Sustainability

REhnu's ultimate goal is sustainable energy for the world: electricity from the sun harvested without CO₂ emission. In addition, our solar farms will use the minimum of raw materials, consume no water, and minimally disturb the land.

Electricity from the sun is sustainable, unlike energy from fossil fuel. By mitigating climate change, it promises longevity for species across the entire planet. Only 0.1% of the land area of the planet is needed to harvest enough sunlight to provide for all the planet’s electrical energy needs.

Payback time for energy and carbon used in manufacture

REhnu has adopted a technology that minimizes environmental impact. Our modules are designed for the minimum of materials used, energy consumed, and carbon released during manufacture. The dish reflectors and their tracking supports, the only components that must be large in order to collect the energy, are made almost entirely of glass and steel. These are common materials made already in huge volume by processes already well developed to conserve energy and to minimize carbon emission. Our design is configured to use as little of these materials as possible, the minimum needed to survive high wind and hailstorms. The unique spaceframe design of REhnu’s generators has the highest structural efficiency of any design. While the photovoltaic cells in the receivers do use some environmentally sensitive materials, they do so in tiny quantities compared to conventional PV panels, because they are 1,000 times smaller.

REhnu’s modules are optimized for minimum mass per kilowatt of peak power output. The total mass of all materials in a complete 8 reflector, 20 kW module, including the steel foundations, is 3.2 metric tons, for a specific mass of 160 kg/kW. More than half the mass, including the foundation, is in the 2 tons of steel, i.e. 100 kg per kilowatt of power produced. The payback time for the energy used in making the steel is 5 months, while the CO2 emitted in its manufacture is paid back in 3 months, assuming the electricity produced replaces that from a coal-fired plant. For the next heaviest material, the glass at 40 kg/kW, the total payback time for both energy and CO2 is 2 months. The mass of aluminum in a module is minimized to one tenth that of the steel, by transferring heat mostly by liquid coolant. Nevertheless, because aluminum manufacture is energy intensive, its payback time is similar, totaling 6 months.

The energy used and carbon dioxide emitted to make all the materials and to manufacture, transport and install REhnu’s farms will be paid back in two years. This is less than for most other forms of renewable energy. Since the productive lifetime exceeds 20 years, the net gain is significant.