Energy Resilience

In an important op-ed in yesterday's Washington Post the former CEO of Intel, Andrew Grove, issued a rebuttal to all the slogans we've been hearing lately promoting energy independence. Without ever mentioning it by name, he also offered a practical alternative to the recently-proposed Pickens Plan. In the process, he has introduced a phrase that might catch on as more precise and pragmatic than either energy independence or energy security: "energy resilience." This notion relies on extending the dominance of electricity into transportation, and on producing this energy carrier from many different primary energy sources, including fossil fuels, various renewable flows, and nuclear energy. An energy economy entirely mediated by electricity would be much less vulnerable to disruptions or price spikes in any one commodity, such as oil.

When confronted with the overwhelming challenges preventing the US from achieving true energy independence in the foreseeable future, many of the advocates of this goal respond that we ought not be overly literal in interpreting it. Independence is a matter of degree, and what they really intend is that we become more energy independent, despite the arrow having pointed steadily in the opposite direction since the early 1980s. If that isn't merely rhetoric, then perhaps they'd be willing to trade in this imprecise slogan for one that represents an equally desirable, yet more achievable goal. Energy resilience could be just what a nation reeling from the inflationary impact of the quadrupling of oil prices in five years is seeking: an economy with the ability to absorb an oil (or natural gas or coal) price shock and keep on growing.

So what might a transition to a more resilient energy economy entail, with electricity powering most transportation, in addition to its other roles? As Dr. Grove notes, shifting our transportation systems to electricity wouldn't be easy, because it will require much new infrastructure and the turnover of most of our vehicle fleet. Powering half of the energy needs of the current US fleet of cars and light trucks would require an additional 40 1,000 MW nuclear power plants or 125,000 MW of additional wind and solar capacity--a seven-fold expansion from current levels--or some combination. In the early years of this transition, we might also consume more natural gas for power generation, not less, because natural gas turbines provide much of the existing base of spare overnight electrical generating capacity that would be used to recharge the first wave of electric cars. In addition, we'll need to upgrade our electrical infrastructure to accommodate more generation from intermittent and cyclical sources, and more sharing between regional grids.

Then there are the cars themselves. Here I think Dr. Grove may be overly optimistic in his estimate of a decade to make this shift. It has taken conventional hybrids, which don't plug into the grid, 9 years to capture 3% of the US car market, though until recently their sales depended more on government incentives and green cachet than on fuel economics. The first original-equipment plug-in hybrid models should reach the market within one to two years, depending on whether Toyota or GM launches first, and until then electric cars such as the Tesla and Aptera will occupy a small niche. Replacing half the 240 million cars and light trucks now on the road by 2020 with plug-ins hybrids and pure EVs would require them to attain a 50% market share within about five years and essentially 100% a few years after that. Dr. Grove suggests retrofitting existing cars to shorten the transition, though I wonder how attractive consumers will find such options. Nor will plug-ins and EVs be the only efficient models vying for market share.

During such a transition our demand for liquid fuels would fall gradually at first, and then more dramatically, while demand for natural gas for power generation would probably rise initially and then level out, depending on how climate change legislation affects the output of our existing coal-fired power plants. Increasing domestic oil and gas production and expanding biofuels output have an important role to play in reducing our net energy imports in the early years of a transition to a strategy of energy resilience. In any case, US oil demand would continue at reduced levels for many years to come, as the long tail of our vehicle fleet turned over, and liquid fuels continued to underpin long-distance travel.

The approach suggested by Dr. Grove has many advantages, and the most important is avoiding the trap of becoming overly reliant on any one source of primary energy, imported or domestic, in the future. In this respect, his idea has an edge over the plan put forward by T. Boone Pickens, though the latter might be simpler to execute. Energy resilience also has thermodynamic efficiency on its side. Because fossil fuels can be used to generate electricity at least twice as efficiently as burning them in internal combustion engines, a US vehicle fleet made up mostly of electric cars would require much less primary energy than the current one, without reducing annual vehicle miles traveled. That would have very beneficial implications for the long-term price of energy, and it would greatly reduce our energy imports. That still might not get us to energy independence, but the combined price and volume effects would shrink our oil import bill to much more manageable proportions.

Maximum Fuel Economy

It's looking increasingly likely that the House version of energy legislation will pass without a specific fuel economy provision comparable to the Senate's higher CAFE standard. Thinking about fuel economy triggered some random thoughts concerning the way we're approaching this problem. While it is quite reasonable and pragmatic to ask how much additional fuel economy we need, we should also be asking two other, related questions: How much more fuel economy can automobiles deliver economically on current fuels without drastic redesign, and is fuel economy even the right metric, in a world that is shifting its focus beyond questions of oil price and availability to the larger consequences of energy use, including climate change?

The first question has long vexed automotive engineers, who don't set out to build cars that deliberately waste fuel. Engineering and economic trade-offs determine how close an actual engine comes to achieving its maximum theoretical thermal efficiency, which for internal combustion is somewhere in the neighborhood of 35-40%. The engines in our cars usually achieve less than 25%, sometimes much less. There are all kinds of strategies that can boost the efficiency of a spark-ignition, Otto-cycle engine--the kind in most American cars. Today's MIT Technology Review looks at one of those, HCCI, which changes the way fuel is mixed in the cylinders. It could achieve diesel-like efficiency gains, and it's welcome news that this may be possible using ordinary gasoline, rather than "designer fuels."

If you look at the other places that energy in a car disappears on its way from the gas tank to the wheels, the engine is only the biggest of many source of losses (see slide #6 of this presentation.) Some of these are unavoidable; you can only make a passenger car so aerodynamic, before it loses functionality. However, designers of hybrids such as the Prius didn't just add electricity; they tackled some of these other losses to boost the car's non-hybrid efficiency, too.

When you add up all the possibilities, and then layer on hybridization, turbo-charging, and other proven technologies, doubling the overall efficiency of any car ought to be possible. And by giving up a bit of weight and power, too, we might be able to triple the fuel economy of the least efficient cars on the road. So when our leaders talk about raising average fuel economy of the new car fleet from 25 mpg to 35 mpg, this should be entirely feasible without requiring the more radical--though possibly desirable for other reasons--step of plug-in hybridization, which adds an external electricity source to the car's powertrain. All of these strategies add cost, however, and that's the crux of the whole argument. Saving 137 gallons of gas per year, the typical quantity associated with boosting the average car's fuel economy by 10 mpg, is only worth about $400/year at current fuel prices. That limits the maximum economic investment in efficiency to about $2000/car. Finding the right solution for each model within that constraint will be the trick.

But is miles per gallon even the right metric? Even if we didn't care about greenhouse gas emissions, the inclusion of increasing quantities of ethanol in the US gasoline pool alters the meaning of the "gallon" part of that ratio. This is compounded by the lower energy content of ethanol. A US fleet running entirely on E-10 will inherently need 3% more fuel than one using 100% petroleum gasoline, reducing average fuel economy from 25 mpg to 24.25. Throw some E-85 and plug-in hybrids into the mix, and it gets even more confusing.

Perhaps Europe has the right answer to this. Their "fuel economy" regulations are based not on the usual European metric of liters of fuel per 100 kilometers, but on grams of CO2 emitted per 100 km. While I'm not sure they yet do this on a well-to-wheels basis--which would factor in the upstream emissions associated with producing gasoline, ethanol or diesel fuel--this just looks like a better metric for the 21st century. The easiest way to drive grams/100 km down is still to increase the efficiency of the vehicle itself, but it's not the only way. This perspective helps avoid potential dead ends that appear to reduce oil consumption, but don't actually reduce energy consumption or total emissions by very much. And it takes us back to the underlying question of the real goal that fuel economy regulations are intended to serve: Is it oil security, energy security, or climate change?