There Are No AC Outlets on Spaceships

Why?

Because the people who design spaceships are the best and brightest technical minds on the planet. They are imbued with common sense and practicality. They know that collecting, storing, and deploying electrical energy to useful work is most efficient in the DC realm. This may seem like a trivial point. But I don’t think it is. In my opinion, the public’s lack of awareness is costing trillions of dollars in misdirected subsidization and costing humanity decades, at least, of carbon abuse.

I’m not smart enough to be a spaceship designer. But in 2018 I retired from a career as a pretty good automation engineer. Over the next few years, I designed a small building as a micro “energy sufficiency” laboratory. The objective was to use locally harvested and stored solar energy as the primary source, then to use that energy as efficiently as possible for electrical work. The grid served as primary backup, and a generator as secondary backup. All design choices focused on what was needed to learn the most, unconstrained by economic incentives for steerage. So, I spent a lot. As you can imagine, this sounds a lot like a prepper’s hideaway. I am off grid at the flip of a switch. My neighbors think I’m nuts.

But what I’m learning is potentially profound.

The most accessible alternative energy for casual users is solar. The more adventurous may also consider small wind. Both solar and wind are correctly characterized as abundant, expensive, and intermittent. The current approach imagines disperse collection points of varying scale connected via a nationwide grid linking these sources to intermittent users, households and businesses. Batteries equip both suppliers and users to adapt to periods of shortage or surplus. Such a system can offer real-time pricing, creating market forces to rationalize production and consumption choices. Consumer behaviors will likely have to change for it to work.

With this approach, melding AC distribution (the grid) with DC storage (batteries), and DC photovoltaic output (the intermittent solar source) is unavoidable. This is as inelegant as it is wasteful. For the last five years, roughly 15% of the energy that my system produced or purchased has been wasted. There is broad variability over shorter periods, from 12%-22%, depending on factors both controllable and uncontrollable. But the waste is nearly evenly split between battery and conversion losses (AC to DC and vice versa). The nameplate performance of my equipment anticipates 7-8% losses for both battery and conversion, so my cumulative loss of 15% is rational.

This understates the inherent waste in the grid approach. A less obvious source is that the old, fragile grid was not conceived for this purpose. The required upgrades are expected to take decades and hundreds of billions of dollars. This will require unmeasurable quantities of concrete, steel, copper, and other materials – all of which will be refined and installed with the fossil-intensive energy of today. Such investments are applauded as socially beneficial infrastructure development. I contend it is a vast waste of resource compared to more immediate, and cheaper, alternatives.

My system was designed to measure and inform. I tinker with it a lot. Now informed, I am confident that much better alternatives exist to provide more abundant, durable, reliable, and efficient electrical power than is even conceivable with our grid-centric approach. This concept begins by designing waste out of the system at every step. To our detriment, this basic principle is being largely overlooked in our zeal to centralize control of the energy delivery system. We need to think more like spaceship designers and less like utility operators.

Here are some relatable examples.

Lighting

The typical 60-watt incandescent bulb can be replaced by a 6-watt LED with equivalent illumination. Many of us have likely replaced our old bulbs with “forever” LED bulbs that screw into the same sockets or connect to the same wiring boxes. Some of us have also been disappointed when we discover that those “forever” lights fail and it is not worth figuring out how to claim the warranty replacement. There is a simple reason. In conventional homes, the light fixtures are powered by 120VAC delivered over #12/2 Romex cable (or equivalent). The innards of the LED bulbs operate at much lower voltage and are most efficient at illumination if provided with DC. Every replacement bulb has electronics to make that adaptation. That in turn creates wasteful heat, which deteriorates the bulb.

If you were designing a spaceship, you would never do this. You would provide the same amount of light while simplifying the bulb to exclude conversion electronics. You would eliminate the connection box (either steel or plastic) that supports light fixtures and houses electrical connections. You would use smaller and lower voltage cabling to deliver DC directly, dramatically reducing both the copper and plastic content of the wiring. If these sources of waste were eliminated at scale, lighting in home construction would be cheaper and better.

Interestingly, this isn’t even developmental. My structure includes 40 LED bulb-less fixtures. My connections are made with CAT6 cables instead of Romex. (For reference, CAT6 cable weighs about 60% of what #12/2 Romex weighs, testifying to the fact that less material is used.) My technology is called Power-Over-Ethernet (“POE”), but there are less complex options. In five years, I have not replaced a single fixture. I expect I never will.

Batteries

To date, less than 15% of residential solar installations include local bulk battery storage. That number is increasing, which is good. This doesn’t include additional storage by directly charging EV batteries, which is also good. “Good” because the native output of solar panels is DC, so no conversion is required to directly charge a local battery. EV’s recover that power directly for mobility, realizing only the battery losses, which again is good. However, to recover battery power for conventional household use requires it to be “inverted” (converted into AC). Inverting loses at least 5% of the energy in addition to the battery loss, so at best only 90% of the photovoltaic source power can be delivered to an AC outlet.

This is worse when batteries are grid-tied with no alternative local source. For example, imagine all the net-metered, roof-top solar installations are producing surplus. To use a remote, grid-tied battery, that power must be inverted, transmitted across the grid to the battery location, then “rectified” (turned back into DC) to be stored in the battery. Later, when the power is recovered from the battery to perform useful work (for other than EV’s) it must be “re-inverted” to power the household outlets. That is three conversions plus battery losses. If each of those processes incurs a 5-6% loss, which is optimistic, only about 80% of the source power is available for useful work. Less given that grid efficiency is not perfect. Worse than this, though, is that 60% of grid power is still supplied by fossil sources. This means that in the normal course, 60% of the energy to charge an EV or other battery is largely by burning fossil fuels. Even more if the charging occurs at night. That makes no sense.

A spaceship designer would assure that any available power was either used immediately for useful work or stored in a battery. Power generation and battery capacity would be coordinated to equip the useful work even when the power source was unavailable. To get the most out of the battery, all useful work would be done by DC devices. This eliminates all the waste associated with conversion and transportation. Also, a spaceship designer would rarely, if ever, burn precious rocket fuel to charge batteries!

Again, this isn’t developmental technology. My customized system to collect and store solar energy is over five years old. My system has operated for days without needing grid power. But when such backup is needed, my generator can seamlessly manage the load without wastefully charging the batteries. There are now more and better fully integrated choices than when I designed mine. DC devices for heating, cooling, refrigeration, lighting and other purposes are already used in industrial, marine, and mobile applications (maybe including spaceships?!?). Wind, an alternative that I haven’t implemented, can generate with equal efficiency in AC or DC.

After my five years’ experience, I conclude with high certainty that energy self-sustaining homes and communities are a much better idea than the grid-reliant option we are taking. It would be just as safe and at least as reliable. It would be inherently less wasteful. In theory, it could be done more quickly because it wouldn’t rely on the build-out of infrastructure.

So why aren’t we doing this?

One impediment is regulation. Developers build their buildings to “code.” Right now, building codes typically anticipate connection to a grid power source and provide a script for safe distribution from that point. To build my structure, I had to work with the local engineering authority to make allowance specifically for what I was doing. As a society, we want such codes, but they inherently discourage this type of innovation.

Another impediment is commercial readiness. Architects, electricians, retailers, and manufacturers do not have depth or scale to offer robust services or hardware options. If you call an appliance store to order a DC washing machine, they won’t know what you’re talking about. There are a small number of specialty suppliers who can provide a very limited number of SKU’s of some things. But until there is some type of demand, the supply community will remain on the sideline.

Those impediments could be overcome, except for the fact that an exclusive alternative is heavily subsidized. Wind farms, solar farms, net-metering, etc are the alternative means of generation. EV’s and battery banks are the storage. Now having been subsidized into existence, to serve a decarbonizing purpose, they rely on grid distribution which is known to be insufficient for the task. So what is the natural next step?

I’m not a huge fan of subsidies and mandates, even though I understand our impulse to provide them. I find it ironic that this is the second time in my life that we have attempted to subsidize an end to fossil fuels. The first was the ethanol subsidy beginning in 1978, answering the Arab oil embargo. It didn’t work. But it did create an industry that I’m not sure we’d miss if it disappeared.

The current panacea is a continent-scale grid tying together every household and business with every scale of energy source with robust storage. A political dream. Even if it works, it will still require the generation scale of fossil and/or nuclear sources. It will be vulnerable to the malevolent forces of nature and humanity. It will require intense administration. This is far from a “free” market.

It will be a monolith. In fifty years, we will wish we hadn’t done it.

Instead, we should invest those decades on a more durable and reliable approach. DC microgrids for neighborhoods with local collection, storage, and backup generation are all technically feasible right now. It doesn’t need a $10B Manhattan Project, just commercial mass. Literally, pilot communities could be designed and built right now. This could come from private investment if not for countering subsidies that indirectly steal the opportunity by stubbornly forcing #12/2 Romex to deliver 30 Amps of 120VAC to every light fixture and outlet even though it’s not needed. We could consume fewer of the earth’s resources while providing for better living. If we are going to subsidize something, it should be to waste less. Just like we do in spaceships.