Lies your mother told you

I recall as a child, many lies my mother told me.

"Your face will freeze like that" (When I screwed it up and went cross-eyed)
"You have to wait 1 hour after dinner before going swimming or you'll get the bends"
"Cod Liver oil is GOOD for you"

The list is almost endless.

In the renewable energy world, there are a number of lies that promoters are now telling you, that are just as false.

LIE NUMBER 1:

"Wood pellets have an energy value of 4,800 kWh per tonne and can be purchased for £190.00 a tonne or 4.0p per kWh."

This is one of those partial truths. In fact - wood pellets DO have a 4.8 MWh per tonne energy value. HOWEVER - this has little to nothing to do with what the energy ultimately COSTS you.

VARIABLE #1 - Moisture Content.

Water has no energy value at all, in fact, the water in pellets needs to be boiled off, before any energy can be created. So - with 10% Moisture - you have 90% fuel / 10% water. That takes the 4.8 MWh down to 4.32 MWh per tonne

VARIABLE #2 - Boiler Efficiency.

No current Biomass boiler operates at 100% efficiency (although - we're working with our partners to develop a condensing system that will come VERY close to that number.) Most are in the 85 to 90% range. Of course - this further reduces the net energy to 3.888 MWh per tonne

VARIABLE #3 - Storage Losses.

Most Biomass Systems use large Buffer / Accumulator tanks. These tanks are heated to a specific temperature, and then the heat is drawn off until the lower set temperature is reached. The boiler then heats the water up again. Of course - if there is no immediate heat demand - the Buffer tank cools down - and heats up the boiler room only. It's rather reminiscent of the way my good wife operates a kettle. If she wants a cup of tea - she fills the kettle right to the brim; boils the water, pours out 1 cup, then REFILLS the kettle! She then boils it AGAIN - so it's "hot for the next cup".

So - figure in at least another 5% for storage losses. This makes the net derived energy 3.694 MWh

VARIABLE #4 - System (Parasitic) losses.

This is the heat that is lost in the pipework that gets the energy to your flat / house / apartment / etc. If the boiler room is located within your building - then this is minimal, as the pipes act as "linear radiators", and contribute to the warmth of the house. (Not such a good thing in summer though.) If however - the boiler is remotely located, or you live on the 14th floor - there are significant losses.

So - the NET EFFECTIVE derived energy is nowhere near what the promoters claim. In fact - it would be usual, to have circa 3.6 MWh, which is only 75% of the original energy.

As a consequence - the cost per kWh is NOT 4.0p, but much closer to 5.3p.
Now - this is STILL better than Gas, Oil, Electric or propane.

Until the industry starts publishing REAL numbers - the general public will continue to be mislead.

LIE NUMBER 2:

Biomass boilers these days are "Set it and Forget it". HOGWASH!
There are few pieces of equipment that require more care, attention and "babysitting" than a well designed Biomass Boiler System. We monitors ours on a 24/7 basis, and attend them at LEAST once a month. (And every fortnight for Larger systems).

The Industry had perpetuated this myth far too long, and it is the root cause of the poor (even Terrible) reputation that Biomass Systems have. If your Boiler system doesn't come with a service plan attached - then I would strongly suggest that you consider another supplier. Even the most sophisticated systems will need a lot of tender loving care to provide the "Warmth without Worry".

I'm off to empty a few ash bins . . . . .

RW