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Grid-interactive co-generating hybrid vehicles

A distributed load-balancing and generation capacity in your garage
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(+5, -1)
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Short version:

Hybrid battery-electric/CNG vehicles as a distributed, grid-connected load-balancing and on-demand generation system, managed by the utility company, by a price-based realtime spot market, decentralised down to the local substation level.

Longer version:

One of the objections to the widespread deployment of electric or plug-in hybrid vehicles is the load this will place on the electricity grid, specifically at its most tenuous extension, the consumer/ neighbourhood end.

One of the objections to the widespread exploitation of (some) renewable energy sources is their intermittency, and the consequent need for, and cost of, some form of load balancing, either as energy storage (batteries etc) or excess, on-demand generating capacity.

Hello two birds, have a stone.

You drive a battery-electric hybrid vehicle, containing batteries, an electric motor, a compressed natural gas (CNG) tank, and either a fuel cell (series hybrid), or a combustion engine (series - separate generator, or parallel - drives electric traction motor as a generator).

When you park your car at home or at work, it hooks up to:

• the town gas supply via a compressor
• the electricity grid
• the building's hot water system
• the LAN.

The first thing that happens is a data handshake/"hello world" between the vehicle, the building hot water system, the local electricity substation, and the local town gas substation. The second is that the onboard computer checks out the state of charge of the battery pack, and the fill level of the onboard CNG tank.

The third thing that happens depends on which management model you adapt. I'll describe here two models: a market based one, and a centrally-planned one. As electricity grids are increasingly moving towards realtime markets as a mechanism for demand management, I'll explain that one first, and in more detail.

In a market model, the local substations give a present-time and local-area spot price for both a kW of electricity and a litre of NG. This is already baked for electricity. When the electricity spot price is low (ie supply > demand) the vehicle buys electricity from the grid, and uses it to top up its own batteries. This provides a local demand management buffer to the grid. When the price is high (supply < demand) it sells electricity back to the grid, either by depleting its own batteries or by purchasing NG to run the generator, or both. The spot price for NG is a factor in calculating which is the optimum source to draw on at any one time.

Whatever heat is generated by energy conversion onboard the vehicle is converted into hot water by the link between the vehicle's cooling system, and the building hot water system.

A parking garage or workplace carpark may have its own substation, and the HVAC/hot water controller would be another independent bidder in the market. At home, the substation would cover a neighborhood. A meta-market operates between the substations to balance demand at the next level up, and so on up to the backbone grid.

The vehicle computer balances the spot price (of NG, hot water and electricity) against expected user demand (ie, needing a full battery pack and CNG tank by 8:00am/5:00pm), and against known patterns of rise and fall in supply and demand (ie, household power demand generally drops at night). It can play hedge games and futures trading against these expected patterns, and determine when during the diurnal cycle is the best time to purchase or sell its resources. It also learns the patterns of user demand for mobility, so it can hedge against them. This feature can be over-ridden by the user, who for example needs a full tank and batteries for a 4am airport run, and is willing to pay slightly more on that day to ensure availability.

In a "command economy" model, the vehicles are remotely managed by the utility to either dump and store excess electricity or supply electricity from batteries or town gas, as per local, realtime supply and demand.

I think a combination of the two models may work the best. The vehicles (and optionally associated infrastructure) may be leased to the user at a fixed cost, with a maintenance contract built in, and the utility buys and sells NG/electricity to/from the vehicles as required. The user pays only their lease costs and mobility costs (kW/litres actually used in transport). This would work best perhaps with large corporate or government fleets, where a "company car" is routinely provided as part of a salary package, at least as an initial roll-out and proof of concept. Bus and taxi fleet would also be worth investigating.

Standardization common amongst such fleets would simplify the provision of a standard vehicle designed to mate with utility infrastructure in the workplace garage. Because of the number of connections required (gas, LAN, electric, HW), an automated hookup system is likely to be necessary, even if these are integrated into a single umbilicus. Standardization will help enormously here, thus motivating towards larger fleets as a first point of deployment. Initial tests could be performed using a slightly modified production Toyota Prius.

At the other extreme, the user would pay (or finance) the upfront cost of the vehicle (and optionally infrastructure) themselves, and enter into a supply/demand contract with the utility. A middle ground would see the vehicles privately owned, and the infrastructure owned and operated by the utility.

At a rough guess, this works out financially advantageous to everyone. The user/fleet owner is assisted in amortizing the cost of the vehicle by taking a powerful, high-tech energy conversion plant which may other otherwise be only utilized for two hours per day, and giving it a productive income-earning capacity 24/7. The utility is assisted by spreading the capital cost of necessary load-management plant across a wide area, negating somewhat the need for upgraded trunk transmission infrastructure, and by sharing the financing burden of that infrastructure with the user.

It might - just, barely - work out possible for the utility to supply the vehicles for free or close to it, and charge only for miles.

As a further refinement: the data connection between the vehicle and utility can be wireless, 24/7, and wired into the GPS nav system. The utility and the vehicle can negotiate the most mutually advantageous routes and parking spots, taking into account departure point, destination, vehicle range, areal supply and demand, and the availability of charging stations.

BunsenHoneydew, Nov 09 2010


       Dear Manufacturer,   

       I bought my networked hybrid car less than a year ago. I've only covered 4,000 miles and yet it's knackered already. During the frequent power interruptions in my area, the car sits in my garage revving it's nuts off all night.
Twizz, Nov 09 2010

       I'm not sure that my brain is up to reading all that during a half hour lunch break. Have a speculative croissant for the time being and I'll get back to you!
DrBob, Nov 09 2010

       The concept of using the battery banks of electric or hybrid electric vehicles as load balancing storage is well discussed in literature on alternative energy.   

       The concept of using the cars as generators isn't, primarily because it's more economical to spin up a single large gas generator than a few hundred (thousand) small ones.
MechE, Nov 09 2010

       This idea is decidedly communist [-]
DIYMatt, Nov 09 2010

       Did you by chance read "The Hydrogen Economy"? I believe there was a whole chapter devoted to this concept.   

       Note: I do not endorse this book personally.
NoOneYouKnow, Nov 09 2010

       I think there is a lot of mileage in the idea of intelligent appliances and machines bidding for resources in an automated online marketplace. [+]
pocmloc, Nov 09 2010

       Many things to like here. I do think that decentralized generation is a less efficient use of natural gas resources. Setting that aside, storage of energy in many small batteries makes sense and would allow more effecient use of a nuclear plant as regards the energy it produces during downtime.   

       The whole thing about decentralized generation is irritating. It should happen but does not because of monopoly and control of power lines. One can erect solar panels up the wazoo but you can only profit from their electricity insofar as you can reduce your own electricity bill. After that you give your electricity to the power company for free. No-one gets paid for the energy they produce. If you could erect a windmill and get paid for its electricity, there would be millions of small time power generators feeding into the grid, especially in remote areas blessed with land. But I think the power companies like to keep control.
bungston, Nov 09 2010

       //No-one gets paid for the energy they produce// They do in some countries, google “feed-in tariff”
pocmloc, Nov 11 2010

       Every state in the USA I've lived in requires that customers be paid for power they generate above and beyond their usage. Depending on the state it ranges from the "avoided cost rate" which is relatively low to the full retail rate, which is noticeable.   

       I also know in Germany they get the full retail rate, and there may be a government subsidy.
MechE, Nov 11 2010

       [Twizz] - are you just amusing yourself, or do you have a point?   

       [MechE] // more economical to spin up a single large gas generator // - Yes, but how scalable is it? And are you including the price of installing/upgrading transmission lines? Are you including the additional price to the householder of hot water and winter heating?   

       [DIYMatt] // communist // - Do you habitually use words to mean the opposite of what they mean in the real world? Or did you not bother to read beyond the first paragraph? What on earth is "communist" about this? These are freely entered into financial agreements between one independent actor and another to buy and sell commodities in a realtime free market. It couldn't be less "communist" if its name was McCarthy.   

       [NoOneYouKnow] // "The Hydrogen Economy"? // - No, I did not. My opinion of the hydrogen economy is that it's a ridiculously expensive white elephant that's never going to happen. I went with CNG and electric because many towns and cities are already widely provisioned for both, and those that aren't generally want them. While CNG is not carbon neutral, it's better than burning distant coal, and better than petrol/gas. It's also ridiculously cheap.   

       [bigsleep] // "Car as power hub for the new home" //   

       I rather think you're missing the point. There's nothing outlandish or new here technologically, it's the system-wide integration and management of existing, baked technologies that is the invention here. And by system-wide, I mean beyond the home (neighbourhood ->substation ->grid).   

       I did think about putting this under a "Business" category or "Energy" or "Public/something" - if you think that would make it clearer, I'll consider it, plus a revised title. I'm not 100% happy with the existing one.   

       // Whats cheaper in cost and energy terms to produce, one power station or a million cars? //   

       One million cars are ~still~ going to be produced and paid for, ~and~ gas power stations and other load management systems.   

       The idea is to integrate the two systems and share the upfront cost in dollars and resources. It may be 30% more costly per watt (or it may not) but if you are splitting it 50/50 with the driver ... that's 65% each.   

       Note I do not endorse these figures.   

       // hugely wasteful. As is driving a car. //   

       I know that, you know that - do you honestly think the private car lifestyle is going to keel over and die tomorrow? Do you think another 100% fuel price rise is going to just make 100% of private car drivers shrug their shoulders and say "Oh well" - or will some move to public transport, some to walking and biking, some to alternative fuels and smaller cars, and some just keep on paying?   

       Don't forget the millions of new private cars coming online in China and India. You gonna go over there and stop them?   

       This is not an idea for the best possible outcome given total political power, a clean slate and rational planning - because NONE of those things exist. This is a less-wrong adaption of existing systems.
BunsenHoneydew, Nov 12 2010

       //not the kind with extra energy conversion and management units.//   

       If you can make it economically viable, they will.   

       I'm all in favour of smaller cities, walking cities, decentralised and localised economies and so forth. I've not heard of the idea of shifting fuel tax to the employer before - is that your own idea? If so, it's worth a post of its own.
BunsenHoneydew, Nov 27 2010


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