ZEB - Zero Energy Buildings explained

All the ideas in Zero Energy buildings have been around in some form for a while. The problem is the key elements, such as demand-response, have been centrally controlled. Sign up for this program months in advance, and then the Power Company controls your [water heater]. But what if I want to stay home today? Too bad. Consumers do not want loss of control. This limits participation.

New initiatives are getting closer to changing this. There are now a couple web services protocols for building controls: oBIX and WS-Devices. The newest Windows now is able to discover such services automatically. Soon there will be software to let your PC discover and operate building systems much as they discover printers today. It is not hard to imagine an agent talking to the power spot market, talking down to the systems, reading the electric meter live…

Some of the so-called “Zero Energy” initiatives envision each building supported by multiple on-site energy collection and generation systems. Based upon the building’s operating posture, and the mix of energy sources available, such a building would pull 35% or less of its total energy budget from the grid. If the facility includes local buffering and storage of electrical energy, whether this buffering is in the form of souped-up traditional batteries or new-fangled hydrogen storage, this become viable.

Power comes over the grid as Alternating Current (AC). Power is stored in batteries as Direct Current (DC). Power from the grid must be converted from AC to DC for storage. Before it is used in your home of office, it must be converted back to DC. Power is lost with each conversion. Power from most on-site generation is DC. On-site DC power generation can be stored in those batteries without the losses you expect converting from the AC grid to DC.

If future houses support DC distribution for internal use, then the batteries can become the primary source for the house. Because this removes the loss from converting the DC battery to AC, this effectively increases power stored in the battery with no new storage technology required. Most devices in modern houses are DC anyway. Those little bricks and wall-warts, the rectangular boxes attached to the plug or in the middle of some power cords convert power from AC to DC. This conversion is very inefficient; a third of the power may be converted to heat before it goes any further. The Galvin Power Initiative (www.galvinpower.org) is a good source for the engineering behind this. With appropriate local buffering (batteries), an awful lot of power consumption can be shifted to off hours without loss of occupant autonomy.

Zero Energy Buildings, then, are engineered to be efficient, make some of their power on-site, and shift energy use to when it is cheaper and more plentiful.

Next – Zero Energy Buildings and Shifting Power Consumption

Solar Thermal Comes Out of the Dark (or is that in from the cold?)

Our culture always looks for the next big thing to be the same as the last big thing. In movies, we see this in sequel after sequel. In television, well, Star Trek was initially pitched as “Wagon Train to the Stars”. In solar power, we see it in the fascination of the press with photovoltaics, the solar silicon sequel to computers.

And so I like to see the rise of Thermal solar power, the less glamorous twin. Thermal power may be able to move out into site generation better, may shine a path to successful energy storage, and may be a better participant in the suite of technologies that will build the home or office microgrid. In the deserts of Arizona and Southern California, large new solar projects based upon thermal capture have recently come on-line.

In Spain, large mirrors with computer controls track the sun and focus the rays on tall towers where traditional steam generation occurs. In this case, the technology of the generation turbine could be that from a coal plant. Two other aspects make this worth notong. First, a considerable part of the effort was in developing the software that tracks the sun and controls the mirror array; this sort of investment scales out very well as the same software can be used repeatedly. More intriguing is a process whereby excess heat is captured and stored in liquid salt. The molten salt stores the heat to allow the production of electricity to continue during gaps in the sunlight.

In the southwest deserts of the USA, more traditional parabolic “satellite receiver” dishes with lots of smaller mirrors follow the sun. They focus the light at the center where Stirling engines generate the electricity. It may be in part sentiment that draws me to Stirling engines; they are Victorian-era technology that is at last useful – the same sentiment that finds me living in a 200 year old house. I also like Stirling engines because they work without the large pressures and temperatures required by turbines.

These two new solar installations are big, very big. Yet I think they might show us a path to decentralized systems that are small. Because they are each heat based, they illuminate what diversity brings to the local energy grid.

The Spanish system stores energy in molten salt. This innovative approach moves solar power away from “only when the sun shines” to a model that can move energy from when you can make it to when you need it. Energy storage is so much more than batteries, or than hydrogen. I’m glad to see heat storage for electrical energy buffering in a large scale application.

The southwestern system uses industrial production quantities of software-driven solar collectors. The dishes should be able to scale down the right size for the home or office. The software will certainly be able to scale down. But the industrial production of Stirling engines is as exciting. Traditional thermal generation requires high temperature differentials, the difference between ambient temperature and your energy source, and high pressures. Stirling engines work at low pressures. Stirling engines work when the temperature differential is low.

Many things in your home or office generate heat. Air Conditioning exhaust, data centers, the furnace chimney, even composting toilets could be producing heat to store in the heat battery. A software driven rooftop dish can be one more. That heat can then drive Stirling engines to produce electricity as needed.

How will we know when it is needed? That is where enterprise-aware software in the office, home-owner driven software in the house come in. Negotiations with the services available in embedded systems determine the need. Negotiations with the power grid about pricing complete the picture.

The third definition of battery is a “collection of related things intended for use together”. A battery of guns is used in war. A battery of electrochemical devices is used to store electricity. A battery of diverse energy storage devices, electrochemical, potential, hydrogen, or thermal may be the building battery – and software will make them work together as a one.

Something’s Gotta Give

Changing business models is hard work. All the new approaches discussed in this BLOG seem not quite justifiable today. They would offer great benefits if they were already set up, but the change, to many, doesn’t make sense. History, and the installed base of markets and technologies, seems to block change.

I work from the precept that long term historical trends do not easily change. The things that drive decision makers will not change. Economic principles are as certain as gravity. We must find solutions to the problems of Energy and Sustainability that acknowledge the reality around us.

I make three assumptions about energy, the use of energy, and the need to deliver energy.

Energy Use per person has been increasing through all of history. It will continue to increase. The number of people using energy will increase. This means that the end-user demand for energy will increase.

Legacy energy sources will get scarcer. The difficulties associated with siting traditional energy generation will increase. The costs of remediating energy siting will increase. This means that the costs of central generation of energy will increase.

Utilities will be unable to build sufficient transmission capability for the needs of the future using current technologies. (Transmission refers to the long distance, high voltage tall towers you see bringing electricity to the fenced-in gray objects at the edge of a neighborhood. From the fenced in area to your house is referred to as Distribution.) Siting new transmission corridors is getting tougher and the lead times longer. One reason that the grid is fragile is that Utilities have been unable to afford adequate transmission expansion; they will be less able to afford it in the future. Increasing energy use will make demands on an infrastructure that cannot keep up with the growth will lead to decreasing reliability.

These three trends, increasing demand, higher cost of generation, and decreasing reliability or transmission, will shake end users, whether in homes, offices, or factories, out of their complacence about current energy provision. This will create the market conditions for technologies and approaches that seem “too risky” today. The risk of standing pat will be seen as larger than the risk of innovation.

I believe innovation will include building systems responsive to enterprise needs and current pricing. I believe innovation will include on-site generation and storage. I believe this innovation will require approaches that accept the heterogeneity of systems legacy and new, of generation systems appropriate to each site, and of storage appropriate for the needs of each business and home. To accomplish this, the underlying processes of each system need to be exposed as discoverable services to agents that are responsible to the owner or tenant for running the building.

Any other approach will take too much customization to ever really grow into a market. Anything that does not grow into a market will leave the needs unmet.