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Low Cost Solar Powered Pumps

Thermofluidics is developing a range of solar thermally powered water pumps for pumping shallow well and surface water to higher pressures.

Thermofluidics has released first video footage of the NIFTE pump in its’ first outdoor trials operating in the Winter Sun after successfully self-starting automatically 15 minutes after sunrise.

NIFTE Open-Circuit Solar Powered Pump
The NIFTE Open-Circuit solar(c.f. solar circulator) pump is intended for drawing water from irrigation canals, ponds, rivers, ground level water storage tanks and shallow wells, and pumping it to up to 10m of pumping head per pumping stage.

table02The technology is currently proven to 1000L/hr, requiring 1kWh of heat input at low head. Following a successful outcome in field trials, which we are currently preparing, we hope to scale this up to 10,000L/hr or more. In future, we also intend to offer an ultra-low cost, low-flow rate solution which uses a single evacuated tube or small flat panel to deliver up to 100L/hr.

The NIFTE Solar pump is ideally suited to pressurising water for horizontal transfer, irrigating sloped or flat land close to rivers, and providing a pressurised water source for drip irrigation and other irrigation methods. It is also well suited to pumping freshwater and grey-water for drinking and sanitation across a wide range of daily pumping requirements.

High Pressure open-circuit applications
Multiple NIFTE devices can be connected in series to achieve higher pressures, sharing the same solar collectors, or each having its own heat source. Thermofluidics is also developing a proprietary hydraulic ram for lifting ground water, or pressurising surface water by up to 100m.

Solar Collectors
We currently specify a range of bought-in flat plate, and evacuated tube solar-thermal collectors, depending on the precise nature of the application, local climate and other considerations. These supply heat to the NIFTE via a gravity-return heat-pipe, to enable optimal performance of the collector without compromising the performance of the pump.

We are interested in forming strategic partnerships with solar collector manufacturers. To learn more, please contact us.

Solar Concentrator
table03As part of our long-term portfolio of NIFTE-related products, Thermofluidics is developing a proprietary non-tracking solar concentrator, to enable the NIFTE to be heated without the need for a solar-thermal collector or heat-pipe connections. To learn more, please click here.

Hybrid systems
The largest fraction of the cost of a NIFTE open-circuit pump is the solar collector. However, this may form part of a hybrid system with water heating or other solar thermal applications also enabled by the simple addition of two 3-port valves. In solar closed-circuit (circulator) applications, the collector is already present, so that the economic case for the NIFTE is overwhelming.

PhotoVoltaic (PV) – electric pumps
PV-electric pumps are either inefficient, requiring large areas of expensive PV modules, or they rely on a costly and fault prone “Maximum Power Point Trackers (MPPTs)”. MPPTs match the output of the PV modules to the electrical requirements of the electric pump, under varying solar conditions and pumping requirements. The NIFTE solar pump does not need a thermal equivalent of an MPPT. If correctly set up, it self-adjusts to changes in sunlight and pumping head by adjusting the flow rate of water it delivers to optimise the operating temperature of the solar-thermal collector.

PV-electric pumping systems have also historically been associated with durability and maintenance problems. Owing to its lack of moving parts and simple construction, we estimate that the NIFTE will not suffer these problems to the same extent. We will shortly be conducting a series of field trials to verify this, and prove the technology in rugged and harsh environments.

Comparisons with PV, grid and diesel alternatives
Typical figures for water consumption and energy savings, costs and carbon emissions associated with low-flow rate (e.g. drip) irrigation pumps are shown in the tables below. Figures are presented for grid powered, diesel, and solar PV. These are compared with estimated figures for the NIFTE solar pump. The tables are presented for irrigation of one Hectare (1Ha = 10,000 m2) of land. Figures are shown for one day of irrigation, and one year of irrigation, based on 5m to 8mm of irrigation per day on irrigated days, and a total pumping head of 10m. They are shown with reference to the footnotes below each table.

Water and energy consumption
The water consumption and energy savings offered by NIFTE are shown in the table below. The table shows significant savings, which propagate through to the economic and carbon emission cases.

table04

  1. Assuming 5 to 8mm irrigation per day
  2. Assuming a total pumping head of 10m (33ft).
  3. Assuming 183 irrigated days per year.
  4. Assuming an electric to hydraulic pump efficiency of 40%
  5. Assuming a diesel engine efficiency of 35%
  6. Assuming a centrifugal pump hydraulic efficiency of 50%
  7. Assuming a Higher Heating Value of diesel ~45MJ/kg
  8. Assuming a density of diesel of 0.85 kg/L

Economic comparison
The table below shows the economic case for the NIFTE solar pump in irrigation. The economic case is comparable with grid- and diesel- pumps over a 15 to 20 year Life Cycle. The figures shown compare the cost of diesel and electricity across the lifetime grid- and diesel-pumps, with the capital (up-front) costs of PV- and NIFTE- solar pumping systems. The capital costs of diesel- and grid- pumps are not shown, as figures vary widely and these are less significant than operating costs for these types of pump. The comparison is a therefore a conservative appraisal of solar solutions.

table05

  1. Assuming a US dollar – British Sterling exchange rate of $1.50 to £1.00
  2. Assuming an electricity price of £0.1per KW hour
  3. Assuming a diesel price of £0.4 to £1.00 per Litre
  4. Assuming an irrigation period of 8 hours per day on irrigated days
  5. Assuming a 15 year service life
  6. Assuming a PV capital cost of £10.8 to £21.5 per hydraulic Watt
  7. Assuming NIFTE capital cost of £2.50 to £6.00 per hydraulic Watt

Capital (up-front) costs. NIFTE versus PV-electric
The table below compares the capital (up-front) costs of PV-electric and NIFTE-solar pumps. The principle advantage of the NIFTE solar pump comes from the much lower cost of the solar collector (than PV modules, by unit area), and their much higher collection efficiency.

table06

  1. Based on square metres of absorber area
  2. Assuming solar irradiation of 1000W/m2
  3. Derived from a range of pump types and scales from various sources

Comparison of CO2 emissions including production and Life Cycle emissions
The table below compares Life Cycle carbon dioxide emissions of grid- and diesel- irrigation pumps with PV-electric and NIFTE solar pumps. The analysis includes estimates of both production emissions, and emissions generated by use. In the solar cases, no emissions are generated by use of the pump.

table07

  1. Assuming 0.43kg of CO2 Emissions per kWh of electricity delivered to the pump
  2. Assuming the production energy of diesel and electric pumps is comparable with that of NIFTE.
  3. Assuming 2.67kg of CO2 Emissions per kWh of heat released by burning diesel
  4. Assuming 0.23kg of CO2 Emissions per electrical kWh across their lifetime
  5. Assuming 60% of PV production consumed in silicon wafers and 40% comparable with NIFTE

Please note that the figures presented on this page are approximate and intended only as a guide. They may also differ from past and future Thermofluidics publications, as we are continually revising and updating our estimates to reflect changes in exchange rates, technology advances and materials costs. For sources for these figures, please contact us.

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