In the 1970s the big thing in vehicles, fuels and the environment was "get the lead out," an effort to remove lead from gasoline. After initial uncertainty and some opposition, the transition to unleaded fuels proved both remarkably easy and effective. I.Q. levels in children in urban America rose in direct response to the reduction in ambient lead levels.

Those really were the good old days in transportation. In addition to the lead phase-out a well-planned and sustained effort to raise average vehicle efficiency standards (the CAFE, or Corporate Average Fuel Economy) increased vehicle mileage standards by a quarter.

Sadly, that effort was not sustained, and vehicle efficiency levels have not changed significantly for over 25 years. These changes illustrate what is possible when achievable yet ambitious targets are codified, enforced, and adjusted as technological, economic, and environmental needs change.

A combination of technological innovation, economic, and environmental necessity is once again altering the vehicle efficiency landscape, and if sustained could significantly alter the energy and environmental footprint of transportation. The new wave of innovation is reminiscent past effort to "get the lead out," only this time the focus is to "get the carbon out" of our transportation fuels and miles traveled.

Perhaps most interesting -- and most hopeful -- about the current wave of innovation: it seems so obvious once formulated. What could be simpler than regulating the carbon intensity of fuels, namely the amount of greenhouse gases per unit of fuel.

Technically, there are all sorts of complications -- the different energy density of different liquid fuels, how electricity should be treated if used to power pure electric or plug-in hybrid vehicles, just for starters -- but conceptually, the low carbon fuel standard is simple and elegant.

There is already a standardized unit of measure for reporting the amount of GHGs released per unit of fuel: the grams of carbon dioxide equivalent per megajoule of fuel delivered to the vehicle (gCO2e/MJ). Despite its bulk, this makes it easy to report the output of greenhouse gases for each different type of fuel input. The numbers will be adjusted, of course, for differences in the in-use energy efficiency of different fuels (e.g., gasoline versus diesel, versus natural gas or hydrogen).

Based on the just-released Low Carbon Fuel Standard prepared by the University of California for the Governor, "regular" gasoline as a value of 85-92 g CO2 eq / MJ, while natural gas has a value of about 80 g CO2 eq / MJ. Electricity in California has an average value of 27 g CO2 eq / MJ (when used to drive an electric vehicle), and cellulosic ethanol derived from municipal solid waste is about 5 g CO2 eq / MJ.

Now we're off to the races: set standards for the average fuel mix for a state, or nation, and then regulate the value down over time, much like the standards in the Clean Air Act. Starting with the gasoline value, 85-92 g CO2 eq / MJ, California is setting -- initially -- a 2020 target of a 10 percent improvement, ideally with a series of future improvements planned. Governor Schwarzenegger signed Executive Order S 7-01, establishing the LCFS, in January of 2007.

And already this year, our Congress has jumped on the bandwagon in a big way: Senators Bernie Sanders (I-VT) and Barbara Boxer (D-CA) have introduced legislation incorporating a Low Carbon Fuel Standard (S.309). In February, Senator John McCain (R-AZ) endorsed a national LCFS. In March, Senators Susan Collins (R-ME), Dianne Feinstein (D-CA) and Olympia Snowe (R-ME) introduced legislation to enact a National Low Carbon Fuel Standard (S. 1073).

Then in May, Senators Boxer, Collins and Joe Lieberman (I-CT) introduced legislation incorporating a Low Carbon Fuel Standard (S. 1297). On the House side Rep. Jay Inslee (D-WA) introduced a Federal Low Carbon Fuels Act (H.R. 2215). And in May Senators Barack Obama (D-IL) and Tom Harkin (D-IA) introduced legislation to enact a National Low Carbon Fuel Standard (S. 1324).

Internationally, the European Commission proposed a European LCFS in January 2007, while British Columbia is set to announce their version at the end of the month.

The value of the LCFS is that is a simple, quantitative metric and milestone that can be used to chart progress and push an ongoing process of innovation, review, monitoring, and reapplication to move fuels to a lower and lower carbon standard.

I am very pleased to be at the Lawrence Berkeley National Laboratory and the University of California at Berkeley, the source of so many critical scientific innovations, to chair this meeting on the state, national, and international opportunities for climate protection that derive from a Low Carbon Fuel Standard.

What was needed to initiate this process? Certainly a clear methodology was required, and while several efforts have been made, I'm very pleased to have been involved in one effort that built on some exceptionally good prior work, and which delivered a clear message that using life-cycle techniques, comparisons across different fuels -- both fossil- and bio-fuels -- made a great deal of sense.

Our analysis of ethanol showed, for example, that not all biofuels are created equal. While ethanol, for example derived from corn but distilled in a facility powered by coal was, in fact, on average worse, than gasoline, some of the envisioned cellulosic-based biofuels could be dramatically better on a g CO2 eq / MJ basis. The model we developed, the ERG Biofuel Meta-Analysis Model, EBAMM, is openly available online at a website that is hosted by my laboratory, http://rael.berkeley.edu/ebamm.

What the LCSF does is to redirect our policies to what we want: lower carbon embedded in our transportation system. What we do not want to do is to "lock in" on pet programs or technologies. A LCFS is just that, a means to spur innovation and set standards based on carbon, greenhouse gases, and its role in global warming. What we do want is energy, and clean energy. California has been a leader in conducting world-leading, transparent, analysis of climate and energy issues.

A fascinating parallel exists to what is taking place on the stationary power side.

Today at least 23 states have adopted minimum clean energy standards for electricity, termed Renewable Energy Portfolio Standards. In California, for example (SB 1078) sets a minimum clean energy requirement in our power mix. California has one of the most aggressive RPS standards in the nation, but a number of states, both 'red' and 'blue' are pursuing important and innovative RPS policies. Just as with the LCFS, the goal of RPS policies is to ratchet the average carbon content -- unit of fuel or per kilowatt hour -- down over time.

A LCFS does one other remarkable thing -- it allows added competitors into the transportation fuel sector. Liquid fuel providers -- producing and selling diesel fuel, gasoline, or biofuels -- and electricity providers -- "fueling" plug-in hybrid vehicles with electricity generated with renewable energy -- can now compete for the transportation dollar. Competition and market forces are tremendously useful, and can lead to both added innovation and lower costs.

Where is all this headed?

Towards a steady evolution to cleaner and cleaner fuels on a carbon (greenhouse gas) basis, for starters. There is no reason to stop at carbon, of course. There are other issues with fuels that we can both measure and need to improve.

For biofuels, for example, impacts range from water use to erosion to potential trade-offs with food production, particularly if a global biofuel industry and trade emerges. A natural next step is to evolve from a low-carbon fuel standard to a sustainable fuel standard. With the Low Carbon Fuel Standard barely off the ground, work has already begun on what might go into sustainable fuel standards. That is the value of such a clear measure: the next steps are presenting themselves.

Daniel M. Kammen is the Class of 1935 Distinguished Professor of Energy at the University of California, Berkeley. He co-directs the Berkeley Institute of the Environment and is founding director of the Renewable and Appropriate Energy Laboratory. He has appointments in the Energy and Resources Group and the Goldman School of Public Policy.