Robotics: A vegetarian robot that forages for fuel and runs on steam power would have a range of military and civilian uses
A ROBOT WITH DIETARY REQUIREMENTS might sound a bit far fetched, but a team of American researchers is developing a machine that will fend for itself by gathering biomass (wood, leaves and grass) to be used as a biofuel to run its steam-driven engine. Who might want such a device? The American army.
The Energetically Autonomous Tactical Robot is known, of course, by its acronym: EATR. It is the brainchild of Robotic Technology of Washington, DC. So far it is only a concept, but a working prototype is in the works. The research, in part funded by America’s Defence Advanced Research Projects Agency, is seen as a way to help soldiers reduce their dependence on fuel supplies. The robot could, for instance, forage for biofuel while a unit on a long-endurance mission rested. It could then be used to recharge their electrical devices, carry some of their equipment or even transport the soldiers.
The EATR uses a robotic arm to gather and prepare vegetation, which it feeds through a shredder into a centrifugal combustion chamber, where it is ignited and then heats a series of coils. The coils contain deionised water (to stop them from furring up like a kettle). As the water inside the coils is superheated the steam is piped to a radial steam engine, which consists of six pistons. The steam drives the pistons, turning a generator which produces electricity. This is stored in batteries that power the electric motors which drive the EATR along.
The steam engine is designed to be a “closed-loop” system, in which water escaping from the cylinders through the exhaust valves is captured and cooled in a condensing unit. This turns the steam back into water, which is then returned to the combustion chamber. As well as using biomass, EATR’s engine could also run on petrol, diesel, kerosene, cooking oil or anything similar that could be scavenged. The ability to consume a wide range of fuels would be important if the vehicle found itself in areas like deserts, where vegetation may not be available and alternative fuel would be needed.
Image-recognition software linked to a laser and camera would allow EATR to recognise plants, leaves and wood. Robert Finkelstein, Robotic Technology’s president, estimates that about 68 kilograms (150 pounds) of vegetation would provide enough electricity for the machine to travel around 160km (100 miles). The company recently received EATR’s engine, which has been developed by Cyclone Power Technology of Florida. The next stage is to integrate the EATR technology into a military vehicle to prove that the idea works. The type of vehicle that will be used has not yet been decided, although it could be a High Mobility Multipurpose Wheeled Vehicle, popularly known as a Humvee, modified to drive itself under robotic control. Dr Finkelstein thinks an EATR prototype could be scurrying around woodland by around 2013.
Such a machine would be extremely useful for the army. With no dependence on external fuel supplies, an EATR would be able to perform long reconnaissance missions in areas which might be deemed too dangerous for soldiers to venture. There are also civilian applications, such as a forestry patrol over large swathes of territory where traditional fuel may be hard to find, but where there is plenty of biomass to keep the EATR going. An agricultural version might navigate around farmland, checking for weed and insect infestations, and feeding itself as it went. It would be a return, in a way, to a time when old-fashioned steam engines once worked in the fields.
This article was first published in The Economist in June 2010.
Energy: Laser beams can deliver energy to machines through thin air. This might be a good way to power drone aircraft or a space elevator
THE PELICAN, a small, remotely controlled helicopter drone weighing less than a kilogram, is powered by a battery that provides about 20 minutes’ flying. And yet, one evening in October 2010, the Pelican took off, rose ten metres and hovered throughout the night. It was brought down in the morning only because the exhibition hall near Seattle, where it was airborne, was about to open for business.
This remarkable feat was achieved with the ingenious use of a laser beam. The laser, aimed from the ground at photovoltaic cells mounted on the Pelican’s underside, charged the chopper’s battery, keeping it aloft for an unprecedented 12 hours and 27 minutes. An optical-tracking system kept the laser beam on target, creating a “scientifically exciting, yet a little boring” experience, according to Michael Achtelik of the Pelican’s German manufacturer, Ascending Technologies, after a long night monitoring flight data.
Keeping drones aloft is not the only putative application of power beaming, as this technology is known. In 2005 NASA, America’s space agency, offered prize money to any team that could build a remotely powered robot able to climb quickly up a cable. Only in 2009, however, were the first of these prizes claimed, when three teams from America and Canada demonstrated climbing robots powered by lasers on the ground. LaserMotive, the Seattle company that designed the Pelican’s laser system, won $900,000 by powering a 5kg robot up almost a kilometre of cable dangling from a manned helicopter. LaserMotive’s beam struck a photovoltaic panel on the robot, generating electricity that turned a set of wheels gripping the cable.
Conventional photovoltaic cells, made of silicon, are designed to collect energy from sunlight. LaserMotive uses special cells made with arsenic and gallium, which are better able to capture the near-infrared wavelengths of its laser beam. The panel on the climbing robot, about the size of a coffee tray, harvested enough power to run a small lawnmower. One of LaserMotive’s founders, Jordin Kare, reckons that a similar laser could deliver about as much energy 20km up if the panel were only a few times larger.
One reason NASA supports power beaming is that it hopes the technology could be used to help run a space elevator. This is a machine, familiar from science fiction, which some engineers think could be made science fact. In essence, it would be a giant cable reaching tens of thousands of kilometres into space to an orbiting satellite. Cable-climbing robots, powered by laser beams shot upward from the ground, or downward from space, would take payloads to orbit. Rockets would thus become redundant. Indeed, Andy Petro of NASA’s technology office in Washington, DC, says power beaming might change the economics of space exploration completely. Lasers beamed from landing craft could, he says, power rovers in sunless areas of the moon or Mars, such as craters where water might be found.
Power beaming is also becoming more efficient. A few years ago lasers typically converted less than 40% of the electrical energy used to run them into beam power. The figure is now about 60%, and costs have dropped – the result of efforts to develop better laser printers, CD burners and even hair-removal devices. Moreover, engineers have worked out how to make laser beams more intense by using short lengths of optical fibre to narrow the beam. Such intense lasers are better suited to power-beaming because the cells that collect the laser light can be smaller.
The Pelican’s successful flight probably means that the first big application for power beaming will be supplying energy to drones. At the moment, most small drones rely on battery power, so their flights are short. LaserMotive reports that American army officials, including some responsible for special-forces kit, have expressed an interest in power-beaming systems for drones. DARPA, the American Defence Department’s technology agency, is also sponsoring research into power beaming. British readers of a certain age may remember that the spaceships flown by Dan Dare, Britain’s answer to Buck Rogers, were powered by “impulse waves”, beamed from Earth. That piece of science fiction, too, may prove not to have been quite so wide of the mark.
This article was first published in The Economist in March 2011.
Clean technology: Finding alternative sources of energy is becoming a pressing military necessity for America’s armed forces
THE AIR AROUND Bagram airfield, the main American base in Afghanistan, is thick with the smell of jet fuel, the roar of aircraft taking off on bombing missions and the constant drone of electricity generators. Outside the ramparts, a snakelike convoy of brightly coloured lorries waits to unload fuel hauled from Pakistan and Central Asia. These are the modern equivalents of the pack mules that once carried military supplies – much of it fodder for the beasts themselves. The British army calculates that it takes seven gallons of fuel to deliver one gallon to Afghanistan.
Modern warfare would be impossible without vast quantities of fossil fuel. It is needed to power everything from tanks to jets to electricity generators that run the communications networks on which Western armies depend. In the punishing climate of Iraq and Afghanistan, moreover, soldiers’ accommodation must be kept cool in hot weather, and warm in the cold. American forces consume more than 1m gallons of fuel a day in Afghanistan, and a similar quantity in Iraq.
Until recently military planners had assumed that fuel would be plentiful and easily available. A Humvee with added armour does just four miles per gallon; an Abrams tank burns four gallons to move a mile, in some conditions. These days, though, America’s armed forces want to reform their gas-guzzling ways; green is no longer just the colour of army uniforms.
What has changed? During the invasion of Iraq in 2003, America’s marines often found themselves outrunning their fuel supplies. “Unleash us from the tether of fuel,” their then commander in Iraq, General James Mattis, later pleaded. As insurgency engulfed the Americans, supply convoys became a favourite target. In July 2006 General Richard Zilmer, the marine general then in charge of American forces in western Iraq, sent out an urgent request for solar panels, wind turbines and other devices to reduce the need for liquid fuels. His troops were being placed “in harm’s way each time we send out a convoy”, he said; protecting supply convoys was drawing forces away from other tasks. And in 2008 the spike in oil prices played havoc with military budgets: the Pentagon’s fuel bill rose from $13 billion in 2007 to about $20 billion.
So it is not a question of preventing climate change, reducing dependence on imported oil, or even complying with President Barack Obama’s green agenda. The need for alternative sources of energy is a military necessity.
In Iraq and Afghanistan about 40% of fuel is used to run electricity generators. A successful quick-fix to reduce energy consumption was to coat military tents with a thick layer of commercial insulating foam, of the kind used for cavity walls in homes, covered with a sealant to protect it from ultraviolet light. Joseph Sartiano, a Pentagon official, says this treatment halves the energy needed for air-conditioning and pays for itself within three to six months, depending on how the price of fuel is reckoned.
If the various generators on a base are linked together in a “smart grid” system, which optimises their operation and distributes power to priority areas, such as communications equipment, a further 20% saving is possible, he adds. Such a grid is being tested at the army’s model forward operating base (FOB) in Fort Irwin, California, along with prototypes of a mobile, hybrid power station that combines solar panels and wind turbines with a conventional generator. America’s marines are creating a smaller model FOB at their base in Quantico, near Washington, DC, to test systems for deployment in Afghanistan by mid-2010.
Another idea, already being tried out at Camp Victory, the main American base in Baghdad, is to convert rubbish into electricity. A battalion of about 500 men typically produces about a tonne of waste every day. A machine called the Tactical Garbage to Energy Refinery (TGER), heats solid waste to produce syngas (synthetic gas, a mixture of carbon monoxide and hydrogen), ferments food slops to produce alcohol, and chemically processes the two to make biodiesel that powers a generator. TGER produces as much as 64 kilowatts of power – enough to run the command post of a battalion.
Such measures should reduce the amount of fuel needed to produce electricity. Much of the Pentagon’s fuel goes to the air force, however, and reducing the consumption of jet fuel is much more difficult. The air force is working to certify all its aircraft to use synthetic fuels made from gas derived from coal or biomass, using the Fischer-Tropsch method used by Germany during the second world war. By 2016 the air force seeks to use a 50:50 blend of synthetic and ordinary jet fuel for half of its aviation requirements within America. But the shift towards synthetic fuel has provoked criticism, because when such fuel is made from coal and then burned in an aircraft engine, more greenhouse gases are emitted overall than would be produced if the aircraft simply burned conventional fuel derived from oil. Nor does it help reduce demand in war zones.
The American navy, for its part, is placing its faith in biofuels. It has tested a biofuel made from the camelina plant in its F-18 Hornet jet. Next it will test biofuels in ship turbines. It is also installing stern flaps on its amphibious vehicles that can reduce fuel use by 2–3%, and developing better coatings to prevent the growth of algae and barnacles on hulls that cause drag and increase fuel consumption.
In October 2009 the USS Makin Island, an amphibious assault ship, was the first of 12 hybrid-powered ships to take to the water. It saved nearly $2m in fuel costs on its maiden voyage alone. At slow speeds, it runs only on an electric motor powered by the ship’s auxiliary turbine. At higher speeds, the main turbine takes over. This is a step on the way to the navy’s ambition to develop all-electric ships. When fully dedicated to missile defence, some ships already devote 40% of their power to electrical systems, says Rear-Admiral Philip Cullom, in charge of the navy’s fleet readiness. “With an all-electric ship it will be a bit like ‘Star Trek’, in which the captain can order power to be moved to the weapons or to the engines,” he says.
For the foreseeable future, clean technology will flow mainly from the commercial to the military sector. But over time, new technologies, such as “blended wing” aircraft and new composite materials, may come out of military-funded laboratories. At the very least, the armed forces could act as crucial early adopters for costly new green technologies.
They are also promoting one important conceptual change: the pricing of fossil fuel. Liquid fuel ordinarily sells for $2–3 a gallon, but by the time it reaches a war zone the cost is much higher: about $15 for delivery to a big FOB in Afghanistan and as much as $400 to an outpost that, say, has to be resupplied by helicopter. This “fully burdened” cost of fuel is seeping into the calculations of military planners. It tries to capture the cost of military logistics, rather than environmental impact. But if military leaders are ready to put a more realistic price on fuel, perhaps other Americans will follow suit.
This article was first published in The Economist in December 2009.