Global Warming Technology - General Biomass

General Biomass and Global Warming

General Biomass Company was founded in 1998 to do something about global warming. Since our founding, the General Biomass web site has carried information on global warming as a public service. This will now be focused on potential technology solutions and public policy. General Biomass needs and welcomes support from investors, partners and applicants to develop our own ability to contribute to solutions. Our area of expertise is cellulosic technology to make glucose and xylose from biomass. Glucose from cellulose and xylose from hemicellulose are the core feedstocks for biofuels, whether ethanol, butanol or designer biofuels. Inquiries about the company should be directed to dgibbs@generalbiomass.com.

Green plants are the only feasible way to remove carbon dioxide from the atmosphere at ambient concentrations (now 382ppm). Plants use solar energy to fix atmospheric carbon into sugars, which can then be made into ethanol, chemicals, and plastics, partially replacing the use of fossil oil and natural gas. Apart from this fossil fuel sparing effect, some biomass crops and processes can sequester CO2, potentially giving carbon negative solutions (decreasing atmospheric CO2). In the United States, it is feasible to replace 25% of the gasoline supply with cellulosic ethanol.

Overview of Global Warming Technology

The scale of technology development and deployment needed to slow global warming appreciably, let alone stabilize atmospheric CO2 at an acceptable level, is truly immense. Potential technologies therefore need to be evaluated on scalability, effectiveness, timing, and cost.

These are defined as follows:
scalability - How much do we need? How much could we do?
effectiveness - What is the net carbon balance? Is this technology worth developing as a solution to global warming?
timing - How soon can we get it?
cost - How much will a ton of carbon reduction cost using this technology? Is the technology cheap enough to become widely available?

Let's start with scale. An approximation of the total amount of carbon-free power needed to cap atmospheric CO2 at double the preindustrial amount can be estimated using an equation called the Kaya identity. This equation has four factors: global population size, per capita GDP, primary energy intensity and carbon intensity. These are multiplied by one another, so the total CO2 reduction needed depends heavily on economic development (hence energy demand) as well as the amounts and types of fuels needed.

This analysis has been done by Dr. Martin Hoffert and colleagues in Energy implications of future stabilization of atmospheric CO2 content, Nature 395: 881-884, 1998. Their conclusion is that tens of terawatts (1 TW = 1 trillion watts) of carbon-emission-free primary power will be required by 2050 to stabilize atmospheric carbon dioxide content at double the preindustrial level. For comparison, the power provided by all combined energy sources today is 10 TW. A massive technical and commercial effort will be required to meet this challenge. Recent evidence suggests that a doubling of CO2 to 750ppm is far too high if we wish to avoid dangerous effects of climate change, and that a more ambitious, lower cap of 450ppm needs to be implemented within a decade. Current investment and government support should be judged in this context, and both are grossly inadequate to achieve these goals.

Effectiveness is a measure of the actual carbon reduction potential of a given technology implementation. This reduction potential can be estimated by an evolving discipline known as Life Cycle Analysis (LCA). LCA has been used by numerous groups to evaluate the net energy balance and carbon balance of ethanol from corn and cellulosic biomass. The two best examples of this analysis are
(1) from Kammen's lab at Berkeley - Farrell et al. (2006) Ethanol Can Contribute to Energy and Environmental Goals
(2) from Michael Wang (2005) at Argonne National Lab in Chicago . An Update of Energy and Greenhouse Emissions Impacts of Fuel Ethanol.
These two references compare a number of studies, and make the point that boundary conditions matter: e.g., do we count just the tractor fuel, or also the energy to make the tractor? Have we considered all the useful outputs? What value do we assign to fossil carbon displacement, which is distinct from gross energy balance?

LCA has been applied repeatedly to ethanol, with the conclusion that cellulosic ethanol offers substantial greenhouse gas benefits compared to gasoline. Going forward, we need to apply the same standards to other proposed alternatives. What is the energy and carbon balance of hydrogen made from grid electricity or natural gas? How many years of operation does it take for a nuclear power plant to pay back the fossil energy used to construct it and create the fuel?

Timing is important because CO2 from burning fossil fuels persists in the atmosphere for hundreds of years. Additionally, CO2 directly reduces the effectiveness of CO2 absorption in the oceans due to acidification. There are numerous positive feedback effects (warming itself causes more warming) in the Earth's climate system, among them the potential release of stored biological carbon from frozen tundra areas (methane from peat bogs in Siberia), and a loss of albedo (reflectivity) as white ice areas are replaced by darker land and ocean. Human carbon emissions create a net injection of carbon roughly on the order of 10 units per year, while the natural land and sea carbon fluxes are on the order of about 100 units per year each. These large natural fluxes are completely beyond the control of humans, hence our only leverage with the climate system is the relatively small amount of fossil carbon we emit by burning or not burning fossil fuels like coal, oil and natural gas. This fossil fuel contribution needs to be reduced rapidly, and it is an open question whether the necessary technologies can developed and deployed rapidly enough.

Cellulosic ethanol is promising because it builds on the existing infrastructure in place because of corn ethanol. In 2006, the U.S. produced about 5 billion gal of ethanol from corn and had 6 million E85-capable flex-fuel vehicles (FFVs) on the road. All U.S. autos can use E10 without modification. Corn ethanol is approaching its limits within a few years, but the infrastructure can be supplied by cellulosic ethanol as that technology develops. Brazil has built a large infrastructure around sugarcane (sucrose) ethanol, and there are many ethanol opportunities in Asia, Latin America and Europe. Cellulosic ethanol can be made from waste paper, which is 40% of municipal solid waste, so urban centers can make cellulosic ethanol from their own resources.

Cost matters because technology deployment on a large scale requires commercial enterprises funded by revenues. There is a great need at present for public funds to support R&D in all these areas, and to subsidize early commercialization. In the longer term, technologies must be embodied in profitable businesses to achieve the scale and longevity necessary. This needs to be an international effort, since the knowledge base, markets and people reside in many countries. Oil-consuming nations will get additional benefits through job creation and the reduction or elimination of wealth transfer for oil imports.

Stabilization Wedges

One way to begin looking at the overall solution is the stabilization wedge model proposed by Pacala and Socolow (2004 - Stablization Wedges: Solving the Climate Problem for the Next 50 Years with Current Technologies, Science 305:968-972). They plot a business-as-usual (BAU) trajectory for fossil carbon emissions through the year 2060 vs a stabilized trajectory at about 500ppm CO2. They divide the roughly triangle-shaped difference between the two curves into 7 wedges, or stabilization triangles. Each wedge can in theory be filled by a different technology at some large quantity, and they suggest 15 alternatives, including biofuels, wind, power plant CO2 capture, and increased vehicle fuel economy. This is an interesting first approximation, and serious consideration of any of the 15 alternatives highlights the magnitude of the task. The criteria given above may be helpful in evaluating these alternatives.

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