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Because of the limited resources available to a seastead, special consideration is needed when choosing appliances. While the below is neither an exhaustive set of appliance types nor of possibilities for each appliance, we believe that it demonstrates the widespread availability of power and water efficient solutions. Similar choices can be made for other “modern necessities”. Note that we’ve chosen to structure this as a discussion of appliances and their replacements (ie “hot water heater” rather than “hot water”), rather than a provision of services.
Because the seastead has a huge thermal mass and floats on the water, temperature extremes will be moderated. Some heating may still be required, depending on season and location. We have a variety of possible heat sources. We can burn fuel, such as diesel, hydrogen, alcohol, or propane, or we can directly convert electricity that we have stored or generated into heat. While getting heat from the sun is a technology as old as the earth, being able to turn wind into heat is a nice improvement.
We can also use the traditional techniques for energy efficient heating to reduce energy costs. Have a lot of insulation, use efficient windows, face them south, store heat during the day, and trap it at night. The environments that a seastead expects to be in, the cost of energy, and the cost of such techniques will dictate whether they are used.
An additional source of seastead heat is waste heat from diesel generators, inverters, batteries, anything else that generates heat as power-loss. Heat exchangers can be used to scavenge this, which increases the effective efficiency of the appliance.
Cooling is unlikely to be a big problem on a seastead for the same reasons as heating: temperatures will be moderated by the thermal mass of the ocean and the seastead. There are a lot of ways to cool seasteads without using power-hungry air conditioners.
Cooling is easier than heating because we can tap a large source of available coolness. We’re not talking about our nation’s teenagers, but about ocean water several hundred feet below the surface. An intake can be placed on the submerged buoyancy portion of the structure, and the only power cost is for pumping. The energy can be partly recovered by running it through a small turbine on the way back down. it’s probably worthwhile having this turbine because there are a number of other circumstances under which we’ll be draining water from the platform, and we might as well get some energy out of it.
Evaporative cooling with a device called a swamp coolers is another interesting low-energy method. Air is sucked through wet pads, causing the water to evaporate and the temperature of the air to drop. The result is a breeze cooler than ambient air temperature which only requires electricity for the fan and a supply of water. The process is depicted in the flash animation below:
Animated GIF for those w/o Flash
Image courtesy of Opalcat, from her Swamp Cooler page.
If saltwater is used, minerals will quickly build up on the pads (scaling). Frequent rinsing in fresh water may alleviate this, and it may or may not be worth using salt depending on how much fresh water is available. Another potential difficulty is that swamp coolers work poorly when humidity is high, which is usually the case over the ocean. Despite these disadvantages, the efficiency of evaporative cooling makes it a strong contender when conditions are appropriate.
{Swamp Coolers are really neat, but humidity over the ocean is always very high so I think they may be no good for us. This section may be removed - P}
There are a number of possibilities for refrigeration. It is important to do a good job, since the refrigerator must keep food cold 24 hours a day. In a standard kitchen, it uses more energy than any other kitchen appliance - around 5 kWhrs/day.
Conventional refrigerators are extremely inefficient. Since electricity is cheap, most people buy a refrigerator based on its color and shelf arrangement rather than its efficiency. Some fridges actually have heaters in the frames to prevent moisture from collecting on the seals and generating mildew. The “frost-free” systems are basically heaters that briefly bring the air in the freezer compartment above freezing to remove the frost. The heat from the compressor and condensor flows past the refrigerator as it escapes. Convenient, yes. Efficient, no.
While some of the commercially available energy-efficient refrigerators are not much better, others like the Sun Frost line use less than 1 kWhr per day. Its hardware is on top, so the heat produced escapes away from the fridge. Good insulation is also very important to reducing the energy requirements.
Strange though it sounds, solar heat can actually be used directly for refrigeration. The secret is an absorption refrigeration cycle discovered in the mid 1800s. A mixture of ammonia and water is heated in one area, and the ammonia evaporates, moves to another area, where it is cooled and condenses. When the liquid ammonia evaporates, it cools the surrounding area. This is an external-combustion system which can use any heat source for power.
The method was used in an icebox cooler called the Crosley Icyball sold in the 1930’s [IcyBall]. The same principle was behind a recently-built solar icemaker, described in Home Power magazine. It used a parabolic trough reflector to focus sunlight onto a tube filled with ammonia. During the day, it charges, and at night, it produces cold which can be used to make ice [SolarIce].
Like many renewable energy systems, this method has the advantage that it requires almost no maintenance and will work forever. 70-year old Crosley’s found in antique stores are often still functional. It uses the sun directly, and fairly inexpensively, both of which are useful. Other heat sources (like stored fuel) can be used on cloudy days. One drawback is that ammonia is a nasty gas, but a well-designed system should be safe.
We can heat our water through a number of means, including passive solar heating, burning fuels, electric heating, and capturing waste heat when it is available. Passive solar heating is likely to be the most efficient method, supplemented by other energy sources when necessary. Being a direct solar method, this is a great way to use solar power. If space onboard is at a premium, floating passive solar water heaters can be deployed. The disadvantage is pumping costs, however it may be possible to transfer heat through convection.
An important part of the hot water system is insulation. The tank itself should be very well insulated, as should the pipes. A significant amount of the energy in a conventional hot water system goes into warming up the metal pipes, which is inefficient and wcan be avoided.
Cooking is a very energy intensive activity - 1000-3000 watts for a burner, 2500-5000 for an oven, and one which is often done by many people at the same time. Thus it represents the toughest kind of load for an energy system. Indeed, many home power systems find that food preparation is their heaviest load of the day. As is often the case, we have a variety of energy sources to choose from, solar, electric, fuel (hydrogen, propane, alcohol). Because it’s such a high load, we may wish to cook with stored fuel rather than electricity. This fuel can be imported or generated by our power system (hydrogen through electrolysis).
A disadvantage to traditional stoves is that they lose a lot of heat (think about how hot a kitchen gets). Not only does the air carry away energy, but you’re heating up a big metal pan along with your food. Microwave ovens waste much less energy, since the radiation bounces around until it’s absorbed by the food. For slow cooking, crock pots (which are well-insulated) lose less heat than a big pot on the stove. Unfortunately, these methods of cooking are not suited to nice meals, so we still expect seastead kitchens to be warm on occasion.
Second, cooking requires a very large amount of power and many people tend to do it at the same time. Thus it represents a difficult drain on any energy system. Our proposed solution is to generate hydrogen through electrolysis, which can be done efficiently with commercially available units when there is excess electricity. The hydrogen is then burned in a stove. As discussed in the fuels section, hydrogen is quite safe. This gives us an alternative method of energy storage, which is useful.
An oven is a box for holding heat. Modern ovens do a poor job of this (warm kitchens again), and thus need heat constantly poured into them. If we just insulate the oven, it will require a lot less energy. Any method can be used to provide the needed heat. Conventional ovens only have the heating element on 20% of the time
As usual, there is the conventional way and the energy-efficient way. Conventional washing machines use 100-230 liters of water per load. When this is hot water, heating costs are a large part of the total energy use. The Staber washing machine uses only 110 to 150 watt-hours and 45 L water per load [Staber]. This is a little high, but not too bad. The reduced water use has a big impact on energy because it means reduced hot-water use. 2 loads / person / week would be a negligible increase in energy expenditure (+0.04 kwhrs/day) but a significant increase in water use (+13 L/day). We can generate that water from Reverse Osmosis with 0.17 kWh/p/day of electricity. So a total of 0.21 kwhrs/person/day does 2 loads a week (not counting water heating energy). That’s well in line w/ our power figures. Another interesting technology is ozone injection. Ozone serves as a better replacement for bleach, works well in cold water, and leaves no chlorine residue. Seasteaders probably won’t do laundry as often as on land, this goes with being a pioneer.
There are extremely energy-efficient dryers, such as the Spin-X, which works by spinning clothes very quickly to extract water with centrifugal force. The manufacturer claims that 2 minutes in it is equiv. to 30 minutes in a normal drier. Uses 25 watts for a 3 minute load - not sure if this means 25 watt-hours, or 25 continuous watts which is 1.25 watt-hours, but either way it’s negligible. The Spin-X does not get clothes dry enough to replace a traditional dryer, but a much shorter dryer run is then needed [CET].
Alternatively, clothes can be dried the old-fashioned way, by being hung out on lines. One potential worry on a seastead is that they could potentially pick up a little salt spray. Also, they’ll dry very slowly because of the high humidity. Given the low energy costs of the spin dryer plus a short heated drying cycle, line drying will probably not be necessarily.
High-efficiency dishwashers such as the Fisher & Paykel Dual DishDrawer use about 20 L/load, while normal dishwashers use about 40L. As energy-efficient appliances go, this is a pretty small improvement, but it’s still not that much water. Much of this water much be hot, which uses additional resources, but we can get hot water with reasonable efficiency through passive solar installations. Another problem is that one way that efficient dishwashers save energy is by using air drying instead of a heat drying cycle. Unfortunately in our humid environment, air drying may not work very well - seasteaders may need to get out the hand towels and dry dishes the old-fashioned way. A clever dehumidification technique would also help - perhaps a solar dehydrator which converts humid air into water and dry air. The humid air could simply be run through a condenser using ocean water for cooling.
A vacuum cleaner is a good example of an appliance with an extremely low duty cycle. It may not be very energy efficent, but that doesn’t matter. Portable floor vacuums use about 500-1000 watts. If each person vacuums for an hour a week, that’s a negligible 0.1 kWhs/week. Similar appliances include power tools (drills, sanders, lathes, saws), ???
There is a large range of energy efficiency for lighting. Three technologies worth mentioning are incandescent lights, fluorescent lights, and Light Emitting Diodes (LED’s). Fiber optic light distribution systems are interesting as well.
Incandescent Bulbs
Incandescence was the first electrical lighting technique invented. We think of incandescent bulbs as electric heaters which happen to make a little light. Their efficiency is only 10%, and they last only 1,000 hours. Halogen bulbs are a more efficient, longer-lasting type of bulb, but they still produce a lot of heat.
Fluorescent Bulbs
Fluorescent bulbs have been used for awhile, although only recently in the home market due to the arrival of the compact fluorescent form factor. They are 4-5 times more energy efficient and last 10,000 - 20,000 hours. While they are more expensive, but their cost is well worth the gains - especially on a seastead where energy is expensive. Unfortunately, these bulbs contain lead and mercury, and thus must be treated as hazardous waste or they will pollute the environment.
Light Emitting Diodes
LED’s are a newer technology from the solid-state electronics field, which have only gotten cheap and bright enough to be used for large-scale lighting in the past decade. Large numbers of traffic lights, for example, have switched to LED’s in the past few years. Because they last so long (100,000 hours), they are the clear choice for locations where replacing bulbs is very difficult. Colored LED’s are about as efficient as fluorescent bulbs, but white ones are only half as efficient. Still, future LED’s will be more efficient that fluorescents. Unlike fluorescents, LED’s do not contain poisonous chemicals.
In the table below we can see the efficiency of each type in terms of how many lumens per watt it produces, as well as the lifetime of the bulb. Cost for the bulb is given per kilo-lumen-year, and electricity cost for the same period, assuming $0.20/kWh. In general, electricity cost dwarfs bulb cost, so efficiency is quite important.
Lumens/Watt Lifetime (hrs) Bulb cost/k-lumen-yr Electricity/k-lumen-yr Total cost/k-lumen-yr
Incandescent 15 750-1,000 $7 571 kWh $121
Fluorescent 60 10,000-20,000 $14 143 kWh $43
LED (white) 25 100,000 $500 350 kWh $570
As you can see, the inefficiency of incandescents and the high cost of LEDs make fluourescents the clear choice. LEDs work well in places where only small points need to be lit, such as emergency lighting strips. They are also better when colored lighting is acceptable, as colored LEDs are cheaper and more efficient.
A neat technology being developed for lighting is the use of fiber optic cables to move light around. These cables are like wires, except they transmit light. One method for using them is a system like the Himawari, which gathers sunlight with lenses, then transmits it via fiber optic cable to wherever needs lighting [Himawari]. This lets us transmit natural sunlight (with UV conveniently attenuated by the system) to deep interior area of the seastead. Another method is to have a main central lamp, and fiber optic cables running to “power” other lamps. So fewer bulbs are needed, and they can be very efficient ones. The main advantage is the elimination of a lot of electrical wiring. This reduces the possibility of fire or electrical accidents as well as requiring less labor to install. it’s especially convenient for ferro-cement structures which don’t have hollow walls to put utilities in. However, this is a new technology and it may not be suitable for seastead use.