EarthTalk, a feature in E Magazine, recently answered a reader query about the benefits of biomass as an energy source. EarthTalk responded with some good info, including:
Biomass is natural material—mostly trees, grasses, forestry waste, and agricultural waste—that can be burned as a source of heat (for warmth and cooking meals) and for generating electricity. In the US, biomass accounts for a little less than 1% of the electricity supply.
Firewood is a classic example of biomass, but biomass is finding more exotic uses too; for instance, as a feedstock for ethanol and biodiesel.
Biomass is a renewable energy source that is carbon-neutral since the CO2 released by burning or otherwise consuming it is recaptured by next year's crop.
All that sounds great, right? Yes, but the EarthTalk piece mentions one potential problem with biomass: To be considered sustainable, biomass cannot be used faster than it grows back. That's a great point. Violating this rule is why so many villages in Africa have an ever-increasing "barren ring" around them, as villagers venture further and further in their unsustainable quest to continue gathering more fuel wood than nature can grow back.
But there are two other big flies in the biomass ointment that the EarthTalk piece overlooks that make the sustainability of biomass at a large scale somewhat dubious.
(1) Soil Health
To do biomass in a truly sustainable manner, one must figure out how much wood, crop residue, or other usable material can be taken away without resulting in long-term degradation of soil quality.
This is related to the "not taking more than can grow back" issue, but it's important in its own right. Taking the entire crop from an area year after year to burn or convert into liquid biofuels leaves no decaying matter to feed the soil organisms that are essential to creating a healthy soil ecosystem. Healthy soil is essential to the long-term productivity of the growing operation. Which brings us to the other major limitation....
(2) Net Energy and External Inputs
Industrial agriculture, which largely ignores true soil health, makes up for that deficiency by adding synthetic fertilizers, which are sourced from fossil fuels and other finite resources. This is the equivalent of a student over-consuming caffeine so he can stay up and cram the night before a big exam or athletes using steroids to enhance performance. There's a notable short-term boost in performance, but in the long run the method is unsustainable (and outright harmful if continued).
As supplies of fossil fuels and other key inputs to industrial agriculture hit their production peaks, those inputs will become increasingly expensive and, ultimately, minimally available. We will then be limited to whatever nutrients can be regained using traditional methods like cover cropping, manure from grazed animals, and waiting for more topsoil to form via weathering and bio-breakdown of rock. Even though such methods produce the healthiest, most sustainable soil, they are comparatively slow—they don't give that quick (but temporary) productivity boost that most modern agriculture operations have become so reliant on.
Without their external inputs, today's biomass operations aren't likely to look so appealing, and they certainly won't scale up to replace any significant percentage of our soon-to-be-declining fossil fuels.
BIOMASS AND SUSTAINABILITY
Is there Such a Thing as Sustainable Biomass?
Soil health is an issue that is routinely ignored in the current rah-rah coverage of ethanol, biodiesel, and biomass. Grinning Planet is in favor of pursuing these energy sources sustainably, but pursuing them in an unsustainable manner merely trades our current bad energy approach for a different bad energy approach, and keeps us on the road to agricultural ruin.
As for net energy—also called "energy returned on energy invested" (EROEI)—it is the key to why none of the wannabe energy solutions are as good as oil from an energy/profit standpoint. Oil is king when it comes to net energy.
Remember that petroleum (as well as coal and natural gas) are essentially concentrated ancient sunlight—things grew and died; collected, heated, and compacted over millions of years; and ultimately became fossil fuels. On such a geological scale, all biofuels, including biomass, are essentially grown and used in real time—with no bank of previously stored inputs providing a "free energy bonus".
NET ENERGY NUMBERS
The energy returned on energy invested for US-sourced petroleum is estimated to be somewhere between 5 and 10. The EROEI for corn-sourced ethanol is less than 2 (and probably closer to 1, when all inputs are correctly accounted for). That sort of shortfall is a big problem as we head into a future of constrained petroleum supplies.
The marginal EROEI of biofuels is why there is no possibility that they can be scaled up to replace any significant portion of petroleum at today's level of energy use. Don't get us wrong—Grinning Planet is no fan of oil. Its reign is coming to a close, and it's imperative that "we leave oil before it leaves us," as Richard Heinberg puts it. But all the happy talk about petroleum alternatives needs to be examined under the cold, hard light of net energy—with the sustainability of each biomass approach verified—to know whether the promises are real or whether biomass is just the latest energy fad and another way for someone somewhere to make a quick buck.
BIOMASS AND SUSTAINABILITY
Grinning Planet Wrap-Up
Whether biomass is burned directly, used to generate electricity, or refined into liquid fuels, it will no doubt have some role in our energy future. But the sustainability limitations on biomass mean we cannot count on it to scale up to help solve our energy problems or our greenhouse gas problems.
Sustainable Ethanol (by Jeffrey Goettemoeller, Adrian Goettemoeller)
Biofuels, Biorefineries, Cellulosic Biomass, Flex-Fuel Vehicles, and Sustainable Farming for Energy Independence
Sustainable Ethanol explores the benefits and limitations of North America's fuel ethanol industry. The book explains how the end of cheap oil is providing an opening for biofuels; how North America can produce significant quantities of biofuels without damaging our food production capacity; how sustainable farming methods are reducing ethanol's reliance on fossil fuels; and how cellulosic ethanol can be made from waste materials and soil-restoring perennial crops.
Biodiesel Basics and Beyond (by William H. Kemp)
A Comprehensive Guide to Production and Use for the Home and Farm
Biodiesel Basics and Beyond aims to separate fact from fiction and to educate potential home, farm, and cooperative manufacturers on the economic production of quality biodiesel from both waste and virgin oil feedstock. The book includes: detailed processes and equipment required to produce biodiesel fuel that meets North American standards; how farmers can use excess oilseed as a feedstock for biodiesel production; the use of the co-byproduct glycerin in the making of soap; a guide to numerous reference materials and a list of supplier data. This is North America's definitive guide to responsibly producing biodiesel from waste vegetable oil while minimizing your environmental footprint in the process.
A Declaration of Energy Independence
How Freedom from Foreign Oil Can Improve National Security, Our Economy, and the Environment (by Jay Hakes)
In response to the oil crises of the 1970s, America developed a bipartisan energy policy that made us safer, greener, and far less dependent on foreign oil. It was so successful that American oil imports fell by 50% and greenhouse gas emissions dropped 9% in just five years. How was this possible, and how can we do it again? A Declaration of Energy Independence, written by one of the country's top energy experts, outlines seven economically and politically viable paths to energy independence.
Peak Everything
Waking Up to the Century of Declines (by Richard Heinberg)
The 20th century saw unprecedented growth in energy availability, food production, and population. The 21st century will be the era of declines—in oil, natural gas, and coal availability; in critical minerals and ores, such as copper and platinum; in fresh water availability and grain harvests; in climate stability; in economic growth; and, ultimately, in global population. To adapt to this profoundly different world, we must begin now to make radical changes to our attitudes, behaviors, and expectations. A combination of wry commentary and sober forecasting on subjects as diverse as farming and industrial design, this book tells how we might make the transition from The Age of Excess to the Era of Modesty with grace and satisfaction, while preserving the best of our collective achievements.