Energy and Global Warming News for May 6: Refrigerated by sunlight; Floating deepwater turbines show promise

Sunlight With Cooling Factor

Although it sounds like a contradiction in terms, using the power of the sun for refrigeration is proving to be an original energy concept. In Tunisia and Morocco, Fraunhofer research scientists are using solar energy to keep perishable foodstuffs such as milk, wine and fruit fresh.

“Refrigerated by sunlight” — we could well see an ecostatement like this printed on food packaging in the years ahead. Solar energy is already being used to power air-conditioning systems in buildings, but now researchers also want to refrigerate fruit and other perishable foodstuffs using energy from the sun. Scientists from the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg are demonstrating that this is feasible in the Mediterranean region using the examples of a winery in Tunisia and a dairy in Morocco. In the MEDISCO project (short for MEDiterranean food and agro Industry applications of Solar COoling technologies) solar plants for refrigerating milk and wine have been installed in cooperation with universities, energy agencies and European companies. The project funded by the European Commission is run by the Polytechnic University of Milan.

“Our method is ideal for countries which have many days of sunshine and in remote areas where there are no conventional means of refrigeration owing to a lack of water and non-existent or unreliable energy sources. It is environmentally friendly and reduces the use of expensive electricity for conventional refrigerators to a minimum,” states Dr. Tomas Nº±ez, scientist at the ISE, listing the system’s advantages. “Refrigeration is always available when the sun shines, which means that it is produced at the times when demand is at its highest.”

Floating deepwater turbines show research promise

As deepwater oil drilling wrestles with a dramatic spill in the Gulf of Mexico, scientists are working to bring safe, reliable, around-the-clock power to market from deepwater wind turbines.

The federal government approved the first U.S. offshore wind project last week, the 130-turbine Cape Wind farm. That project, consisting of turbines planted on the seabed in shallow water off Massachusetts’ scenic Cape Cod, has spent years mired in controversy that has focused largely on aesthetics.

But a research team at Worcester Polytechnic Institute (WPI) is exploring the physics and engineering that could let turbines float on platforms 20 miles off the coast, where the curvature of the Earth would hide them from shore views.

The work, supported by a $300,000 grant from the National Science Foundation, began last summer and is focused on developing computer modeling tools and water tank studies to let researchers test how wave and wind forces would affect deepwater turbines.

“Deepwater wind is the next frontier,” said David Olinger, an associate professor of mechanical engineering at WPI and a principal investigator on the project. Farther offshore, the wind becomes more reliable than on land, where it often blows for just part of the day, he explained, so turbines could spin as much as 80 percent of the time. Offshore winds are also often stronger.

The turbines the team is looking at are generally 5-megawatt systems, more than half again the size of typical land-based turbines used today and big enough to power about 500,000 typical homes. The turbine assemblies would be floated in water more than 200 feet deep.

Olinger said his project is doing “fairly fundamental work” to quantify how a wind platform will respond to particular wave and wind patterns. It is developing computer models that will predict how systems will respond to waves of a certain frequency and size, and will test those predictions using scale models at a nearby water flume test facility.

Rich farmers still reaping most federal money

Despite promises that the 2008 farm bill would direct federal money toward struggling small farms rather than the wealthiest farmers, the proportion of payments going to those farmers was virtually unchanged last year, according to a new report based on Freedom of Information Act requests to the U.S. Department of Agriculture.

The database of farm payments, released today by the Environmental Working Group, shows that 10 percent of farmers received 62 percent of federal farm payments last year, the same percentage as in the previous two years.

“They are well dug in,” said Ken Cook, president of the Washington, D.C.-based advocacy organization. “They have a strong interest in defending the status quo.”

House Agriculture Chairman Collin Peterson (D-Minn.) and former Senate Agriculture Chairman Tom Harkin (D-Iowa), the two head negotiators of the farm bill, declined to comment through their spokesmen. Sen. Blanche Lincoln (D-Ark.), Harkin’s successor, said only that the bill “made great strides to improving farm programs.”

Is China making empty threats on energy targets?

China’s premier Wen Jiabao delivered a big speech on Wednesday urging all levels of government to work with an ‘iron hand’ to improve energy efficiency. This came after official data showed the country’s energy intensity actually increased in the first quarter of the year “” by 3.2 per cent “” despite its pledge to reduce energy intensity by 20 per cent between 2006 and 2010.

China’s new ranking as the biggest greenhouse gas emitter, and its reluctance to commit to binding carbon emissions targets, make its ability to meet its own energy targets extremely important. And so far, the showing is not good “” despite the praise heaped on China in the lead up to Copenhagen.

According to a China Daily article, Wen said in March that country’s energy fell by 14.38 per cent  between 2005 and 2009. If they have risen already this year, that makes achieving the target by the end of this year look rather challenging. So, Wen reportedly announced new measures on Wednesday.

China First-Quarter Energy Use Per Unit of GDP Rises

China, the world’s fastest-growing major economy, used 3.2 percent more energy per unit of gross domestic product in the first quarter, adding to pressure to cut consumption for the rest of 2010, Premier Wen Jiabao said.

“Rapid growth” in industries including power generation, steel, nonferrous metals, construction materials, petroleum and chemicals increased China’s consumption of energy, Wen said in a statement published on the Ministry of Industry and Information Technology’s website today.

China cut energy use per unit of GDP by 14.38 percent between 2006 and 2009, and plans to reduce consumption by 20 percent in the five years to 2010. The economy expanded 11.9 percent in the first quarter, the fastest pace in almost three years, boosting consumption of electricity, oil and coal.

The first-quarter growth in energy use “greatly increases the pressure on the last three quarters,” Wen said. The government wants industries including steel, cement and coal to reduce overcapacity and cut pollution, the State Council, or Cabinet, said yesterday.

13 Responses to Energy and Global Warming News for May 6: Refrigerated by sunlight; Floating deepwater turbines show promise

  1. Mike Roddy says:

    I’m interested in hearing how the floating wind turbines can be cost effectively designed to avoid being tipped over in storms. If that is possible, this could be a great technology.

  2. Doug says:

    Mike — maybe they could just let them tip over, at least a bit. Probably don’t want to let the blades touch the water and get hammered by storm waves, but otherwise, what’s the harm in letting it tilt 45 degrees or more? The base presumably would be weighted such that it will automatically right itself when the wind stops blowing.

  3. Doug says:

    The last paragraph of the “solar fridge” article, for those of us wondering if they’re just talking about solar panels driving refrigerators or something:

    The scientists have installed concentrating collectors which direct the sunlight onto an absorber by means of a reflector. This makes it possible to convert the solar radiation into hot water with a temperature of 200 degrees. “This extreme water temperature is necessary in order to drive the absorption refrigeration machine for the high external temperatures that prevail there. We do not use electricity to provide the refrigeration, we use heat. The result is the same in both cases: refrigeration in the form of cold water or — in our case — a water-glycol mixture,” explains N??ez. As the absorption refrigeration machine produces temperatures of zero degrees, the experts use the mixture to prevent the water from freezing. The water-glycol solution is collected in cold accumulators and then pumped through a heat exchanger, which cools the milk. “We use a slightly different system for wine, with the refrigerant flowing through coiled pipes in the wine tanks,” says N??ez.

    So looks like a more direct use, so it should be more efficient, but it would be nice to know how these “absorption refrigeration machines” work…

  4. Doug says:

    Searched a bit for absorption refrigeration, and found a decent explanation here:

    It sounds like the efficiency may be less than conventional electricity-powered refrigeration, but since this application is getting the heat directly from the sun, perhaps that counters it. The efficiency also improves with higher temperatures, though these guys say they’re only using 200 degrees here.

    Here’s the paragraph with the most understandable explanation:

    The basic absorption cycle employs two fluids, the absorbate or refrigerant, and the absorbent. The most commonly fluids are water as the refrigerant and lithium bromide as the absorbent. These fluids are separated and recombined in the absorption cycle. In the absorption cycle the low-pressure refrigerant vapor is absorbed into the absorbent releasing a large amount of heat. The liquid refrigerant/absorbent solution is pumped to a high-operating pressure generator using significantly less electricity than that for compressing the refrigerant for an electric chiller. Heat is added at the high-pressure generator from a gas burner, steam, hot water or hot gases. The added heat causes the refrigerant to desorb from the absorbent and vaporize. The vapors flow to a condenser, where heat is rejected and condense to a high-pressure liquid. The liquid is then throttled though an expansion valve to the lower pressure in the evaporator where it evaporates by absorbing heat and provides useful cooling. The remaining liquid absorbent, in the generator passes through a valve, where its pressure is reduced, and then is recombined with the low-pressure refrigerant vapors returning from the evaporator so the cycle can be repeated.

    Another interesting bit:

    In short, absorption cooling may fit [your situation] when a source of free or low-cost heat is available, or if objections exist to using conventional refrigeration. Essentially, the low-cost heat source displaces higher-cost electricity in a conventional chiller.

  5. Mark says:

    Outstanding letter from 255 National Academy of Science Members and 11 Nobel Prize winners, pushing back on McCarthy-like threats and making a strong case for the science of climate change. They have suggested that the scientific community is as certain of AGW as they are of the “Big Bang” and evolution.

    This is a must read.

  6. mike roddy says:


    Yeah, that makes sense- maybe outer ring flotation devices. My concern was complete tipping over, but I suppose it’s preventable.

    These kinds of costs tend to be kicked down the road, but often make or break feasibility.

  7. Brooks Bridges says:

    Thanks Doug – for providing details. I wondered.

    On the deep water floating platforms: Rotating blades are, in a sense, gyroscopes. So they wouldn’t “like” being tilted. Therefore, I assume they must be stabilized in some way. My concern would be rogue waves. They can be virtually impossible to predict.

  8. Leif says:

    Brooks Bridges, #7: I expect you will see something like a long standing floating pole that sea state has relatively little effect on.

  9. Leland Palmer says:

    Yeah, solar air-conditioning, using the same principle as solar refrigeration, has be around for a long time, in niche applications.

    I believe that the old propane powered refrigerators, often used in motor homes and other “off the grid” applications, use the same principle.

    If I recall right, there is yet another solar air conditioning technology which uses a solar regenerated desiccant and efficient evaporative cooling:

    I guess there are several types, according to Wikipedia.

  10. Bob Wallace says:

    Mike –

    “The turbine, known as Hywind, towers 213 feet above the waterline, but the steel spar on which it is mounted plunges another 328 feet below the surface, where it is anchored to the sea floor by three stabilizing cables. The spar is filled with water and rocks to provide ballast that keeps the turbine from capsizing in rough seas.”

    Here’s a page that shows the underwater parts…

  11. Bob Wallace says:

    As for rogue waves, these turbine towers don’t present a lot of area against which a wave can push. Compared to their overall mass….

  12. Leland Palmer says:

    Jeez, I hope that figure of 11.9 percent for Chinese first quarter growth is a typo or misquote of some sort. Hopefully, they mean an annual rate of 11.9 percent, or about three percent growth in the first quarter.

    Annual growth of about 10 percent per year is scary enough, IMO.

  13. John Redford says:

    re: sun-powered refrigerators – One other advantage here is that a well-insulated storeroom does not need to be cooled continuously. You can drive down the temperature during the day and and then let it float overnight. It’s the same kind of thermal storage of energy that they’ve been talking about for power-tower systems, but using cold rooms instead of tanks filled with steam. The room has to be insulated enough to handle a few days of cloudy weather, but those are likely to be cooler than sunny days anyway.