Biomass briquettes, and wood pellets, fit this bill admirably.
But surely burning logs is eco-friendly?
Because logs come from a renewable resource we tend to think of them as the ultimate green fuel...but this isn't always the case.
First of all, to be an efficient and cost-effective fuel, logs need to be low in moisture content and as dense in structure as possible. Because of the rush to buy woodstoves and boilers, in the UK it is becoming increasingly difficult to find firewood that is truly dry. Tarring up of the flue and window glass that doesn't stay clear are signs that your logs are too wet.
Secondly, although burning wood from sustainably managed trees reduces our net CO2 production compared with using fossil fuels such as oil and coal, there is a lot of misunderstanding about what ecological sustainability actually involves.
We hear the expression 'sustainable forestry' a lot these days and it's based on the theory that if you plant a new tree for every old one you cut down, you can carry on using wood forever without damaging the planet. In actual fact, though, in terms of the species felled, you need to replace like with like, so forestry isn't by any means automatically sustainable. Also, it's calculated that we'd need to plant at least 5 new trees for every one felled to be even keeping up with the status quo.
Deciduous (hardwood) logs come mostly from trees that have taken a long time to grow and so have become part of a complex and surprisingly extensive eco-system, comprising many invertebrates, plants, fungi and mammals. These ecosystems have been shown to be delicately balanced and although they may eventually re-establish themselves, especially when sensitive re-planting takes place, the felling of a deciduous wood for firewood can mean that many local species die out completely due to loss of habitat.
A newly-planted tree, therefore, has considerably reduced ecological value than an old-gowth (mature) tree that may be hundreds of years old. You could plant hundreds of saplings and they wouldn't replace, ecologically, even a dozen ancient trees of the same species.
In Scotland we have a very large resource of softwoods, with a lot of non-native Sitka Spruce, Japanese Larch and Norway spruce. These have very little ecological value. Most of us will have tried to battle our way through those dark, dry, sterile lower stories, falling into the furrows and getting crispy little branches stuck in our hair, and can testify that there's not much wildlife in there.
Using these softwoods for firewood logs (instead of hardwoods) is certainly possible but they require a lot of drying time. We used to take spruce thinnings out of our wood and store the cut logs for two years before buring them in the woodstove. Any sooner and they just didn't have the same burning and heating value.
Whilst logging can lay waste to large areas of land that may take a very long time to regenerate, when it's softwoods that you're felling, then whatever comes in its wake is likely to be an improvement ecologically. These days the Forestry Commission and large forestry companies often replant, after harvesting sitka, with hardwoods or mixed species and there is far greater environmental awareness regarding forest edge design and species selection for sustainablilty.
But that can take a long time...and the UK is substantially lacking in forest cover compared to many other countries in the world.
And the sobering truth is that, in order to source sufficient truly dry firewood logs to supply the Wood Fuel Co-operative members at a competitive price, we would have needed to import it from Eastern Europe! Insane but true!
So, rather than do that, or fell more of our precious UK woodlands for fuel, if we can make use of waste timber and paper products that have already been taken out of the ecosystem, and get a greater calorific (heating) value out of them, and pay less money for more heating, and have fewer handling, storage and mess problems, then these biomass briquettes really make sense!