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For several decades, the international fusion community has had a goal of using a high quality fusion plasma for central station electrical power generation. Continued progress has been made toward the ultimate goal of high quality fusion plasmas with good confinement, mainly in tokamak experimental reactors. However, the commitment to begin construction of an engineering test reactor has not been made. One of the underlying reasons for delaying this large commitment is the lack of favorable economic projections for a fusion-generated cost of electricity¹.

Even though the cost of fusion fuel is very inexpensive, the plant capital cost is very expensive, which significantly increases the cost of electricity. The only new electric generating plants currently being purchased in the U.S. are gas turbine units, because they are relatively inexpensive, can be brought on line quickly, and are fueled with low-cost, abundant natural gas. Existing coal and fossil plants are being used to the maximum extent possible. New, capital-intensive, electric-generating plants are not being considered for the near future, even though there is a growing awareness of the resource depletion and environmental impact of using hydrocarbon fuels.

It is time to step back and reconsider all the products fusion can provide as an inexhaustible energy source. Additional products, other than generation of electrical power, may have more benefits and fewer risks, especially in the near term.

A complete set of fusion products was investigated to examine common categories of applications and markets served by these products. An evaluation methodology was developed to assess which applications might be attractive in terms of market potential, environmental considerations, economic impact, risk, and public perception. This methodology was used to assess the proposed applications. The results indicated that several applications might be promising products for the fusion energy source.

Fusion has many very attractive attributes. It is an unlimited, renewable energy source. Although it is a nuclear process, fusion can be safe with no long-lived radioactivity. It can create temperatures in excess of that in the Sun, high-energy neutrons, energetic particles, and a wide range of radiation products. It can dissociate dangerous chemical compounds or transmute long-lived radioactive fission products. It can create new chemical compounds, including abundant supplies of clean-burning hydrogen. And it can do all of this without any excess carbon dioxide and greenhouse effects. Fusion has the promise to deliver unlimited energy for humankind and to help clean up the problems created by our prior energy production and warfare by-products.

The US Department of Energy (DOE) funded a study within the Advanced Reactor Innovation and Evaluation Study (ARIES) project to assess other non-electric fusion applications to provide worthwhile new products. A methodology was developed to evaluate a wide range of products with a broad spectrum of attributes. Several fusion products are highlighted and recommended for consideration as potential fusion applications.

Figure 1 is the study task flow of the major steps in the assessment process. The first step in the process was to survey and catalogue the potential applications for fusion. Next, a decision analysis methodology was developed to evaluate very dissimilar product applications. This decision analysis methodology was validated with prior large, high-technology programs that have succeeded, failed, or were canceled. Following validation, the identified fusion applications were assessed with the methodology. Rank ordering of the alternate fusion products determined the most promising products to recommend for consideration.

To determine which applications could best be accomplished with fusion, the entire range of alternative product applications was examined. There have been prior studies that surveyed the opportunities for fusion to provide a range of applications and products. An EPRI-sponsored review² of the status and options for fusion in 1977 provided the starting point for this study. The General Atomics FAME Study³ examined the technical processes and economics of many alternate fusion applications. A more recent assessment⁴ of near-term commercial opportunities from long range fusion research was conducted by G. L. Kulcinski and was incorporated in our database. Specific data on various applications by their advocates have contributed to the understanding of the concepts, products, and the intended markets and marketing strategy.

The products identified include process heat, electricity, hydrogen fuels (and synthetic fuels), desalination, waste processing, ore reduction, transmutation of elements, detection/remote sensing, and space propulsion. Some of these product applications are unique to fusion, while others must economically compete with existing energy technologies. Some of the applications are independent of fusion confinement concepts. Others may effectively use a smaller fusion device or a confinement concept previously judged unsuitable for electrical power generation.

Table 1 is a compilation of the fusion products that may be obtained from the various forms of fusion energy. There is some similarity among products that may be produced with neutrons, charged particles, and radiation. But there are also unique products associated with each of the forms of fusion energy. For instance, hydrogen can be produced using neutrons, charged particles, and radiation. On the other hand, some alternate fusion confinement concepts would be better matched with certain products.

Use of DT fuel, and DD to a lesser extent, would be best matched to the neutron-related products in the first column of Table 1. Advanced fuels (such as D³He, p⁶Li, and p¹¹B) would best be suited for the charged particle applications shown in the second column. All fusing plasmas radiate a broad spectrum of radiation with a concentration in synchrotron radiation harmonics and X-rays. If the radiation products in the third column require a specific electromagnetic frequency, the plasma can be seeded with the appropriate impurity.

The next step in the assessment is to formulate an appropriate decision analysis methodology to assess and prioritize the market potential of the fusion products identified in Table 1. As noted in Figure 1, the initial step is to identify the critical attributes for a successful product that meets the perceived expectations of the customer and/or decision maker (performance, schedule or cost).

History has provided several examples of large projects that attempted to commercialize innovative, high-technology products, see Table 2. Some have succeeded; others have failed. But we can learn from both results. By examining these products, a set of attributes was developed to characterize those future products that might have a higher likelihood of success.

The projects in Table 2 were examined to determine the customers' expectations, if expectations were met, and if the project was successful in commercializing the product. Key features, benefits, and risks in each of these projects were identified and examined. From that examination, a set of attributes was selected to characterize the potential project and help guide the decision maker as to the benefits and risk in deciding to undertake (support) the project. Some of the attributes could be measured directly, such as product economics and schedule; but others are indirect values such as good will, strategic advantage, and environmental impact. Table 3 lists the general categories determined from the examination of the past projects and the detailed attributes adopted for this assessment. Weighting values were assigned to each of the attributes according to the perceived importance to the decision makers. Some of the long-term market trends suggested in the December 1997 Kyoto Climate Change Conference were incorporated into the weighting scheme.

The identification and ranking of these attributes appear to be rather arbitrary and judgmental, but much of the information is in the public record and literature. Even if the specific values are subject to interpretation, the observed trends can be of value. After all, we are using past data to predict the future acceptance of an evolving product.

The attributes are separated into several groups or factors. Market factors help determine how well the product can penetrate the proposed market (necessity for the product and the market potential) and the uniqueness of the product. Environmental factors examine how well the product will help preserve or restore the natural resources and the level of environmental impact (positive or negative). Economically, can the new product compete on a competitive basis and will it significantly improve the U.S. Gross National Product? Risk is assessed in regard to return on capital, maturity of the technology, and time to market. The public perception is measured in terms of perceived prestige arising from the product and public or governmental support.

After the attributes and weights are established, an additive utility theory methodology is used to qualitatively evaluate the proposed applications in terms of their market potential, environmental considerations, economic impact, risk, and public perception. Both multiplicative and additive utility functions⁵ were considered for the decision methodology. The multiplicative utility function was deemed to be inappropriate in this assessment because a score of zero in any single attribute would disqualify the product from further consideration. This might be very appropriate when all the concepts under consideration are well developed. In that case, a concept should be disqualified if it has a fatal flaw or cannot reach a mandatory threshold value. But at this stage in the definition of the fusion products, a score of zero should not eliminate a product from consideration because it might be capable of improving that particular attribute. An additive utility function will penalize the product with a zero score, but not eliminate it from further consideration. Therefore, the decision analysis methodology was determined to be:

SCORE = S (Attribute Weight) x (Attribute Value)

Weights = 1 to 3; Values = -5 to +5

The attribute values for each product were established to be on a scale of -5 (for the least attractive attribute) to +5 (for the most attractive attribute). The use of positive and negative attribute values is arbitrary, but this positive and negative value approach helps the evaluator more easily judge positive and negative attributes. Each of the attributes was assigned a qualitative description of the least attractive, neutrally attractive, and most attractive attributes to help reduce the bias of the evaluator. This methodology was tested with the prior projects listed in Table 2, and the results correlated well with historical data. Thus, the methodology was validated for use on the proposed fusion products.

A set of candidate fusion products was selected for assessment from those contained in Table 1 as representative of the entire spectrum of options. The choice of a fusion confinement concept is immaterial in assessing many of the attributes of the product, especially the market factors, the public perception factors, and many of the environmental factors.

But when the risk factors of investment, technology maturity, and time to market are considered, a confinement concept must be mated with the product to complete the assessment. The intent was to evaluate a complete range of possible fusion products. However, only a limited number of the products and confinement concepts that were most likely to yield a competitive and successful product were evaluated.

Table 4 illustrates the selected fusion products (identified in the first row) and the assumptions and descriptions used to describe and evaluate those products. The second row lists the key assumptions for each product, such as confinement concept and processes assumed. The left-hand column lists the attributes that are addressed for each product. The associated attribute weighting factors are shown in the second column. The individual attribute values for each product are shown in the corresponding spreadsheet cells.

This evaluation process was first completed by the author. Next, it was reviewed by a small assessment group from the ARIES team and then by the entire ARIES project team and some fusion experts from the University of Wisconsin Fusion Technology Institute. Meanwhile, several product advocates critiqued the methodology and assessment. Comments from all these sources were integrated into the preliminary assessment data shown in Table 4. The weighted sum scores for each product are shown on the bottom row of the table. A rank-ordered graph of these scores is shown and discussed in the next section.

Using the adopted decision methodology and the weighting scheme of the criteria attributes, the weighted sum of the products in Table 4 indicates the relative attractiveness of the considered products in regard to the current US market. This data is pictorially presented in Figure 2.

The most favored fusion application was determined to be production of hydrogen fuels, closely followed by transmutation of nuclear wastes, dissociation of chemical compounds, electricity production, and space propulsion. These applications are recommended for consideration as promising fusion products. Electricity production remains an application that is still highly favored. There is significant incentive to continue to develop fusion to generate electricity, but the competitive incentive remains to be credibly postulated and, ultimately, demonstrated.

To understand why these products are evaluated as such, one has to critically examine the attributes of the chosen products and weighting methodology used. Only two of the products were rated at the maximum positive value of +5 for a single attribute, and none were scored at the maximum negative value. Most individual scores were in the middle of the range. The maximum weighting sum for any product was only 40% of the highest possible score.

The products that scored well in the weighted sums had several individual attributes that scored relatively high. These products were generally perceived to have shorter developmental times, more mature technologies, and good public support. They also required less investment capital to reach the market. Conversely, the breeder application was rated as the least attractive and was not viewed as being currently needed in the US marketplace — a large investment would be required, a long time to market is foreseen, and an immature technology is assumed.

To help understand the process, the high score for each attribute is highlighted as a gray cell in Table 1. The production of hydrogen scored well because it captured the highest scores in 7 of the 12 attributes. It is judged a highly necessary product, with significant market potential. It helps to prolong critical petroleum resources while greatly improving the environment by not releasing any CO₂ when used. Since it will likely become a large-scale product, it will improve the U.S. Gross National Product. Since it is substantially helping the resources and the environment, it would generate a lot of public support and prestige. On the negative side, it is not viewed as being overly competitive at present, would require a lot of investment capital, needs to be technically developed, and has significant time to market. Nevertheless, the larger positives outweigh the negatives; making hydrogen (or synfuel) production the highest scoring fusion product. Production of hydrogen with fusion has been proposed with several different processes.

The transmution of nuclear wastes and disassociation of chemical wastes rated closely as the second and third choice, respectively. They would likely be produced by entirely different fusion confinement processes. Each is highly rated for different reasons.

Transmutation of nuclear wastes would likely be a compact device with excellent confinement. The nuclear wastes would be in containers, housed in the reactor, exposed to the neutrons for long periods of time. This product is rather a fusion-unique product with significant market potential, especially with appeal to cleaning up the nuclear waste and not despoiling the environment. The neutral attributes are helping with resources, competitive nuclear disposal costs compared with other disposal options, helping the GNP, prestige, and public support. The scores of some of these attributes could be increased, but it might carry a risk to highly publicize those attributes. The negative aspects are not highly negative because it is viewed as being a compact device not requiring a huge capital investment, has a reasonable technical maturity, and would require a nominal time to market. The high marks for this product coupled with moderate negative scores yield a highly-rated product of transmutation of nuclear wastes.

The dissociation of both industrial and warfare chemical wastes would likely be best processed with a less efficient fusion confinement device, such as a mirror or tandem mirror. Sometimes the application of these devices in this manner is referred to as the "plasma torch." The chemical wastes are introduced into the exhaust region of the plasma where they are heated to the point of dissociation into individual elements. Various techniques would separate the element streams for further chemical processing and recycling. This product scored highly for environmental improvement, low investment (small device), and high public support (environmental impact). It does not significantly help the natural resources. There are nominal scores in necessity, uniqueness, market potential, and prestige, which does not help or hinder this concept. Because it is a small device, the negatives associated with competitive price, technical maturity, time to market, and investment are not dominant. In fact, this product scored highest of all products in this investment category; all other products were viewed as more negative.

Interestingly, the two electrical generating plants (the large, central station plant and the smaller, local generating plant) are judged to have nearly identical scores by trading off the lower cost of electricity for the larger plant versus the smaller investment, shorter technical maturity, shorter time to market, and higher public support of the smaller plant. These two electrical generating products have only one of the highest rated attributes between them, yet because they scored well in almost all categories and had only a limited number of negative scores, they scored among the higher-rated products.

The last product of notable mention is fusion space propulsion. The uniqueness of having a virtually unlimited or truly unlimited fuel supply, depending if fuel is harvested during flight, is the most highly-rated attribute. There is a spectrum of options for the key parameters of thrust and specific impulse (I_sp) shown in Table 5.

The high thrust option probably could not compete with other low-tech, chemical propulsion options currently available, mainly for earth and lunar transfer missions. The ultra-high specific impulse option would be excellent for a very deep space probe or stellar rendezvous, but the time frame for a reasonable market is too distant to consider. The moderate-to-small thrust/very high specific impulse option is a very good candidate for planetary explorations to achieve much shorter flight times for both unmanned and manned missions. As stated above, fusion space propulsion is a unique product with unlimited fuel capacity that could continue to provide thrust and electrical power throughout the flight (accelerating for half the flight and decelerating the other half). Considering the alternatives that would have to carry significant amounts of fuel or relinquish the shorter mission goals, this might be the most competitive product for fusion. Since this might produce a "relatively" short flight time to the outer planets, this would suggest high prestige and public support. The negative aspects remain the investment costs, technical maturity, and time to market.

The remaining fusion products had few high attribute scores to elevate their position. Because they are generally related to smaller fusion devices, they did not have many large negative scores. So they all scored well above the neutral or zero score. Thus they all should be retained for further examination and concept improvement.

The fusion-fission breeder has many negative attributes. There is no large market for fission fuel at this time; hence, the necessity for the product is not positive and the market potential is low. The concept would be a large plant, requiring significant capital investment, with a long time to market. The few small benefits presently cannot outweigh the larger, negative aspects of the fusion-fission breeder concept.

A decision analysis methodology has been developed to assess the attractiveness of alternate fusion products. In addition, this methodology tool can be modified to assess the merits of alternate fusion confinement approaches in different product applications.

The results from the decision analysis methodology would suggest that it might be beneficial to further investigate and develop the higher ranked products such as production of hydrogen or synfuels, transmutation of nuclear waste, dissociation of hazardous chemical compounds, detection and remote sensing, and space propulsion for interplanetary transfer and deep-space probes. Some ofthe alternate fusion confinement schemes and advanced fuels may be well suited to these applications.

This analysis should not be considered as a final evaluation result; rather it is intended to be used as a tool to assess the relative merits of each product. It helps highlight where improvements could be made to enhance the value, merit, and perception of each product. As fusion technology advances, product developments mature, investment strategies change, and public needs evolve, this tool could be altered to reassess the attractiveness of the alternate fusion products.

This research was sponsored by the US Department of Energy under UCSD Purchase Order 10087872.