Saturday, February 23, 2008

wind power mandates, PHEVs, and smart grid synergies

The problems created by large amounts wind power can be solved through the control of Plug in Hybrid Electric Vehicles (PHEVs) by way of Smart Grid Technology.

I'll get to what that means in a minute. First, though, lets cover who should care: if you do think CO2 is a problem and don't think biofuels are a silver bullet, or if you are an Electric Power Systems Engineer in the Pacific Northwest (PNW) of the US, you should care. I've tried to write this in a way that is understandable to anyone patient or bored enough to read it, without sacrificing too much detail or precision.

The basic idea is simple: adding large amounts of wind power to an electric grid also adds lots of problems, adding large numbers of intelligently controlled PHEVs to the same electric grid may help solve these problems.

The electric grid is the biggest, most powerful machine in the world. It moves very slowly. Before wind was introduced as a big player, it also moved very predictably. People consume more power during certain times of the day, so the system is set up to generate more power during those times of the day. A very precise equilibrium between production and consumption is always maintained. Any deviation from this equilibrium causes big problems. Up until today, the system can only control the production of power to maintain this equilibrium. It has no say whatsoever on how much power is consumed, by whom, or when so long as you pay your bill.

In the PNW, most of our power comes from large scale hydroelectric dams mostly built during the first half of the century. As it happens, the electric consumption in the PNW hasn't changed significantly in decades because we embrace conservation, so we have plenty of power to go around at some of the lowest rates in the world ($.02/kWh in some counties). We have no need whatsoever for additional production capacity. We do, however, have a new "Energy Independence Act" (independent from what, I have no idea, since virtually none of our electric energy is imported) I-937 that requires us to produce lots of power from wind. 15% of the energy delivered to customers will have to come from wind sources by 2020. I, along with the rest of the power industry in the state, think this is ridiculous but I won't be distracted from my theme. Instead, I'll pretend that it is a good idea and just try to figure out how to make it work.

The problem with wind power is that it depends on the wind blowing. Wind is difficult to forecast and changes rapidly. A given wind plant might go from 0% output to 100% back to 0% in the course of an hour. This is problematic for the system because it forces the other power sources to constantly adjust their power output so that the precise equilibrium between production and consumption can be maintained. This constant adjustment is expensive and requires that other power sources be run outside of their most economical range. In the PNW, running a plant outside of its most economical range often means spilling water over the top of a dam instead of running it through turbines to produce power, which is effectively the same thing as throwing energy away. Today, in the PNW, this cost is just starting to be imposed on the wind plants. Even though only 3% of the region's power comes from wind today, the problems caused by wind plants will increase the cost of wind power by 10% (about $23 million this year). By the time wind power represents 15% of the power consumed, this cost will probably have risen significantly, both in absolute and relative terms. The first part of the question, then, is how to minimize this cost.

The second part of the question is what to do with all of this new power that we don't need.

Conceptually, at least, the answer is simple: we increase the amount of energy consumed and stored. The best way to do this is with Plug in Hybrid Electric Vehicles (PHEVs). PHEVs are vehicles that run partially on electric energy stored on board that has been taken from the electric power system and partially on another source, usually a small internal combustion engine. The Chevy Volt is one example where all of the power to the wheels comes from the electric motor and the internal combustion engine is used only to charge the batteries. A Toyota Prius that has been modified so that it can recharge it's batteries from the electric grid would be an example where the power to the wheels comes from both the internal combustion engine and the electric motor. (I have strong opinions about both of these cars and how wrong they are, but I won't go into them right now.) The good part about PHEVs is that they can significantly reduce our fossil fuel consumption and CO2 output in the PNW. The really good part about them is that they would represent a huge new demand for this excess electric power that the wind energy mandate will force us to produce. The best part about them, though, is that they have the capacity to reduce the cost of integrating wind energy into our system by reducing the need to run our hydro dams outside of their most economical range. But these latter large benefits can only be captured by proceeding intelligently and with an understanding of the total power system. If we start using a large number of PHEVs without considering how they will impact the system, we will almost certainly make the cost of integrating new wind energy higher instead of lower.

Which brings us to the smart grid system. The idea behind the smart grid is that some consumers of power would be willing to make small modifications to the way they consume power if it benefited the environment, reduced their cost, and had minimal impact on their lifestyle. The mechanism for achieving this is a tool that looks at the market price of electricity and decides whether or not to consume power in a specific way at that moment. For example, you get home, park your PHEV and plug it in. You don't care when it recharges, as long as it is done before tomorrow morning, so you tell it to charge in the most economical mode. It looks at the current price of electricity and the expected overnight price and decides to run later and it saves you a little bit of money. If the price unexpectedly goes up while it is charging, it stops charging until the price comes back down again. If the price goes even higher, it may decide to sell some power back to the supplier. If you want to recharge now, you switch it out of the economy mode and it recharges right now. But you don't have to think about it. You just plug it in and set it in either the economy or the performance mode. The beauty of this mechanism is that it not only saves the consumer money, but it also provides a way for the power supplier to influence how much power is consumed and when by setting the price.

If it is the middle of a windy night in the spring in the PNW where all of the dams and all of the wind turbines are providing full power, the electricity to charge your PHEV might be nearly free. If it is a cold snap in the early winter, the dams are struggling to meet load and the wind turbines aren't running at all, electricity might be expensive enough that your charger decides you would be better off using the internal combustion engine to charge the batteries to power your commute. More importantly, there would often be borderline cases where the wind power increases and then decreases again repeatedly through the night. As the wind power increases, the market price for electricity would fall and your charger would turn on. As the wind power decreases, the price would rise again and your charger might stop charging your batteries.

Through this mechanism, you would get the most economical charge for your batteries and the power system would get the most economical way of maintaining the equilibrium between the power produced and consumed, thus reducing the integration cost of wind power, allowing a larger percentage of our energy consumption to be served by wind power.

There are a good number of details to be worked out (the PHEVs, the smart grid charger, and the market used by the smart grid charger are all still mostly theoretical, for example. and all have significant social, political, and bureaucratic barriers to overcome. I don't think there are significant technical barriers, but I am a bit of an optimist when it comes to technology), but I think that the potential benefits are so important that working them out is a high priority.

That is my excessively long, but hopefully understandable understanding of the subject. I hope somebody finds it interesting. Otherwise, I've just wasted the better part of a beautiful Saturday morning.


leila said...

no, i get it! i GET IT! and it does seem magically optimistic---my kind of sustainable technology---but it also makes complete and utter sense.

babe, this WAS interesting and understandable. i have absolutely no questions.

except, if the powers that be realize that forcing wind is a mistake and take the mandatory wind thing back, then what would be an optimal set-up for sustainable/renewable energy production/consumption, say, in the PNW? i especially like how cars and reducing their impact on the environment played a big part in what you discussed here, so please include them as a consideration in your response to my question.

leila said...


shaun said...

if i was dictator of the PNW, the energy/CO2 policy would be:

utilities would have to charge 5 minute market pricing to all customers within 3 years

new large hydro projects and improvements to the current ones would be considered

the sale of compact fluorescent bulbs would be banned as of tomorrow. they just don't make sense here (or anywhere else that uses heating more than air conditioning)

any energy (oil, gas, natural gas, electricity, ethanol) would be taxed based on it's CO2 contribution to the atmosphere at point of sale, starting at a small amount today and slowly increasing. the tax income would be used to support energy research to try to make the region a world leader in the area.

any device with a peak consumption of more than 1kW (ovens, dishwashers, clothes dryers, PHEV chargers) would be required to include the capability to respond to market price signals and frequency deviations (they could include an override mode that ignores market signals)

i would add a the expected lifetime fuel cost and tons of CO2 contribution to the sticker on every new car, using real-life observed fuel efficiency (from the data that all modern cars already collect instead of ridiculous EPA estimates)

i would consider measures to address energy intensive imported goods produced in unsustainable ways, such as anything from China, but i have no idea what could actually be reasonably done in that arena. for cars especially, huge amounts of energy goes into their production, but i don't know of a practical way to produce that information or what could be done with it

i think these measures would be effective ways to associate the energy costs and CO2 production with the consumption of it and transmit the costs to the customers so they could choose to respond to the signals. or not to. those that choose not to respond to the signals, would be funding energy research

it really would require a dictator to accomplish these sorts of things, though

liamk said...

I read it and bookmarked it so I could read it again, several times.
All this talk about forcing wind, you guys are killing me, I'm being so restrained.