· 14 min read
Piezoelectric floor
Piezoelectric floor in Tokyo (Photo: PIEZO BLOG)
The piezoelectric effect is a physical phenomenon where certain materials generate an electrical voltage when mechanically compressed or vibrated. This principle formed the basis for the development of piezoelectric floors, which can convert the energy of footsteps into electricity.
Piezoelectric elements are embedded under the floor covering, which are deformed under the influence of a person’s weight and generate an electric charge. This, in turn, can be accumulated in batteries or used directly to power low-power devices — from LEDs to sensors and Wi-Fi routers.
Piezoelectric floor concept (Photo: ResearchGate)
For example, one step of an adult can produce about 100–1000 μWh, and in a day, an entire floor with high traffic (train station, shopping center) can generate several hundred Wh. This is enough to power several dozen LED lamps or one CCTV camera, as well as charge about 50 smartphones.
In 2008, piezoelectric mats were installed near the entrance to the platform of a Tokyo station: with each step of a person weighing ~60 kg, about 0.1 W was generated for one second. This power was used to light festive installations and an LED screen that displayed data on generation in real time. A similar project was implemented in a London nightclub in 2009.
Piezoelectric floor in a London nightclub (Photo: NBC News)
Advantages
• Environmentally friendly: energy is generated without carbon emissions.
• Futuristic: innovative element of urban design.
• Modular: easy to scale, can be installed in a limited area or in an entire building.
Disadvantages
• High installation cost: one square meter can cost from $100 to $300.
• Low power: such floors are not enough to provide lighting or heating — they are only suitable for auxiliary functions.
• Wear: piezoelectric elements are subject to constant mechanical stress and require replacement after five to ten years.
Wave energy
Wave Energy Project devices in Perth, Australia (Photo: The New York Times)
Wave energy is a method of generating electricity that uses the kinetic energy of ocean waves. The most common technology for capturing it is buoys that move with the waves. This process activates a piston or magnets that rotate a generator and produce electricity. Similar installations have been operating in Spain, the UK and Australia for over a decade.
Wave power station in the UK (Photo: ResearchGate)
Advantages
• Reliability: unlike solar and wind energy, sea waves are more predictable and constant. In addition, the buoys are equipped with a “survival mode” during a storm: the generators are hidden under water or part of the cables are untied to reduce the load on the fastenings, and in calm conditions the station automatically returns to work.
• High energy capacity: 100–500 kW per buoy per day (this is from 2 thousand to 12 thousand kW⋅h) in good conditions — this is enough to charge up to 480 thousand smartphones.
• Scalability: from individual buoys to entire farms on the coast.
Computer image of a wave power plant (Photo: Civil Engineers)
Disadvantages
• Complexity of operation: the aggressive marine environment causes corrosion, fouling with shells and algae, which damages the equipment.
• Impact on the environment: buoys in coastal waters can disrupt the migration routes of fish and marine mammals.
Solar power tower
A solar power tower is an engineering solution that combines the principles of a greenhouse, a ventilation shaft, and a wind turbine. A transparent dome with a diameter of 100 to 1,000 m is erected around the perimeter, covering the ground. Sunlight heats the air under the dome. In the center of the structure there is a high tower (up to 1,000 m), through which hot air rapidly rises, creating a powerful upward flow. The higher the tower, the greater the difference in air pressure between its base (where the air is heated) and the top (where it is colder). This difference creates an intense flow, accelerating the air to a speed that is sufficient to rotate the turbines.
Solar power tower in Spain (Photo: Dutton Institute)
The turbines are located at the base inside the column: along the perimeter or in a ring structure. The air heated under the dome rushes up and passes through the blades, driving the generators. One of the most ambitious projects is the Buronga Solar Tower in Australia, 1 km high, which is designed for a capacity of 200 MW, enough to supply 50–70 thousand homes. It is currently in the development stage. Smaller prototypes were installed in Spain (height — 195 m) and were planned in the USA (800 m), but scaling was postponed due to high costs.
Solar power tower concept in the USA (Photo: New Atlas)
Advantages
• Low operational load: no moving parts at height, main mechanisms are located near the ground.
• Combined use: the area under the dome can be used for agriculture or greenhouses.
• Continuous operation: due to the heat capacity of the earth, the installation can operate even after sunset.
Disadvantages
• Very high costs: the construction of the tower, dome, cooling systems and turbines requires an investment of $500 million. For comparison: an average hydroelectric power station with a capacity of 100–200 MW costs about $150–500 million.
• Climate restrictions: a large plot of land and a dry sunny climate are required — the stations are not suitable for northern latitudes.
• Complexity of implementation: it is necessary to ensure resistance to wind loads, it will be necessary to design new cranes, conveyor systems and welding methods for the giant dome. In addition, construction is associated with high risk due to multi-year guarantees. Because of this, none of the mega-projects have been fully implemented yet, although small-scale models exist.
Geothermal greenhouse
Geothermal greenhouse in the USA (Photo: The Interfaith Center)
A geothermal greenhouse is a structure for year-round plant cultivation, in which the Earth’s internal heat is used to maintain a stable temperature and humidity. The design is based on a system of underground heat exchangers (round or U-shaped tubes) laid at a depth of 1.5 to 4 m, where the soil temperature remains almost constant (usually from +8 to +12 °C).
Geothermal greenhouse operation diagram (Photo: ATTRA)
Operating principle
• At a depth of 2–3 m, the soil temperature is stably maintained in the range of +8 °C to +15 °C, even when there is severe frost on the surface. A fan pumps cooled air from the greenhouse through underground pipes.
• As it moves, the air heats up, returns to the greenhouse and maintains the heat balance. This prevents extreme cooling to the outside level. For more heat-loving crops, backup heating may be required.
• Due to the heating of the air, it is simultaneously dried, which prevents condensation and the development of mold.
Advantages
• Energy efficiency: reduced electricity or gas consumption by 20–30% compared to conventional greenhouses.
• Stable microclimate: even temperature without strong fluctuations, which has a positive effect on plant growth.
• Seasonality: the ability to grow heat-loving crops in regions with a cold climate.
Geothermal greenhouse in the USA (Photo: Cowboy State Daily)
Disadvantages
• High investment: the cost of excavation work, pipes and control systems can be from $60 to $100 per 1 sq. m of greenhouse.
• Difficulty of installation: requires qualified geotechnical calculation of the depth and capacity of pipes, waterproofing and protection from root formation.
• Area: heat exchangers take up a significant area around the greenhouse.
• Limitations: rocky or water-saturated soil can complicate the installation of pipes and reduce efficiency.
Solar chimney
Solar chimney project for a private house (Photo: Maximus Center)
A solar chimney is a heating and cooling system that operates on natural air convection. The design is a vertical installation lined with materials that can absorb solar radiation.
Several solar chimneys (Photo: Natural Building Blog)
How it works
• Air heating: the sun’s rays pass through a transparent panel and heat the dark inner surface of the chimney.
• Convection: the warm air inside the shaft becomes lighter and rises, creating a draft.
• Circulation: due to the draft, fresh and often cold air is sucked through holes or special channels into the room, maintaining a constant air exchange.
• Cooling: the structure draws the warm air from the room out, creating a fan effect without electricity.
• Heating: with special panels and a layer of soil, a reverse cycle can be used — warm air is directed through the soil before being supplied to the room.
Advantages
• Minimal operating costs: no moving parts, completely passive.
• Environmentally friendly: no electricity consumption and carbon emissions.
• Simplicity: can be installed on existing buildings without major architectural changes.
Solar chimney in an experimental eco-house in the USA (Photo: Harvard HouseZero)
Disadvantages
• Seasonal dependence: efficiency drops significantly on cloudy days.
• Large dimensions: a high shaft (usually 15–20 m) is required for a significant air flow.
• Difficulties in regulation: without automation, it is difficult to maintain an accurate temperature and ventilation speed.
• Condensation: when the air inside the shaft cools sharply, moisture may form on the walls, which over time leads to corrosion or mold formation.
Disinfection by the sun
Solar Disinfection in Canada (Photo: Landscape Ontario)
Sun disinfection is a method of destroying pathogens, weeds and pests in the soil or on surfaces through the action of ultraviolet and infrared radiation from the sun’s rays.
The bed is covered with a film with high transparency to sunlight. A “greenhouse effect” is created under it: solar radiation passes inside, heats the soil or surface, and the heat is retained, increasing the temperature. During intensive heating, a black film is used: such a layer absorbs heat more strongly. Direct UV radiation damages the DNA of microorganisms, bacteria and fungal spores, which leads to their death.
Solar disinfection in India (Photo: Natraj)
A regular bed without film also heats up, but the heat quickly dissipates and reaches no more than +30°C — this is not enough to kill most pathogens.
Advantages
• Safety: no chemicals are used, and residual toxic substances do not accumulate in the soil and plants.
• Simplicity: minimal technological requirements and low cost of materials.
• Universality: suitable for any type of agriculture.
Disadvantages
• Seasonality: depends on the intensity of solar radiation and climatic conditions, so the technology is difficult to use in northern and cloudy regions.
• Limited effectiveness: not all pathogens die at temperatures up to +60 °C, some heat-resistant spores survive.
• Risk of destruction: heavy precipitation can tear off the film, which will disrupt the entire process.
• Soil structure disturbance: long-term coverage and high temperatures can kill not only pests, but also beneficial microorganisms, which will negatively affect soil fertility.
Light pipes
Light pipes are systems designed to transfer natural sunlight from the roof or facade of a building to interior spaces.
Comparison with conventional light (Photo: ResearchGate)
Working principle
• The collector (dome or flat) captures diffused and direct sunlight.
• A tube with reflective walls directs the light along the channel with minimal losses.
• A diffuser in the ceiling of the room distributes the light evenly, preventing glare.
Diagram of a light pipe (Photo: ExplainThisStuff)
Advantages
• Reduction in energy consumption: up to 100% natural light during the day, saving on electricity.
• Improved microclimate: natural light has a positive effect on well-being and performance.
• Versatility: light pipes are suitable for most types of roofs and buildings.
Disadvantages
• Weather-dependent: low efficiency on cloudy days or in winter.
• Light loss: the longer the pipe, the less efficient — every 3 m takes up to 10–20%.
• Limited control: without additional blinds or filters, it is impossible to regulate the light intensity.
• Risk of leaks: with poor installation, problems with roof waterproofing are possible.
Solar oven
Solar oven in Spain (Photo: Wikimedia Commons)
A solar oven is a portable device that uses a magnifying glass or special lens to focus the sun’s rays. They are collected in one point, and the concentrated energy heats food or boils water.
Solar oven from China (Photo: Made-in-China)
How it works
• The lens collects the sun’s rays and focuses them into a small beam, increasing the density of solar energy to 500–1000 W/m2. A conventional oven has a power of about 6000 W/m2.
• At the focal point, the temperature reaches from +200 to +500 °C, which is more than enough for frying, baking and boiling.
• The user adjusts the angle and orientation of the lens relative to the Sun to maintain optimal focus.
DIY Solar Oven (Photo: Reddit)
Advantages
• Completely autonomous: does not require fuel or electricity.
• Efficiency: cooking speed is comparable to gas stoves.
• Lightweight and portable: the standard weight of the unit does not exceed 2–3 kg, so it is easy to transport.
Disadvantages
• Weather dependent: only works in bright sunlight without clouds.
• Danger of burns and fires: concentrated rays can cause dry vegetation to ignite.
• Requires constant adjustment: it is necessary to regularly adjust the direction of the lens.
• Limited volume: cooking is possible only in small portions.
Home wind generator
Home wind generator project (Photo: WindCycle)
A home wind generator is a homemade installation for generating electricity from wind flow. It features a flexible configuration of blades, a generator, and a mounting system for specific user conditions. Its average power is about 3 kWh — enough to charge 50 portable batteries during the day.
Operating principle
• The blades capture the kinetic energy of the wind and set the rotor in motion.
• The rotor is connected to an electric generator.
• The generated alternating current is stabilized by a charge controller, after which it goes to batteries or to the household network.
Homemade wind turbine in India (Photo: Mongabay-India)
Advantages
• Design flexibility: can be adapted to specific tasks.
• Equipment savings: can be made from scrap materials and old generators.
• Educational value: the project is suitable for teaching the basics of renewable energy and engineering.
• Energy flexibility: reduces dependence on centralized energy sources.
Disadvantages
• Low reliability: homemade gearboxes and mounts can quickly fail.
• Noise and vibration: occurs due to improper blade balancing and a lack of anti-vibration solutions.
• Instability: energy depends on wind speed; requires a battery system.
• Maintenance requirements: regular lubrication, tightening of components, and inspection of the electrical system.
Home mini hydroelectric power station
Mini hydroelectric power plant project in the USA (Photo: Practical Survivalist)
A mini hydroelectric power plant is a low-power system for generating electricity from the kinetic energy of running water (river, stream or canal). Typically, the power of such a system varies from 100 W (powering 5–10 LED bulbs) to 20 kW (full power supply for a two-story country house).
Operating principle
• Water intake: through a water intake device (grate and sluice), water is directed to the impeller.
• Turbine: depending on the pressure and flow rate, different types of devices can be used.
• Generator: the turbine rotates an electric generator through a shaft, which produces alternating current.
• Control system: includes a frequency regulator, rectifier and inverter, which supplies power to the household network or batteries.
Home mini hydroelectric power station from the USA (Photo: Powersprout)
Advantages
• Stability: unlike the sun and wind, water usually flows relatively evenly, providing round-the-clock energy production.
• High efficiency: small hydro turbines can achieve efficiency of 80%.
• Reliability: with proper maintenance, the service life can exceed 25 years.
Home mini hydroelectric power station from the UK (Photo: GivEnergy)
Disadvantages
• High costs: land and hydraulic installation works, installation of a generator and automatic control system.
• Water resource requirements: sufficient pressure and water flow (more than 20 l/s) — a rarity in small rivers in summer.
• Environmental risks: channel change, impact on fish migration, need for approval from environmental authorities.
• Difficult mobility: the installation is stationary, so it is difficult to dismantle or transport when changing your place of residence.
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