohol found in your favourite after-work drinks. Ethanol for fuels is usually produced by the fermentation of sugar, which is in turn derived from food produce such as corn.
The resulting product of this process is a colourless, almost odourless, volatile and highly flammable liquid. Ethanol burns blue and the flame is not always detectable in normal light. This is one of the challenges of creating ethanol fire pits: how to create an aesthetically pleasing flame. Indeed, the unseen technology behind ethanol burning fire pits is the way that the burning action draws air into the burner to create a yellow flame.
The key advantage to ethanol fireplaces and fire pits is that they burn entirely cleanly – the products of ethanol combustion are carbon dioxide and water. They can be burned indoors without venting and placed pretty much anywhere that can provide for clearance to flammable objects and enough air exchange. This usually means that ethanol fire pits are easier to install and can be moved if desired. It also means that when used for heating, they are 100% efficient, in that all the heat is transferred into the space. Ethanol is often touted as green or ‘eco’ due to its renewable sources and clean burning.
Another advantage is the fact that ethanol fire pits are essentially burning pots of fuel. They are reservoirs that are ignited directly, somewhat akin to high-tech versions of those fondue burners that were so popular in the seventies. This means that there is no gas line to run and that there is really nothing to go wrong with them. The top manufacturers of ethanol fire pit burners produce extremely high quality units that can be expected to last a lifetime.
The disadvantages to using ethanol-fueled fireplaces and fire pits are primarily aesthetic. The burners tend to be small: there is an optimum ‘orifice’ size which is needed to create a desireable flame; also, the fuel is relatively expensive, so too large a burner would be rather costly to operate. This is not to say that larger burners do not exist. Ethanol fire pits must have a relatively large, unobstructed opening. This may or may not be seen as a disadvantage, depending upon the desired look, but it does mean, that whatever the design, this must be accounted for.
Functionally, ethanol fire pits used in outdoor applications, do not fare too well in wind. Unlike their gas counterparts, the fuel of ethanol fire pits is not supplied at pressure so the fire tends to get flattened or blown around wildly by the breeze. Some outdoor fire pit designs incorporate glass shielding to mediate this effect, but again, depending on the desired look, this may be undesirable.
Ethanol fire pits are by nature modern fire pits. Most burner designs are constructed in sleek stainless steel and often have very linear or geometric flame configurations. The designs work extremely well in modern and minimalist applications where the flame is the centre of attention. Manufacturers of ethanol burners have taken on the constraints of the fuel with design vigour, reinventing the fireplace around this contemporary fuel.
Images from www.ecosmarfire.com and www.planikausa.com