Tag Archives: cars

Double-Decker Solar Cells Capture More Sunlight

Swiss engineers have demonstrated tandem solar cells layered so they can catch more of the solar spectrum, providing a route to cheaper and more efficient solar power. The cells are not yet ready for commercial applications, but could mark a major step forwards for renewable energy.

Traditional solar cells present engineers with a fundamental problem. The colors in sunlight are photons of different energies,but individual cells can only extract the same amount of energy from each photon, leaving designers with a choice. One path involves collecting high-energy photons and missing out on the majority of the Sun’s photons whose energy is too low. The alternative is to harvest a larger portion of the spectrum, but only get a small amount of energy from each photon, so that much of the potential of higher energy photons is wasted.

This problem can be resolved by placing different types of cells on top of each other, with the top layer catching high-energy photons while letting those of lower energy through to be captured by another cell below. Multi-junction cells that stack four layers upon each other have achieved 46 percent efficiency,but at prices notviable for most circumstances. An alternative path is to split sunlight with a prism so that each cell gets the light for which it is most suited.

Professor Ayodhya Tiwariis co-leader of a team at Empa-Swiss Federal Laboratories who have announcedin Nature Communicationsaproof of conceptfor a way to make the top cell cheaply enough for widespread use, while still letting most of the unused light through.

Tiwari’s version uses the new wondermaterialperovskitefor the top cell, with copper indium gallium diselenide below. Perovskite is a naturally occurring mineral that can also be manufactured for energy-collecting purposes. Although still not as efficient as the best solar cells, progress in perovskite materialhas happened far more rapidlythan any other solar material ever tried.

While most solar cells, perovskites included,require high-temperature manufacturing, greatly adding to the cost, Tiwari created the top layer at 50C (122F), opening up the possibility of very cheap mass production.

The test cells used perovskite crystals to collect 14.2 percent of the energy in sunlight, while letting 72 percent through. The cell below captured another 6.3 percent. The total efficiency of 20.5 percent is similar to the best commercial cells and nothing exceptional by laboratory standards. However, Tiwari claimed in a statementthat 30 percent efficiency is in sight for the cells made this way.”What we have achieved now is just the beginning,” he said.”We will have to overcome many obstacles before reaching this ambitious goal.”

Higher efficiency, even at the same price per watt, would makesolar energy more attractivewhere space is limited (such as the roofsof electric cars)and reduces the costs of installation and associated infrastructure.

Perovskite cells currently lack the durabilityof silicon crystals though, particularly when exposed to water, and this remains the biggest obstacle to their widespread use.

Read more: http://www.iflscience.com/physics/double-decker-solar-cells-capture-more-sunlight-0

Toyota releases fuel cell patents for royalty-free use to all


Toyota senior vice president of automotive operations Bob Carter on stage at CES 2015.
Image: Mashable, Christina Ascani

LAS VEGAS — Toyota just rocked the auto industry by announcing that it is opening to the public 5,680 of its patents related to fuel cell technology for royalty-free use.

Bob Carter, the company’s senior vice-president of automotive operations, delivered the news on Monday at CES, following an elaborate presentation that touted the strengths of its fuel cell vehicle, the Toyota Mirai.

There was a collective gasp from the audience after Carter’s announcement, likely because the decision could help jumpstart this area of the automotive industry, which is exactly what Toyota is counting on.

By eliminating traditional corporate boundaries, we can speed the development of new technologies, and move into the future of mobility more quickly, effectively and economically,” Carter said.

Just before Carter made his announcement, famed theoretical physicist Michio Kaku delivered a speech about the future of technology in general, as well as the future of cars as represented by the Mirai. (For fans of Kaku, it was both a treat to see him, but also a slight letdown that one of the leading minds behind superstring theory is promoting cars — no matter how futuristic those cars may be.) All in all, Toyota’s point was clear: It is focused on future tech, and the Mirai (Japanese for “future”) is a big part of that focus.

Toyota Fuel Cell event at CES 2015

Dr. Michio Kaku on stage at CES 2015.

Image: Mashable, Christina Ascani

For many, Toyota’s patent announcement will bring to mind Tesla’s 2014 decision to make its electric-vehicle technology open to competitors. It’s unclear what this new approach to patents means for the automotive industry, but when a major company like Toyota follows Tesla into the royalty-free patent space, it suggests a clear trend toward greater openness.

“The first generation hydrogen fuel cell vehicles, launched between 2015 and 2020, will be critical,” Carter said. “[Their launch will require] a concerted effort and unconventional collaboration between automakers, government regulators, academia and energy providers.”