July 2009 Archives

Under a major initiative to boost research in renewable energy, the Department of Energy (DOE) proposed to fund eight multi-disciplinary "Innovation Hubs" in next year's budget. Each "Hub" consists of research in the following areas:

• solar electricity
• fuels from sunlight
• batteries and energy storage
• carbon capture and storage
• grid materials, devices, and systems
• energy efficient building systems design
• extreme materials
• modeling and simulation

The hubs were explained more thoroughly in a DOE document:

"Each Hub will focus on a single topic, but with work spanning the gamut from (i) basic research through (ii) engineering development to (iii) partnering with industry in commercialization. Each Hub will comprise a highly collaborative team utilizing multiple scientific, engineering, and where appropriate, economics, and public-policy disciplines, working largely under one roof. By bringing together top talent across the full spectrum of R&D performers—including universities, private industry, non-profits, and government laboratories—each Hub is expected to become a world-leading R&D center in its topical area.

Further details of the DOE document can be found here.

It actually sounds amazing, but as exciting as it is on paper, however, it is now clear that the future of the $280 million request is uncertain. In fact, when it came time for the House to decide to fund the Hubs, they only gave one Hub any money at all (Basic Energy Sciences). But the ultimate fate of the funding for the Innovation Hubs will be decided in a conference committee that will convene after the Senate passes its version of the legislation.

Meanwhile, President Obama and his staff still support funding all eight hubs, though, and they released the following statement to that effect: "The Administration strongly opposes reductions in funding for the Energy Innovation Hubs... The Hubs will advance highly promising areas of energy science and technology from their early stages..."

Partisan politics aside, I can't seem to grasp what is going on here. What happened to funding "the next Apollo mission?" Why is this funding being pulled from research and development when it's needed most?

Can electricity come from evaporation?

Dr. Michael Maharbiz and his colleagues¹ like to think so. Their recently published article shows that a small amount of energy can be scavenged from water evaporating from a "microfabricated leaf." The idea was inspired by water transport in plants, to wit, the researchers noticed that "trees pump water hundreds of feet into the air without active pumps by maintaining a large negative pressure gradient across their vasculature," but harnessing this action for human usage is a difficult task. There have been other researchers who have used the evaporation of water to drive flow in microchannels, but none have used this concept to generate electrical power.

In their paper, Dr. Maharbiz's team presents the idea for what they call "energy scavenging from evaporation–driven motion." But where does the energy come from? As a liquid flows across a surface, there is evaporation, creating a gas–lquid interface. This interface can be thought of as a moving dielectric surface, changing the electrical properties of the fluid. There is a 1 µF capacitor embedded in the surface and as more fluid evaporates, there is a potential increase of 2-5 µvolts induced across that storage capacitor.

These gradients, Dr. Maharbiz notes, occur in many places including the surface of the skin during perspiration, near the surface of bodies of water, and at the soil–air interface.

¹Charge–pumping in a synthetic leaf for harvesting energy from evaporation–driven flows, Ruba T. Borno, Joseph D. Steinmeyer, and Michel M. Maharbiz, Applied Physics Letters 95, 013705 (2009).