Tomorrow's Mobile Power Plants - Part 2
By Bill Moore
What is "possible" in theory often bogs down in the muddy mire of reality. Just because it is theoretically possible to use the family car or truck as a mini-power plant that feeds electricity to the grid, as well as powering the home, doesn't necessarily mean it will happen, at least not overnight. There are numerous technical, political and social issues confronting such a radical concept. But the future is encouraging, provided all the relevant parties agree on a systematic approach to the opportunity.
As EV World continued our dialog with Alec Brooks, a vice president at electric vehicle systems innovator, AC Propulsion of San Dimas, California, we asked about some of the practical considerations to implementing this, the ultimate distributed generation application.
Assuming your hybrid-electric car of the future has the necessary components to not only generate AC current at 60 Hz, but has the ability to send it off-board the vehicle, what special considerations, if any, will the homeowner have to make to make use of this power? According to Brooks, there are two options. The first is a simple, manual connection where you plug your car's generator into your house wiring through a device called a GenerLink made by a subsidiary of Potomac Edison. It mounts under the electricity meter and enables you to plug in a small portable generator while automatically disconnecting the house from the grid (See Part 1 on issue of "anti-islanding"). A second device would sense when power from the grid has dropped and would automatically do the cut over. Total cost today would be under $1000 Brooks estimated and in volume, maybe less.
An Emissions Surprise.
The next hurdle is the question of vehicle emissions, especially a hybrid-electric car running off of gasoline. Here Brooks was on less theoretical grounds. He and his colleagues had just completed the week prior to our interview a set of tests using a Toyota Prius, which the EPA has rated as a "super ultra-low emission vehicle" or SULEV. Running the car on a dynamometer at 60 mph, Brooks measure the mechanical energy reaching the wheels and the emissions being generated by the 4-cylinder gasoline engine. While this doesn't, obviously, simulate an idling car parked in the garage generating electrical power, it did give Brooks and his team some surprising insights into overall emission.
"One of the things we were curious about is whether these super clean... SULEV vehicles can produce mechanical power or through a generator, electrical power with clean enough emissions that you could actually consider using vehicles as distributed generation systems. So, with some assistance from the California Air Resources Board testing laboratory dynamometer we actually tested a Prius last week on their chassis dynamometer, running at constant speed. It was not a vehicle drive cycle," Brooks admitted, adding that instead they ran the vehicle at a constant speed. They also allowed for the emissions system to warm up and stabilize. They ran the car at three different power output levels from 10kw to 16kw.
"The interesting thing is," he continued, "the emissions were, in some cases, not measurable at all for NOX and hydrocarbons. You still had some CO emissions that where consistent with super ultra low emission vehicles, but the NOX emissions were... surprisingly low and perhaps even lower than (a) natural (gas) central power plant."
Brooks said that they discovered that at these relatively low power settings, the engine didn't overheat despite the lack of air flow over the radiator. The issue of carbon monoxide would have to be more carefully studied, as well.
"You'd have to study it a bit more to decide whether it was suitable for residential applications. But I think there would be certain application, say in business environments where it would be no worse, and in most cases better than other forms of distributed generation that are being explored, especially the NOx emissions are far, far lower than these microturbines."
Brooks told EV World that the NOx emissions he recorded for the Prius were .003 grams per kilowatt-hour, "when you could measure it," he said. By comparison the current emissions from a "popular microturbine are .223 grams/kW hr, or about seventy times higher."
"It could be one of the cleanest forms of distributed generation that really works out," Brooks commented. He also noted that the Prius already has, pretty much all the necessary electronics already incorporated into its hybrid-electric drive train to make electrical power generation practical. He said it has a generator, a super clean gasoline engine and a second inverter for feeding power back to the grid. Such a set up would generate 10 kW of electricity, easily meeting the power needs of most American homes.
In order to get emissions down even further he suggested giving the Prius -- or any future hybrids -- have dual fuel capability. Such a vehicle would use gasoline when on the road and low-pressure natural gas, for example, when working as a stationary generator at home. The owner would hook-up the car at night using a quick connect, natural gas or propane coupling. The car would then generate the home's electricity during the peak usage times in the early evening. This would help reduce the amount of electricity used from the grid and thereby -- again theoretically -- reducing the family's electricity bill.
Of course, the economics of such a scenario still have to be proven. Centrally-generated electricity may always cost less than distributed generation. However, if you factor into this equation the additional value you would derive from an investment that spends most of its operational service doing nothing, then the numbers might begin to make sense.
He said that at $1.50 per gallon of gasoline in the US, the kilowatt-hour rate for the Prius-scenario works out to be a surprising 13.5 to .14 cents per kW/hr. Compare this to the current "suspected" wholesale rate for electricity in California, estimated at between 30 and 40 centers per kW/hr and the Prius-home generator idea starts to look attractive, especially if consumers begin to pay rates close to the real cost of production.
"The big scale economics work," Brooks said, "but on an individual basis you may have to have it sold into the ISO (independent system operator) as a spinning reserve and they could call it up." This of course then raises thorny issues like FERC regulations. "It's a complicated set of rules that I think are navigable, but in some cases we may need to get new tariffs or some laws amended to make the capabilities these vehicles offer easier to implement into the system."
Looking at the Hydrogen Fuel Cell Option
Brooks and his associates also looked at how to integrate future fuel cell EVs into such a system. Here he suggested it would be advisable to have a separate source of hydrogen to run the fuel cell so as to not delete any that is stored onboard the vehicle.
More daunting are the economics, Brooks said. This is essentially because right now the cost of hydrogen is much higher than the cost of natural gas. When comparing the relative efficiencies of current fuel cell technology to convert hydrogen with the hypothetical Prius using natural gas, they are nearly identical. "You have the same efficiency, but you probably have somewhere around double the cost for the basic energy that you¹re starting with in the gaseous fuel in hydrogen."
Given these economics, Brooks believes it makes more sense let one's vehicle generate electricity at ones place of business. He can envision a parking lot full of vehicles generating electricity for profit on a hot summer day when electricity demands are highest. "It would be an added source of generating capacity," he noted.
Improving EV Economics
One of the big challenges facing California's Air Resource Board (CARB) is finding ways of making EV's make good economic sense, Brooks explained. This is why CARB has taken serious interest in this concept. If a serious case can be made for electric-drive vehicles as potential revenue producers, this may serve as a powerful incentive for consumers to buy these vehicles.
In addition, CARB's staff is currently working on a set of standards for distributed generation emissions, so better understanding the emissions of EVs-as-generators also interests them.
Considering Grid-Connected Hybrids
According to Brooks, AC Propulsion has been studying grid-connected hybrids since the early 1990s when Alan Coccini, the company president drove an electric vehicle across the US pulling a small, trailer-mounted generator-set. Part of the trip was made on grid-connected electricity and the rest using electricity from the trailer-generator, he noted.
"If you have battery only range that is sufficient for most of your driving, you might find out that you hardly ever run the engine itself, and you find that recharging at home is more convenient than going to the gas station. You have no range anxiety because you do have that engine with you."
Brooks revealed that AC Propulsion has a proposal under consideration to build a tri-fuel, grid-connected hybrid. The three fuels are gasoline, natural gas and electricity. The goal is to demonstrate very clean distributed generation and zero emission driving capability.
"We should be able to demonstrate very clean distributed generation and zero emission operation of the vehicle and super-low emissions while its operating as a hybrid vehicle."
In Brook's mind a "grid-connected" hybrid vehicle could mean a couple different things. The traditional concept is a hybrid-electric vehicle that operates much of the time using power from its grid-recharged battery electric-drive. That concept is beginning to evolve to hybrid's which connect to the grid for the purpose of also putting power back into the local power pool.
Where To From Here?
It doesn't take a lot of imagination to picture a time in the not too distant future when homes will be equipped with an EV-grid interconnect. The will give the owner the option of using his electric-drive vehicle to power his home in an emergency or, assuming the regulatory hurdles can be surmounted, selling spinning reserve power under contract to the local utility. Brooks believes all of the technology is now in place to make this a reality in the near future. He thinks that by creating additional value in the vehicle, it will help mitigate the cost issues.
"If there are obstacles (it is because) this is a very multi-disciplinary, system-wide solution that gets into (the) operation of the power grid and emission regulations and public utility commissions and distribution utilities such as Edison and (LA)DWP. It cuts across many different business areas of those businesses. It is a complex area that has lots of different considerations," Brooks stated, adding that AC Propulsions goal is to make this scenario a reality for battery electric vehicles.
As for the tzero program at AC Propulsion, Brooks told EV World that it is going more slowly than the company would like. He said there are people willing to buy the vehicle but that the company is looking for ways to spread their drive system across more lines of vehicles so costs can be brought down. AC Propulsion has also develop a lower-priced drive system, one that already has EV-to-grid charging incorporated into to.
He concluded by saying that he thinks battery electric vehicles have a great future, despite the widespread misrepresentation in the press that CARB was pulling back from its support of BEVs. He pointed out that when you compare the available P-ZEV credits compared to ZEV credits, it could be cheaper for carmakers to comply with the mandate with battery electrics than with advanced partial-zero emission vehicles.
The question is will people want to buy them? They might if they someday could turn that BEV or hybrid into a revenue maker instead of a revenue breaker.
blog comments powered by Disqus