Saturday, June 27, 2009

Can the US lower carbon emissions by 17% by 2020?

The House of Representatives narrowly passed a bill to drive the US economy toward a less carbon intensive future. President Obama is pushing the Senate to likewise pass this bill that he would like to sign into law soon. The bill intends to cut US carbon emission by 17% in 2020 compared with a base year of 2005. The part of the bill that may actually accomplish its intended target is the part that steers Americans toward smaller and lighter personal vehicles. Consumers may actually save money in buying smaller cars as their first cost and ongoing operating costs are certainly lower than larger vehicles. The part of the bill that is real tricky is in electric power generation where incentives will be given to operate geothermal, wind, PV, solar thermal, biomass, and nuclear power stations and taxes will be imposed on coal, natural gas, and hydrocarbon liquid fired stations.

The least costly methods for power generation are coal and natural gas and the most costly is PV. The office of management and budget has estimated that the average consumer will pay approximately $100 extra per year for their energy as a result of this bill. I have no real data that confirms this. PV electricity is much more expensive to generate than natural gas and it is also intermittent. The power grid will need additional transmission lines and point of use energy storage to overcome the interruptible nature of PV or even wind. Nuclear, geothermal and biomass are base-load generators that can operate 24 by 7. The wildcard in all of this is whether plug in hybrid or pure plug in vehicles will be deployed on a large scale in the next decade. This hinges on the cost of lithium batteries and a good deal of government money is being thrown at this area.

My chemical engineering experience leads me to believe that the cost improvement in lithium ion batteries a decade from now will be moderate and nowhere near the rate of cost improvement in devices such as semiconductors or LCD TVs. Unfortunately a fractional Moore’s Law will hold for lithium batteries. The underlying limitation to the learning curve is that the electrochemistry requires a certain mass of anode, cathode, and electrolyte to store a certain quantity of energy and deliver a certain instantaneous amount of power. My prognostication is that ten years from now the cost of a lithium ion battery system will drop from approximately $900 per kilowatt hour of storage to approximately $650 per kilowatt hour of storage.

The Tesla Roadster has some 55 kilowatt hours of battery storage, the Prius only has 1.5 kilowatt hours of storage as the Prius is primarily powered by its gasoline engine. The Volt plug in hybrid GM is proposing has approximately 16 kilowatt hours of battery storage. Because of the high cost of the batteries my forecast is that plug in hybrids that are capable of 40 miles of electric travel will still be too expensive in ten years from now to capture more than a very small share of the market. Traditional hybrids will capture a third of the market in a decade and small lighter cars will also capture a similar fraction. Bigger cars will still be common with a similar market share to traditional hybrids. A plug in hybrid that goes 8 to 10 miles may be more commercially successful than the targeted 40 mile range battery intensive vehicle. If we do have plug in hybrids with 3 or 4 kilowatt hours of onboard batteries then it is quite plausible that one would recharge at night at home and the operating cost for the 10 miles that one would travel on the batteries will be perhaps 25 cents. If there are five million of these vehicles perhaps some 20 million kilowatt hours of night time power can be stored. Let’s assume the nightly charging last 8 hours, this means some 2.5 million kilowatts or some 2,500 megawatts of power generation capacity will be needed. This is a miniscule fraction of the approximately 800,000 megawatts of power generation that are in place presently in the USA.

The success of the whole plug in program hinges on the lightest metal in the periodic table and this is Li, which are incidentally the first two letters in my name. I wish I could help the planet by inventing a new less expensive material called Lindsayium but alas this is not possible and my suggestion to help meet the 17% reduction goal is to walk, bike, carpool or take the bus.


  1. I think your right- walking, carpooling and the bus will help make the 17% target but perhaps we should think about driving and riding in cars and buses that are powered by natural gas?


  2. Yeah natural gas is good. T Boone knows what he is talking about. As methane has 4 hydrogens for one carbon atom and gasoline has only two hydrogen for one carbon atom there is less CO2 per mile with a NG vehicle than a gasoline vehicle. About 25% less CO2 per mile

  3. Natural gas has done wonders for pollution in India (ie Delhi) for small auto-rickshaws, but I do not think it is scalable to larger vehicles or long distances as the energy density is so low compared to liquid fuel.

    Solar/Wind will lower help us hit our target of CO2 "pollution" but we will pay more for it certainly.

    Technology will get to the point where the variable costs of these solutions (including storage to reduce intermittentcy) will make them comparable to coal.

    In my lifetime, we WILL see 5 cents/Kw wind and solar that runs 24/7. I am committed to helping solve this problem.

  4. Ajay

    You are the man to make it happen. Compressed natutural gas is fairly enrgy dense but you are right not as dense as gasoline or diesel. A large welding cylinder has about 300 scf of natural gas at 2,000 psi. This is about 280,000 BTU LHV or about 2.5 gallons of gasoline. The welsing cylinder has a mass of over 120 pounds the 2.5 gals of gasoline inclding a tank for it would have a mass of less than 20 pounds hence the CNG vehicle has more mass and the fuel tank takes up more space. But the motorist will save money compared with buying gasoline Lindsay