Understanding Wood Pellet Boilers – A simple guide

April 30, 2008

What are wood pellets?

Wood pellets are small pellets of compressed saw dust. Simply put saw dust is a by product of other more lucrative wood processing. This saw dust is dried to a specified moisture content, and compressed by a very high pressure machine. Generally no glue or binding agent is required other than the sap from the timber itself.

The benefits of wood pellets are

  • Its easy to transport
  • It is clean
  • It complies to standards. Things which have standard sizes, shaped and moisture content can easily be designed for

So these pellets, how do they get to the boiler?

No, a shovel is not required. The pellets are blown from a delivery truck up to 20m to a storage unit. In the past there has been a lot of hassle with dust, but this was largely down to the use of agricultural feed trucks being used to deliver the pellets. As dust is not really an issue for agriculture, they did not have dust minimisation technology, and it was a mess. If you use one of the large suppliers these days, there is little problem.

So the pellets are in the storage unit… what now? Well the next stage is getting it to the boiler. The simplest solution here is to use a screw system. These systems turn very slowly and draw the pellets from the storage unit to the boiler.

Understanding Wood Pellet Boilers

And.. Combustion

Combustion… Explain?

Wood pellet boilers are fed into the “burner” where they are burned. The burner in all boilers does much the same job. It’s a place where the fuel is mixed with air to provide the optimal conditions for combustion, and lit. Before you know it the combustion gases are travelling through the heat exchanger where it heats up the water.

Understanding Wood Pellet Boilers

Understanding Wood Pellet Boilers

Heat exchanger

The flame from the burner, and the resultant combustion gases escape into the boiler, transferring their heat to the water circulating through the heat exchanger within the boiler. The heat is then distributed the house using a wet system. In most cases water flows through the heat exchanger in the boiler, absorbing heat from the flam and the combustion gases. This hot water is then circulated around the house to radiators, underfloor heaters and hot water cylinders.

For more infor See  my boilers post

Thanks to





for the pix!

Free wheeling in your car

April 28, 2008

I’m a fan of getting that extra mile out of a tank of petrol (well diesel… but ya know), and as such have been known to allow my car to freewheel up to lights… I mean come on… surely freewheeling (despite the illegalness) has to be the most efficient… right?

Well it turns out… NO…

If you take the car out of gear, the engine needs a little fuel so it doesn’t conk out. If you leave it in fuel the idea is that the engine is kept going by the inertia, and so doesn’t need fuel.

So its like this, if you are going to free wheel for a very long way… then it will make sense. If it’s a shorter distance like up to the lights, then leave the car in gear. The engine will actually take energy out of the wheels to keep going, and so use less fuel. It will also slow the car a bit, and so you’ll need less breaks… do the savings ever end?

Grants for Insulation

April 25, 2008

The post your looking for is here

Today Eamon Ryan announced the launch of the long awaited home insulation grants scheme. Only a pilot at the moment (North Tipp, Clare, Limerick and Dundalk), it should be launched nationally in 2009. The max grant is €2,500. The pilot bit is a bit of disappointment, but probably sensible as it will allow a supply chain to get into shape. Technologies which can be included are attic insulation, interior or exterior wall insulation, low emissions double-glazing, heating control or a range of other energy efficient works. Regular readers of this blog are aware that I belly on about insulation a lot, and I really encourage everyone to take part in this scheme. If you’re unlucky enough to not live in Clare, get ready for the National launch.

Fair play to Eamo for this one, looking forward to seeing the nods of approval his way from quarters that are generally critical of him!

Earth Day – Colbert’s Response

April 23, 2008

Yesterday was Earthday. That means a day to celebrate earth… yes?

Thanks to Colbert

Static Electricity… the future?

April 21, 2008

Options for Domestic Electricity Generation

April 18, 2008

Wednesday saw an announcement by Eamon Ryan that they are working on allowing houses in Ireland to export Electricity (not here yet… but working on it). This has been resisted by the ESB forever, and for not crazy reasons… but anyway… here a quick one on options for generating electricity in your home.

Domestic Wind Power: Wind power is a good option for Ireland. Payback (time when savings pay back the cost) is in the region of 10 years or so, which isn’t really great… considering they don’t last forever… Issues with them are safety of installation. So them actually falling down… And the electrical side… them killing you or an electrician…

Solar Photovoltaic: PV is the great white hope of electricity generation. They convert light from the sun to electricity… and if the sun stops shinning… we’ve got bigger problems… Payback in Ireland is worse than Wind… more like 20 years, but otherwise… they are just so great!!!

Hydro power: Water from rivers. These are great, but you need the perfect fall of water, and at moment damning any river is sooo against the rules, that it is unlikely that anyone will manage make use of them.

Micro CHP: Combined Heat and Power Units are pieces of equipment that combine an electrical generator and a boiler. They are really efficient and good and stuff, but the problem is that you need to require heating and electricity at the same time. People generally need heating and hot water in the morning, before they get up, so the only way they will work here is thanks to the new announcement by Eamo . As for payback, well we’ll see. SEI have a trial going on at the moment.

And that’s it… nothing better than a 10 year payback. Even Tony will agree that the heating systems beat the socks off them. So my advice.. go for a wood chip boiler…

Or insulation…. Always insulation….

Attitudes Towards Energy Efficiency

April 10, 2008

The majority of the work I do relates to renewable energy’s less attractive, more financially sensitive brother, energy efficiency. Attitudes towards Energy Efficiency is an interesting topic (well I think). Energy Efficiency is about achieving goals, using less energy… Simple as that. So the ways that can be done is

  • Equipment that uses less energy (a technical solution)CFL bulbs, putting in insulation etc
  • Using Equipment for less time (a control solution)Sensors and timers
  • Reducing the quality of service required from equipment to a more appropriate level (an engineering solution) – Turning down the heating

Now the way people see these things is quite different, but truth is, the type of efficiency that dominates peoples views… is the last one. And people associate a reduction in the quality of service they get… with being poor. People associate having their houses really warm, really well lit, driving big cars, having double size fridges… all that… with affluence. And people like to project affluence.

So… that’s why I’m particularly interested in a proposal I heard the other day. At the moment Irish Cars registrations plates are of the format 07 CE 2344. The 07 refers to the year of the car. CE refers to the county of registration, and the other number… well that’s just a number. Now its been pointed out to me in the past that having the year on the registration encourages people to buy new cars… to show off like… everyone wants to show off their new car. So, this proposal is to change the year number with an energy rating. The idea is that people will want to show off how energy efficient their car is…


Energy Efficiency is at a disadvantage, people think that doing it… makes you look uncool/poor/less attractive to women/men… so using something like this, which makes gas guzzlers wear a dunce hat… is a good idea

Energy Efficiency is a great idea on the merits of the energy/money/CO2 saved, and shouldn’t need to use psychological crap like this.

This is a similar plan what Toyota did with the Prius… It looks different from other cars so green people can show off how green they are.

We could also discuss how Energy Efficiency, encouraging people to consume less… is not the Capitalist/American way…. And so cannot/should not succeed. This is also an interesting discussion (well… again… to me)

So… opinions???