Tag Archives: energy

Updated Renewables & Burnables Venn diagram

In a post last year entitled “Reframing ‘renewable energy’ & ‘bioenergy’” I introduced several diagrams, including a simple Venn depiction of how various forms of bioenergy are found in the overlap of “renewables” and what is burned or combusted to release energy. I’ve made a few minor changes to that diagram (detailed at the end of this post), and present the updated version below.

Why this Venn?

As I contended in my post last year, “renewable energy” is a problematic concept in that it is kind of a catch-all for several forms of non-fossil fuels, and definitions of it vary. A particular problem is the common opposition of “renewable” and “fossil,” which obscures the “double life” of bioenergy sources (both “renewable” in most definitions, and burned or combusted like fossil fuels but unlike other renewables, dubbed here “clean energy”).

The two operant categories at this level of analysis would then be “renewable” and “burnable/combustible” (the latter recognizing that some bioenergy forms like wood are burned with minimal processing, while others such as biofuels are processed for combustion). These are simply and appropriately representable in a Venn diagram.

Ideally this diagram, or a more professional image conveying the same information, can help encourage more clarity in reports on or discussions of energy sources. In particular, it is important to move beyond the simple opposition between “renewable” and “fossil,” and to be more specific at all times about the kind(s) of renewable energy being referred to.

Deeper analysis

In my post last year I explored other ways of categorizing energy sources, including without use of the “renewable” or “combustible/burnable” categories. One of several aspects I hope to return to is the inclusion of another relatively minor subcategory of forms of bioenergy that are not burned.

An academic article published by Atte Harjanne and Janne M. Korhonen in Energy Policy this past April – “Abandoning the concept of renewable energy” – looks at how “renewable” is used and potentially misused, and suggests that an alternative framework for categorizing forms of energy could inform better policy. I hope to return to this as well.

This space is complex, contested, and vitally important for understanding and dealing with the energy and environmental challenges ahead. 


The original Venn diagram had “Pure renewables” as the heading above geothermal, solar, etc., which I changed to “Clean energy” pursuant to a discussion on Twitter with some nuclear energy proponents.

I added the header “Bioenergy” to the brown overlap, to make clear that this represents a group separate from “Clean energy.”

Also in the interests of clarity, I underlined the titles of the two circles, “Renewable” and “Combustible / Burnable” in colors corresponding to the circles they represent.

Finally, I added “peat” to the list of fossil fuels, but in parentheses. From what I read, categorization of peat in this regard is not clear.


Earth Day 2017: Let’s stop industrial-scale burning of wood for energy

EarthDay2017This year’s Earth Day (22 April 2017) has as its theme “Environmental & Climate Literacy.” In that spirit, I’d like to suggest that environmental and climate literacy require attention to the impact of industrial scale burning of forests, and the question of whether it makes sense as an investment in reducing carbon emissions.

Yesterday there were articles in the press celebrating Britain’s first full day of energy without burning coal since 1882. You have to dig in some articles (not all) to find out that they’re still doing a lot of burning to produce energy, including of imported pelletized wood, which comes mainly from a combination of waste wood (which is limited in quantity) and cutting forests in the southeast United States.

The rationale for cutting, processing, transporting, and burning massive amounts of wood to generate electricity is that it is “carbon neutral.” That is, the carbon released in burning the wood can be accounted as part of a cycle with growing trees (which captures carbon, as part of the natural plant growth process).

But is burning wood on this scale really carbon neutral? And are other externalities, such as environmental impact at points of harvest, adequately taken into account? Should industrialized countries, which otherwise have been pretty good about managing forests – and have been preaching to developing nations about forest conservation and management – be exploiting its forest resources as “nature’s powerhouse” (in the terms of FAO‘s unfortunate slogan for International Day of Forests last month)?

In a recent article entitled “Can We Have Our Forests and Burn Them Too?,” former CIFOR director-general Frances Seymour questions the rush to use wood for power generation based on the current approach to carbon accounting. and points out that the carbon cycle for trees is a very long one. A study by Chatham House, “The Impacts of the Demand for Woody Biomass for Power and Heat on Climate and Forests,” analyzes the accounting issues in more detail, concluding among other things, that “a proportion of the emissions from biomass may never be accounted for.” Similar issues are summarized in a paper on the Friends of the Earth-UK site entitled “Burning Wood for Power Generation The Key Issues Explained.”

The push to burn wood to generate energy, in short, is policy-driven (the science of the matter being read in a way favorable to certain outcomes), and may actually be worse in total impact than cleaner fossil fuels.

Big plants, big impact, small energy?

Among the big biomass/wood burning energy plants in Britain are Drax and Steven’s Croft. (BiofuelWatch has a map of all plants). Taken together, they seem to be having a big impact on forests and the “biomass market” (see for instance this EU press release about the potential impact of Drax), but surprisingly not accounting for that big a proportion of Britain’s overall energy – only 6.7% on the coal-free day, according to the UK Electricity National Control Centre (thanks to Steve Patterson for the pointer):

And the conversion of facilities from coal-burning to wood-burning was expensive (again regarding Drax, see this critical opinion piece). Might it not have made more sense to convert to gas and/or invest in other non-burning renewables?

“Transgenic” forests in the future?

As bad as the pelletizing of forests for electricity generation is today, it could get worse. Research on genetically engineered trees aims to enhance growth and change wood characteristics, with one of the main aims being production for energy (pellets but also biofuel). The continued use of wood to generate power on an industrial scale will generate funds and interest in further developing and planting these organisms, unfortunately probably without regard to impacts on the environment.  (Two older pieces give some perspectives – in The Guardian, 2012, and Earth Island via Salon, 2013.)

Missing the “sweet spot” for wood energy

I have some small experience with wood energy, and my perspective on the larger issues comes in part from two sources. The first began with work on forestry projects in Mali and Guinea which had as part of their purpose, helping rural people grow trees for firewood to use in cooking, rather than cutting natural growth. I’ve maintained an interest and awareness of the problems involved in this source of energy, and various programs and proposals to ameliorate environmental, health, and other problems associated with it. The second is installing and using a fireplace insert in our home, which uses purchased local firewood (coming from cleared and fallen trees in the region), as well as smaller branches and in a couple of instances fallen trees near our residence.

Five key concepts are involved here (I discussed four of these – not transfer – in more detail in the post, “Biofuels reconsidered“):

  1. local;
  2. small scale;
  3. minimal processing;
  4. more direct transfer of heat energy; and
  5. use of waste – that is wood that would otherwise go into a landfill, I am told.

When you get these five together, that’s what I’d consider the “sweet spot” for wood energy, the optimal position for energy efficiency and environmentally sustainable wood use. Sometimes it is hard to stay in that spot, or next to impossible, such as in communities in West Africa I have known – so small scale plantations, and medium-distance transport of wood becomes necessary. Or in the US, the market drives producing wood for fireplaces and firepits (those small mesh-packaged batches of split wood for sale outside supermarkets).

On the scale of, say, Drax and its suppliers, however, they’re off on all counts, pretty much by design: long distance between supply and use; very large scale; medium processing (not as bad as wood to liquid biofuel); indirect transfer (the heat released from burning only indirectly produces electricity, so there is energy loss); and due to the scale of demand, live trees are harvested and plantations made, with all kinds of externalities. Industrial scale burning of wood for energy in advanced economies, in other words, misses all the five criteria for optimal energy efficiency and environmental sustainability. So, if the “carbon neutrality” of this practice is also contested, why are we doing this?

Decoupling forests and energy

Which brings me back to the FAO’s disheartening – from the point of a former (re)forester and lifelong environmentalist – slogan for International Day of Forests (IDoF) on March 21: “The forest: nature’s powerhouse.” Their effort to link the small-scale household use of firewood (which for many is a simple necessity, not a preference) with industrial scale power generation from pelletized forests was misguided, in my opinion (and I believe that of many others). Their attempt to point to a long-term role of forests in energy generation and need for policy support to that end seems shortsighted. Do we really expect to devote a significant percentage of our dwindling forest lands to inefficient energy generation? (I annotated their infographic, which is included at the end of this post.)

Wood energy is a reality for many today, but it is not a vision for long-term development. It is time to plan for the gradual split between energy – the technology for which is “ephemeralizing” away from burning and combustion – and forests – which have critically important climatic roles in addition to supplying wood and other forest products for our use.

Of course, we will always like to sit by a wood fire on a cold night or at a campsite, or to grill over charcoal, but that kind of use should be as close to the “sweet spot” of optimization as possible.

Ms. Seymour in her article cited above had a memorable summation of the arguments she made (it’s not a long read, and highly recommended): “Whether temperate or tropical, we can’t have our forests and burn them too.” Hopefully FAO and other major agencies and organizations concerned with the future of forests and/or energy will take that assessment to heart.

Comments on FAO infographic “Forests and Energy” from IDoF 2017.

Biofuels reconsidered

CPL Press, Biochemical routes to liquid biofuelsBiofuels – fuel derived from organic matter – are generally considered to be more environmentally friendly than fossil fuels in that they are renewable and, in theory at least, “carbon neutral.” However there are downsides to biofuel, such as the energy and resources to produce them, and in the case of fuel produced from food and oil crops, potential impacts on food markets. The picture is more complex.

Are some biofuels more environmentally friendly and beneficial to the socio-economy than others? What is the place of biofuels in the overall energy equation of the future? Without going into a long discussion, here are a few proposed maxims that may be useful in considering such questions. These are derived from some discussions a few years back and intended as relative measures rather than absolute binary choices:

  1. Gathered is better than purpose grown. For example deadwood chopped into firewood is less costly to produce (land, water, inputs, energy) than crops grown for biofuel. Waste matter is a potential energy source that could be “gathered” for that purpose, although requiring processing. Jatropha seeds collected from hedgerows costs little in land compared to a plantation of jatropha created for seed production. Production of algae for conversion to biofuels requires infrastructure and much water. One problem with gathering biomass suitable for energy from nature or human activity is that it tends to be diffuse and limited (with the possible exception of human waste products). For example wood waste as a byproduct from logging and sawmills is a source of energy but the volume produced (which can be collected) is a function of other activities and not one easily increased.
  2. Less processing is generally better. Processing does have the advantage of yielding a more concentrated and often more portable energy source, but it has energy costs and externalities. A simple example is turning firewood into charcoal, which involves burning off the volatile constituents (energy generally wasted) but yielding a lighter and more concentrated energy source. Towards the other extreme, fuel ethanol production from corn (maize) is a multi-step process. The energy balance (output from a given input) of such processes is a matter of some controversy, but probably all would agree that if it were possible to produce a given unit of biofuel with less steps and inputs, the outcome would be more positive.
  3. Less distance is generally better. Getting firewood locally (as we do in our home for a fireplace insert) involves less cost, and in theory at least, more potential for responsible management, than shipping firewood around the world. Of course no one proposes import-export of firewood, but other diverse biomass is exported for production of biofuels. One example is palm oil from Southeast Asia to make biodiesel in Europe. A big part of this is transportation, which of course is part of the fossil fuel market too, but with less flexibility in the case of biofuels (one can find petroleum sources in various locations, but some types of biomass inputs like palm oil are very region-specific and possibly not substitutable).
  4. Small is beautiful. Smaller scale production of biofuels has less of an impact on the environment and economy than larger scale operations. A big issue is use of finite land and water resources. Some years back I worked on a project in Mali which had as a major goal promotion of planting woodlots with villages which could then, so the thinking went, harvest wood from those lots for their their cooking needs. Small and local, this might seem to make sense, but in fact it meant taking land out of agricultural rotation for an uncertain future outcome. An even smaller and apparently more successful approach in another region of the same country a few years later was planting of jatropha in lines along roads and field boundaries – no lot required. Contrast with large plantations of annual biofuel crops which can have enormous impact in an area to serve needs far away (impacts being potentially both positive and negative, but with clear opportunity costs for types of land use and agriculture).

Another perspective on biofuels is worth adding to the mix here. Generally biofuels are considered along with technologies such as solar, wind, and wave energy as cleaner alternatives to fossil fuels. However biofuels work on the same paradigm as fossil fuels – burning something to release energy (with byproducts such as carbon dioxide). It can be argued therefore that biofuels are actually more like fossil fuels except for the premise that they are carbon neutral, and the fact that diverse biomass sources for biofuel production are arguably less substitutable than say crude petroleum from diverse locations.

Again the picture is complex, and all this is not to say that biofuels as a whole are bad. Rather there may be some types of biofuel and approaches to incorporating them into the larger energy equation that make more sense than others. Conversion of waste into fuel would be elegant – turning a problem into a resource. On the other hand, devoting land and water to growing crops or other biomass specifically to process and ultimately burn doesn’t seem sustainable in a world faced with a growing population and impending climate changes.

Longer term, the energy market will certainly follow Buckminster Fuller‘s observation about the “ephemeralization” of technology, which we see the beginnings of already with advances in utilizing solar and wind power. Eventually the burning of substances for energy will become marginal in the global energy equation.Facebooktwitterredditpinterestlinkedintumblrmail