In this paper, we conduct a techno-economic analysis of a 1000 MWe solar tower aided coal-fired power generation system for the whole life cycle. Firstly, the power output (from coal and solar thermal energy) under variable direct normal irradiance and grid demand are studied. Secondly, a financial assessment is performed, including profits and losses of the plant project. Thirdly, sensitivity analysis is taken on some external factors that can affect the cost or profits and losses of the plant project. The results indicate that the project has high profits with an internal rate of return (IRR) of 8.7%. In addition, the effects of solar tower field cost, power purchase agreement (PPA) price of solar thermal electricity, coal price, and the interest rate of debt on the main criteria decrease gradually. Therefore, it is better to improve solar tower technology first, and then look for low-interest debts from banks to cope with the reduction of PPA price of solar thermal electricity and the increase of coal price. Despite the introduction of solar tower field increasing levelized cost of electricity (LCOE), it contributes to the reduction of CO_{2} capture cost compared to the case of standard coal-fired power plants.
Coal-fired power generation is the most common method of power generation in China. By the end of 2014, the electricity generated by coal accounted for 70.5% of all electricity produced in China [
Many researchers have conducted in-depth studies on solar tower aided coal-fired power generation system (STCG). As early as 1975, Zoschak et al. [
Apart from thermodynamic studies, many researchers analyzed the solar aided coal-fired power plants from other points of view, such as environmental, economic, etc. Suresh et al. [
The studies above showed the advantages of parabolic trough solar aided coal-fired power generation systems in solar thermal utilization, economic benefits (compared with parabolic trough solar thermal power plants), and environmental benefits. However, few researchers have paid attention to STCG. Among them, Ozturk et al. [
Despite the fact that above mentioned studies were focused onto STCG power plant thermal characteristics, detailed economic studies have not been addressed yet. In this paper, a 1000 MWe STCG is adopted for techno-economic analysis over the full life cycle of the plant.
Firstly, STCG is operated under off-design conditions during the whole life cycle due to the changes of direct normal irradiance and grid demand. Later total power output, power output from solar thermal energy and coal, are figured out by solar contribution method.
Secondly, the economic characteristics of solar tower aided coal-fired power plant project are studied by relevant criteria (net present value (NPV), IRR, etc.).
Finally, considering solar multiple, PPA price of electricity from solar thermal energy, plant investment, and coal price, a sensitivity analysis is conducted to study the impacts on the main economic criteria by external factors.
This study could be used as a starting point for solar-tower-aided coal-fired power plant project planning.
Revenue from selling electricity is the main income of solar tower aided coal-fired power plant project and therefore, power output calculation can affect income assessment of the project.
STCG power output consists of two parts, namely electricity generated by the solar tower field and coal-fired power generation systems. Due to the indirect generation of solar thermal energy in STCG, the total power output should be distinguished according to different energy sources. In this paper, solar contribution method described in the literature [
Solar contribution is defined as the proportion of electricity (generated with solar thermal energy) to the total amount of power generated by the STCG. The solar contribution method is based on the second law of thermodynamics and thermo-economic theories, and can overcome some shortcomings of traditional evaluation methods by taking energy quality into consideration, and it is suitable for both power boosting and fuel saving modes [
Financial assessment of plant project can pre-judge the direct and indirect economic benefits to some extent providing investors bases for decision making.
In this section, the financial models are first introduced from electricity prices and two perspectives (cost and income); then some static and dynamic indicators are explained with or without consideration of the time value of money.
Electricity feed-in tariff plays a key role in the revenue of a plant. In China, there are four main pricing mechanisms: case-by-case pricing, benchmark pricing, average pricing of a local province, and bidding pricing [
Coal with 5000 kcal/kg lower heating value (LHV) is taken as the base coal. When the difference between the price of electricity coal and the base coal is no bigger than CNY 30/t, the policy of coal–electricity price linkage will not be activated and the changes in cost is undertaken by plants owners; when the difference is bigger than CNY 30/t, the policy will be activated according to the changed part of the price.
The calculation of the policy of coal electricity price linkage is
(1) Capital Cost
The capital cost of STCG includes direct capital cost and indirect capital cost.
For STCG, the direct capital cost
Due to lack of real solar tower aided coal-fired power plants, the capital cost
Capital cost of both the solar tower power plant and coal-fired power plant have been taken from literature [
(2) Operation and Maintenance Cost
The operation and maintenance (O&M) cost consists of fixed cost and variable cost.
The variable O&M cost in the
The O&M cost can also be calculated by a simplified method [
In order to guarantee the secure and stable high efficiency operation of the plant, annual overhaul and technological transformation are needed, whose costs are also included in the O&M cost.
(3) Insurance Cost
The method for calculating insurance cost in the
(4) Fuel Cost
Coal is the only fuel used by a STCG plant, and the annual coal consumption depends on grid demand and annual DNI. The fuel cost in the
(5) Interest of Debt
The interest of debt accounts for a large proportion of the debt repayment. The repayment is a dynamic process, so the interest paid to the bank in each year is different. The interest in the
The available money used to pay the bank depends on the annual income. The proportion of the available money to the annual income is called debt service coverage ratio (DSCR) [
Taking the discount rate into consideration, the income equivalence of the 0th year in the
If the available money in each year is converted to the 0th year by discount rate and then accumulated, the debt repayment capacity of the project can be obtained. The debt repayment capacity equals to the maximum debt the project owner(s) can borrow from the bank. If the debt is beyond the debt repayment capacity, that means the total income of the project cannot cover the debt from the bank.
In the repayment process, the available money each year is first used to pay for the interest, and then for the principal cash.
(6) Revenue of Electricity
Electricity revenue is the main income for a plant project, and it is related to the electricity market and government policies. Electricity price of different electricity sources (fossil fuels or renewable energy) differs along with different pricing mechanisms (see
The electricity revenue of a STCG plant comes from the electricity generated by solar thermal energy and coal.
(7) Taxes
The main taxes imposed on a plant project include the value-added tax (VAT), the income tax, and the additional tax.
The VAT is a turnover tax based on the added value of goods during circulation. The taxable amount of a general taxpayer equals the difference between the current output tax and the current input tax
The income tax is a tax imposed on taxpayers with their taxable income. The income tax rate for enterprises in China is 25%.
The additional tax is a tax levied in accordance with a certain proportion of the regular tax, including urban maintenance and construction tax, educational surtax, etc. Based on current laws and regulations, the rates of urban maintenance and construction tax and educational surtax are 7% and 3% of the regular tax respectively.
• Static Indicators
Static indicators refer to the indexes calculated directly with cash flows without considering the time value of money. They include static pay-back period, return on investment, etc.
(1) Static Pay-Back Period (SPP)
The static pay-back period is the time needed to recover the total investment without considering the time value of money, namely the time needed for accumulative net cash flows to just cover the total investment during project’s life cycle. Generally, there are two forms of the static pay-back period: the operation period including or not the construction period. In this paper, the construction period is included into the static pay-back period (SPP), whose calculation method also fits the dynamic pay-back period. The static pay-back period and the dynamic pay-back period are generally calculated with the unit of year.
The static pay-back period (SPP) can reflect the investment pay-back time with a simple calculation method. However, the time value and the cash flows after the static pay-back period are not considered, so it cannot accurately reflect the effect of different investment methods on the project.
(2) Return on Investment (ROI)
The ROI refers to the ratio between the annual profit and the total investment of the project in normal productive years. If the annual profit changes drastically during the project’s life cycle, the average annual pre-tax profit can be used instead of the annual profit in a particular year.
A project is worth investing when the ROI is no less than the benchmark yield of the project.
(3) Rate of Return on Common Stock Holders’ Equity (ROE)
The ROE refers to the ratio between the annual after-tax net profit and the total capital of the project in normal productive years. If the annual after-tax net profit changes significantly during the project’s life cycle, the average annual after-tax net profit can be used instead of the annual after-tax net profit.
• Dynamic Indicators
Dynamic indicators refer to the indexes calculated with cash flows considering the time value of money. They include dynamic pay-back period, net present value, internal rate of return, LCOE, etc.
(1) Dynamic Pay-Back Period (DPP)
Compared with the static pay-back period presented above (SPP), the dynamic pay-back period (DPP) is the time needed to recover the total investment considering the time value of money, namely the time needed for accumulative net cash flows discounted by the benchmark yield to just cover the total investment during the project’s life cycle. Units of the dynamic pay-back period (DPP) are the same ones as the static pay-back period (SPP).
The time value of money is considered in the analysis of the dynamic pay-back period, overcoming the disadvantages of the static pay-back period. Therefore, the dynamic pay-back period is longer than the static pay-back period. However, the calculation considering the time value of money is more complex, and the cash flows after dynamic pay-back period are ignored. Dynamic pay-back period will be meaningless if the net cash flows are negative after the dynamic pay-back period, and some other indicators are needed for financial evaluation of the project.
(2) Net Present Value
The NPV is the accumulation of annual net cash flows discounted by the benchmark yield to the beginning of the project. The time value of money and the temporal distribution of cash flows in the project life cycle are considered in calculating NPV, which can reflect the profits and losses of the project by money. The NPV can be calculated as [
Annual net cash flows are the difference between the annual cash inflows and annual cash outflows
The NPV is a dynamic indicator that can reflect the profitability of the technical solution in the project life cycle. If the NPV is higher than 0, extra revenue can be obtained besides the profits that can meet the profitability requirement of the benchmark yield; if the NPV is equal to 0, the project can meet the profitability requirement of the benchmark yield and is financially feasible; if the NPV is lower than 0, the profit cannot meet the profitability requirement of the benchmark yield, and the project is not financially feasible.
(3) Internal Rate of Return (IRR)
The IRR is the discount rate when the total cash inflows and outflows at present are equal to each other (i.e., NPV = 0), which is the rate of return desired by investors. The IRR is also known as investors’ tolerance of inflation.
The IRR can be calculated as
When the IRR is equal to the average inflation rate during the project’s life cycle, the project will not generate profits but is still feasible; if the IRR is lower than the average inflation rate, the project may probably suffer losses; if the IRR is higher than the average inflation rate, the project may probably earn profits. This is the most practical and important significance of the IRR for a project, especially for projects with a long pay-back period.
(4) Levelized Cost of Electricity
The LCOE is an assessment criterion used to evaluate the cost of power generation technologies. It is related to capital cost, O&M cost, insurance cost, power output, and debt, etc. The LCOE is defined as the ratio between the overall cost and the total power output of project in its life cycle [
In the numerator of the equation above, the annual cost in each year is discounted. For the 0th year, the annual cost means the capital cost, which does not need to be discounted. Therefore, the equation above can be expressed as
Considering the investment, the power output and the time value of money, the LCOE can reflect the generating cost of the project. Therefore, the LCOE is an important criterion to assess the generating cost of a plant project.
A STCG consists of three parts: solar tower field, coal-fired power generation system, and salt-water/steam heat exchangers. Diagram of STCG plant can be found in
In
Reheated steam heated by the high-temperature solar thermal energy can further absorb energy in the reheater set in the boiler before reaching the target temperature. While feedwater is heated by using low-temperature solar thermal energy and later pumped into the boiler in order to absorb heat until reaching the target temperature.
Due to the fact that solar thermal energy plays an auxiliary role in the coupled system, the coal-fired power generation system should operate as stably as possible under optimized design conditions. Power plant should run based on grid demand, and the operation strategy should be adjusted according to the DNI. Under design point conditions, the solar tower field can provide enough thermal energy to generate 100 MWe under different solar multiples with different heliostat fields or thermal energy storages. When thermal energy from solar tower field and storage tank is sufficient to generate 100 MWe, the solar tower field will supply the thermal energy to the coal-fired power generation system, and the flow rate of the molten salt out of the hot tank will remain unchanged. If solar thermal energy is not sufficient to generate 100 MWe, the salt-water/steam heat exchangers will be cut off, so as to make the coal-fired power generation system run under its own operation conditions, with the solar tower field being in the state of heat accumulation and preservation.
Due to the fact that solar thermal energy plays a secondary role in the coupled system, solar thermal energy provided by the solar tower field will never exceed the demand of the reheat steam even under off-design conditions. Therefore, molten salt flow rate in the salt-water/steam heat exchangers does not need frequent adjustments under off-design operation conditions, and the solar tower field can run according to its own operation strategy.
Financial models presented in
Project investment mainly includes the investment in construction and operation. Construction investment consists of fixed assets investment, interest during construction, working capital, etc. The operation investment consists of fuel cost, O&M cost, insurance cost, payroll and benefits, interest during operation, and taxes.
For STCG plant project, the construction capital cost consists of the investment in solar tower field and coal-fired power generation system. The investments in turbines, regenerative system, condenser, and generator for the solar tower power plant are not considered, since solar tower thermal energy generates electricity by sharing the turbines, condenser, and generator with the coal-fired power plant, which can reduce the investment in solar tower system. The capital cost break-down of a solar tower aided coal-fired power plant project are shown in
As shown in
The capital cost of a 100 MWe solar tower power plant (with 15 h of thermal energy storage) is United States Dollar (USD) 900 million. The capital cost of power cycle accounts for about 11.3% of that of the solar tower power plant, with the rest included in the capital cost of the STCG plant project. Most of the capital cost of a solar tower field is due to the heliostat field and the receiver, which is larger than half of that of the solar tower power plant (
It can be seen from
The investment of the coal-fired power generation system in STCG is the same to that of a coal-fired power plant. The total capital cost of 1000 MWe coal-fired power plant is USD 496.9 million, and the estimated investment is shown in
In
Working capital is set to buy coal and equipment and to pay the employees by the end of the construction period. In this paper, the working capital is set to be 2% of the capital cost of a STCG plant project.
The operation investment consists of fuel costs, O&M costs, insurance costs, payroll and benefits, interest during operation and taxes, etc.
Daily O&M cost (including mirror cleaning, component replacement and maintenance, etc.) is necessary when running a STCG plant. Due to the lack of real STCG plants, the annual O&M cost (Equation (5)) has been set to be 2% of the capital cost of the STCG plant project [
Insurance purchasing for solar tower power plant is particularly important, so the annual insurance (Equation (6)) is set to be 0.5% of the capital cost of the STCG plant project [
The coal price changes in real time under the effect of the coal market. In this paper, the 5000 kcal coal is adopted to calculate the electricity price (Equation (1)) with the price index of electricity coal and the standard coal consumption rate [
Considering that this size of plant employs 200 workers with an average salary (including welfare) of USD 12,500/person-year.
Cost depreciation is based on the fixed assets. In this paper, the residual rate of fixed assets is seen as 0, and the depreciation period is 25 years.
Plant owner shall pay sales taxes and additional taxes (Equation (14)) for the revenue of electricity, and pay income taxes according to the profits of the project. According to the national standards, the corporate income tax rate is 25% and the value-added tax rate is 17%. Additional taxes include the urban maintenance and construction tax and the educational surtax, with the tax rates being 7% and 3% of the VAT, respectively.
According to the agreement between the project owner and the bank, the debt should be paid within the repayment period. The interest rate for long-term (longer than five years) debt is 4.9% [
The assumed STCG is located in Delingha, China, and the main designing parameters of this plant are shown in
A STCG plant generates electricity according to grid demand. The ratio between solar thermal energy and coal changes in real time according to the DNI and power demand. The hourly parameters—including grid demand, power output, coal consumption, DNI, and others—are needed for the techno-economic analysis of a STCG plant project in its life cycle.
The grid always dispatches electricity from coal-fired power plants according to the electrical load in its supply area. Coal-fired power plants always run under off-design conditions because of the large variation range of electricity dispatch. Annual electricity grid demand for 1000 MWe coal-fired power plant can be found in
The STCG plant in this paper is assumed to be located in Delingha, Gansu Province, China. DNI data for this location are taken from National Renewable Energy Laboratory (NREL) [
Due to the fact that there is only 1 year’s data for grid power dispatching but 15 years’ data for the DNI while power plant life cycle is set to 25 years, some data must be reused for life cycle analysis. Annual DNI data along the 15 years database significantly changed, then it was decided to consider only DNI data for the 10 years providing closer DNI to the annual average value.
Power plant models are built and verified using Ebsilon Professional [
Annual power output, annual coal consumption, and annual DNI of the STCG plant project are shown in
It can be seen from
Annual power output from solar thermal energy and coal depends on the annual DNI of every year. By the end of the year, these differences are not that obvious as it was observed in
Total coal consumption of the STCG plant is 34,547,047.5 t, lower than that of a coal-fired power plant with same power dispatching for its whole life cycle, which is translated into a CO_{2} emissions reduction of about 13,125,410 t (107.7 g/kWh in a whole life cycle). When calculating CO_{2} emission, a kind of real coal is used [
Due to the lack of real STCG plants, electricity prices for this kind of technology cannot be found. In this paper, existing electricity prices (for solar thermal power plants and coal-fired power plants) are taken in order to analyze the revenue of electricity of a STCG plant project.
For the electricity generated by solar thermal energy, the PPA price is 18.75 cents/kWh [
Due to the lack of electricity coal price index for the past 25 years, 2014 monthly price index has been taken as the annual price index to calculate the electricity price. Therefore, there is a small change on the electricity price, and the average electricity price for coal electricity is 5.558 cents/kWh.
A financial analysis is to study the financial issues about investment and revenue of a plant project, including capital cost, income, pay-back period, profit rate, etc.
Profitability is one of the most noteworthy indexes for an enterprise. The total cost of a STCG plant project is USD 5.03 billion, the total revenue of electricity sales is USD 9.41 billion, and the total profit is USD 3.06 billion.
The financial summary of 1000 MWe STCG plant project is shown in
The static pay-back period (SPP) of the plant project is 12.24 years, and all the cost can be recovered in 11 years (excluding the construction period). The return of the investment of the project is 8.89%, and the profit and tax investment ratio is 12.72%. The debt-to-assets ratio of the project reduces from 81.20% (at the beginning of operation period) to 2.06% (in the last year of the repayment period), indicating strong repaying ability and low financial risk of the project.
If the benchmark yield is assumed to be 8%, the dynamic pay-back period (DPP) of the project will be 23.45 years (including the construction period). The IRR after tax of the project is 8.68%, and the NPV after tax is USD 80.74 million. The IRR of the project is higher than the assumed benchmark yield with high NPV, indicating that the project is worth investing.
After calculation, the investment of this project is 1432 USD/kW, and the LCOE is 0.062 USD/kWh, lower than that (0.19 USD/kWh) reported from installed solar tower thermal power plants [
In [
As for the economic issue, the LCOEs of STG, CPG, and STCG are 0.19, 0.037, and 0.062 USD/kWh respectively. In addition, the LCOE of STCG is lower than the average LCOEs of STG and CPG, because the total investments of STG and CPG are higher than that of STCG when they can generate the same amount of electricity. Therefore, STCG is not simply putting solar tower power plant and coal-fired power plant together, but being more efficient and cost-efficient in electricity generation.
The static and dynamic indicators of a STCG plant project are affected by many factors, including area of the solar tower field, capital cost of the solar tower field, capital cost of the coal-fired power generation system, coal price, electricity price for solar thermal energy and coal, interest rate of debt, etc.
The solar tower field studied in the STCG can provide enough heat to generate 100 MWe, and the solar multiple is also based on this capacity. For different solar multiples (SM), the area of heliostat field and thermal energy storage capacity will change greatly. The investment of solar tower field accounts for over half of the total investment in the STCG plant project as it was discussed in
Coal-fired power generation is a proven technology with stable investment. Due to coal electricity price linkage policy discussed on
In
The sensitivity analysis above shows that the decrease of the capital cost of the solar tower field, coal price, and interest rate, or the increase of PPA price of solar electricity is beneficial for cost recovery and obtaining more profits. It is expected that as solar tower power generation technology becomes more developed, the capital cost of the solar tower field and PPA price of solar electricity will decrease gradually. The effect of the two factors on the main assessment indicators are opposite to each other. The capital cost of the solar tower field has greater effect on the main indicators than PPA price of solar electricity. This is due to the fact that capital cost of the solar tower field accounts for more than 60% (SM = 2.5) in the total capital cost a STCG plant project. Coal prices change according to the coal market, but have little effect on the project because of the coal–electricity price linkage policy. Although the interest rate of debt has less effect on the main indicators than the other three factors (i.e., the capital cost of the solar tower field, coal price, PPA price of solar electricity), it is an important factor that cannot be ignored. Therefore, low interest debt (3%) from the Asian Development Bank is beneficial to gaining more profits from a plant project [
Compared with CPG systems, STCG can enhance utilization efficiency while decreasing the generating cost of solar energy, reducing coal consumption and CO_{2} emissions, as well as decreasing the cost of carbon capture. However, the LCOE of STCG is higher than that of CPG for the same plant size due to the high investment of the solar tower field.
As it can be observed from
In order to promote STCG technology deployment and coal consumption reduction and its associated CO_{2} emissions, plant owners should get an allowance equivalent to the LCOE price difference between STCG and CPG. From the analysis above, when external influencing factors (coal price, solar tower field price, interest rate, or PPA of solar electricity) change on a range of ±30%, LCOE of STCG is always higher than that of CPG in a range of 1.67 to 2.71 cents USD/kWh. In order to reduce the distances between CPG and STCG technologies, partial or total price difference should be covered by the introduction of solar subsidies. Apart from the cost of electricity generation on STCG plants, there is another aspect to be considered, and it is about the CO_{2} emissions, for the case of the CPG reference plant, these are of 110 million tons per year, while for the case of STCG plant they are reduced to 97 million tons per year (calculated considering real coal [
In this paper, technical and economic characteristics of 1000 MWe STCG plant project are analyzed. Some conclusions about power output, financial conditions, and profits and losses of the project are as follows:
In the life cycle of a STCG plant project, 1.36 × 10^{5} GWh electricity can be generated with selling revenue of USD 9.4 billion. SPP and DPP of the project are 12.2 years and 23.5 years (including construction period) respectively. NPV of the project is USD 80.7 million, IRR of the project is 8.7%, and LCOE of the project is 0.062 USD/kWh, indicating a good profitability.
When solar multiple of STCG increases from 1.0 to 2.5, SPP and DPP of the project will be lengthened by 2.8 years and 9.5 years respectively, NPV and IRR will decrease by 77.5% and 31.2% respectively, and LCOE of the project will increase by 33.0%. The results indicate that the capital cost of the solar tower field is the key factor for more profits from the project.
The effect of the capital cost of the solar tower field, PPA price of solar electricity, coal price, and interest rate of debt on the main indicators (i.e., pay-back period, NPV, IRR) will be gradually decreased. In order to ensure project profits, it is better to develop technology for solar tower power generation and acquire low interest debt so as to offset the effect of the decrease of electricity price and the increase of coal price.
Solar tower aided coal-fired power plant (STCG plant) will increase the LCOE; and meanwhile will contribute on carbon capture price reduction of coal-fired power plant. In this case, an STCG plant will need an allowance of 1.99 cents USD/kWh as generation policy.
We are grateful for the Program for National Basic Research Program of China-973 Project (No. 2015CB251505), National Natural Science Foundation of China (No. 51106048), and National High-tech R&D Program of China (863 Program) (2012AA050604); Supported by the Fundamental Research Funds for the Central Universities is also highly appreciated. The authors would like to thank “Comunidad De Madrid” for its support to the ALCCONES project (S2013/MAE-2985) through the Program of R&D activities between research groups in Technologies 2103, co-financed by structural funds.
Yong Zhu conceived and built the models of related systems; Yong Zhu and Rongrong Zhai calculated and analyzed financial data together; Yong Zhu, Yongping Yang and Miguel Angel Reyes-Belmonte wrote the manuscript, Yong Zhu, Rongrong Zhai and Miguel Angel Reyes-Belmonte revised the manuscript; and Miguel Angel Reyes-Belmonte helped in English modification. All authors agreed on the final version of the manuscript.
The authors declare no conflict of interest.
Diagram of STCG.
Capital cost break-down of the solar tower aided coal-fired power plant project.
Annual hourly power dispatching of a coal-fired power plant from the grid company.
Annual power output and coal consumption of the STCG.
Monthly power output and coal consumption of STCG.
Accumulative after-tax net-cash-flow in the life cycle of 1000 MWe STCG.
Effect on LCOE, IRR, and NPV of STCG by solar multiple.
Effect on SPP and DPP of STCG by different factors.
Effect on NPV of a STCG plant by different factors.
Effect of different factors on IRR for a STCG plant.
Effect of different factors on LCOE for STCG plant.
Comparisons between LCOE of STCG and CPG.
Estimated investment of 100 MWe solar tower field.
Parameters | Units | Value | Proportion (%) |
---|---|---|---|
EPC Contractors Costs | Million USD | 751.8 | 94.12 |
Site Preparation | Million USD | 39.0 | 4.89 |
Heliostat Field | Million USD | 297.6 | 37.26 |
Receiver System | Million USD | 132.8 | 16.63 |
Tower | Million USD | 13.8 | 1.73 |
Thermal Energy Storage System | Million USD | 87.7 | 10.98 |
Balance of Plant | Million USD | 50.6 | 6.34 |
EPC Contractors Engineering | Million USD | 57.8 | 7.24 |
Contingencies | Million USD | 72.3 | 9.05 |
Owners Costs | Million USD | 47.0 | 5.88 |
In Total | Million USD | 798.7 | 100 |
Estimated investment of 1000 MWe coal-fired power generation system.
Parameters | Units | Value | Proportion (%) |
---|---|---|---|
Construction Cost of Project | Million USD | 101.3 | 20.39 |
Acquisition Cost of Equipment | Million USD | 228.2 | 45.92 |
Installation Cost of Project | Million USD | 109.5 | 22.04 |
Other Costs | Million USD | 57.9 | 11.65 |
Main designing parameters of STCG plant.
Systems | Parameters | Value |
---|---|---|
Solar Tower Field | Annual DNI (W/m^{2}) | 2385.1 |
Heliostat area (m^{2}) | 1.50 × 10^{6} | |
Mass flow rate of molten salt for heating water/steam(kg/s) | 580.7 | |
Solar Multiple | 2.5 | |
Inlet temperature (°C) | 301.8 | |
Outlet temperature (°C) | 565 | |
Thermal energy transferred to coal-fired power system (MW_{th}) | 243.1 | |
Coal-Fired Power System | Generating capacity (MW) | 1008.3 |
Parameters of main steam (MPa/°C/t/h) | 25.0/600/2733.4 | |
Parameters of reheated steam (MPa/°C/t/h) | 4.25/600/2273.4 | |
Press of condenser (kPa) | 5.6 | |
Coal consumption rate (g/kWh) | 236.4 |
Financial summary of 1000 MWe STCG.
Parameters | Units | Value | Remarks |
---|---|---|---|
Total Electricity Selling Income | Million USD | 9413.1 | |
Electricity Selling Income from Solar Energy | Million USD | 2641.3 | |
Electricity Selling Income from Coal | Million USD | 6771.8 | |
Total Costs | Million USD | 5028.9 | |
Investment during Construction Period | Million USD | 1378.1 | 2-year construction period |
Capital Cost | Million USD | 1295.6 | |
Interest during Construction Period | Million USD | 56.6 | |
Working Capital | Million USD | 25.9 | |
Investment during Operation Period | Million USD | 3650.7 | 25-year operation period, 15-year repayment period |
O&M Costs | Million USD | 647.8 | |
Insurance Costs | Million USD | 162.0 | |
Fuel Costs (Equation (7)) | Million USD | 2340.5 | |
Payroll & Benefit | Million USD | 62.5 | |
Interest during Operation Period (Equation (8)) | Million USD | 438.0 | |
Sales Tax and Additional Taxes | Million USD | 1322.6 | |
Total Profit | Million USD | 3061.6 | |
ROI (Equation (16)) | % | 8.89 | |
Profit and Tax Investment Ratio | % | 12.72 | |
ROE (Equation (17)) | % | 35.45 | |
IRR (Equation (21)) | % | 8.68 | After tax |
NPV (Equation (19)) | Million USD | 80.74 | After tax |
SPP (Equation (15)) | years | 12.24 | Including construction period, after tax |
DPP (Equation (18)) | years | 23.45 | Including construction period, after tax |
Debt to Assets Ratio | % | 81.20 | Before operation |
% | 2.06 | In the last year of the operation period | |
Investment per kW | USD/kW | 1432 | |
LCOE (Equations (22) and (23)) | USD/kWh | 0.062 |
Variation trends of main impact factors along with the changes of external factors
Impact Factors | SPP | DPP | NPV | IRR | |
---|---|---|---|---|---|
Capital cost of the solar tower field | Increase by 10% every time | +5.93% | +12.33% | −112.25% | −10.37% |
PPA price of solar electricity | −3.48% | −8.15% | +72.68% | +5.59% | |
Coal price | +3.32% | +7.66% | −66.2% | −5.15% | |
Interest rate of debt | +1.69% | +3.24% | −23.94% | −1.92% |