Thursday, July 18, 2013

Prepregs boost marine quality

Using high performance fibres that are already impregnated with resin is, say the proponents of prepregs, a sure way of building consistent quality into fibre reinforced plastic (FRP) products. Aircraft builders became convinced some time ago, but constructors of marine craft have followed suit as customers for premium yachts and some commercial craft seek top performance with structures that are exceptionally light, stiff and strong.

Prepregs have become a primary means to achieve this winning combination. These materials avoid the nagging inconsistencies associated with traditional FRP processing, especially the variable quality achieved by different laminators working on different days in different conditions with non-consistent material mixes. Bulk material manufacture under controlled factory conditions ensures that prepregs provide high and consistent fibre-to-resin ratios, along with even fibre wet-out during cure. For their part, fabricators are happy to abandon messy wet lay-up and spray-up operations together with their associated volatile emissions. They can worry less about resin viscosity since this is controlled as a function of the cure, while concerns over precise mixing of catalyst, accelerator and resin are avoided. Less resin is wasted and laminators operate in a cleaner and healthier working environment. Multilayer materials simplify the lay-up process because some of the lay-up has already been done and is inherent in the material.

Although carbon epoxy composite has become a marine industry mainstay in recent years, glass and aramid prepregs are also available, with polyester, vinyl ester or epoxy resins. In the past, prepregs had to be cured under pressure at high temperature – typically 175°C for aerospace structures – and this held back any penetration into the marine sector, where most constructors have neither the desire nor the finance to acquire and operate large autoclaves. However, the advent of materials that cure at lower temperatures and with vacuum bag consolidation, with only minor sacrifice of performance and quality in the cured product, made prepregging viable for high-end marine craft constructors. Low temperature prepregs now available can be cured at atmospheric pressure (vacuum bagging) at temperatures as low as 65°C, avoiding the need for autoclaves and reducing energy needed during the cure cycle. Resin chemistry manipulation has made this possible. Prepreg suppliers use resins from various manufacturers, though some have developed their own bespoke formulations to meet specific customer needs.

Sunday, July 14, 2013

Types of renewable energy

The power of water is abundant—approximately 73 percent of all renewable energy according to the Energy Information Administration (EIA). Hydropower is generated using the mechanical energy of flowing water by forcing it through piping called a penstock, which then turns a generator in order to produce electricity. Water power also consists of wave and tidal energy, which are both in the infant stage of research, as scientists try to discover how to harness the energy produced from movement of the ocean. The Hoover Dam is the largest hydropower system in the U.S.Solar cells made from silicon absorb the sun's radiation, also called photovoltaic cells. The photovoltaic process involves the movement and displacement of electrons to absorb the sun's radiation and create electricity, but there are also solar systems that use large-scale mirrors to heat water, or produce high temperatures and generate steam, which is used to turn a generator.Wind power is a very simple process.

A wind turbine converts the kinetic energy (motion) of wind into mechanical energy that is used to generate electricity. The energy is fed through a generator, converted a second time into electrical energy, then fed into the grid to be transmitted to a power station. Wind power is abundant in California and Texas, with the two largest wind farms in the world residing in West Texas. Wind is unique because it carries incentives for farmers to give parcels of land for building wind turbines, and has the most potential as far as widespread adoption due to the large areas of land with consistent wind available to harness.The process involves trapping heat underground, then building energy that rises near the surface in the form of heat. When this heat naturally creates hot water or steam, it is harnessed and then used to turn a steam turbine to generate electricity. The Italians were the first to use geothermal energy for commercial purposes in the early 1900s.Biomass is a very versatile form of renewable energy. Biomass power plants burn biomass fuel in boilers to heat water and turn a steam turbine to create electricity. Biomass fuel is everything from wood to landfill trash, which is currently being used to convert into methane for the production of dry natural gas. Agricultural research is seeing unique results, including dairy farms in Texas converting cow manure into energy.

Wednesday, July 10, 2013

Birds, bats, and wind farms

The Wildlife Society Bulletin reports that wind farms kill over 573,000 birds in the United States annually, including about 83,000 hawks, eagles and falcons. Research suggests that the number of bats that are killed may be double that of birds, making it well over 1,000,000 bats killed annually. As one official told me, large bats such as the Big Brown Bat and Hoary Bat are being “decimated at an alarming rate” particularly in the Eastern United States. However these numbers may not be entirely accurate since not all information is made available to the public – at least in Idaho that is. In Idaho, information on wind farms located on private land is proprietary and therefore not available to the general public.Furthermore, there is no state oversight for wind farms and their relationship with agencies such as the state Fish and Game (F&G) Department is cooperative rather than regulative; in other words, to some degree wind farm owners and developers can choose whether or not to cooperate with the state F&G Department. On private land, any regulation comes from county Planning and Zoning committees although F&G has input. So the regulation of wind farms on private land can be inconsistently applied from one county to the next.In speaking with various officials, it became clear that there are some State legislatures and representatives who have leased their land to these wind farms, so it’s highly unlikely that the State of Idaho would support any changes in wind farm regulation or their releasing of information. To further complicate matters, the federal government turns a blind eye to wind farms and has never fined a wind farm for any of the deaths, although each one of the 83,000 raptors killed annually is a federal crime.

One of the reasons for so many bird deaths is that wind farms are constructed in areas of strong wind currents – the exact wind currents that birds use, which drives the birds directly through the wind farms. In Idaho, some of these large wind farms have been constructed in Sage Grouse and Sharptail Grouse habitat. The impact to sage hen (grouse) is not necessarily death by turbine blades, but loss of habitat; sage grouse avoid tall structures such as trees, etc. and wind farms located in sage grouse habitat drive the birds away, further reducing their habitat. For years now, there has been a debate over whether or not to list the sage hen as an endangered species, and Idaho is working to bring back the sharptail, both of which could be detrimentally affected by wind farms. In Bingham county, several proposals to construct a wind farm at the mouth of Wolverine Canyon have been denied and residents strongly opposed their construction in this recreational area. Should this wind farm be constructed, essentially 45 miles of the Blackfoot Mountains from Blackfoot to Ririe would be in wind farms.Yet ironically, environmentalists who can so severely impact the oil and logging industries, turn a seemingly blind eye to ecological devastation caused by this source of “green energy”; the State of California can shut off water to farmers in the San Joaquin Valley to preserve the delta smelt – an endangered fish, yet allow 10,000 bird deaths annually in the Altamont Pass wind turbines. The federal government has prosecuted oil and power companies with federal crimes for birds killed in waste ponds or electrocuted on power lines. In 2009, Exxon Mobile paid $600,000 for killing 85 birds in five states. PacifiCorp paid more than $10.5 million in 2009 for electrocuting 232 eagles along power lines and at its substations. According to the Canada Free Press, 28 dead birds were discovered in oil waste pits and maximum penalty for each charge under the Migratory Bird Act is six months in prison and a $15,000 fine.