Climate change – Our moral dilemma

What should we do?

Fight global warming or postpone our plans for generating green energy until the recession is over?

Fortunately research at Lancaster University suggests that a new generation of Latent Power Turbines could produce electricity that is both cheap and clean.

The big engineering breakthrough is that LP Turbines can operate using low grade heat at 100^oC or cooler. This will allow coal, gas and nuclear power stations to generate more electricity without consuming more fuel.

Solar powered LP Turbines could convert Greece, Italy, Spain and Portugal into green power houses supplying Northern Europe with clean energy.

Figure 1 A cross section through a glass house for use in warm Southern European countries. In addition to generating electricity, these units would create jobs and wealth based on food production.

On this page we will concentrate on the economic and green benefits of LP Turbines. For a detailed discussion of our technical proposal please click here.

Article summary

Our research has resulted in designs for two types of Latent Power Turbine.

The dry air turbine This is the simplest design. It exploits local environment heat or the release of latent heat on the outside walls of the turbine unit. It has a maximum size for effective performance.

The moist air turbine This can be built on a larger scale. It exploits the release of latent heat when steam condenses inside the turbine unit.

Figure 2. Lancaster University research demonstrated that both designs have a surprisingly high thermal efficiency.

The dry air turbine can extract heat from a warm dry environment, but, where possible a moist air or steamy environment is preferred because of the large amounts of heat liberated when water vapour condenses.

The new turbines are more like “canned wind turbines” than the traditional steam turbines found in most power stations.

In order to grasp the full potential of LP Turbines you need to think of water vapour as a type of fuel with the condensation of one kilogram of vapour releasing approximately 2.6x 10⁶ Joules of energy.

A common type of water vapour that people are familiar with is the steam coming out of a kettle boiling at atmospheric pressure and 100^oC. These are ideal conditions for injecting steam into moist air LP Turbines. But as we explain in Section Three on the technical page, dry air turbines are capable of running on far cooler water vapour. They can for example, exploit the small quantities of moisture present in steam turbine exhausts or the air of damp North European summers.

For the rest of this page we will assume that you take the technical arguments “as read” and simply want to discovery some applications for the new technology.

Summary of applications

• Improving the efficiency of fossil fuel power stations.

• Reducing the cost of carbon capture processes.

• Converting low grade industrial waste heat into electricity.

• Improving the efficiency of solar thermal power stations.

• Improving the efficiency of geothermal power stations.

• Reducing the operating pressure and temperature of nuclear reactors without reducing power production efficiency.

• Air conditioning large buildings while producing power instead of consuming it.

• Reducing air temperature and humidity in underground railway tunnels.

• Micro-power generation away from the grid in warm climates.

• Combined power production and water desalination units.

1          Improving the efficiency of fossil fuel power stations.

Figure 3. The steam turbines used in fossil and nuclear power stations are not very efficient. A typical coal fired power station can only exploit about 59% of the energy fed into the turbine. The remaining energy is trapped as latent heat in the “cool” turbine exhaust steam. In this illustration the cooling towers at Ferrybridge power station are dumping the waste heat into the atmosphere. (Original photograph courtesy of SSE.)

Figure 4. This block diagram pinpoints two problems with existing fossil fuel power station design: (i) a large fraction of the energy extracted from the fuel has to be thrown away as low grade heat; (ii) inland power stations damage the environment by extracting large quantities of (cooling) water from local rivers and aquifers.

The alternative to cooling towers

A large array of dry air turbines could be used instead of a condenser and cooling towers for extracting the latent heat from steam turbine exhausts. Such arrays could be retrofitted to existing fossil fuel power stations, allowing their working lives to be extended in the face of increasingly stringent EU emission control legislation. Retrofitting could also avoid an energy famine following the anti-nuclear reaction to the Fukushima disaster.

 Figure 5. The principle of an LPT based steam condensing unit.

The heat released by condensation acts as turbine fuel instead of being dumped into the environment. This type of power production will earn carbon credits instead of costing them.

Figure 6. LP Turbines can be used to increase power output without increasing fuel consumption. There is no need for cooling water, so the local environment is also protected.

2          Carbon capture

Fossil fuel power stations will only become truly “green” if the carbon dioxide they produce can be captured and buried. The snag with existing techniques for carbon capture is that they are very energy intensive and are predicted to increase energy costs by about 25%. In Section 5.4 of our technical proposal we explain how LP Turbines could convert carbon capture into a net energy generating process.

3          Nuclear power stations

Nuclear reactors could run cool for the limited purpose of producing atmospheric pressure steam.
Compared with conventional reactors, cool nuclear would be very safe and produce less nuclear waste per unit of electricity.

Figure 7.Atmospheric pressure nuclear power stations would generate all of their electricity using LP Turbines.

This change to more benign steam requirements could force a complete rethink on reactor design. Hopefully, it will one day result in the construction of thorium based nuclear reactors. Thorium reduces the nuclear waste problem and cannot be made into bombs.

4          Micro-power generation

The design shown in Figure 5 would be useful in environments where there is also a demand for moist air cooling.

Combined micro-power and solar desalination plants are a feasible option. Solar radiation would be used to evaporate water vapour from brine and a dry air turbine would act as the heat sink for vapour condensation.

5          Large scale solar thermal power stations

Figure 1 is reproduced below. An additional note 5 has been added.

Figure 8. This LP Turbine “fuel production plant” can also act as a moderate output water desalination plant. Depending on solar intensity, each square meter of external glasshouse surface will deliver 2- 4 litres of potable water per day.

Our patents describe several designs of solar thermal power stations; this is just one of them.

Figure 9. This block diagram shows the key processes in our  "glasshouse" solar thermal LP Turbine design.

The Type 1 heat pump referred to is explained on our technical proposal page.

What happens when the sun goes down?

This problem is already being addressed by engineers building solar thermal power stations in Spain, Australia and elsewhere. We can build on this expertise, but thanks to the novel features of LP Turbines, implement them more effectively. Here are some brief notes:

(i) Combined solar thermal and gas fuelled power stations

Natural gas would be burned to produce additional heat when the solar power is inadequate.

The combustion process produces water vapour and carbon dioxide. Consequently, LP Turbines will be inherently more efficient than conventional gas turbines because they can harness the latent heat released when the water vapour condenses. The carbon dioxide  would be fed back into the glass houses to speed up the rate of plant growth.

Combined solar and gas fuelled power stations would be a good option for Southern European countries because they could operate at full output throughout the year.

Rice growing paddy fields produce methane which is a potent greenhouse gas. This climate change threat could be converted into a virtue by growing rice inside the LPT glass houses and using the methane rich air as the air supply for natural gas combustion. (Methane is the principle component of natural gas., so gas purchase prices would be reduced.)

(ii) Combined solar thermal and bio fuel

The bulk of the bio fuel could be grown inside the glass houses. A dedicated hot (i.e., no water filled cavity walls) glass house would be assigned for drying out the fuel. The moist air produced by drying the fuel would be used to power LP Turbines.

(iii) Combined solar and geothermal

The efficiency of geothermal power stations can be improved by replacing conventional steam turbines with LP Turbines. Combining solar and geothermal LPT systems offers a further advantage: the geothermal rock can be “rested” during daylight hours, allowing it to warm up again.

(iv) Molten nitrate salt heat storage

Several existing industrial processes use high temperature waste heat to melt nitrate salt mixtures. When the mixtures are subsequently allowed to solidify, the latent heat released can be exploited. Typical melting temperatures exceed those required for normal LP Turbine operation. We can get round this problem using the Type One Heat Pumps described in Section 5.1 on our technical proposal page.

6          Using LP Turbines to create tourism and engineering jobs in Southern Europe

Figure 10. A pontoon version of the solar powered LPT power station would provide moorings for boats. The coast will be cloudier than inland. The heat stored in the warm sea water will prevent sharp changes in power output when the sun goes in.

Municipal garbage and other bio mass could be burned to supplement the solar energy. (The modern syngas method for converting rubbish into fuel is cleaner and more efficient than traditional incineration methods that have upset environmentalists in the past.)

Local entrepreneurs will devise ways of making money from the power plant, for example using it as a sauna or tropical fish farm.

Engineering: Designing and building the pontoons would revive the Greek shipping industry.

Figure 11 Greece, Italy, Portugal and Spain could become the green energy generating sunshine economies of Europe.

7          LP Turbines could make the deserts bloom

(Map courtesy of Guinness Publishing.)

Fig. 12. The World’s desert assets. In addition to the true deserts shown, all the populated continents have extensive tracts of semi-arid scrublands. These could become economically productive regions if solar LP Turbine systems were introduced.

What fraction of the deserts need to be colonised by solar LP Turbine units to meet our total energy needs?

Q. What is the solar intensity available?

A. “The suns intensity at the Earth’s surface depends on latitude and season. The average value over a 24 hour period across the whole of the Earth’s surface is about 300 watts per square metre.” Holkham, T, The Last Word, New Scientist, p105, 2006.

For the following calculations we will make the cautious assumption that solar powered LP Turbine units deliver 250 watts per square metre, for eight hours/day, 300 days/year, giving an annual output per square metre of 600 kilowatt hours/year (600 x 10⁶ kW hours/km³/year)

Information sources:

Desert areas, The Guinness World Data Book, ISBN 0-85112960.9

Primary energy statistics, USA Energy Information Administration, http://www.eia.doe.gov/

The above table assumes that during bright sunshine daylight hours the LP Turbine outputs exceed current demands, with surplus electricity being used to liberate hydrogen and oxygen by passing an electric current through water. These gases are stored and used to fire gas turbines during periods of darkness or high cloud cover.

In the long term, the world could acquire the bulk of its energy from solar sources 24 hours/day using a world-wide electricity super-grid to transmit electricity to areas currently in darkness. Preferably, superconducting cables would be used to minimise transmission losses. A novel refrigerator design for cooling cables to superconducting temperatures is described on our Superconductors and Cryocoolers web page.

8          How to make replanting the rain forests profitable
– without subsidy or handouts!

Daytime rain forest temperatures are lower than in deserts at the same latitude, but the air remains warm and humid throughout the night. This will allow LP Turbine power stations based in rain forests to operate 24/7 without any form of backup heating.

 Figure 13. This is a plan view of a rain forest based LPT power station. (Not to be confused with a Dalek on a bad hair day!)

Replanted rain forests can earn extra money by acting as carbon sequestration sites. The following vertical cross section through an LPT moist air conduit and adjacent land shows how.

 Figure 14. The archaeological evidence suggests that biochar can remain locked in rain forest soil for more than a millennium. Rain forests growing on improved soil have a lower canopy and denser undergrowth. This should improve the moist air holding capacity of the forest. [“Hand made”, New Scientist, P42, 4 June, 2011.]

9    Reducing air temperature and humidity in underground railway tunnels

 Figure 15. Heat trapped in underground tunnels could be converted into electricity.

 10         Current state of development

The university research stage has been completed. We now need to scale up the size of the LP Turbine units before building a generator that is large enough to deliver a significant quantity of power to the national grid. Please click to see details of our technical proposal.

We estimate that the next stage of work will cost about £120 k and take approximately six months. We are currently seeking partners and funding for this work. Please contact us.