A New Way to Drill For Geothermal Energy

Potter Drilling has launched the next phase of research into their technique for drilling to hot rock for geothermal heat energy.  With financial backing from Google getting the science past early work using air, Potter has crossed the development threshold to draw more funding.

The new drilling technique that uses superheated steam instead of air is being tested this year.  The technique relies on superheated steam to drill through the hard crystalline rocks that contain geothermal heat. The method for generating the superheated steam was developed by Oxford Catalysts, based in the UK. Dave Wardle, business development director for Instant Steam technology at Oxford Catalysts, said current drilling techniques are laborious and use rotating drill bits to cut through the rock.  “With crystalline rock you wear out the drill bits very fast,’ he said. ‘This new technology provides a chemical way of cutting rock at reasonably fast speed. There are no moving parts.”

The system works with a catalyst developed by Oxford Catalysts and a special drilling tool designed by Potter Drilling. The “Instant Steam” catalyst is contained inside the drill head, which is attached to a flexible coiled pipe. Wardle explained that when peroxide and methanol are piped into the catalyst bed, the catalyst carries out a combustion reaction and produces 800º C steam.  That’s hot.

When the steam contacts the rock surfaces it causes the rock crystalline grains to expand. As the grains expand, micro-fractures occur in the rock and small particles, called spalls, are ejected.  According to Oxford Catalysts Potter Drilling is not the first company to use spallation drilling technology.  Using air, spallation drilling was used commercially between the 1940s and 1960s for ore mining and was adapted to geothermal drilling by the US Department of Energy in the 1970s.  Air spallation drilling demonstrated impressive drilling performance, producing 8 inch to 12 inch boreholes to depths of 1,100 feet at rates faster than 50 feet per hour in solid granite.

The Potter drilling process starts by applying a high-intensity fluid stream to a rock surface to expand the crystalline grains within the rock. When the grains expand, micro-fractures occur in the rock and small particles called spalls are ejected. The process is accelerated by several factors including inherent stress in the rock formation.

Potter Drilling Process Steps.  Click image for the largest view.Potter Drilling Process Steps. Click image for the largest view.

Using steam and fluids allows much deeper drilling, with Potter expecting to get to as much as 30,000 feet, a depth that would allow exploiting geothermal extraction across much of the U.S.

Using fluids and heat pose three other advantages.  The borehole is much more stable, the rock particles and chips can be carried out from extreme depths, and adding the heat greatly improves the early work using air in faster drilling speeds.

Potter and its financial backers believe this technology could be the key to furthering power generation from geothermal energy, which currently only generates 10,000MW around the world.  It’s sure to turn heads in the petroleum and deep rock mining world as well.

Going for geothermal heat in the absence of hot subsurface water as is most common now, is being called engineered geothermal systems or “EGS.”  Potter’s point is this is different to other forms of geothermal power because EGS power plants can be developed anywhere that hot impermeable rock exists below ground.  But you have to bring your own water.  I might suggest that water or gases could be used to move the heat from depth, especially if the water is lost downhole.

Stuart Haszeldine, an expert from Edinburgh University’s School of Geosciences offers that many consider geothermal energy a renewable source and electricity produced from it would have a relatively low carbon footprint, saying, “The carbon cost is the drilling of the hole, but these holes last for many decades.”

Haszeldine expects that electricity produced from geothermal energy plants have the potential to be on a similar cost level to coal-fired power plants.

The EGS concept, originally know as Hot Dry Rock, was pioneered and patented in the early 1970s at Los Alamos National Laboratory by Potter Drilling cofounder Bob Potter and his coworkers.  EGS is one of the few sources of renewable energy with the promise of solving the increasing global demand for energy while addressing climate-change issues—and doing so for a price that is competitive with coal. The graphic that follows is from the Potter page explaining EGS with a Flashplayer and a small video from Google explaining the potential of EGS.

Engineered Geothermal System Diagram From Potter Drilling.  CLick image for a larger view.Engineered Geothermal System Diagram From Potter Drilling. CLick image for a larger view.

The EGS being man-made may be developed anywhere that hot impermeable rock exists.  That opens up a great deal of territory to low cost heat energy extraction.  Worthy of note is that the drilling issue and the technologies downhole are the matters of interest.  Binary systems for withdrawing the heat are in operation now with development work under way for more and better types of systems.  The electrical generation would be standard, with models chosen by energy availability.

Geothermal remains a slowly developing field, but is getting pushed by smart private investors such as Google who is funding Potter.  The geothermal resource is huge, a relatively simple concept to explain and lacks the sexiness of much of the technology that is in development for alternative energy sources.  Its also energy extraction, not a fuel so can go straight to grid so allowing more electrification.  Its also should be quite low cost an important matter for getting and keeping the economy moving and growing.

This is a good field.  It lacks the sexiness, but when the full details are known, it should be the “cash cow” investors dream about.  Thanks, Google.  Go Potter go!

Original post: New Energy and Fuel

Renewable Energy in Hong Kong

The Electrical and Mechanical Services Department commissioned a two-stage consultancy study in late 2000 to investigate the feasibility of wider application of renewable energy technologies in Hong Kong. Findings from the Stage 1 Study suggest that the renewable energy technologies that are considered potentially feasible for wide-scale application in Hong Kong are solar power, wind power and energy from waste.

Hong Kong has been using solar energy for over 20 years, albeit in a very small scale and mainly for water heating application. The first solar hot water heating installation was installed in 1980 for a bathhouse in Stanley. There are also a number of solar water heating installations for low-rise houses in some suburban areas and a few for swimming pools. The largest system installed so far in the territory is at the Sheung Shui Slaughter House where the system is used to pre-heat the incoming water in the slaughtering process.

Apart from using solar energy for heating purpose, solar energy was also harnessed locally by photovoltaic systems to generate electrical energy. Since the 1980s solar cells have been employed to power small automatic weather monitoring points in various locations in Hong Kong. In addition to using photovoltaic systems in small and stand-alone applications, a number of Building Integrated Photovoltaic systems in both government and private projects have emerged recently and showcased the successful integration of the photovoltaic system with the electrical systems of the buildings. These projects include Wanchai Tower, EMSD Headquarters at Kai Tak, Science Park and the “Green School” at Ma Wan, etc.

So far Hong Kong only has a few small wind turbines installed. The Hong Kong Observatory has successfully made use of small wind turbines coupled with photovoltaic panels to form hybrid arrays to supply electricity to some of their weather monitoring stations in remote sites.

The utilisation of landfill gas (mainly methane) as an energy source has not been extensive in Hong Kong. At present, most landfill sites use landfill gas as a heating fuel in the landfill’s leachate treatment plant and also as a primary fuel to power generation plants to produce electricity for on-site consumption. One of the landfill sites succeeds in utilizing landfill gas to feed a nearby town gas production plant as process fuel to crack naphtha in the production of town gas.

Social and Economic Concerns

Large-scale renewable energy schemes, however, could cause concerns about the consequence on the surroundings. Large open spaces are generally required for the exploitation of energy either from the sun or wind. Land is scarce in Hong Kong and most available potential renewable energy sites are either located in areas targeted for various urban developments, or in our country park areas where natural and wildlife conservation measures are in place. In addition, the visual and noise impacts of renewable energy installations, although subjective to some extend, can be a major concern to the public.

Furthermore, the development cost of renewable energy at present is still high. Based on the “user-pay” principle, consumers using renewable energy will be required to pay a higher energy price.

Urge for Wider Adoption of Renewable Energy

The urge for wider adoption of renewable energy is emerging as an irreversible worldwide trend. Apart from looking at renewables from the environmental angle, the search for new energy sources as substitutes for fossil fuels is another reason providing the drive.

With a projected world population of 10 billion by the year 2050, the increasing global energy
demand will bring about more rapid depletion of the world’s fossil fuel reserves. The possible tightening of energy supplies in future will inevitably result in higher prices of fuels and electricity.

Renewable energy can reduce the reliance on exhaustible sources of fossil fuel. Developed countries are now making more and more investments on the development of the related technology on renewable energies. We would envisage that when those equipment and systems for harnessing renewable energies are to be produced on a massive scale, the unit price of electricity so generated could be comparable to conventional electricity generated from fossil fuels.

Renewable Energy Explained

In contrast to the fossil fuels, renewable energies, as the name suggests, exist perpetually and in abundant quantity in the environment. They areready to be harnessed, inexhaustible, and more importantly, they are environment-friendly. However, the term “renewable energy” has no official or commonly accepted definition.

As an example, the Renewable Energy Working Party of the International Energy Agency defined renewable energyto mean energy that is derived from natural processes that are replenished constantly.

Typical renewable energy sources are wind, heat & light from the Sun, oceanwave, purposely-growth energy crops, potential energy of running water, geothermal energy, etc. Energy generated from waste is termed as one  kind of renewables in some countries. Others regard it as a waste disposal process rather than a renewable source, since there are pollutants generated as by-products, although modern technology has significantly reduced the pollutant emission to a very low level.

Modern solar thermal technologies capture sunlight and utilise its energy to produce hot water, steam and electricity. Apart from using purposely designed equipment to capture the solar energy, buildings in cold countries can be designed to make the best use of the heat energy from the sun by incorporating appropriate design features such as large south-facing windows and special building materials that absorb and slowly release thesun’s heat for warming the building interior.

Solar photovoltaic technologies, on the other hand, employs photovoltaiccells made from semi-conducting materials such as silicon to produce directcurrent electricity when they are exposed to the sun. In the absence of moving components that are subject to wear and tear, photovoltaic cells canoperate for a very long period without much maintenance commitment. Thesimplest and most common type of photovoltaic cells provides power towatches and calculators, while the more sophisticated “state-of-the-art” photovoltaic systems can generate electricity to supplement local consumption in a building or a designated system, and the excess power caneven be fed to the city electrical grid.

Wind is the movement of air molecules, resulting from variations in airpressure created by difference in solar heating over the earth surface. Wind turbine is a device which captures the kinetic energy of wind to turn agenerator for producing electrical power. Nowadays wind farms employing groups of wind turbines located either on land or on near-shore waters are becoming more and more common to harness the wind energy for mass production of electricity.

Other forms of renewable energy technology like hydroelectric power, wavepower, geothermal energy and energy form vegetation are also gaining increasing popularity in power generation. However the exploitation ofthese forms of renewables is very often dictated by geographical conditions, and thus the extent of their application usually has a wide variation amongst countries.

Municipal solid waste commonly refers to residential and commercial refuse, and takes up the largest percentage of waste generation in industrialized countries. There are three basic processes that are currently used toconvert municipal solid waste into useful heat or electricity, viz, thermal process, biological processes, and landfill gas utilisation. All three methods produce energy from organic materials present in the waste that would otherwise be converted naturally into methane or carbon dioxide; both are undesirable by-products as they are the main constituents of greenhouse gases.